ORCID Profile
0000-0002-3743-3171
Current Organisation
Edge Hill University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Frontiers Media SA
Date: 19-02-2021
Abstract: Introduction: Sodium bicarbonate (NaHCO 3 ) is a well-established nutritional ergogenic aid that is typically ingested as a beverage or consumed in gelatine capsules. While capsules may delay the release of NaHCO 3 and reduce gastrointestinal (GI) side effects compared with a beverage, it is currently unclear whether the capsule size may influence acid–base responses and GI symptoms following supplementation. Aim: This study aims to determine the effects of NaHCO 3 supplementation, administered in capsules of different sizes, on acid–base responses, GI symptoms, and palatability. Methods: Ten healthy male subjects (mean ± SD: age 20 ± 2 years height 1.80 ± 0.09 m weight 78.0 ± 11.9 kg) underwent three testing sessions whereby 0.3 g NaHCO 3 /kg of body mass was consumed in either small (size 3), medium (size 0), or large (size 000) capsules. Capillary blood s les were procured pre-ingestion and every 10 min post-ingestion for 180 min. Blood s les were analyzed using a radiometer (Radiometer ABL800, Denmark) to determine blood bicarbonate concentration ([ HCO 3 - ]) and potential hydrogen (pH). GI symptoms were measured using a questionnaire at the same timepoints, whereas palatability was recorded pre-consumption. Results: Capsule size had a significant effect on lag time (the time [ HCO 3 - ] changed, T lag ) and the timing of peak blood [ HCO 3 - ] ( T max ). Bicarbonate T lag was significantly higher in the large-sized (28 ± 4 min) compared with the small-sized (13 ± 2 min) capsules ( P = 0.009). Similarly, T max was significantly lower in the small capsule (94 ± 24 min) compared with both the medium-sized (141 ± 27 min P & 0.001) and the large-sized (121 ± 29 min P & 0.001) capsules. The GI symptom scores were similar for small-sized (3 ± 3 AU), medium-sized (5 ± 3 AU), and large-sized (3 ± 3 AU) capsules, with no significant difference between symptom scores ( F = 1.3, P = 0.310). Similarly, capsule size had no effect on palatability ( F = 0.8, P = 0.409), with similar scores between different capsule sizes. Conclusion: Small capsule sizes led to quicker T lag and T max of blood [ HCO 3 - ] concentration compared to medium and large capsules, suggesting that in iduals could supplement NaHCO 3 in smaller capsules if they aim to increase extracellular buffering capacity more quickly.
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.APERGO.2012.09.005
Abstract: This study aimed to assess the effect of portable gas analysis system carriage on energy expenditure (EE) during incremental treadmill running. Eight males (Mean ± SD) age 25.0 ± 9.47 y, body mass 78.5 ± 8.39 kg, completed an experimental trial (PT) during which they wore the system in a chest harness and a control trial (CT) when the system was externally supported. Each protocol consisted of 4 min stages at speeds of 0, 4, 7, 10, 12, 14 km h(-1). Increments continued until volitional exhaustion. The EE was greater (3.95 and 7.02% at 7 and 14 km h(-1) respectively) during PT (p < 0.05) but no significant differences were observed during standing, walking or VO(2max.) (4.10 ± 0.53, and 4.28 ± 0.75 l min(-1) for CT and PT respectively), HR or RPE. Portable gas analysis systems therefore only increase EE when running sub-maximally, but VO(2max) is unaffected, suggesting that using portable gas analysis systems in field-based situations is appropriate for maximal aerobic capacity measurement, but the effects of prolonged use on EE remains unclear.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2016
Publisher: BMJ
Date: 16-11-2020
DOI: 10.1136/BJSPORTS-2020-102859
Abstract: Investigate the incidence and burden of injuries by age group in youth football (soccer) academy players during four consecutive seasons. All injuries that caused time-loss or required medical attention (as per consensus definitions) were prospectively recorded in 551 youth football players from under 9 years to under 19 years. Injury incidence (II) and burden (IB) were calculated as number of injuries per squad season (s-s), as well as for type, location and age groups. A total of 2204 injuries were recorded. 40% (n=882) required medical attention and 60% (n=1322) caused time-loss. The total time-loss was 25 034 days. A squad of 25 players sustained an average of 30 time-loss injuries (TLI) per s-s with an IB of 574 days lost per s-s. Compared with the other age groups, U-16 players had the highest TLI incidence per s-s (95% CI lower-upper): II= 59 (52 to 67) IB=992 days (963 to 1022) and U-18 players had the greatest burden per s-s: II= 42.1 (36.1 to 49.1) IB= 1408 days (1373 to 1444). Across the cohort of players, contusions (II=7.7/s-s), sprains (II=4.9/s-s) and growth-related injuries (II=4.3/s-s) were the most common TLI. Meniscus/cartilage injuries had the greatest injury severity (95% CI lower-upper): II= 0.4 (0.3 to 0.7), IB= 73 days (22 to 181). The burden (95% CI lower-upper) of physeal fractures (II= 0.8 0.6 to 1.2 IB= 58 days 33 to 78) was double than non-physeal fractures. At this youth football academy, each squad of 25 players averaged 30 injuries per season which resulted in 574 days lost. The highest incidence of TLI occurred in under-16 players, while the highest IB occurred in under-18 players.
Publisher: Informa UK Limited
Date: 22-01-2019
DOI: 10.1080/02640414.2019.1568173
Abstract: This study investigated the effects of two separate doses of sodium bicarbonate (NaHCO
Publisher: Springer Science and Business Media LLC
Date: 27-01-2023
DOI: 10.1007/S00421-023-05140-4
Abstract: Sodium bicarbonate (SB) supplementation can improve exercise performance, but few studies consider how effective it is in female athletes. The aim of the study was to establish the effect of in idually timed pre-exercise SB ingestion on 2 km rowing time trial (TT) performance in female athletes. Eleven female CrossFit® athletes (mean ± SD age, 29 y ± 4 y, body mass, 64.5 kg ± 7.1 kg, height, 1.7 m ± 0.09 m, peak oxygen uptake [VO 2peak ], 53.8 ± 5.7 mL·kg −1∙ min −1 ). An initial trial identified in idual time-to-peak [HCO 3 − ] following enteric-coated 0.3 g·kg −1 BM SB ingestion . Participants then completed a 2 km TT familiarisation followed by a placebo (PLA) or SB trial, using a randomised cross-over design. The ingestion of SB improved rowing performance (514.3 ± 44.6 s) compared to the PLA (529.9 ± 45.4 s) and FAM trials (522.2 ± 43.1 s) ( p = 0.001, p η 2 = 0.53) which represents a 2.24% improvement compared to the PLA. In idual time-to-peak alkalosis occurred 102.3 ± 22.1 min after ingestion (range 75–150 min) and resulted in increased blood [HCO 3- ] of 5.5 ± 1.5 mmol⋅L −1 (range = 3.8–7.9 mmol⋅L −1 ). The change in blood [HCO 3- ] was significantly correlated with the performance improvement between PLA and SB trials ( r = 0.68, p = 0.020). Ingesting a 0.3 g·kg −1 BM dose of enteric-coated SB improves 2 km rowing performance in female athletes. The improvement is directly related to the extracellular buffering capacity even when blood [HCO 3- ] does not change ≥ 5.0 mmol⋅L −1 .
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2009
Publisher: Georg Thieme Verlag KG
Date: 08-2004
Abstract: Participants in the sport of adventure racing often choose to go without sleep for a period of greater than 24 h while partaking in prolonged submaximal exercise. This study examined the effect of 30 h of sleep deprivation and intermittent physical exercise, on the cardiorespiratory markers of submaximal exercise in six subjects. Six subjects with the following physical characteristics participated in the study (mean +/- SD): age 22 +/- 0.3 years, height 180 +/- 5 cm, body mass: 77 +/- 5 kg, VO2peak 44 +/- 5 ml. kg (-1). min (-1). Three subjects engaged in normal sedentary activities while three others cycled on a cycle ergometer at 50 % VO2peak for 20 min out of every two hours during thirty hours of sleep deprivation. One week later sleep deprivation was repeated with a cross over of subjects. Every four hours, subjects completed assessments of cardiorespiratory function during 50 % VO2peak cycling. A 3 x 8 repeated measures ANOVA revealed a significantly lower heart rate with sleep deprivation (p 0.05) on respiratory gas exchange variables. Neither sleep deprivation, nor a combination of sleep deprivation and five hours of moderate intensity cycling, appear to be limiting factors to the physiological capacity to perform submaximal exercise.
Publisher: Informa UK Limited
Date: 09-03-2021
Publisher: Informa UK Limited
Date: 21-08-2017
DOI: 10.1080/15438627.2017.1365294
Abstract: Fifty-nine men completed a VO
Publisher: Elsevier BV
Date: 08-2001
Publisher: Springer Science and Business Media LLC
Date: 22-02-2017
DOI: 10.1007/S40279-017-0699-X
Abstract: Current evidence suggests sodium bicarbonate (NaHCO This study aimed to evaluate the degree of reproducibility of both time to peak (TTP) and absolute change in blood pH, HCO Male participants (n = 15) with backgrounds in rugby, football or sprinting completed six randomised treatments entailing ingestion of two doses of 0.2 g·kg HCO Our results indicate that both TTP and absolute change in HCO
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2015
Publisher: Springer Science and Business Media LLC
Date: 23-10-2022
DOI: 10.1007/S40279-021-01575-X
Abstract: Extracellular buffering supplements [sodium bicarbonate (SB), sodium citrate (SC), sodium/calcium lactate (SL/CL)] are ergogenic supplements, although questions remain about factors which may modify their effect. To quantify the main effect of extracellular buffering agents on exercise outcomes, and to investigate the influence of potential moderators on this effect using a systematic review and meta-analytic approach. This study was designed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Three databases were searched for articles that were screened according to inclusion/exclusion criteria. Bayesian hierarchical meta-analysis and meta-regression models were used to investigate pooled effects of supplementation and moderating effects of a range of factors on exercise and biomarker responses. 189 articles with 2019 participants were included, 158 involving SB supplementation, 30 with SC, and seven with CL/SL four studies provided a combination of buffering supplements together. Supplementation led to a mean estimated increase in blood bicarbonate of + 5.2 mmol L Extracellular buffering supplements generate large increases in blood bicarbonate concentration leading to positive overall effects on exercise, with sodium bicarbonate being most effective. Evidence for several group-level moderating factors were identified. These data can guide an athlete's decision as to whether supplementation with buffering agents might be beneficial for their specific aims.
Publisher: Springer Science and Business Media LLC
Date: 17-01-2018
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2010
Publisher: Frontiers Media SA
Date: 22-09-2016
Publisher: SAGE Publications
Date: 03-2021
Abstract: The association between injury risk and skeletal maturity in youth soccer has received little attention. To prospectively investigate injury patterns and incidence in relation to skeletal maturity in elite youth academy soccer players and to determine the injury risks associated with the skeletal maturity status, both overall and to the lower limb apophysis. Descriptive epidemiology study. All injuries that required medical attention and led to time loss were recorded prospectively during 4 consecutive seasons in 283 unique soccer players from U-13 (12 years of age) to U-19 (18 years). The skeletal age (SA) was assessed in 454 player-seasons using the Fels method, and skeletal maturity status (SA minus chronological age) was classified as follows: late, SA year behind chronological age normal, SA ±1 year of chronological age early, SA year ahead of chronological age and mature, SA = 18 years. An adjusted Cox regression model was used to analyze the injury risk. A total of 1565 injuries were recorded 60% were time-loss injuries, resulting in 17,772 days lost. Adjusted injury-free survival analysis showed a significantly greater hazard ratio (HR) for different status of skeletal maturity: early vs normal (HR = 1.26 [95% CI, 1.11-1.42] P .001) and early vs mature (HR = 1.35 [95% CI, 1.17-1.56] P .001). Players who were skeletally mature at the wrist had a substantially decreased risk of lower extremity apophyseal injuries (by 45%-61%) compared with late ( P .05), normal ( P .05), and early ( P .001) maturers. Musculoskeletal injury patterns and injury risks varied depending on the players’ skeletal maturity status. Early maturers had the greatest overall adjusted injury risk. Players who were already skeletally mature at the wrist had the lowest risk of lower extremity apophyseal injuries but were still vulnerable for hip and pelvis apophyseal injuries.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2015
Publisher: SAGE Publications
Date: 02-1999
DOI: 10.2466/PMS.1999.88.1.188
Abstract: The aim of this study was to determine the aerobic fitness of Tasmanian secondary school children aged 11 to 16 years. A random s le of Tasmanian secondary schools was undertaken and then all children within each grade in the school were tested. In all, 6061 children undertook the test, 2981 boys and 3080 girls. The test consisted of a 20-m shuttle run in time to a prerecorded timing sequence. Each child had to complete as many shuttles as possible while staying in time with the beep. The test ceased for each child when they could no longer reach the marker at the same time or prior to the generated sound. The analyses indicated that there was a significant main effect of grade and sex. Children in lower grades completed fewer shuttles than the children in higher grades, and boys completed more shuttles than girls within each grade. Students in government-run schools completed significantly fewer shuttles than their nongovernment school counterparts ( p .0001). On a regional basis, there were no differences between children in the north and south of Tasmania as each completed 5.7 ± 0.1 shuttles but children in the northwestern region of the state completed a significantly greater number of shuttles. An estimation of mean V̇O 2 max based upon shuttle stages completed indicated that these values ranged from a low of 40.6 ml · kg −1 · min. −1 in 13-, 14-, and 15-yr.-old girls to a high of 50.4 ml · kg −1 · min. −1 in 16-yr.-old boys. Comparisons between this and similar data suggest that Tasmanian school children are less fit than their counterparts around the world. In conclusion, normative data for Tasmanian school children were developed and distributed to schools throughout Tasmania for use by teachers in evaluating the fitness of their students.
Publisher: Informa UK Limited
Date: 08-10-2019
DOI: 10.1080/15438627.2018.1523168
Abstract: Eccentric hamstring strength is an aetiological risk factor for soccer injury. The temporal pattern of recovery post-exercise is critical in injury management. 18 male professional soccer players completed baseline assessments of eccentric hamstring strength at isokinetic speeds of 60, 150 and 300°· s
Publisher: Georg Thieme Verlag KG
Date: 04-2006
Abstract: The present investigation examined the relationship between the running velocity at the lactate turnpoint (vLTP) and the time at which VO2max can be sustained (TVO2max) during a continuous run to exhaustion at the minimal running velocity that elicits VO2max (vVO2max). Seven moderately-trained endurance runners undertook three tests on a treadmill. The first test was to determine vVO2max the second to determine the time to exhaustion during a constant velocity run at vVO2max (Tlim vVO2max) and TVO2max and the third to determine the vLTP. Pearson's correlation coefficient was used to determine the association between the vLTP (%vVO2max i.e. the relative vLTP) and TVO2max, and between other selected physiological variables. Correlations between the relative vLTP and TVO2max, expressed as a percentage of T(lim vVO2max (the relative TVO2max r=0.82), and between TVO2max and Tlim vVO2max (r=0.89), were significant at the p<0.05 level. All other correlations between selected measured physiological variables were found to be statistically insignificant. The main finding of this present study is that the relative vLTP demonstrated a significant positive correlation with the relative TVO2max. The physiological mechanism by which the lactate turnpoint may influence the relative TVO2max has not been elucidated, but may be due to a combination of decreasing the time to attain VO2max and increasing Tlim vVO2max. The present investigation has demonstrated that the lactate turnpoint may influence the relative time at which VO2max can be sustained during a continuous run to exhaustion at vVO2max, although further research is required to substantiate these findings.
Publisher: Human Kinetics
Date: 2020
Abstract: Enteric-formulated capsules can mitigate gastrointestinal (GI) side effects following sodium bicarbonate (NaHCO 3 ) ingestion however, it remains unclear how encapsulation alters postingestion symptoms and acid–base balance. The current study aimed to identify the optimal ingestion form to mitigate GI distress following NaHCO 3 ingestion. Trained males (n = 14) ingested 300 mg/kg body mass of NaHCO 3 in gelatin (GEL), delayed-release (DEL), and enteric-coated (ENT) capsules or a placebo in a randomized cross-over design. Blood bicarbonate anion concentration, potential hydrogen, and GI symptoms were measured pre- and postingestion for 3 hr. Fewer GI symptoms were reported with ENT NaHCO 3 than with GEL ( p = .012), but not with DEL ( p = .106) in the postingestion phase. Symptom severity decreased with DEL (4.6 ± 2.8 arbitrary units) compared with GEL (7.0 ± 2.6 arbitrary units p = .001) and was lower with ENT (2.8 ± 1.9 arbitrary units) compared with both GEL ( p .0005) and DEL ( p = .044) NaHCO 3 . Blood bicarbonate anion concentration increased in all NaHCO 3 conditions compared with the placebo ( p .0005), although this was lower with ENT than with GEL ( p = .001) and DEL ( p .0005) NaHCO 3 . Changes in blood potential hydrogen were reduced with ENT compared with GEL ( p = .047) and DEL ( p = .047) NaHCO 3 , with no other differences between the conditions. Ingestion of ENT NaHCO 3 attenuates GI disturbances for up to 3 hr postingestion. Therefore, ENT ingestion forms may be favorable for those who report GI disturbances with NaHCO 3 supplementation or for those who have previously been deterred from its use altogether.
