ORCID Profile
0000-0002-3331-1177
Current Organisations
University of Pittsburgh
,
Murdoch University
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Publisher: Springer Science and Business Media LLC
Date: 21-09-2016
DOI: 10.1007/S00421-015-3264-Z
Abstract: Locomotive efficiency is cited as an important component to endurance performance however, inconsistent observations of age-related changes in efficiency question its influence in the performance of masters athletes. This study examined locomotive efficiency in young and masters triathletes during both a run and cycle test. Twenty young (28.5 ± 2.6 years) and 20 masters (59.8 ± 1.3 years) triathletes completed an incremental cycling and running test to determine maximal aerobic consumption (VO2max) and the first ventilatory threshold (VT1). Participants then completed 10-min submaximal running and cycling tests at VT1 during which locomotive efficiency was calculated from expired ventilation. Additionally, body fat percentage was determined using skin-fold assessment. During the cycle and run, VO2max was lower in the masters (48.3 ± 5.4 and 49.6 ± 4.8 ml kg(-1) min(-1), respectively) compared with young (61.6 ± 5.7 and 62.4 ± 5.2 ml kg(-1) min(-1), respectively) cohort. Maximal running speed and the cycling power output corresponding to VO2max were also lower in the masters (15.1 ± 0.8 km h(-1) and 318.6 ± 26.0 W) compared with the young (19.5 ± 1.3 km h(-1) and 383.6 ± 35.0 W) cohort. Cycling efficiency was lower (-11.2%) in the masters compared with young cohort. Similar results were observed for the energy cost of running (+10.8%) however, when scaled to lean body mass, changes were more pronounced during the run (+22.1%). Within trained triathletes, ageing can influence efficiency in both the run and cycle discipline. While disregarded in the past, efficiency should be considered in research examining performance in ageing athletes.
Publisher: Canadian Science Publishing
Date: 12-2018
Abstract: This study examined the effect of 2 forms of exercise on glucose tolerance and the concurrent changes in markers associated with the interleukin (IL)-6 pathways. Fifteen sedentary, overweight males (29.0 ± 3.1 kg/m 2 ) completed 2 separate, 3-day trials in randomised and counterbalanced order. An oral glucose tolerance test (OGTT 75 g) was performed at the same time on each day of the trial. Day 2 of each trial consisted of a single 30-min workload-matched bout of either high-intensity intermittent exercise (HIIE alternating 100% and 50% of peak oxygen uptake) or continuous moderate-intensity exercise (CME 60 % of peak oxygen uptake) completed 1 h prior to the OGTT. Venous blood s les were collected before, immediately after, 1 h after, and 25 h after exercise for measurement of insulin, C-peptide, IL-6, and the soluble IL-6 receptors (sIL-6R soluble glycoprotein 130 (sgp130)). Glucose area under the curve (AUC) was calculated from capillary blood s les collected throughout the OGTT. Exercise resulted in a modest (4.4% p = 0.003) decrease in the glucose AUC when compared with the pre-exercise AUC however, no differences were observed between exercise conditions (p = 0.65). IL-6 was elevated immediately after and 1 h after exercise, whilst sgp130 and sIL-6R concentrations were reduced immediately after exercise. In summary, exercise was effective in reducing glucose AUC, which was attributed to improvements that took place between 60 and 120 min into the OGTT, and was in parallel with an increased ratio of IL-6 to sIL-6R, which accords with an increased activation via the “classical” IL-6 signalling pathway. Our findings suggest that acute HIIE did not improve glycaemic response when compared with CME.
Publisher: Human Kinetics
Date: 08-2018
Abstract: Purpose : To examine the effect of postexercise cold-water immersion (CWI) protocols, compared with control (CON), on the magnitude and time course of core temperature ( T c ) responses. Methods : Pooled-data analyses were used to examine the T c responses of 157 subjects from previous postexercise CWI trials in the authors’ laboratories. CWI protocols varied with different combinations of temperature, duration, immersion depth, and mode (continuous vs intermittent). T c was examined as a double difference (ΔΔ T c ), calculated as the change in T c in CWI condition minus the corresponding change in CON. The effect of CWI on ΔΔ T c was assessed using separate linear mixed models across 2 time components (component 1, immersion component 2, postintervention). Results : Intermittent CWI resulted in a mean decrease in ΔΔ T c that was 0.25°C (0.10°C) (estimate [SE