Publisher: Springer Science and Business Media LLC
Date: 24-01-2019
Publisher: Informa UK Limited
Date: 2013
DOI: 10.1080/15438627.2012.738442
Abstract: This study examined the effects of high and low glycemic index (GI) carbohydrate preexercise meals (2.5 g CHO/kg body mass) on cycle performance in untrained females. Ten females, cycled at 60% VO(2 max) to exhaustion, on two occasions. After fasting, subjects ate an isocaloric, high glycemic index (HGI)/low glycemic index (LGI) meal in a random order. Blood s les were taken at rest ostprandial/during and after exercise and blood glucose and lactate were measured. Ingestion of the LGI meal resulted in a performance time of 67.4 ± 8.4 min versus an HGI time of 48.9 ± 10.0 min (p = 0.02). Fifteen minutes after the HGI meal there was a significant increase (p < 0.001) in glucose levels, which was not seen in the LGI trial. Twenty minutes into the HGI exercise trial, there was a large decline in blood glucose concentration beyond resting levels. Based on this work, we found that untrained female participants should utilize LGI meals preexercise for endurance activities rather than HGI meals.
Publisher: Frontiers Media SA
Date: 11-11-2016
Publisher: Informa UK Limited
Date: 12-2003
DOI: 10.1080/714041039
Abstract: Light to moderate exercise has been associated with an increase in immune function and reduced risk of infectious diseases. Conversely, heavy exercise has been implicated in suppression of many immune parameters and a concomitant increased risk of infectious diseases. Infections can result in lost training time and negatively affect the performance of the elite athlete. Exercising during an infection can also increase the risk of secondary complications, such as viral myocarditis and post-viral fatigue syndrome. In addition to immunosuppression, other factors responsible for increased infection rates among athletes are close bodily contact with other people during training and competition, and environmental factors during the pursuit of sporting activities that increase exposure to pathogens. Although there is a generally higher risk of infection among athletes compared to the general population, some sports are associated with a particularly high risk for certain infections. These are skin infections in rugby and wrestling, infections of the foot in long-distance runners, and ear infections in those involved in water sports. Upper respiratory tract infections are the most frequently reported disability among all athletes and are the cause of more lost training days than all other infections put together. Transmission of blood-borne pathogens, although very uncommon in the athletic setting, are the cause of the most serious infections an athlete may develop. When considering the negative impact of infections on performance, it seems prudent that athletes use interventions to decrease the immunosuppressive effects of heavy exercise, and to minimize exposure to pathogens as far as practically possible. Management of the infected athlete is especially important if there is to be a speedy return to full training, and if the incidence of a relapse or secondary complications are to be minimized.
Publisher: Informa UK Limited
Date: 09-2013
Publisher: Informa UK Limited
Date: 31-03-2015
DOI: 10.1080/02640414.2015.1025235
Abstract: The effects of sodium phosphate and caffeine supplementation were assessed on repeated-sprint ability. Using a randomised, double-blind, Latin-square design, 12 female, team-sport players participated in four trials: (1) sodium phosphate and caffeine, (2) sodium phosphate and placebo (for caffeine), (3) caffeine and placebo (for sodium phosphate) and (4) placebo (for sodium phosphate and caffeine), with ~21 days separating each trial. After each trial, participants performed a simulated team-game circuit (4 × 15 min quarters) with 6 × 20-m repeated-sprints performed once before (Set 1), at half-time (Set 2), and after end (Set 3). Total sprint times were faster after sodium phosphate and caffeine supplementation compared with placebo (Set 1: P = 0.003 Set 2: d = -0.51 Set 3: P < 0.001 overall: P = 0.020), caffeine (Set 3: P = 0.004 overall: P = 0.033) and sodium phosphate (Set 3: d = -0.67). Furthermore, total sprint times were faster after sodium phosphate supplementation compared with placebo (Set 1: d = -0.52 Set 3: d = -0.58). Best sprint results were faster after sodium phosphate and caffeine supplementation compared with placebo (Set 3: P = 0.007, d = -0.90) and caffeine (Set 3: P = 0.024, d = -0.73). Best sprint times were also faster after sodium phosphate supplementation compared with placebo (d = -0.54 to -0.61 for all sets). Sodium phosphate and combined sodium phosphate and caffeine loading improved repeated-sprint ability.
Publisher: Springer Science and Business Media LLC
Date: 21-09-2017
Publisher: Georg Thieme Verlag KG
Date: 09-2007
Abstract: The aim of this work was to examine the association between the polymorphisms in nuclear respiratory factor (NRF2) gene and endurance capacity measured prior to and after an 18-wk endurance training program in young Chinese men. The phenotypes measured were running economy (RE) and VO(2max). The RE was determined by measuring submaximal VO(2) for 5 min at a constant running speed of 12 km x h (-1) and VO(2max) was measured during an incremental test to volitional exhaustion. Genomic DNA was extracted from white cells of peripheral blood and the genotypes were examined in SNPrs12594956, rs8031031 and rs7181866 by PCR-RFLP. Genotype distributions were in Hardy-Weinberg equilibrium at three loci, and linkage disequilibrium was observed (LD D' = 1 and r (2) = 0.903) between rs8031031 and rs7181866. The VO(2max) was associated with rs12594956 at baseline while the training response of VO(2) at RE, was associated with rs12594956, rs8031031 and rs7181866. When the three SNPs were considered together, those carrying the ATG haplotype had 57.5 % higher training response in VO(2) at RE (p = 0.006) than non-carriers. In conclusion, polymorphisms in NRF2 gene may explain some of the between-person variance in endurance capacity.
Publisher: Informa UK Limited
Date: 07-2006
DOI: 10.1080/15438620600651132
Abstract: It is widely acknowledged that the importance of sound theoretical guidance is essential to any academic discipline. A common recommendation within the adherence literature related to sport injury rehabilitation has been the need to establish clear theoretical frameworks to guide research and practice. As such, an increasing amount of literature has employed conceptual models that include protection motivation theory, health action process approach, cognitive appraisal models, and attribution theory. Therefore, the purpose of this review is to critically evaluate these contemporary theoretical approaches that have been utilised within the sport injury rehabilitation adherence literature. Alongside this, practical implications emerging from this research base are outlined and future recommendations are suggested that may be of benefit to sports medicine practitioners and researchers alike.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2009
Publisher: Springer Science and Business Media LLC
Date: 05-2019
Publisher: Springer Science and Business Media LLC
Date: 05-07-2016
Publisher: Informa UK Limited
Date: 2009
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2012
Publisher: Informa UK Limited
Date: 04-06-2020
DOI: 10.1080/15438627.2019.1627546
Abstract: This study aimed to assess the thermoregulatory and cardiovascular responses of WC basketball players during international competitions. Eleven female (7 spinal cord injured (SCI) and 4 Non-SCI) National team WC basketball players volunteered for the study. Testing occurred during a four-game series against the same international competitor (temp 22.1 ± 1.2°C, relative humidity (RH) 55 ± 2%). Hydration habits were monitored and heart rate, skin (SkT) and gastrointestinal (Tc), were recorded. Athletes arrived hydrated for all games (urine specific gravity, 1.014 ± 0.002). Players lost a mean of 0.5 ± 0.1% body mass due to sweat loss and replaced ~69% of fluid losses. SCI athletes played 21 ± 4 min while Non-SCI played 14 ± 6 min. SCI athletes had a mean SkT throughout the game of 35.2 ± 0.2°C and Non-SCI of 36.2 ± 0.2°C. SCI SkT rose a mean of 6.3 ± 1.1°C and Non-SCI 6.8 ± 0.9°C. SCI Tc rose a mean of 1.0 ± 0.2°C and Non-SCI a mean of 0.9 ± 0.4°C. 2/10 players reached a Tc>39°C (SCI athlete class 1, 39.4°C Non-SCI class 4.5 athlete, 39.5°C). There were differences between players in Tc responses, due to variability in playing time. Monitoring Tc during competition is encouraged to understand competition specific responses and identify athletes at risk of heat-related fatigue.
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.GAITPOST.2008.10.062
Abstract: Transtibial utees are at an increased risk of falling compared to age-matched, able-bodied in iduals. The aim of this study was to compare the gait patterns of recent utee fallers vs. non-fallers during level walking by investigating joint kinematics, kinetics and variability of temporal-spatial parameters. Eleven participants (fallers=6 non-fallers=5) walked along a 10-m walkway at their self-selected pace while three-dimensional kinematic and kinetic data were collected. The fallers had a significantly greater first peak vertical GRF (p=0.01) and load rate on the prosthetic limb than the non-fallers (p=0.03). Joint range of motion was similar between the two groups. Joint moment profiles were similar for the ankle and hip, with more noticeable differences at the knee. On the intact limb, the fallers also showed significantly smaller A1 and larger H2 power bursts and greater variability of swing time duration compared to the non-fallers. The non-fallers had a smaller load rate and knee moment that remained extensor suggesting they could make compensatory adjustments to maintain stability on the prosthetic side by modifying muscular demands of the knee extensors. This research suggests that falls prevention and prosthetic rehabilitation programmes should focus on improving knee muscle strength of the prosthetic limb, and eccentric ankle and hip strength of the intact limb, to improve stability and progression, particularly during weight transfer onto single support of the prosthetic limb.
Publisher: Springer Science and Business Media LLC
Date: 30-07-2008
DOI: 10.1007/S00726-008-0144-4
Abstract: Heat shock proteins are highly conserved proteins and play an important chaperone role in aiding the folding of nascent proteins within cells. The heat shock protein response to various stressors, both in vitro and in vivo, is well characterised. However, basal levels of heat shock protein 70 (Hsp70) have not previously been investigated. Monocyte-expressed Hsp70 was determined every 4 h, over a 24 h time period, in 17 healthy male subjects (177 +/- 6.4 cm, 75.7 +/- 10.9 kg, 19.8 +/- 4.3 years) within a temperature and activity controlled environment. Core temperature was measured at 5-min intervals during the 24 h period. Hsp70 showed significant diurnal variation (F = 7.4 p < 0.001), demonstrating peaks at 0900 and 2100 hours, and a nadir at 05.00. Core temperature followed a similar temporal trend (range = 35.96-38.10 degrees C) and was significantly correlated with Hsp70 expression (r(s) = 0.44 p < 0.001). These findings suggest a high responsiveness of Hsp70 expression in monocytes to slight variations in core temperature.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-1999
DOI: 10.1097/00005768-199909000-00018
Abstract: The accumulated O2, calculated by an extrapolation procedure from measurements of the O2 uptake at moderate powers, has been suggested as a measure of the anaerobic energy release during high intensity exercise. While some suggest that repeated 10-min bouts are required to establish the relationships in question, other use bouts of shorter durations. The purpose of this study was to examine how different exercise durations influence the calculated accumulated O2 deficit. Eight endurance trained male cyclists with the following characteristics (Mean +/- SE): age, 25 +/- 3 yr weight, 69.9 +/- 1.7 kg: height, 178.2 +/- 1.0 cm and VO2max 57.5 +/- 2.4 mL x kg(-1) x min(-1) volunteered for participation in this study. The O2 uptake was measured at 2-4, 4-6, 6-8, and 8-10 min of exercise at ten different constant powers. These O2 uptakes were used to establish four relationships between the power and O2 demand for each subject. On a separate day the subjects cycled at a power of 336 +/- 42 W (corresponding to about 110% of the maximal O2 uptake) for 296 +/- 43 s to exhaustion while the O2 uptake was measured continuously. For each subject the accumulated O2 deficit was determined from the different relationships. The accumulated O2 deficit determined from the relationships from the 2 to 4-min exercises in the pretests were significantly less than the value calculated from the relationships obtained after the 8-10 min of exercise at constant power, the values being 39.6 +/- 11.6 mL O2 eq x kg(-1) and 53.4 +/- 14.6 mL O2 eq x kg(-1), respectively. This study suggests that reducing the exercise duration used in the pretests to establish the relationships between power and O2 demand from 10 min may lead to a too low accumulated O2 deficit.
Publisher: Springer Science and Business Media LLC
Date: 05-1999
Abstract: The aim of this study was to determine whether a dose of 300-mg x kg(-1) body mass of sodium bicarbonate would effect a high-intensity, 1-h maximal cycle ergometer effort. Ten male, well-trained [maximum oxygen consumption 67.3 (3.3) ml x kg(-1) x min(-1), mean (SD)] volunteer cyclists acted as subjects. Each undertook either a control (C), placebo (P), or experimental (E) ride in a random, double-blind fashion on a modified, air-braked cycle ergometer, attached to a personal computer to which the work and power data was downloaded at 10 Hz. Fingertip blood was s led at 10-min intervals throughout the exercise. Blood was also s led at 1, 3, 5, and 10 min post-exercise. Blood was analysed for lactate, partial pressure of Carbon dioxide and oxygen, pH and plasma bicarbonate (HCO-) concentration. Randomly chosen pairs of subjects were asked to complete as much work as possible during the 60-min exercise periods in an openly competitive situation. The sodium bicarbonate had the desired effect of increasing blood HCO3- prior to the start of the test. The subjects in E completed 950.9 (81.1) kJ of work, which was significantly more (F(2,27) = 5.28, P < 0.01) than during either the C [835.5 (100.2) kJ] or P [839.0 (88.6) kJ] trials. No differences were seen in peak power or in the power:mass ratio between these three groups. The results of this study suggest that sodium bicarbonate may be used to offset the fatigue process during high-intensity, aerobic cycling lasting 60 min.
Publisher: Springer Science and Business Media LLC
Date: 08-09-2018
Publisher: Georg Thieme Verlag KG
Date: 07-2008
Abstract: The aim of this study was to observe the influence of pre-exercise sodium bicarbonate (NaHCO3) ingestion and varying recovery modes on acid-base recovery from a single bout of supramaximal exercise. Nine male subjects completed four separate, randomized cycle ergometer exercise trials to volitional fatigue at 120% maximum power output, under the following conditions: 0.3 g.kg(-1) BW NaHCO3 ingestion with passive recovery (BICARB P), 0.3 g.kg (-1) BW NaHCO3 ingestion with active recovery (BICARB A), placebo ingestion with passive recovery (PLAC P) and placebo ingestion with active recovery (PLAC A). Capillary blood s les were obtained every minute for 15 min during recovery. Significant main effects for pH were observed for time (F = 42.1, p < 0.001), intervention (BICARB and PLAC) (F = 1117.3, p < 0.001) and recovery condition (F = 150.0, p < 0.001), as the BICARB condition reduced acid-base perturbation. Significant interaction effects were observed between conditions (BICARB and PLAC) for active and passive recovery modes (F = 29.1, p < 0.001) as the active recovery facilitated H+ removal better than the passive condition. Pre-exercise alkalosis attenuates blood acid-base perturbations from supramaximal exercise to exhaustion, regardless of whether the recovery mode is active or passive. These findings suggest that in iduals may benefit from introducing a pre-exercise alkalotic condition while including passive recovery during high-intensity training protocols.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2016
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.JSAMS.2015.12.006
Abstract: Feedback deception is used to explore the importance of expectations on pacing strategy and performance in self-paced exercise. The deception of feedback from a previous performance explores the importance of experience knowledge on exercise behaviour. This study aimed to explore the acute and residual effects of the deception of previous performance speed on perceptual responses and performance in cycling time trials. A parallel-group design. Twenty cyclists were assigned to a control or deception group and performed 16.1km time trials. Following a ride-alone baseline time trial (FBL), participants performed against a virtual avatar representing their FBL performance (PACER), then completed a subsequent ride-alone time trial (SUB). The avatar in the deception group, however, was unknowingly set 2% faster than their FBL. Both groups performed faster in PACER than FBL and SUB (p<0.05), but SUB was not significantly different to FBL. Affect was more negative and Ratings of Perceived Exertion (RPE) were higher in PACER than FBL in the deception group (p<0.05). The presence of a visual pacer acutely facilitated time trial performance, but deceptive feedback had no additional effect on performance. The deception group, however, experienced more negative affect and higher RPE in PACER, whereas these responses were absent in the control group. The performance improvement was not sustained in SUB, suggesting no residual performance effects occurred.
Publisher: Elsevier BV
Date: 2010
DOI: 10.1016/J.JSAMS.2008.08.005
Abstract: The purpose of this work was to investigate the effect of multidirectional soccer-specific fatigue on hamstring muscle strength and angle of peak torque. Sixteen male semi-professional soccer players (mean+/-S.D.: age: 21.3+/-2.9 years height 185.0+/-8.7 cm body mass 81.6+/-6.7 kg) completed the SAFT(90), a multidirectional, intermittent 90-min exercise protocol based on data from English Ch ionship soccer matches. Prior to exercise (t(0)), at half-time (t(45)) and post-exercise (t(105)), subjects performed three maximal dominant limb isokinetic contractions (Biodex, System 3) at 120 degrees s(-1) through a 90 degrees range for concentric and eccentric knee flexors and concentric knee extensors. Analysis of variance revealed significant time dependant reductions in gravity corrected eccentric hamstring peak torque, and consequently in the functional hamstring:quadriceps ratio (P 0.05). Data analysis also revealed significant differences for Angle of Peak Torque for eccentric hamstrings (P<0.05) which was significantly higher at the end of each half (t(45): 37+/-15 t(105): 38+/-18 degrees ) than the pre-exercise value (t(0): 28+/-12 degrees ). There was a time dependant decrease in peak eccentric hamstring torque and in the functional strength ratio which may have implications for the increased predisposition to hamstring strain injury during the latter stages of match-play.
Publisher: Elsevier BV
Date: 06-2009
DOI: 10.1016/J.APMR.2008.12.024
Abstract: To quantify postural responses in utee fallers versus nonfallers by using computerized dynamic posturography. All participants completed standard protocols on the Sensory Organization Test (SOT) and Motor Control Test (MCT) of the NeuroCom Equitest. Human performance laboratory in a university in the United Kingdom. Transtibial utees (n=9) and able-bodied subjects (n=9) (all categorized into fallers and nonfallers according to their falls history in the previous 9 mo). Not applicable. Equilibrium and strategy scores on the SOT. Postural response latency and weight distribution on the MCT. Equilibrium scores were highest when somatosensory information was accurate, but there were no differences between the groups. Strategy scores were lower when visual cues and somatosensory information were inaccurate, and the fallers and nonfallers used a combination of ankle and hip strategies to prevent a loss of balance. The utee nonfallers indicated they had a greater reliance on visual input even when it was inaccurate compared with the utee fallers, whereas the control fallers used the hip strategy significantly more compared with the control nonfallers (SOT condition 6: 56+/-22 vs 72+/-10, P=.01). Weight distribution symmetry showed that the utee nonfallers bore significantly more weight through their intact limb compared with the utee fallers during backward and forward translations (P<.05). The SOT and MCT appeared to be population specific and therefore did not reliably identify fallers among transtibial utees or distinguish between community-dwelling control fallers and nonfallers. Amputee and control fallers can prevent a fall during challenging static and dynamic conditions by adapting their neuromuscular responses. The results from this study have important implications for utee gait rehabilitation, falls prevention, and treatment programs.
Publisher: Georg Thieme Verlag KG
Date: 2007
Abstract: The purpose of this study was to determine the reproducibility of time at or above 90 % (t (90 % )VO (2max)) and 95 % (t (95 % )VO (2max)) maximal oxygen uptake during an intermittent treadmill run to exhaustion. Twenty-two distance runners (age 38.0 +/- 7.1 yrs) performed two identical incremental and two identical intermittent tests on four separate days. Respiratory exchange was measured continuously throughout each test by an automated open-circuit gas analysis system. The incremental test consisted of increases in treadmill speed every minute until volitional exhaustion. The highest averaged 30-s oxygen uptake (VO (2)) value was defined as VO (2max) and the minimum speed that elicited VO (2max) was defined as vVO (2max). The intermittent test consisted of 30-s work intervals ran at 105 % vVO (2max) interspersed by 30-s relief intervals ran at 60 % vVO (2max) and was continued until volitional exhaustion. The time that VO (2) was at or above 90 % and 95 % of the mean maximum values elicited during the two previous incremental tests was determined for the intermittent tests. The mean t (95 % )VO (2max) was 232 (SD 174) s and 244 (SD 195) s and the mean t (90 % )VO (2max) was 480 (SD 220) s and 488 (SD 252) s, for trial 1 and trial 2, respectively. Reproducibility statistics for t (95 % )VO (2max) and t (90 % )VO (2max), respectively, were: 95 % limits of agreement 12 +/- 227 s and 8 +/- 328 s coefficient of variation 34.5 % and 24.5 % and intraclass correlation coefficient 0.80 and 0.75. Statistical power analysis indicated that this level of reproducibility would allow mean differences of 15 - 20 % between intermittent training protocols to attain statistical significance in future experimental research, with s le sizes probably within the resources of most researchers.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2013
Publisher: Springer Science and Business Media LLC
Date: 02-1994
DOI: 10.1007/BF00244033
Publisher: Wiley
Date: 12-01-2007
Publisher: Georg Thieme Verlag KG
Date: 19-05-2009
Abstract: The aim of this study was to investigate the effect of a multi-directional soccer-specific fatigue protocol on sprinting kinematics in relation to hamstring injury risk. Nine semi-professional soccer players (Mean +/- SD: Age: 21.3 +/- 2.9 year Height 185.0 +/- 8.7 cm Body Mass 81.6 +/- 6.7 kg) completed the SAFT(90) a multi-directional, intermittent 90 min exercise protocol representative of soccer match-play. The 10m sprint times and three-dimensional kinematic data were recorded using a high-speed motion capture system (Qualisys Track Manager) every 15 min during the SAFT(90). A significant time dependent increase was observed in sprint time during the SAFT(90) (P<0.01) with a corresponding significant decrease in stride length (P<0.01). Analysis of the kinematic sprint data revealed significantly reduced combined maximal hip flexion and knee extension angle, indicating reduced hamstring length, between pre-exercise and half-time (P<0.01) and pre-exercise and full-time (P<0.05). These findings revealed that the SAFT(90) produced time dependent impairments in sprinting performance and kinematics of technique which may result from shorter hamstring muscle length. Alterations in sprinting technique may have implications for the increased predisposition to hamstring strain injury during the latter stages of soccer match-play.
Publisher: Springer Science and Business Media LLC
Date: 2006
DOI: 10.2165/00007256-200636020-00003
Abstract: The maximal oxygen uptake (V-dotO(2max)) is considered an important physiological determinant of middle- and long-distance running performance. Little information exists in the scientific literature relating to the most effective training intensity for the enhancement of V-dotO(2max) in well trained distance runners. Training intensities of 40-50% V-dotO(2max) can increase V-dotO(2max) substantially in untrained in iduals. The minimum training intensity that elicits the enhancement of V-dotO(2max) is highly dependent on the initial V-dotO(2max), however, and well trained distance runners probably need to train at relative high percentages of V-dotO(2max) to elicit further increments. Some authors have suggested that training at 70-80% V-dotO(2max) is optimal. Many studies have investigated the maximum amount of time runners can maintain 95-100% V-dotO(2max) with the assertion that this intensity is optimal in enhancing V-dotO(2max). Presently, there have been no well controlled training studies to support this premise. Myocardial morphological changes that increase maximal stroke volume, increased capillarisation of skeletal muscle, increased myoglobin concentration, and increased oxidative capacity of type II skeletal muscle fibres are adaptations associated with the enhancement of V-dotO(2max). The strength of stimuli that elicit adaptation is exercise intensity dependent up to V-dotO(2max), indicating that training at or near V-dotO(2max) may be the most effective intensity to enhance V-dotO(2max) in well trained distance runners. Lower training intensities may induce similar adaptation because the physiological stress can be imposed for longer periods. This is probably only true for moderately trained runners, however, because all cardiorespiratory adaptations elicited by submaximal training have probably already been elicited in distance runners competing at a relatively high level.Well trained distance runners have been reported to reach a plateau in V-dotO(2max) enhancement however, many studies have demonstrated that the V-dotO(2max) of well trained runners can be enhanced when training protocols known to elicit 95-100% V-dotO(2max) are included in their training programmes. This supports the premise that high-intensity training may be effective or even necessary for well trained distance runners to enhance V-dotO(2max). However, the efficacy of optimised protocols for enhancing V-dotO(2max) needs to be established with well controlled studies in which they are compared with protocols involving other training intensities typically used by distance runners to enhance V-dotO(2max).
Publisher: Springer Science and Business Media LLC
Date: 25-09-2006
DOI: 10.1007/S00726-006-0400-4
Abstract: Heat shock proteins (HSPs) are synthesised by cells subsequent to a stress exposure and are known to confer protection to the cell in response to a second challenge. HSP induction and decay are correlated to thermotolerance and may therefore be used as a biomarker of thermal history. The current study tested the temperature-dependent nature of the heat shock response and characterised its time profile of induction. Whole blood from 6 healthy males (Age: 26 +/- (SD) 2 yrs Body mass 74.2 +/- 3.8 kgs VO(2max): 49.1 +/- 4.0 ml.kg(-1).min(-1)) were isolated and exposed to in vitro heat shock (HS) at 37, 38, 39, 40, and 41 degrees C for a period of 90 min. After HS the temperature was returned to 37 degrees C and intracellular HSP70 was quantified from the leukocytes at 0, 2, 4, and 6 h after heat treatment. The concentration of HSP70 was not different between temperatures (P > 0.05), but the time-profile of HSP70 synthesis appeared temperature-dependent. At control (37 degrees C) and lower temperatures (38-39 degrees C) the mean HSP70 concentration increased up to 4 h post HS (P < 0.05) and then returned towards baseline values by 6 h post HS. With in vitro hyperthermic conditions (40-41 degrees C), the time-profile was characterised by a sharp rise in HSP70 levels immediately after treatment (P < 0.05 for 40 degrees C at 0 h), followed by a progressive decline over time. The results suggest a temperature-dependent time-profile of HSP70 synthesis. In addition, the temperature at which HSP70 is inducted might be lower than 37 degrees C.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-1997
Publisher: Frontiers Media SA
Date: 25-03-2021
Publisher: Informa UK Limited
Date: 02-10-2014
DOI: 10.1080/15438627.2014.944300
Abstract: To quantify the influence of soccer-specific fatigue on reactive dynamic balance, ten male professional soccer players (age 24.7 ± 4.4 yr, body mass 77.1 ± 8.3 kg, VO2max 63.0 ± 4.8 ml·kg·min(-1)) completed an exercise protocol replicating the activity profile of match-play. Pre-exercise, and at 15 min intervals, players completed three balance tasks requiring response to a system perturbed to induce either plantar flexion of the ankle or inversion of the ankle (by rotation or translation). ANOVA revealed a significant main effect for exercise duration in each task, with both reaction time and total centre of gravity displacement tending to increase during each half. In all three trials there was a significant increase in medio-lateral and anterior-posterior displacement, the planar perturbation of the platform evoking a multi-angular response. Dynamic balance performance decreased as a function of time during each half, suggesting a greater risk of injuries at these specific times, in accord with epidemiological observations of ankle sprain injury.
Publisher: BMJ
Date: 06-1986
DOI: 10.1136/BJSM.20.2.56
Abstract: Alcohol has been used as an aid to performance for a considerable period of time in many athletic endeavours. Five sprinters and five middle distance athletes were tested to determine whether differing levels of alcohol (0.01 mg X ml-1, 0.05 mg X ml-1 and 0.10 mg X ml-1) had differing effects upon performance times in the 100 m, 200 m, 400 m, 800 m and 1500 m events. Blood alcohol concentration (BAC) was estimated from breath alcohol concentration (BrAC) using a hand held Drager Alcotest 7310 and a Borkenstein Breathalyser. Alcohol affected all but the 100 m event to varying degrees. In the 200 m the performance decreased when the level of intoxication increased. This was not the case in the 400 m which showed a difference between the two lower levels of alcohol consumption (0.01 mg X ml-1 to 0.05 mg X ml-1) but not between the 0.05 mg X ml-1 and 0.10 mg X ml-1. In the middle distance events the 800 m was most adversely affected. We concluded that alcohol is not an ergogenic aid in so much that it does not improve performance. In the 100 m events, performance remained stable. More research in this area is warranted.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-1993
Publisher: Elsevier BV
Date: 06-2016
Publisher: Human Kinetics
Date: 05-2019
Publisher: Georg Thieme Verlag KG
Date: 08-2000
DOI: 10.1055/S-2000-3833
Abstract: The aim of this study was to determine the effects of different conditions of heat and humidity on two multiple bouts of high intensity cycling with 60 min recovery between each bout. Eight males (age: 25.5+/-1.8 yr, height: 179.0+/-3.7 cm weight: 72.3+/-4.0 kg VO2peak: 51.5+/-2.4 ml x kg(-1) x min(-1), Peak Aerobic Power: 366+/-13 W) volunteered for this study. After undertaking VO2peak testing, all participated randomly, in three consecutive 30 s Wingate tests in three different environmental conditions being: Normal (22 degrees C/30% RH), Wet (30 degrees C/85% RH), and Hot (40 degrees C/40% RH). Subjects were then monitored for the 60 min post-exercise period after which time they repeated the Wingate tests and were again monitored for 60 min. Blood s les were taken pre, immediately post exercise, and at 1, 5, 10, 15, 30, 45, and 60 min into each of the recovery periods and analysed for lactate, pH, and hematocrit. Heart rate was monitored continuously throughout exercise (5 s average) and recovery (60 s average). Weight was measured pre exercise and at 15, 30, 45, and 60 min post-exercise. Urine s les were collected at the same time and analysed for osmolality. The results of the experiment indicated that environmental conditions had no effect on the performance of either series 1 or 2 Wingate tests. Neither were there any changes in weight throughout the three conditions or across the condition. Post exercise pH levels were lower than pre exercise values (p < 0.0001) and the reverse was true for blood lactate levels (p < 0.0003). We conclude that anaerobic exercise is not unduly affected by hot or humid conditions when subjects can re-hydrate according to decreases in body weight.
Publisher: Informa UK Limited
Date: 08-12-2017
DOI: 10.1080/17461391.2017.1410233
Abstract: To quantify the effects of acute hypoxic exposure on exercise capacity and performance, which includes continuous and intermittent forms of exercise. A systematic review was conducted with a three-level mixed effects meta-regression. The ratio of means method was used to evaluate main effects and moderators providing practical interpretations with percentage change. A systemic search was performed using three databases (Google scholar, PubMed and SPORTDiscus). Eligibility criteria for selecting studies: Inclusion was restricted to investigations that assessed exercise performance (time trials (TTs), sprint and intermittent exercise tests) and capacity (time to exhaustion test, TTE) with acute hypoxic (<24 h) exposure and a normoxic comparator. Eighty-two outcomes from 53 studies (N = 798) were included in this review. The results show an overall reduction in exercise performance/capacity -17.8 ± 3.9% (95% CI -22.8% to -11.0%), which was significantly moderated by -6.5 ± 0.9% per 1000 m altitude elevation (95% CI -8.2% to -4.8%) and oxygen saturation (-2.0 ± 0.4% 95% CI -2.9% to -1.2%). TT (-16.2 ± 4.3% 95% CI -22.9% to -9%) and TTE (-44.5 ± 6.9% 95% CI -51.3% to -36.7%) elicited a negative effect, whilst indicating a quadratic relationship between hypoxic magnitude and both TTE and TT performance. Furthermore, exercise less than 2 min exhibited no ergolytic effect from acute hypoxia. Summary/Conclusion: This review highlights the ergolytic effect of acute hypoxic exposure, which is curvilinear for TTE and TT performance with increasing hypoxic levels, but short duration intermittent and sprint exercise seem to be unaffected.
Publisher: Human Kinetics
Date: 12-2007
Abstract: Recently, superoxygenated-water beverages have emerged as a new purported ergogenic substance. This study aimed to determine the effects of superoxygenated water on submaximal endurance performance. Eleven active male subjects, VO 2max 52.6 ± 4.8 mL · kg −1 · min −1 , height 180.0 ± 2.0 cm, weight 76.0 ± 7.0 kg, age 24 ± 1.0 y (mean ± SD), completed a 45-min cycle-ergometry exercise test at 70% of their previously predicted maximal power output with a 10-min rest period, followed by a 15-min time trial (TT). Thirty minutes before the exercise test subjects consumed 15 mL of either superoxygenated water (E) or placebo (P water mixed with low-chlorine solution). Subjects then completed the test again a week later for the other condition (double-blind, randomized). The physiological variables measured during exercise were VO 2 , VCO 2 , respiratory-exchange ratio (RER), V E , PO 2 , PCO 2 , blood lactate (bLa–), and heart rate (HR). Mean distance covered and the average power output for the 15-min TT were also measured as performance indicators. There were no significant differences in VO 2 , VCO 2 , RER, V E , bLa − , PO 2 , and HR ( P .05) during the exercise tests. Neither were there any significant improvements in the total distance covered (P 9.01 ± 0.74 km vs E 8.96 ± 0.68 km, P .05) or the average power output (P 186.7 ± 35.8 W vs E 179.0 ± 25.9 W, P .05) during the 15-min TT. Based on these results the authors conclude that consuming 15 mL of superoxygenated water does not enhance submaximal or maximal TT cycling performance.
Publisher: Informa UK Limited
Date: 06-1991
DOI: 10.1080/02640419108729876
Abstract: Eight trained male cyclists who competed regularly in track races, were studied under control, alkalotic (NaHCO3) and placebo (CaCO3) conditions in a laboratory setting to study the effect of orally induced metabolic alkalosis on 60 s anaerobic work and power output on a bicycle ergometer. Basal, pre- and post-exercise blood s les in the three conditions were analysed for pH, pCO2, pO2, bicarbonate, base excess and lactate. All blood gas measurements were within normal limits at basal levels. There were significant differences in the amount of work produced, and in the maximal power output produced by the cyclists in the experimental condition when compared to the control and placebo conditions (P less than 0.01). The post-exercise pH decreased in all three conditions (P less than 0.05) and post-exercise pCO2 increased significantly in the alkalosis trial (P less than 0.01). In the alkalotic condition, the pre-exercise base excess and HCO3- levels were both higher (P less than 0.05) than the basal levels, suggesting that the bicarbonate ingestion had a significant increase in the buffering ability of the blood. Post-exercise lactate levels were significantly higher (P less than 0.05) after the alkalotic trial when compared to the other two conditions, immediately post-exercise and for the next 3 min. Post-exercise lactate levels were higher than basal or pre-exercise levels (P less than 0.001). This was true immediately post-exercise and for the next 5 min. The results of this study suggest that NaHCO3 is an effective ergogenic aid when used for typically anaerobic exercise as used in this experiment. We feel that this ergogenic property is probably due to the accelerated efflux of H+ ions from the muscle tissue due to increased extracellular bicarbonate buffering.
Publisher: Elsevier BV
Date: 02-2006
DOI: 10.1016/J.PHYSBEH.2005.11.009
Abstract: This study examined the effect of 30 h of sleep deprivation and intermittent physical exercise, on both cognitive and psychomotor function as well subjective ratings of mood. Six subjects with the following physical characteristics participated in the study (Mean +/- S.D.): age 22 +/- 0.3 years, height 180 +/- 5 cm, body mass: 77 +/- 5 kg, VO2peak 44 +/- 5 ml kg(-1) min(-1). Three subjects engaged in normal sedentary activities while three others cycled on a cycle ergometer at 50% VO2peak for 20 min out of every 2 h during 30 h of sleep deprivation. One week later sleep deprivation was repeated with a cross over of subjects. Every 4 h, subjects completed simple and two-choice reaction time tasks at both rest and during exercise, a computerized tracking task, a number cancellation task, and an assessment of subjective mood state as measured by the POMS questionnaire. A 3 x 4 repeated measures ANOVA revealed that resting but not exercising reaction times were significantly slower with sleep deprivation. Sleep deprivation was also associated with significantly greater negative disturbances to subjective vigour, fatigue and depression assessed by the Profile of Mood States questionnaire. Compared to those who have been deprived of sleep alone, in iduals that performed 5 h of intermittent moderate exercise during 30 h of sleep deprivation appeared to be more vulnerable to negative mood disturbances and impairment in reaction times. This could result in greater risk of accident due to a reduced capacity to respond quickly.
Publisher: Springer Science and Business Media LLC
Date: 19-02-2008
Publisher: Georg Thieme Verlag KG
Date: 25-05-2009
Abstract: This study aimed to establish the effect of age and pubertal development on relative peak torque in youth footballers. One hundred and fifty-seven subjects were arranged into U12-U18 age groups of these 133 also completed a self-reporting measure of pubertal development (PDS) and were grouped accordingly. Bilateral isokinetic testing included mean peak torque/body weight (PT/BW) and angle of peak torque (AoPT) for reps 2-4 of 5 in concentric quadriceps (CQ), concentric hamstrings (CH) and eccentric hamstrings (EH) at 60 degrees s(-1). Two minutes rest were provided between concentric and eccentric tests for both legs. A significant increase with age was noted for PT/BW in CQ, CH and EH (P<0.05), although POST HOC analyses revealed different patterns of significance dependent upon muscle and type of contraction. Specifically, the U18 s (CQ:2.20 nm/kg, CH:1.39 nm/kg, EH:2.16 nm/kg) were not significantly stronger than the U16 s and U15 s (CQ:2.42/2.29 nm/kg, CH:1.41/1.27 nm/kg, EH:2.22/2.15 nm/kg) even though they had entered full time training. The relationship between EH PT/BW and AoPT showed a weak but significant inverse correlation (P<0.001 R= -0.390 and -0.346 for dominant and non dominant legs). The findings of this study present unique football specific normative and age/PDS group data for PT/BW and AoPT, and the corresponding relationship between these variables.
Publisher: Georg Thieme Verlag KG
Date: 06-1990
Abstract: Nine male recreational cyclist served as subjects in this experiment which included a control, placebo and caffeine trial. The aim of the experiment was to determine whether a 10 mg.kg-1 dose of caffeine given three hours prior to an incremental cycle ergometer exercise test, for caffeine naive subjects, would increase the time to exhaustion and therefore increase the amount of work undertaken by the cyclists. The cyclists initially worked at 100 watts for three minutes and then increased the workload by 50 watts every three minutes until exhaustion. Blood was drawn at the beginning of the test and every three minutes from an ante-cubital vein and was analysed for blood lactate, glucose and free fatty acids (FFA). Respiratory analysis was also undertaken and heart rate was monitored throughout the test. Subjects in the caffeine trial worked significantly longer and performed more work (p less than 0.05) than they did in either the control or placebo trials. FFA's were also significantly higher in this trial (p less than 0.05) and the lactate threshold was moved to the right as a percentage of the VO2max, which suggests less acidity and a decreased bicarbonate flushing. The respiratory exchange ratio data was significantly lowered (p less than 0.05) during workloads between 250 and 450 watts. No changes were seen in blood glucose or heart rates during the experiment. In conclusion, we feel that a 10 mg.kg-1 dose of caffeine is an ergogenic aid during incremental exercise when it is taken 3-4 hours prior to the exercise in fasting subjects who have diets low in caffeine.
Publisher: Informa UK Limited
Date: 25-01-2018
DOI: 10.1080/15438627.2018.1431537
Abstract: Soccer presents a metabolic challenge which is not necessarily matched by players' habitual dietary intake. To examine the effects of a bespoke diet, 22 players completed the Ball Sport Endurance and Sprint Test (BEAST
Publisher: Springer Science and Business Media LLC
Date: 11-1993
DOI: 10.1007/BF00376458
Abstract: Antibiotic use is associated with several antibiotic-related harms in vulnerable, older long-term care (LTC) residents. Suboptimal antibiotic use may also be associated with harms but has not yet been investigated. The aim of this work was to compare rates of poor clinical outcomes among LTC residents with UTI receiving suboptimal versus optimal antibiotic treatment. We conducted a retrospective cohort study among residents with an incident urinary tract infection (UTI) treated in Veterans Affairs LTC units (2013-2018). Potentially suboptimal antibiotic treatment was defined as use of a suboptimal initial antibiotic drug choice, dose frequency, and/or excessive treatment duration. The primary outcome was time to a composite measure of poor clinical outcome, defined as UTI recurrence, acute care hospitalization/emergency department visit, adverse drug event, Clostridioides difficile infection (CDI), or death within 30 days of antibiotic discontinuation. Shared frailty Cox proportional hazard regression models were used to compare the time-to-event between suboptimal and optimal treatment. Among 19,701 LTC residents with an incident UTI, 64.6% received potentially suboptimal antibiotic treatment and 35.4% experienced a poor clinical outcome. In adjusted analyses, potentially suboptimal antibiotic treatment was associated with a small increased hazard of poor clinical outcome (aHR 1.06, 95% CI 1.01-1.11) as compared with optimal treatment, driven by an increased hazard of CDI (aHR 1.94, 95% CI 1.54-2.44). In this national cohort study, suboptimal antibiotic treatment was associated with a 6% increased risk of the composite measure of poor clinical outcomes, in particular, a 94% increased risk of CDI. Beyond the decision to use antibiotics, clinicians should also consider the potential harms of suboptimal treatment choices with regards to drug type, dose frequency, and duration used.
Publisher: American Dairy Science Association
Date: 08-2007
Abstract: With the introduction of a protein milk payment system in New Zealand in 1988, there was an influx of North American (NA) Holstein-Friesian (HF) genetics into New Zealand (NZ) dairy herds, leading to an increase in the average percentage of NA genetics in NZ HF cows--from 2% in 1980 to 38% in 1999. Of interest has been the effect this change has had on farm profitability and on the management required for these animals, as well as the phenotypic changes that have occurred within the national herd under the breeding programs operated in NZ from 1970 to 1990. The objective of this study was to quantify differences in body dimensions, body weights, and puberty-related parameters among 3 strains of HF, representing animals of NZ origin representative of the genetics present in 1970 and 1990 and of NA origin with 1990s genetics. A total of 172 animals born in 1999 were compared. The strains were 1) NZ70, a strain of NZ Friesian (average 7% NA genetics) equivalent to high-genetic-merit (high Breeding Worth) cows farmed in the 1970s 2) NZ90, a strain of HF of NZ origin (average 24% NA genetics) typical of the animals present in the 1990s and 3) NA90, a strain of HF of NA origin (average of 91% NA genetics) typical of animals present in the 1990s. The differences in BW among all strains were significant at 6 and 12 mo of age. At 15 and 24 mo, the 2 NZ strains were significantly lighter than the NA90 animals. At 24 mo of age (i.e., prior to first calving), the NA90 strain animals (BW = 515 kg) were 22 and 34 kg heavier than the NZ90 and NZ70 strains. The body length of the NA90 strain was greater than either of the 2 NZ strains the differences among the NA90 strain and the 2 NZ strains varied from 2 to 6 cm, with the differences generally being greater at older ages. The trend in heart girth difference among strains was similar to that observed for body length. The wither height of the NA90 animals was greater than that of the NZ strains by 1 to 7 cm, although there was no significant difference between the NA90 and NZ90 strains at birth. At puberty the NA90 heifers were 20 d older and 20 kg heavier than the NZ90 heifers, which in turn were 25 kg and 25 d older than the NZ70 heifers. The NA90 strain had a heavier mature body weight, and their older age at puberty suggested either that they mature later or that, under pastoral conditions, their growth rate is limited by their inability to consume sufficient metabolizable energy as grazed pasture, with a consequent delay in puberty. Results from this study will be useful in revising target BW in growing heifers of different germplasm.
Publisher: Informa UK Limited
Date: 03-1990
DOI: 10.1080/02701367.1990.10607481
Abstract: It is known that an increased level of red blood cell 2,3-diphosphoglycerate (DPG) shifts the oxyhemoglobin dissociation curve to the right, thus allowing a greater unloading of oxygen at the tissue level. It has been hypothesized that phosphate might help increase VO2max by increasing 2,3-DPG level. Eight trained cyclists underwent three cycle ergometer tests (control, placebo, and experimental) to determine whether phosphate ingestion had any positive effect on VO2max, time to exhaustion, serum 2,3-DPG, and serum phosphate levels. We found no change between the control, placebo, or experimental conditions in pretest serum phosphate levels, but we did find increases in 2,3-DPG levels in the phosphate condition (p less than .05), which suggests that even a small amount of phosphate could increase levels of 2,3-DPG. We also found significant differences in VO2max between the control (p less than .05) and placebo (p less than .02) conditions and also in time to exhaustion between the three conditions (p less than .05). We suggest that phosphate may have an ergogenic effect, but clearly more work needs to be undertaken to ascertain the amount of phosphate required and the magnitude of the effect.
Publisher: Georg Thieme Verlag KG
Date: 11-08-2023
Abstract: Pre-exercise alkalosis and an active recovery improve the physiological state of recovery through slightly different mechanisms (e. g. directly increasing extracellular bicarbonate (HCO3 (-)) vs. increasing blood flow), and combining the two conditions may provide even greater influence on blood acid-base recovery from high-intensity exercise. Nine subjects completed four trials (Placebo Active ( PLAC A), sodium bicarbonate (NaHCO3) Active ( BICARB A), Placebo Passive ( PLAC P) and NaHCO3 Passive ( BICARB P)), each consisting of three, 30-s maximal efforts with a three min recovery between each effort. Pre-exercisealkalosis was evident in both NaHCO3 conditions, as pH and HCO3 (-) were significantly higher than both Placebo conditions (pH: 7.46 ± 0.04 vs. 7.39 ± 0.02 HCO3 (-): 28.8 ± 1.9 vs. 23.2 ± 1.4 mmol·L (-1) p<0.001). In terms of performance, significant interactions were observed for average speed (p<0.05), with higher speeds evident in the BICARB A condition (3.9 ± 0.3 vs. 3.7 ± 0.4 m·s (-1)). Total distance covered was different (p=0.05), with post hoc differences evident between the BICARB A and PLAC P conditions (368 ± 33 vs. 364 ± 35 m). These data suggest that successive 30-s high intensity performance may be improved when coupled with NaHCO3 supplementation.
Publisher: Springer Science and Business Media LLC
Date: 08-2001
Abstract: The aim of this study was to investigate whether increasing the duration of workloads from 3 min to 8 min during incremental exercise would influence workload (W), oxygen consumption (VO2) and heart rate (HR) at the lactate threshold (LT) and the onset of blood lactate accumulation (OBLA). Two groups of six male cyclists were assigned to a well-trained (WT) and recreational (REC) group on the basis of their performance in a maximal incremental r test. Each subject then performed two incremental lactate tests (EXT) consisting of six workloads of either 3 min (EXT3-min) or 8 min (EXT8-min) duration. At the completion of each workload whole capillary blood s les were obtained for the determination of blood lactate (BLa) concentration (mM). Power output (Watts, W), HR and VO2 were averaged in the final minute of each workload as well as in the third minute of the EXT8-min. The workload, HR and VO2 at the LT and OBLA were subsequently determined from the data of EXT3-min and EXT8-min. The results demonstrate that workload and VO2, but not HR, at the LT and OBLA were higher in the WT cyclists. At the same time, the workload at the LT obtained from the results of the EXT3-min was significantly (P < 0.05) higher then the value obtained in the EXT8-min in the WT subjects but not the REC subjects. However, the workload, VO2 and HR at the OBLA, together with the VO2 and HR at the LT were not significantly different when calculated from data obtained from EXT3-min or EXT8-min. The data obtained in this study suggest that incremental exercise protocols using workloads of duration longer than 3 min have the effect of increasing the workload at the LT in well-trained cyclists. However, the OBLA determined in exercise tests using stage increments of either 3 min or 8 min is similar in cyclists of different training status.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2008
Publisher: Georg Thieme Verlag KG
Date: 05-1996
Abstract: The aim of this experiment was to investigate the effects of differing pedalling speeds on the power-duration relationship during high intensity cycle ergometry with pedal cadences of 50 (low), 90 (intermediate) and 110 (high) r.min-1. This hyperbolic power-duration relationship can be described as: (P - phiPA).t = W', where P = power output, t = time to exhaustion, and phiPA and W' are constants. Eight volunteer male subjects, aged 24 +/- 2.6 yr, with no competitive cycling training took part in this study and each undertook thirteen tests on a Lode BV Excalibur Sport V1.52 cycle ergometer over an eight week period. The first exercise bout was a 30 W.min-1 incremental cycle at 50 r.min-1 to volitional fatigue. This allowed the identification of a range of power outputs that would be used to construct and examine the power-duration relationships for each subject at 50, 90 and 110 r.min-1. At both 50 and 90 r.min-1, power outputs of 30 W above and below and 60 W above the highest work rate, as well as the maximum work rate achieved during the incremental exercise test were chosen, while at 110 r.min-1, the power outputs chosen were 25 W above and below as well as 50 W above the highest work rate achieved during the incremental exercise test and also the maximum work rate achieved during the incremental exercise test were chosen. These four work rates for each pedalling frequency were chosen because they would have exercise times to exhaustion in the range of 1-10 minutes. Each exercise bout was preceded by four minutes of unloaded cycling and then the work rate was adjusted quickly to the desired load setting by the previously programmed computerised ergometer. The results of this work indicate that for the group of subjects studied, pedalling a cycle ergometer at 50 r.min-1 allows subjects to pedal for a significantly greater time than when pedalling at either 90 or 110 r.min-1. phiPA at 50 r.min-1 was significantly greater than when pedalling at either 90 (F(1,21) = 7.47, p < 0.01) or 110 r.min-1 (F(1,21) = 10.83, p 0.22) difference between phiPA at 90 and 110 r.min-1, F(1,21) = 1.36. W' however, was not significantly different when the data for 50 r.min-1, 90 r.min-1 and 110 r.min-1 were compared (F50 r.min-1 (1,21) = 0.95 p > 0.41 F90 r.min-1(1,21) = 0.79, p > 0.53 F110 r.min-1 (1,21) = 0.78, p > 0.53). Our hypothesis, that endurance performance was reduced when recreational cyclists pedal at a high cadence when compared to a low cadence was correct. Maximum sustainable power output during cycle ergometry was higher at 50 r.min-1 than at either 90 or 110 r.min-1. At the intermediate cadence endurance was better than at the high but worse than at the low cadence. In conclusion, during endurance cycling, recreaional cyclists should pedal at lower rather than higher cadences.
Publisher: Informa UK Limited
Date: 29-03-2012
DOI: 10.1080/15438627.2012.660830
Abstract: Heat shock protein 72 (HSP72) is expressed in response to stress and has been demonstrated to follow a diurnal expression pattern within monocytes and is sensitive to changes in core temperature. Numerous studies have shown changes in HSP72 expression within cell lines exposed to hyperbaric conditions. No studies have investigated changes in HSP72 expression in vivo. Six males participated in the study and were exposed to hyperbaric air and hyperbaric oxygen a week apart. Monocyte HSP72 was analyzed by flow cytometry at 09:00, 13:00, 17:00, 21:00 with hyperbaric oxygen or hyperbaric air breathing commencing at 15:00 for 78 min at a pressure of 2.8 ATA. HSP72 under normoxia followed the established trend however, following the hyperbaric air or oxygen exposure a reduction in detectable HSP72 was observed at 17:00 and 21:00. No changes in core temperature were observed between 13:00 and 21:00 for any condition. The data show that HSP72 expression is impaired following hyperbaric air (HA) exposure, when compared with control or hyperbaric oxygen (HO) exposure.
Publisher: Informa UK Limited
Date: 30-07-2018
DOI: 10.1080/02640414.2018.1504369
Abstract: This investigation assessed the effect of dietary nitrate (NO
Publisher: Public Library of Science (PLoS)
Date: 07-2021
DOI: 10.1371/JOURNAL.PONE.0248456
Abstract: The timing of sodium bicarbonate (NaHCO 3 ) supplementation has been suggested to be most optimal when coincided with a personal time that bicarbonate (HCO 3 – ) or pH peaks in the blood following ingestion. However, the ergogenic mechanisms supporting this ingestion strategy are strongly contested. It is therefore plausible that NaHCO 3 may be ergogenic by causing beneficial shifts in the strong ion difference (SID), though the time course of this blood acid base balance variable is yet to be investigated. Twelve highly trained, adolescent swimmers (age: 15.9 ± 1.0 years, body mass: 65.3 ± 9.6 kg) consumed their typical pre-competition nutrition 1–3 hours before ingesting 0.3 g∙kg BM -1 NaHCO 3 in gelatine capsules. Capillary blood s les were then taken during seated rest on nine occasions (0, 60, 75, 90, 105, 120, 135, 150, 165 min post-ingestion) to identify the time course changes in HCO 3 – , pH, and the SID. No significant differences were found in the time to peak of each blood measure (HCO 3 – : 130 ± 35 min, pH: 120 ± 38 min, SID: 98 ± 37 min p = 0.08) however, a large effect size was calculated between time to peak HCO 3 – and the SID ( g = 0.88). Considering that a difference between time to peak blood HCO 3 – and the SID was identified in adolescents, future research should compare the ergogenic effects of these two in idualized NaHCO 3 ingestion strategies compared to a traditional, standardized approach.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2011
Publisher: Springer Science and Business Media LLC
Date: 2007
DOI: 10.2165/00007256-200737120-00002
Abstract: Although the concept of maximal oxygen uptake (V-dotO(2max)) was conceived as early as 1923, the criteria used to establish whether a true V-dotO(2max) has been attained have been heavily criticised. Consequently, an improvement in the methodology of the existing criteria, or development of new criteria, is required. In order to be valid across experimental studies, new or improved criteria need to be independent of exercise modality, test protocol and subject characteristics. One procedure that has shown potential for yielding valid V-dotO(2max) criteria is the verification phase, which consists of a supramaximal constant speed run to exhaustion performed after the incremental phase of a V-dotO(2max) test. A peak oxygen uptake (V-dotO(2peak)) in the verification phase that is similar (within the tolerance of measurement error, e.g. within 2%) to the V-dotO(2max) value attained in the incremental phase would indicate that a true V-dotO(2max) has been elicited. Verification of the maximal heart rate would also indicate that a subject has given a maximum effort. Although the validity of the present methodology for identifying an oxygen uptake (V-dotO(2)) plateau is questionable, a V-dotO(2) plateau criterion based on the in idual slope of the V-dotO(2)-work-rate relationship should improve its validity. This approach also allows determination of the 'total V-dotO(2) plateau', which is in contrast to currently used V-dotO(2) plateau criteria that are based on the difference in V-dotO(2) between only two test stages or V-dotO(2) data points. The ratings of perceived exertion scale has been criticised for being a one-dimensional measure of physical effort and V-dotO(2max) criteria based on a multidimensional psychophysiological approach should increase validity. Visual analogue scales can be used to assess aspects such as muscular pain, determination and overall perceived effort. Furthermore, they are easy to complete and have demonstrated good reliability and validity in clinical and health settings. Future research should explore these and other potential approaches to developing new or improved V-dotO(2max) criteria, so that, ultimately, a standardised set of V-dotO(2max) criteria can be established. At present, however, the greatest challenge is identifying V-dotO(2max) criteria that remain valid across studies.
Publisher: Informa UK Limited
Date: 28-02-2022
Publisher: Human Kinetics
Date: 2015
Abstract: Power meters have traditionally been integrated into the crank set, but several manufacturers have designed new systems located elsewhere on the bike, such as inside the pedals. This study aimed to determine the validity and reliability of the Keo power pedals during several laboratory cycling tasks. Ten active male participants (mean ± SD age 34.0 ± 10.6 y, height 1.77 ± 0.04 m, body mass 76.5 ± 10.7 kg) familiar with laboratory cycling protocols completed this study. Each participant was required to complete 2 laboratory cycling trials on an SRM ergometer (SRM, Germany) that was also fitted with the Keo power pedals (Look, France). The trials consisted of an incremental test to exhaustion followed by 10 min rest and then three 10-s sprint tests separated by 3 min of cycling at 100 W. Over power ranges of 75 to 1147 W, the Keo power-pedal system produced typical error values of 0.40, 0.21, and 0.21 for the incremental, sprint, and combined trials, respectively, compared with the SRM. Mean differences of 21.0 and 18.6 W were observed between trials 1 and 2 with the Keo system in the incremental and combined protocols, respectively. In contrast, the SRM produced differences of 1.3 and 0.6 W for the same protocols. The power data from the Keo power pedals should be treated with some caution given the presence of mean differences between them and the SRM. Furthermore, this is exacerbated by poorer reliability than that of the SRM power meter.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2002
Publisher: Canadian Science Publishing
Date: 10-2006
DOI: 10.1139/H06-023
Abstract: This study investigated the utility of a verification phase for increasing confidence that a “true” maximal oxygen uptake had been elicited in 16 male distance runners (mean age (±SD), 38.7 (± 7.5 y)) during an incremental treadmill running test continued to volitional exhaustion. After the incremental test subjects performed a 10 min recovery walk and a verification phase performed to volitional exhaustion at a running speed 0.5 km·h –1 higher than that attained during the last completed stage of the incremental phase. Verification criteria were a verification phase peak oxygen uptake ≤ 2% higher than the incremental phase value and peak heart rate values within 2 beats·min –1 of each other. Of the 32 tests, 26 satisfied the oxygen uptake verification criterion and 23 satisfied the heart rate verification criterion. Peak heart rate was lower (p = 0.001) during the verification phase than during the incremental phase, suggesting that the verification protocol was inadequate in eliciting maximal values in some runners. This was further supported by the fact that 7 tests exhibited peak oxygen uptake values over 100 mL·min –1 (≥ 3%) lower than the peak values attained in the incremental phase. Further research is required to improve the verification procedure before its utility can be confirmed.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2010
Publisher: Springer Science and Business Media LLC
Date: 2007
DOI: 10.2165/00007256-200737100-00003
Abstract: This article investigates whether there is currently sufficient scientific knowledge for scientists to be able to give valid training recommendations to long-distance runners and their coaches on how to most effectively enhance the maximal oxygen uptake, lactate threshold and running economy. Relatively few training studies involving trained distance runners have been conducted, and these studies have often included methodological factors that make interpretation of the findings difficult. For ex le, the basis of most of the studies was to include one or more specific bouts of training in addition to the runners' 'normal training', which was typically not described or only briefly described. The training status of the runners (e.g. off-season) during the study period was also typically not described. This inability to compare the runners' training before and during the training intervention period is probably the main factor that hinders the interpretation of previous training studies. Arguably, the second greatest limitation is that only a few of the studies included more than one experimental group. Consequently, there is no comparison to allow the evaluation of the relative efficacy of the particular training intervention. Other factors include not controlling the runners' training load during the study period, and employing small s le sizes that result in low statistical power. Much of the current knowledge relating to chronic adaptive responses to physical training has come from studies using sedentary in iduals however, directly applying this knowledge to formulate training recommendations for runners is unlikely to be valid. Therefore, it would be difficult to argue against the view that there is insufficient direct scientific evidence to formulate training recommendations based on the limited research. Although direct scientific evidence is limited, we believe that scientists can still formulate worthwhile training recommendations by integrating the information derived from training studies with other scientific knowledge. This knowledge includes the acute physiological responses in the various exercise domains, the structures and processes that limit the physiological determinants of long-distance running performance, and the adaptations associated with their enhancement. In the future, molecular biology may make an increasing contribution in identifying effective training methods, by identifying the genes that contribute to the variation in maximal oxygen uptake, the lactate threshold and running economy, as well as the biochemical and mechanical signals that induce these genes. Scientists should be cautious when giving training recommendations to runners and coaches based on the limited available scientific knowledge. This limited knowledge highlights that characterising the most effective training methods for long-distance runners is still a fruitful area for future research.
Publisher: Informa UK Limited
Date: 10-09-2008
DOI: 10.1080/15438620802310784
Abstract: A systematic review of the literature was undertaken to assess the efficacy of static stretching as part of the warm-up for the prevention of exercise-related injuries. Computer-aided literature search for articles post-1990 and pre-January 2008 related to static stretching and injury prevention using MEDLINE, SPORT Discus, PubMed, and ScienceDirect databases. All relevant randomised clinical trials (RCTs) and controlled clinical trials (CCTs) satisfying inclusion/exclusion criteria were evaluated by methodological assessment to score the studies using accredited criteria. Seven out of 364 studies met the inclusion/exclusion criteria. All four RCTs concluded that static stretching was ineffective in reducing the incidence of exercise-related injury, and only one of the three CCTs concluded that static stretching did reduce the incidence of exercise-related injury. Three out of the seven studies noted significant reductions in musculotendinous and ligament injuries following a static stretching protocol despite nonsignificant reductions in the all-injury risk. All RCTs scored over 50 points (maximum possible score = 100), whereas all CCTs scored under 45 points. There is moderate to strong evidence that routine application of static stretching does not reduce overall injury rates. There is preliminary evidence, however, that static stretching may reduce musculotendinous injuries.
Publisher: BMJ
Date: 21-12-2010
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2010
DOI: 10.3109/03093646.2010.480964
Abstract: Stair walking relies on concentric contraction of the ankle plantarflexor and knee extensor muscles, which are either absent or weakened in transtibial utees. As a result the risk of falling is increased in this population. The aim of this study was to compare the gait patterns of transtibial utee fallers and non-fallers during stair ascent. Eleven participants (fallers = 6 non-fallers = 5) walked along a 3-m walkway and ascended a three-step staircase with handrails, at their self-selected pace, while three-dimensional kinematic data were collected from the lower limbs. A force plate was embedded into the first step and kinetic data were measured for the intact lead limb only. The fallers walked significantly faster (p = 0.00) and exhibited less hip flexion (p = 0.05) and less anterior pelvic tilt (p = 0.04) compared to the non-fallers. The fallers had significantly greater first and second peak vertical ground reaction force (GRF) on the intact limb than the non-fallers (p = 0.05 and p = 0.01, respectively) contributing to the significantly larger ankle (p = 0.02) and hip moments (p = 0.04). These findings suggested the utee non-fallers performed mechanically demanding tasks more cautiously. Two of the participants self-selected a 'step to' gait pattern, ascending one step at a time. This may be considered a compensatory mechanism for the lack of ankle mobility and functional muscle performance in these two transtibial utees.
Publisher: Springer Science and Business Media LLC
Date: 09-03-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2008
Publisher: BMJ
Date: 09-1986
Abstract: The aim of this study was to determine the effects of caffeine ingestion on estimated substrate utilisation during treadmill running at an initial level of 70%-75% of maximal oxygen consumption after which subjects ran to exhaustion. Twelve subjects undertook either a control, placebo, a small (10 mg X kg-1) or a large (15 mg X kg-1) dose of caffeine in a double-blind design to determine whether caffeine affected the substrate usage during running. Venous blood was collected prior to and during the experimental runs and was later analysed for free fatty acids (FFA), glycerol, triglycerides, lactate and glucose concentrations. The results of this experiment suggest that maximal running performance can be increased by large doses of caffeine. Furthermore, the subjects' respiratory exchange ratios were lower and FFA concentrations were higher following the ingestion of large amounts of caffeine than during other trials, suggesting that a larger proportion of energy was derived from fat being used preferentially during the trial following ingestion of this large dose of caffeine. The subjects rating of perceived exertion (RPE) were lower following the ingestion of a large dose of caffeine than it was in any of the other trials. This study differs from others in this area in so much that caffeine has been found to have positive effects during maximal running when used in large doses.
Publisher: Wiley
Date: 18-10-2021
DOI: 10.1111/SMS.14059
Abstract: Physeal injuries have been overlooked in epidemiological research in youth sports. Our prospective study investigated the incidence, severity, and burden of physeal injuries in a youth elite football academy. In total, 551 youth male football players from under‐9 to under‐19 were included and observed over four consecutive seasons. Injuries involving the physis were diagnosed and recorded according to type, location, and diagnosis. Injury incidence (II), severity (days lost), and injury burden (IB) were calculated per squad per season (25 players/squad). There were 307 physeal injuries: 262 apophyseal (85%), 26 physeal (9%), 2 epiphyseal (1%), and 17 other physeal injuries (5%) with 80% (n=245) causing time‐loss. The overall mean incidence of time‐loss physeal injuries was 6 injuries/squad‐season, leading to a total of 157 days lost/squad‐season. The U‐16s had the highest burden with 444 days lost per squad‐season [median: 20 (95% CI: 12–30) days II: 10 (95% CI: 7.3.1–13.4)]. Apophyseal injuries of the hip–pelvis resulted in the greatest burden [median: 13 (95% CI: 10–17) II: 2.5 (95% CI: 2.1–3.0)]. Peak apophyseal injury incidence per body parts occurred in U‐11 for foot–ankle (II: 2.4 95% CI: 1.0–4.9), U‐14 for knee (II: 4.5 95% CI: 2.7–7.1), and U‐17 for hip–pelvis (II: 6.4 95% CI: 4.2–9.3). Physeal injuries accounted for a quarter of all‐time loss with the largest injury burden in U‐16. Most physeal injuries involved the lower limb and affected the apophysis. Physeal and apophyseal injuries incidence, burden, and pattern vary substantially depending on age. Hip–pelvic apophyseal injuries accounted for the largest injury burden.
Publisher: Human Kinetics
Date: 2018
Abstract: The nutritional intake of ultraendurance athletes is often poorly matched with the requirements of the sport. Nutrition knowledge is a mediating factor to food choice that could correct such imbalances. Therefore, the purpose of this study was to develop and validate a questionnaire to assess the nutrition knowledge of ultraendurance athletes. Nutritional knowledge was assessed using a modified sports nutrition knowledge questionnaire (ULTRA-Q). Four independent assessors with specialization in sports nutrition confirmed the content validity of the ULTRA-Q. Registered sports nutritionists, registered dietitians, and those without nutrition training completed the ULTRA-Q on two separate occasions. After the first completion, a significant difference in nutrition scores between groups ( p ≤ .001) provided evidence of construct validity. After the second completion, intraclass correlation coefficients comparing nutrition scores between time points (.75–.95) provided evidence of test–retest reliability. Subsequently, experienced ultraendurance athletes (male: n = 74 and female: n = 27) completed the ULTRA-Q. Athletes also documented their sources of nutrition knowledge for ultraendurance events. The total nutrition knowledge score for ultraendurance athletes was 68.3% ± 9.5%, and there were no significant differences in knowledge scores between males and females (67.4% ± 9.6% and 70.7% ± 9.3%, respectively) or between runners and triathletes (69.1% ± 9.7% and 65.1% ± 9.4%, respectively). In general, it appeared that ultraendurance athletes favored other athletes (73%) over nutrition experts (8%) as a source of nutritional information. The findings of this study indicate that ultraendurance athletes had a reasonable level of nutrition knowledge, but interathlete variability suggests a need for targeted nutrition education.
Publisher: Springer Science and Business Media LLC
Date: 21-08-2021
DOI: 10.1007/S00421-021-04774-6
Abstract: As a nitric oxide (NO) enhancer, citrulline malate (CM) has recently been touted as a potential ergogenic aid to both resistance and high-intensity exercise performance, as well as the recovery of muscular performance. The mechanism has been associated with enhanced blood flow to active musculature, however, it might be more far-reaching as either ammonia homeostasis could be improved, or ATP production could be increased via greater availability of malate. Moreover, CM might improve muscle recovery via increased nutrient delivery and/or removal of waste products. To date, a single acute 8 g dose of CM on either resistance exercise performance or cycling has been the most common approach, which has produced equivocal results. This makes the effectiveness of CM to improve exercise performance difficult to determine. Reasons for the disparity in conclusions seem to be due to methodological discrepancies such as the testing protocols and the associated test–retest reliability, dosing strategy (i.e., amount and timing), and the recent discovery of quality control issues with some manufacturers stated (i.e., citrulline:malate ratios). Further exploration of the optimal dose is therefore required including quantification of the bioavailability of NO, citrulline, and malate following ingestion of a range of CM doses. Similarly, further well-controlled studies using highly repeatable exercise protocols with a large aerobic component are required to assess the mechanisms associated with this supplement appropriately. Until such studies are completed, the efficacy of CM supplementation to improve exercise performance remains ambiguous.
Publisher: Springer Science and Business Media LLC
Date: 23-03-2012
DOI: 10.1007/S00726-012-1265-3
Abstract: HSP72 is rapidly expressed in response to a variety of stressors in vitro and in vivo (including hypoxia). This project sought a hypoxic stimulus to elicit increases in HSP72 and HSP32 in attempts to confer protection to the sub-maximal aerobic exercise-induced disturbances to redox balance. Eight healthy recreationally active male subjects were exposed to five consecutive days of once-daily hypoxia (2,980 m, 75 min). Seven days prior to the hypoxic acclimation period, subjects performed 60 min of cycling on a cycle ergometer (exercise bout 1-EXB1), and this exercise bout was repeated 1 day post-cessation of the hypoxic period (exercise bout 2-EXB2). Blood s les were taken immediately pre- and post-exercise and 1, 4 and 8 h post-exercise for HSP72 and immediately pre, post and 1 h post-exercise for HSP32, TBARS and glutathione [reduced (GSH), oxidised (GSSG) and total (TGSH)], with additional blood s les obtained immediately pre-day 1 and post-day 5 of the hypoxic acclimation period for the same indices. Monocyte-expressed HSP32 and HSP72 were analysed by flow cytometry, with measures of oxidative stress accessed by commercially available kits. There were significant increases in HSP72 (P < 0.001), HSP32 (P = 0.03), GSSG (t = 9.5, P < 0.001) and TBARS (t = 5.6, P = 0.001) in response to the 5-day hypoxic intervention, whereas no significant changes were observed for GSH (P = 0.22) and TGSH (P = 0.25). Exercise-induced significant increases in HSP72 (P < 0.001) and HSP32 (P = 0.003) post-exercise in EXB1 this response was absent for HSP72 (P ≥ 0.79) and HSP32 (P ≥ 0.99) post-EXB2. The hypoxia-mediated increased bio-available HSP32 and HSP72 and favourable alterations in glutathione redox, prior to exercise commencing in EXB2 compared to EXB1, may acquiesce the disturbances to redox balance encountered during the second physiologically identical exercise bout.
Publisher: Elsevier BV
Date: 2021
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2010
Publisher: Springer Science and Business Media LLC
Date: 11-1992
DOI: 10.1007/BF00243514
Publisher: BMJ
Date: 21-05-2007
Publisher: Springer Science and Business Media LLC
Date: 1994
DOI: 10.1007/BF00599239
Publisher: Springer Science and Business Media LLC
Date: 16-06-2015
DOI: 10.1007/S00421-015-3201-1
Abstract: Sodium phosphate (SP) and beetroot juice (BJ) supplementation was assessed on repeated-sprint ability (RSA). Thirteen female team-sport participants completed four trials: (1) SP and BJ (SP + BJ), (2) SP and placebo (for BJ), (3) BJ and placebo (for SP) and (4) placebo (for SP + BJ), with ~21 days separating each trial. After each trial, participants performed a simulated team-game circuit (STGC) consisting of four 15 min quarters, with a 6 × 20-m repeated-sprint set performed at the start, half-time and end. Total sprint times were between 0.95-1.30 and 0.83-1.12 s faster for each RSA set and 3.25 and 3.12 s faster overall (~5% improvement) after SP compared with placebo and BJ, respectively (p = 0.02 for sets 1, 2 and overall Cohen's effect size: d = -0.51 to -0.90 for all sets and overall). Additionally, total sprint times were 0.48 s faster after SP + BJ compared with placebo (set 2 p = 0.05, ~2% improvement). Furthermore, best sprints were 0.13-0.23 and 0.15-0.20 s faster (~6% improvement p < 0.01) after SP compared with placebo and BJ, respectively, for all sets (d = -0.54 to -0.89). SP improved RSA in team-sport, female athletes when fresh (set 1) and during the later sets of a STGC (sets 2 and 3). Specifically, total and best sprint times were faster after SP compared with placebo and BJ.
Publisher: SAGE Publications
Date: 04-1986
DOI: 10.2466/PMS.1986.62.2.491
Abstract: 6 experienced orienteers were subject to a VO 2max treadmill test, two days prior to undertaking two tests of visual perception. One test was conducted while the subjects were in a rested state while the other was conducted while they were under a state of fatigue. Fatigue was defined as a state in which the subjects were working at or above their anaerobic threshold which had been determined previously from their VO 2max test. The tests in both the fatigue and rest condition were of a similar nature, that is, the subjects were presented slides of orienteering checkpoints at regular intervals followed by a slide showing a set of questions which the subjects had to answer verbally. Two sets of slides were employed and these were approximately counterbalanced between both subjects and conditions. Points were awarded for the correct answers and the two conditions were then compared. The Wilcoxon test for two correlated s les was used and showed a significant difference between the fatigue and rest scores at p 0.05. The data suggest that under the influence of fatigue, an orienteer's ability to perceive visual information is greatly impaired.
Publisher: Informa UK Limited
Date: 14-10-2019
DOI: 10.1080/15438627.2018.1530999
Abstract: Inadequate nutritional intake has been reported during ultra-endurance training and competition. While substandard nutritional knowledge may contribute to inappropriate nutritional choices, the relationship between these variables is often weak. As such, this study investigated the importance of a range of factors to the food choices of ultra-endurance athletes. An existing food choices questionnaire was extended to reflect the main factors proposed to influence the food choices of these athletes. The questionnaire was pilot tested with endurance athletes, during which, it was refined and reassessed for internal consistency and test-retest reliability. Subsequently, 101 experienced ultra-endurance athletes completed the amended questionnaire. Athletes also documented dietary restrictions or strategies employed in preparation for competition. The factors rated as important by the majority of the athletes were "provides me with energy", "do not cause me gastrointestinal discomfort" and, "are nutritious". Despite the high importance of the provision of energy, only 38.2% of participants reported following a high carbohydrate diet in preparation for competition. In addition, given that nutritious foods are typically high in fibre, it is likely that this factor may conflict with the avoidance of gastrointestinal discomfort. The potential incompatibility of these factors may help explain the observed suboptimal nutritional intake.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2010
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2009
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2000
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2007
DOI: 10.1519/R-20015.1
Publisher: Springer Science and Business Media LLC
Date: 04-09-2013
DOI: 10.1007/S40279-013-0094-1
Abstract: The aim of an optimal pacing strategy during exercise is to enhance performance whilst ensuring physiological limits are not surpassed, which has been shown to result in a metabolic reserve at the end of the exercise. There has been debate surrounding the theoretical models that have been proposed to explain how pace is regulated, with more recent research investigating a central control of exercise regulation. Deception has recently emerged as a common, practical approach to manipulate key variables during exercise. There are a number of ways in which deception interventions have been designed, each intending to gain particular insights into pacing behaviour and performance. Deception methodologies can be conceptualised according to a number of dimensions such as deception timing (prior to or during exercise), presentation frequency (blind, discontinuous or continuous) and type of deception (performance, biofeedback or environmental feedback). However, research evidence on the effects of deception has been perplexing and the use of complex designs and varied methodologies makes it difficult to draw any definitive conclusions about how pacing strategy and performance are affected by deception. This review examines existing research in the area of deception and pacing strategies, and provides a critical appraisal of the different methodological approaches used to date. It is hoped that this analysis will inform the direction and methodology of future investigations in this area by addressing the mechanisms through which deception impacts upon performance and by elucidating the potential application of deception techniques in training and competitive settings.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2002
Publisher: Canadian Science Publishing
Date: 04-2009
DOI: 10.1139/H08-146
Abstract: In this study, criteria are used to identify whether a subject has elicited maximal oxygen uptake. We evaluated the validity of traditional maximal oxygen uptake criteria and propose a novel set of criteria. Twenty athletes completed a maximal oxygen uptake test, consisting of an incremental phase and a subsequent supramaximal phase to exhaustion (verification phase). Traditional and novel maximal oxygen uptake criteria were evaluated. Novel criteria were: oxygen uptake plateau defined as the difference between modelled and actual maximal oxygen uptake % of the regression slope of the in idual oxygen uptake–workrate relationship as in the first criterion, but for maximal verification oxygen uptake and a difference of ≤4 beats·min –1 between maximal heart rate values in the 2 phases. Satisfying the traditional oxygen uptake plateau criterion was largely an artefact of the between-subject variation in the oxygen uptake–workrate relationship. Secondary criteria, supposedly an indicator of maximal effort, were often satisfied long before volitional exhaustion, even at intensities as low as 61% maximal oxygen uptake. No significant mean differences were observed between the incremental and verification phases for oxygen uptake (t = 0.4 p = 0.7) or heart rate (t = 0.8 p = 0.5). The novel oxygen uptake plateau criterion, maximal oxygen uptake verification criterion, and maximal heart rate verification criterion were satisfied by 17, 18, and 18 subjects, respectively. The small in idual absolute differences in oxygen uptake between incremental and verification phases observed in most subjects provided additional confidence that maximal oxygen uptake was elicited. Current maximal oxygen uptake criteria were not valid and novel criteria should be further explored.
Publisher: Informa UK Limited
Date: 2011
DOI: 10.1080/0308353
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2016
DOI: 10.1519/JSC.0000000000001437
Abstract: Mosher, SL, Sparks, SA, Williams, EL, Bentley, DJ, and Mc Naughton, LR. Ingestion of a nitric oxide enhancing supplement improves resistance exercise performance. J Strength Cond Res 30 (12): 3520–3524, 2016—Studies have established that supplementation of nitrate increases nitric oxide which in turn improves exercise performance. The current study aimed to investigate the effects of nitrate ingestion on performance of bench press resistance exercise until failure. Twelve recreationally active (age, 21 ± 2 years, height, 177.2 ± 4.0 cm, weight, 82.49 ± 9.78 kg) resistance-trained men participated in the study. The study used a double-blind, randomized cross-over design, where participants ingested either 70 ml of “BEET It Sport” nitrate shot containing 6.4 millimoles (mmol −1 ·L −1 ) or 400 mg of nitrate or a blackcurrant placebo drink. Participants completed a resistance exercise session, consisting of bench press exercise at an intensity of 60% of their established 1 repetition maximum (1RM), for 3 sets until failure with 2 minutes rest interval between sets. The repetitions completed, total weight lifted, local and general rate of perceived exertion (RPE), and blood lactate were all measured. The results showed a significant difference in repetitions to failure ( p ≤ 0.001) and total weight lifted ( p ≤ 0.001). However, there were no significant difference between blood lactate over the 2 trials ( p = 0.238), and no difference in Local ( p = 0.807) or general ( p = 0.420) indicators of fatigue as measured by RPE. This study demonstrates that nitrate supplementation has the potential to improve resistance training performance and work output compared with a placebo.
Publisher: Informa UK Limited
Date: 2001
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2017
Publisher: Springer Science and Business Media LLC
Date: 08-12-2010
DOI: 10.1007/S00421-010-1756-4
Abstract: Growth hormone (GH) is a commonly used drug aimed at improving sport performance. The aim of this study is to evaluate the immunomodulatory effects of short-term administration of recombinant GH (rhGH) in healthy young males. NK cell number, activity and phenotype, T cell number, CD4(+) (Th1/Th2) cytokine production of IL2, IL4, IL6, IL10, TNF-α and IFN-γ and CD4(+)/CD8(+) ratio with particular attention to the possible correlation to IGF-I production were investigated. 30 males (27 ± 9 years) were randomly assigned to placebo (n = 15) or drug (rhGH) 1 mg/day groups (n = 15) with daily injection for 7 days. IGF-I plasma concentration and flow cytometry data were generated at baseline and days 8, 15, 22 and 29 post injection. Data analysis used General Linear Model with repeated measures, Bonferroni correction factor and significance at p ≤ 0.05. Serum IGF-I levels (ng/mL) increased significantly (p ≤ 0.01) on day 8 (0.48 ± 0.78) after injections compared to baseline (0.31 ± 0.07) and days 15 (0.33 ± 0.06), 22 (0.29 ± 0.05) and 29 (0.29 ± 0.06). A significant time effect was noted in IL10 secretion (pg/mL) from day 15 (P = 35.14 ± 19.93, rhGH = 26.63 ± 16.39) to days 22 (P = 61.32 ± 20.41, rhGH = 74.99 ± 46.91) and 29 (P = 101.98 ± 67.25, rhGH = 107.74 ± 122.58). There was no correlation between IGF-I and NK activity, phenotype or number along with T lymphocyte number, CD4(+)/CD8(+) ratio or Th1 and Th2 cytokine production. In conclusion, cytokine secretion spectrum was not affected by short-term rhGH administration in young males.
Publisher: Elsevier BV
Date: 2010
DOI: 10.1016/J.JSAMS.2008.11.006
Abstract: This study investigated the effects of low or high glycaemic index (GI) foods consumed prior to a 40 km time trial (TT) on metabolism and subsequent endurance performance. Ten male cyclists consumed high GI or low GI meals, providing 1 g kg(-1) body mass of carbohydrate, 45 min prior to the TT. The TT performance was significantly (p=0.009) improved in the low (93+/-8 min) compared to the high GI trial (96+/-7 min). Low GI carbohydrate oxidation rate (2.51+/-1.71 g min(-1)) was higher (p=0.003) than the HGI carbohydrate oxidation rate (2.14+/-1.5 g min(-1)). Fat oxidation rate was significantly higher (p=0.002) for the high (0.27+/-0.17 g min(-1)) than the low GI trial (0.16+/-0.14 g min(-1)). Insulin rose significantly following the high compared to the low GI meal (p=0.008) but dropped significantly to similar values throughout the TT. No significant differences in either TGA or FFA concentration were observed between the trials. The low GI meal led to an increase in the availability of carbohydrate and a greater carbohydrate oxidation throughout the exercise period, which may have sustained energy production towards the end of exercise and led to the improved TT performance observed.
Publisher: Georg Thieme Verlag KG
Date: 1999
Abstract: The aim of this present study was to evaluate the effect of the number of submaximal exercise bouts used to construct the power-VO2 regression, on calculations of MAOD through the sequential and systematic removal of the highest and lowest submaximal VO2 values from the standard ten point regression line. Eight trained male cyclists participated in this study. The mean (+/- SD) age, height, weight and VO2max for the subjects were 25+/-7 yr, 178.2+/-3.0 cm, 69.9+/-4.9 kg and 57.5+/-6.9 ml x kg(-1) x min(-1). After VO2max testing each subject undertook ten submaximal exercise bouts at between 30% and 90% VO2max and one supramaximal bout calculated to elicit 100% VO2max. Expired gases were measured via open circuit spirometry. The mean power output of the supramaximal bout was 336.5+/-442.5 W and the mean duration was 269.4+/-42.9 s. The correlation coefficients ranged from 0.981 to 0.996 while the MAOD values ranged from 29.6+/-15.7 ml O2 eq x kg(-1) to 61.3+/-44.7 ml O2 eq x kg(-1). When compared to the standard ten points, as a percentage difference, this difference ranged from 4.1+/-3.6% to 83.7+/-54.9%. The main finding of this study is that inaccuracies occur in the measurement of MAOD when less than ten points are used in the calculation. Further study is required for the development of a standardised protocol for the accurate, valid and reliable measurement of MAOD.
Publisher: Springer Science and Business Media LLC
Date: 09-05-2020
DOI: 10.1007/S00421-020-04387-5
Abstract: Enteric-coated sodium bicarbonate (NaHCO 3 ) can attenuate gastrointestinal (GI) symptoms following acute bicarbonate loading, although the subsequent effects on exercise performance have not been investigated. The purpose of this study was to examine the effects of enteric-coated NaHCO 3 supplementation on high-intensity exercise performance and GI symptoms. Eleven trained male cyclists completed three 4 km time trials after consuming a placebo or 0.3 g∙kg –1 body mass NaHCO 3 in enteric-coated or gelatin capsules. Exercise trials were timed with in idual peak blood bicarbonate ion concentration ([HCO 3 – ]). Blood acid–base balance was measured pre-ingestion, pre-exercise, and post-exercise, whereas GI symptoms were recorded pre-ingestion and immediately pre-exercise. Pre-exercise blood [HCO3 − ] and potential hydrogen (pH) were greater for both NaHCO 3 conditions ( P 0.0005) when compared to placebo. Performance time was faster with enteric-coated (− 8.5 ± 9.6 s, P = 0.044) and gelatin (− 9.6 ± 7.2 s, P = 0.004) NaHCO 3 compared to placebo, with no significant difference between conditions (mean difference = 1.1 ± 5.3 s, P = 1.000). Physiological responses were similar between conditions, although blood lactate ion concentration was higher with gelatin NaHCO 3 (2.4 ± 1.7 mmol∙L –1 , P = 0.003) compared with placebo. Furthermore, fewer participants experienced GI symptoms with enteric-coated ( n = 3) compared to gelatin ( n = 7) NaHCO 3 . Acute enteric-coated NaHCO 3 consumption mitigates GI symptoms at the onset of exercise and improves subsequent 4 km cycling TT performance. Athletes who experience GI side-effects after acute bicarbonate loading may, therefore, benefit from enteric-coated NaHCO 3 supplementation prior to exercise performance.
Publisher: Georg Thieme Verlag KG
Date: 07-01-2013
Abstract: The aim of this study was to determine the external validity of Taekwondo-specific exercise protocols. 10 male international Taekwondo competitors (age 18±2 years) took part in a ch ionship combat and an exercise protocol that simulated the activity pattern of Taekwondo combat. Heart rate and venous blood s les were obtained in both settings. Despite similarity in the activity profiles, the ch ionship Taekwondo combats elicited higher (p<0.05) heart rate (188±8 beats.min - 1), plasma lactate (12.2±4.6 mmol.L - 1), glucose (10.3±1.1 mmol.L - 1), -glycerol (143.4±49.4 µmol.L - 1), -adrena-line (2.7±1.7 nmol.L - 1) and noradrenaline (14.3±9.4 nmol.L - 1) responses than the -Taekwondo exercise protocol (heart rate: 172±4 beats.min - 1 plasma lactate: 3.6±2.7 mmol.L - 1 glucose: 5.9±0.8 mmol.L - 1 glycerol: 77.7±21.3 µmol.L - 1 adrenaline: 0.6±0.2 nmol.L - 1 and noradrenaline: 3.0±1.1 nmol.L - 1). This discrepancy in the physiological responses appeared to be mediated by a reduced stress response in the Taekwondo exercise protocol. These findings suggest that Taekwondo-specific exercise protocols are not appropriate to study the physiological demands of Taekwondo. -Strategies designed to increase the stress response in this setting may be necessary to improve the external validity of this experimental framework.
Publisher: Routledge
Date: 2015
Publisher: Springer Science and Business Media LLC
Date: 1992
DOI: 10.1007/BF00376437
Abstract: Desbuquois dysplasia is a rare autosomal recessive chondrodysplasia characterised by short stature, joint laxity, facial dysmorphism, a "Swedish key" appearance of the proximal femur, advanced carpal and tarsal bone age, and hand anomalies consisting of phalangeal dislocations and an extra ossification centre distal to the second metacarpal. However, the latter changes are not consistently observed in all Desbuquois patients, defining two distinct groups, based on the presence or absence of hand anomalies. We have performed a genome wide search in four inbred Desbuquois families with typical hand anomalies originating from France, Sri-Lanka, the United Arab Emirates, and Morocco. Here, we report on the mapping of a disease gene to chromosome 17q25.3 (Zmax=4.61 at theta=0 at locus D17S1806) in the 9.5 cM interval defined by loci D17S802 and D17S1822. The present study supports the genetic homogeneity of the clinical subtype with hand anomalies and will hopefully help in identifying the Desbuquois dysplasia gene.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2009
Publisher: Informa UK Limited
Date: 10-1992
DOI: 10.1080/02640419208729940
Abstract: Nine healthy male subjects who were all participating in athletic events volunteered to take part in this study, the aim of which was to determine whether there are specific dosages of sodium bicarbonate (HCO3-) that are useful as an ergogenic aid as far as anaerobic performance times are concerned. A control, placebo (CaCO3 500 mg kg-1) and five dosages of bicarbonate (100, 200, 300, 400 and 500 mg kg-1) were used. The anaerobic test consisted of pedalling a Repco Exertech cycle ergometer for 1 min during which total work (kJ) and peak power (W) were measured. The subjects completed more work in the 200 (P < 0.05), 300, 400 and 500 mg kg-1 (P < 0.005) trials with most work being undertaken in the 300 mg kg-1 trial (41.9 kJ min-1). Peak power was not significantly different from the control until the 300 mg kg-1 dose, and there were no further changes from this with increasing doses of HCO3-. The highest level of peak power achieved was 1295 +/- 72.8 W at the 300 mg kg-1 dosage. Blood pH indicated that after ingestion of all but the 100 mg kg-1 dose, a state of alkalosis was achieved (P < 0.005), and this was also indicated by changes in base excess. Bicarbonate levels increased post-ingestion in all but the 100 mg kg-1 dose, with these changes reflecting the changes that occurred in the work output. Blood lactate (BLa) levels increased post-exercise (P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
Publisher: Informa UK Limited
Date: 10-1992
DOI: 10.1080/02640419208729941
Abstract: Four groups of male subjects participated in anaerobic testing on a Repco EX10 cycle ergometer to determine the effectiveness of sodium bicarbonate (0.3 g kg-1 body mass) as an ergogenic aid during exercise of 10, 30, 120 and 240 s duration. Blood was collected 90 min prior to ingestion of sodium bicarbonate (NaHCO3), after ingestion of NaHCO3 and immediately post-exercise from a heated (43-46 degrees C) fingertip and analysed immediately post-collection for pH, base excess, bicarbonate and lactate. The total work undertaken (kJ) and peak power achieved during the tests were also obtained via a Repco Work Monitor Unit. Blood bicarbonate levels were again increased above the control and placebo conditions (P < 0.001) and blood lactate levels were also increased following the bicarbonate trials. The pH levels fell significantly (P < 0.05) below the control and placebo conditions in all trials. The results indicate that NaHCO3 at this dosage has no ergogenic benefit for work of either 10 or 30 s duration, even though blood bicarbonate levels were significantly increased (P < 0.05) following ingestion of NaHCO3. For work periods of 120 and 240 s, performance was significantly increased (P < 0.05) above the control and placebo conditions following NaHCO3 ingestion.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2008
Publisher: Informa UK Limited
Date: 08-03-2019
DOI: 10.1080/15438627.2019.1586707
Abstract: This study evaluated the chronic effects of nitrate (NO
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2015
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2014
Publisher: Georg Thieme Verlag KG
Date: 21-01-2015
Abstract: This work sought to determine the fitness responses and energy expenditure (EE) following once-weekly hill climbing for 16 weeks on different slopes. A cohort of 98 healthy, sedentary subjects (49 female, 49 male) completed the program at their preferred climbing pace. Body composition, resting metabolic rate (RMR) and VO2max were measured. EE was measured on 4 slopes (11.6°, 19.9°, 14.9°, and 28.6°) at the subjects' preferred speed. In males, weight, body mass index, fat mass significantly decreased (P<0.05), and RMR showed an increasing trend, but the difference was not significant (P=0.051). In females, the muscle mass increased significantly, and fat (%) and fat mass significantly decreased (P<0.05). Absolute and relative of VO2max, ventilation (VE) improved significantly in both sexes (P<0.01). Energy expenditure was similar on different slopes, but shows gender-specific values of approximately 50.4 and 33.6 kJ/min for males and females, respectively. The regression equation of EE (kJ/min)=[1.724×(female=1, and male=2)+(-0.072×age)+0.106×weight+0.024×HR+0.136×slope+1.487×velocity]×4.2. In conclusion, hill climbing at a subjects' preferred velocity is a vigorous-intensity physical activity for energy cost and, performed once weekly, enhances cardiorespiratory fitness and reduces fat mass, therefore making it a viable exercise for most people.
Publisher: Springer Science and Business Media LLC
Date: 12-1990
DOI: 10.1007/BF00236058
Publisher: Informa UK Limited
Date: 2006
DOI: 10.1080/15438620500528257
Abstract: The aim of this study was to quantify response to a soccer-specific intermittent (INT) treadmill protocol based on notational analysis of match-play. Ten male semiprofessional football players (age 24.7 +/- 4.4 yr, body mass 77.1 +/- 8.3 kg, VO2max 63.0 +/- 4.8 ml x kg x min(-1)) completed the 90 minute INT protocol and a steady-state (SS) protocol eliciting the same distance covered. Physiological (heart rate [HR], ratings of perceived exertion [RPE], blood lactate concentration, salivary cortisol concentration) and mechanical (electromyography [EMG] of biceps femoris and rectus femoris) responses were obtained at 15 minute intervals throughout each protocol. The physiological and mechanical responses were typically greater during the INT protocol than during the SS protocol, tending to increase as a function of exercise duration. The INT activity profile induces cumulative mechanical load on the musculoskeletal system. The increased incidence of injury toward the latter stages of match-play is attributed to compromised movement mechanics, rather than physiological strain.
Publisher: Springer Science and Business Media LLC
Date: 08-1999
Abstract: We have evaluated whether sodium bicarbonate, taken chronically (0.5 g x kg(-1) body mass) for a period of 5 days would improve the performance of eight subjects during 60 s of high-intensity exercise on an electrically braked cycle ergometer. The first test was performed prior to chronic supplementation (pre-ingestion) while the post-ingestion test took place 6 days later. A control test took place approximately 1 month after the cessation of all testing. Acid-base and metabolite data (n = 7) were measured from arterialised blood both pre- and post-exercise, as well as daily throughout the exercise period. The work completed by the subjects in the control and pre-ingestion test [21.1 (0.9) and 21.1 (0.9) MJ, respectively] was less than (P<0.05) that completed in the post-ingestion test [24.1 (0.9) MJ F(2,21) = 3.4, P<0.05, power = 0.57]. Peak power was higher after the 5-day supplementation period (P<0.05). Ingestion of the sodium bicarbonate for a period of 5 days resulted in an increase in pH (F(5,36) = 12.5, P<0.0001, power = 1.0) over the 5-day period. The blood bicarbonate levels also rose during the trial (P<0.05) from a resting level of 22.8 (0.4) to 28.4 (1.1) mmol x l(-1) after 24 h of ingestion. In conclusion, the addition of sodium bicarbonate to a normal diet proved to be of ergogenic benefit in the performance of short-term, high-intensity work.
Publisher: Informa UK Limited
Date: 25-09-2013
DOI: 10.1080/15438627.2013.825796
Abstract: Dehydration has been shown to augment cellular stress. Glycerol hyperhydration can delay dehydration, which may decrease the level of pre- and post-exercise oxidative stress. This study aimed to compare the effects of glycerol (G) or water (W) hyperhydration with no hyperhydration (C) on oxidative stress, thermoregulation, and cycle performance. Seven trained males consumed 1.2 g of glycerol·kg⁻¹ body mass (BM) in 26 ml·kg⁻¹ BM water or equal volume water to achieve hyperhydration followed by a 90 min time trial. Total glutathione increased post exercise (PE) in all trials (p < 0.01), while oxidized glutathione (p < 0.05) and protein carbonyl concentrations (p < 0.001) were increased PE for the C trial only. Mean body temperature and heart rate increased with exercise but were not different between interventions. Total distance covered and power outputs were not different between interventions. Fluid intake attenuated oxidative stress but did not enhance thermoregulation or performance.
Publisher: Georg Thieme Verlag KG
Date: 04-2007
Abstract: Previous studies have reported large between-subject variations in the time to exhaustion during intermittent running at the velocity at V(.-)O (2max) (vV(.-)O (2max)). This study aimed to determine which physiological factors contribute to this variability. Thirteen male runners (age 38.9 +/- 8.7 years) each completed five treadmill running tests two incremental tests to determine V(.-)O (2max), vV(.-)O (2max), the lactate threshold velocity (vLT) and the running velocity--V(.-)O (2) relationship the third test to determine the time to exhaustion during continuous running at vV(.-)O (2max) (t (lim)cont) the fourth to determine the maximal accumulated oxygen deficit (MAOD) the fifth to determine the time to exhaustion during intermittent running at vV(.-)O (2max) (t (lim)int). Relief intervals during the intermittent test were run at 70 % vV(.-)O (2max). The vLT-vV(.-)O (2max) difference was significantly correlated with t (lim)int (r = - 0.70 p = 0.007). The correlation coefficient increased to r = - 0.83 (p < 0.001) when the difference between the relief interval velocity and the vLT was deducted from the vLT-vV(.-)O (2max) difference (theoretically representing the net depletion of the MAOD during each work/relief interval cycle). The main finding of this study was that 49 % of the variance in t (lim)int was explained by the vLT-vV(.-)O (2max) difference, compared to 74 % for t (lim)cont. However, a further 20 % of unique variance in t (lim)int could be explained with the inclusion of the relief interval velocity-vLT difference. Theoretically, runners with the largest relief interval velocity-vLT difference will replete their anaerobic capacity to a greater extent during each relief interval, thereby increasing time to exhaustion.
Publisher: Frontiers Media SA
Date: 08-05-2018
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2007
Publisher: Informa UK Limited
Date: 09-12-2017
DOI: 10.1080/15438627.2016.1258645
Abstract: This study determined variability in time-to-peak pH after consumption of 300 mg kg
Publisher: Informa UK Limited
Date: 02-12-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2006
Publisher: Georg Thieme Verlag KG
Date: 11-2007
Abstract: Effects of methodological differences on the determination of time at VO (2max) (t (VO2max)) during intermittent treadmill running were investigated. Subjects performed three incremental tests to volitional exhaustion: a continuous protocol with 1-min stages (Cont-INC ([1-min])), and two discontinuous protocols of 2-min (Dis-INC ([2-min])) and 3-min (Dis-INC ([3-min])) stage durations. For each test, VO (2max) and the running velocity associated with V.O (2max) (vVO (2max)) were determined. On a fourth visit, subjects performed an intermittent test with 30-s work and relief intervals run at 105 % and 60 %, respectively, of the vV. (2max) determined during Cont-INC ((1-min)). The t (VO2max) during the intermittent test was determined using three different criteria: VO (2) data points > or = 100 % VO (2max) determined in Cont-INC ((1-min)) (t (VO2max[100 %])), > or = 95 % VO (2max) (t (VO2max[95 %])) and > or = VO (2max) minus 2.1 ml . kg (-1) . min (-1) (t (VO2max[- 2.1])). The V.O (2max) means (SD) for Cont-INC ((1-min)), Dis-INC ((2-min)) and Dis-INC ((3-min)) were 4093 (538), 4096 (516), and 3980 (488) mL . min (-1), respectively. The t (VO2max) means (SD) were: t (VO2max(100 %)) 163 (227) s, t (VO2max(95 %)) 418 (439) s, and t (VO2max(- 2.1)) 358 (395) s. All differences in t (V.O2max) were significantly different (p < 0.05). Differences in t (VO2max) due to using V.O (2max) values derived from using different V.O (2) time-averages were significantly different (p < 0.05). Methodological differences should be considered during interpretation of previous studies.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2007
DOI: 10.1007/S00726-007-0004-7
Abstract: Heat shock proteins (Hsp) are well known to be expressed in response to a range of cellular stresses. They are known to convey protection against protein denaturation and a subsequent immediate stress. Inducible heat shock protein 70 (Hsp70) is among the most studied of these stress proteins and its role and function are discussed here in terms of thermal and in particular exercise preconditioning. Preconditioning has been shown to confer cellular protection via expression Hsp, which may be of benefit in preventing protein damage following subsequent periods of exercise. Many studies have used animal models to gather data on Hsp70 and these and the most recent human studies are discussed.
Publisher: Georg Thieme Verlag KG
Date: 19-03-2009
Abstract: This study aimed to analyse the effect of age on muscle peak torque (PT), and Hamstring (H): Quadricep (Q) ratio in elite youth footballers. To date, no study has considered age-group playing level and pubertal development in this population. One hundred and fifty-seven elite youth footballers in the age groups U12 to U18 volunteered to participate in this study, 133 of these were further grouped for pubertal development. Prior to testing subjects completed separate familiarisation, a three minute cycle ergometer warm up (resistance 50-60W), and two sub-maximal repetitions. Concentric and eccentric isokinetic PT measures for reps 2-4 of H and Q muscle action were taken at 60 degrees s (-1). From this, conventional and functional H: Q ratio was calculated along with dominant: non dominant ratio for the concentric Q and H, and eccentric H conditions. Significant main effects were observed for the age ubertal development group and PT in all muscles and conditions (P<0.05). Of particular interest was a significant main effect for age and Functional H: Q (P<0.05), which suggested a move away from equality at U18. Our study provides normative data for coaches, trainers and clinicians working with youth footballers and may also have connotations for injury prevention and performance.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2000
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2017
Publisher: Georg Thieme Verlag KG
Date: 02-2002
DOI: 10.1055/S-2002-20133
Abstract: This study aimed to compare the performance of a new portable lactate analyser against other standard laboratory methods in three conditions, normal (20 +/- 1.3 degrees C 40 +/- 5 % RH), hot (40 +/- 2.5 degrees C 40 +/- 5 % RH), and humid (20 +/- 1.1 degrees C 82 +/- 6 % RH) conditions. Seven healthy males, ([Mean +/- SE]: age, 26.3 +/- 1.3 yr height, 177.7 +/- 1.6 cm weight, 77.4 +/- 0.9 kg, .VO(2)max, 56.1 +/- 1.9 ml x kg x min(-1)) undertook a maximal cycle ergometry test to exhaustion in the three conditions. Blood was taken every 3 min at the end of each stage and was analysed using the Lactate Pro LT-1710, the Accusport, the Analox GM7 and the Kodak Ektachem systems. The MANOVA (Analyser Type x Condition x Workload) indicated no interaction effect (F(42,660), = 0.45, p > 0.99, Power = 0.53). The data across all workloads indicated that the machines measured significantly differently to each other (F(4,743) = 14.652, p < 0.0001, Power = 1.00). The data were moderately to highly correlated. We conclude that the Lactate Pro is a simple and effective measurement device for taking blood lactate in a field or laboratory setting. However, we would caution against using this machine to compare data from other machines.
Publisher: SAGE Publications
Date: 10-1998
DOI: 10.2466/PMS.1998.87.2.575
Abstract: The purpose of this study was to identify the most accurate predictor of VO 2 max from a variety of running tests. 32 young adult male undergraduates of (mean ± SE) age 20.14 ± 0.34 yr., height 179.4 ± 1.8 cm, weight 73.7±2.8 kg, and VO 2 max 57.89 ± 1.1 ml · kg −1 · min. −1 were randomly tested on four different predictive VO 2 max running tests to assess their actual VO 2 max, based on a continuous, progressive treadmill protocol and obtained via gas analysis. The four tests consisted of a treadmill jogging test, 1.5 mile run, Cooper's 12-min. run, and the 20-m progressive shuttle-run test. An analysis of variance applied to means indicated significance. Post hoc analysis between the means with correction by Scheffé showed significant difference between the predictive submaximal treadmill jogging test and the 12-min. run but no other difieren .es. The strength of the relationship between predictive tests and VO 2 max varied, wit 1 the 12-min run having the highest correlation of .87, followed by the 1.5 mile rur .87, 20-m progressive shuttle run .82, and the treadmill jogging test .50. The 12-min. run had the highest correlation of all tests with VO 2 max in young men, with active to trained levels of fitness. The 1.5 mile and 20-m shuttle run also provided accurate predictions of VO 2 max and so should be used for an accurate prediction of young men's VO 2 max.
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.JSAMS.2015.02.004
Abstract: The purpose of this study was to investigate excess postexercise oxygen consumption (EPOC) induced by isocaloric bouts of continuous and intermittent running and cycling exercise. This was a counterbalanced randomized cross-over study. Ten healthy men, aged 23-34yr, performed six bouts of exercise: (a) two maximal cardiopulmonary exercise tests for running and cycling to determine exercise modality-specific peak oxygen uptake (VO2peak) and (b) four isocaloric exercise bouts (two continuous bouts expending 400kcal and two intermittent bouts split into 2×200kcal) performed at 75% of the running and cycling oxygen uptake reserve. Exercise bouts were separated by 72h and performed in a randomized, counter-balanced order. The VO2 was monitored for 60-min postexercise and for 60-min during a control non-exercise day. The VO2 was significantly greater in all exercise conditions compared to the control session (P<0.001). The combined magnitude of the EPOC from the two intermittent bouts was significantly greater than that of the continuous cycling (mean difference=3.5L, P=0.001) and running (mean difference=6.4L, P<0.001). The exercise modality had a significant effect on net EPOC, where running elicited a higher net EPOC than cycling (mean difference=2.2L, P<0.001). Intermittent exercise increased the EPOC compared to a continuous exercise bout of equivalent energy expenditure. Furthermore, the magnitude of EPOC was influenced by exercise modality, with the greatest EPOC occurring with isocaloric exercise involving larger muscle mass (i.e., treadmill running vs. cycling).
Publisher: Springer Science and Business Media LLC
Date: 1988
DOI: 10.1007/BF00691236
Abstract: World population growth will be increasingly concentrated in the urban areas of the developing world however, some scholars caution against the oversimplification of African urbanization noting that there may be "counter-urbanization" and a prevailing pattern of circular rural-urban migration. The aim of the paper is to examine the ongoing urban transition in South Africa in the post-apartheid period, and to consider the health and social policy implications of prevailing migration patterns. Two data sets were analysed, namely the South African national census of 2001 and the Agincourt health and demographic surveillance system. A settlement-type transition matrix was constructed on the national data to show how patterns of settlement have changed in a five-year period. Using the sub-district data, permanent and temporary migration was characterized, providing migration rates by age and sex, and showing the distribution of origins and destinations. The comparison of national and sub-district data highlight the following features: urban population growth, particularly in metropolitan areas, resulting from permanent and temporary migration prevailing patterns of temporary, circular migration, and a changing gender balance in this form of migration stepwise urbanization and return migration from urban to rural areas. Policy concerns include: rural poverty exacerbated by labour migration explosive conditions for the transmission of HIV labour migrants returning to die in rural areas and the challenges for health information created by chronically ill migrants returning to rural areas to convalesce. Lastly, suggestions are made on how to address the dearth of relevant population information for policy-making in the fields of migration, settlement change and health.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-1999
DOI: 10.1097/00005768-199906000-00019
Abstract: The aim of this study was to determine the effects of a 4-wk in idualized training program using Vmax as the exercise intensity and utilizing between 60 and 75% of a subject's Tmax as the exercise duration. Five male, middle-distance, trained subjects with the following characteristics (mean +/- SD): age, 22.8 +/- 4.5 yr height, 181 +/- 4.7 cm weight, 74.1 +/- 3.2 kg skinfolds based on five areas, 35.9 +/- 3.9 and VO2max, 61.5 +/- 6.1 mL O2 x kg min(-1) volunteered to participate in this study. Before the training program, the subjects completed a 3000-m time trial, and three each of VO2max/Vmax and Tmax tests. Subjects then completed a 4-wk training program on the treadmill and were then retested on the VO2max/Vmax and Tmax tests. Pretraining versus posttraining results showed significant (P < 0.05) increases in average Vmax (20.5 km x h(-1) vs 21.3 km x h(-1) posttraining), Tmax (225.5 s vs 300.9 s posttraining), and VO2max (61.5 mL O2 x kg x min(-1) vs 64.5 mL O2 x kg x min(-1)). The 3000-m time trial decreased significantly from a pretraining value of 616.6 s to a posttraining value of 599.6 s (P < 0.05). The results of this study indicate that by utilizing between 60 and 75% of Tmax as an exercise duration and using Vmax as an exercise intensity that these two parameters can be extremely valuable in the prescription of exercise programs for athletes.
Publisher: Journal of Athletic Training/NATA
Date: 02-2015
DOI: 10.4085/1062-6050-49.3.57
Abstract: Successful training involves structured overload but must avoid the combination of excessive overload and inadequate recovery. The aim of this study was to determine the incidence of functional overreaching (FOR), nonfunctional overreaching (NFOR), and overtraining syndrome in elite female wrestlers during their normal training and competition schedules and to explore the utility of blood markers for the early detection of overreaching. Classification of FOR, NFOR, and overtraining syndrome was based on the European Congress of Sports Medicine position statement. Case series. China Institute of Sport Science. Over an 8-year period, 114 wrestlers from the women's Asian wrestling team were monitored to help identify if and when they experienced FOR, NFOR, or overtraining syndrome. Creatine kinase, hemoglobin, testosterone, and cortisol were measured throughout the period to identify whether wrestlers were outside the reference intervals (constructed from normal recovery data) during periods of overreaching and not overreaching. Among the 114 athletes, there were 13 (3.6%) instances of FOR, 23 (6.4%) instances of NFOR, and 2 (0.6%) instances of overtraining syndrome. The diagnostic sensitivity for FOR was 38%, 15%, 45%, and 18% for creatine kinase, hemoglobin, testosterone, and cortisol, respectively. The diagnostic sensitivity for NFOR was 29%, 33%, 26%, and 35% for creatine kinase, hemoglobin, testosterone, and cortisol, respectively. Specificity was 79%, 88%, 90%, and 82% for creatine kinase, hemoglobin, testosterone, and cortisol, respectively. Post hoc analysis showed no mean differences in creatine kinase (F = 0.5, P = .47), hemoglobin (F = 3.8, P = .052), testosterone (F = 0.2, P = .62), or cortisol (F = 0.04, P = .85) between monitoring periods when wrestlers were and were not diagnosed with FOR and NFOR. Coaches and sports scientists should not use single blood variables as markers of overreaching in elite female wrestlers.
Publisher: The Endocrine Society
Date: 10-2012
DOI: 10.1210/EN.2012-1463
Abstract: Thyroid hormone (TH) is essential for vertebrate brain development. Most research on TH and neuronal development focuses on late development, mainly the perinatal period in mammals. However, in human infants neuromotor development correlates best with maternal TH levels in the first trimester of pregnancy, suggesting that TH signaling could affect early brain development. Studying TH signaling in early embryogenesis in mammals is experimentally challenging. In contrast, free-living embryos, such as Xenopus laevis, permit physiological experimentation independent of maternal factors. We detailed key elements of TH signaling: ligands, receptors (TR), and deiodinases during early X. laevis development, before embryonic thyroid gland formation. Dynamic profiles for all components were found. Between developmental stages 37 and 41 (~48 h after hatching, coincident with a phase of continuing neurogenesis) significant increases in T(3) levels as well as in mRNA encoding deiodinases and TR occurred. Exposure of embryos at this developmental stage for 24 h to either a TH antagonist, NH-3, or to tetrabromobisphenol A, a flame retardant and known TH disruptor, differentially modulated the expression of a number of TH target genes implicated in neural stem cell function or neural differentiation. Moreover, 24-h exposure to either NH-3 or tetrabromobisphenol A diminished cell proliferation in the brain. Thus, these data show first, that TH signaling exerts regulatory roles in early X. laevis neurogenesis and second, that this period represents a potential window for endocrine disruption.
Publisher: Elsevier BV
Date: 07-2015
DOI: 10.1016/J.JSAMS.2014.07.003
Abstract: Whilst the presence of a competitor has been found to improve performance, the mechanisms influencing the change in selected work rates during direct competition have been suggested but not specifically assessed. The aim was to investigate the physiological and psychological influences of a visual avatar competitor during a 16.1-km cycling time trial performance, using trained, competitive cyclists. Randomised cross-over design. Fifteen male cyclists completed four 16.1km cycling time trials on a cycle ergometer, performing two with a visual display of themselves as a simulated avatar (FAM and SELF), one with no visual display (DO), and one with themselves and an opponent as simulated avatars (COMP). Participants were informed the competitive avatar was a similar ability cyclist but it was actually a representation of their fastest previous performance. Increased performance times were evident during COMP (27.8±2.0min) compared to SELF (28.7±1.9min) and DO (28.4±2.3min). Greater power output, speed and heart rate were apparent during COMP trial than SELF (p<0.05) and DO (p≤0.06). There were no differences between SELF and DO. Ratings of perceived exertion were unchanged across all conditions. Internal attentional focus was significantly reduced during COMP trial (p<0.05), suggesting reduced focused on internal sensations during an increase in performance. Competitive cyclists performed significantly faster during a 16.1-km competitive trial than when performing maximally, without a competitor. The improvement in performance was elicited due to a greater external distraction, deterring perceived exertion.
Publisher: Springer Science and Business Media LLC
Date: 12-10-2007
DOI: 10.1007/S00726-007-0507-2
Abstract: The purpose of this study was to delineate the effects of hyperthermia and physical exercise on the heat shock protein 70 (HSP70) response in circulating peripheral blood mononuclear cells (PBMCs). Six healthy, young (age: 24 +/- 3 yrs), moderately trained males (VO(2max): 48.9 +/- 2.7 ml x kg x min(-1)) undertook two experimental trials in a randomised fashion in which the core temperature (T (c)) was increased and then maintained at 39 degrees C during a 90 min bout by either active (AH) or passive (PH) means. AH involved subjects cycling at 90% of their lactate threshold in attire designed to impede heat loss mechanisms. In the PH trial, subjects were immersed up to the neck in a hot bath (40.2 +/- 0.4 degrees C), once the critical T (c) was achieved, intermittent cycling and water immersions were prescribed for the AH and PH conditions, respectively, to maintain the T (c) at 39 degrees C. HSP70 was measured intracellularly pre, post and 4 h after trials, from circulating PBMCs using an ELISA technique. T (c) reached 39 degrees C quicker in PH than during AH trials (PH: 21 +/- 4 min vs. AH: 39 +/- 6 min P 0.05). AH induced a marked leukocytosis in all sub-sets (P < 0.05). PH generated significant monocytosis and granulocytosis (P 0.05). There were no significant increases in intracellular HSP70 at 0 h (AH: Delta - 21.1 +/- 44.8 PH: Delta + 12.5 +/- 32.4 ng/mg TP/10(3)/microl PBMCs P > 0.05) and 4 h (AH: Delta - 30.0 +/- 40.1 PH: Delta + 36.3 +/- 70.4 ng/mg TP/10(3)/microl PBMCs P > 0.05) post active and passive heating. Peak HSP70 expressed as a fold-change from rest was also not increased by AH (1.1 +/- 0.9 P > 0.05) or PH (3.2 +/- 4.8 P > 0.05). There were no significant differences between the AH and PH trials at any time-point, and the HSP70 response appeared to be in idual specific. These results did not allow us to delineate the effects of hyperthermia and other exercise associated stressors on the heat shock response and therefore further work is warranted.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Lars Mc Naughton.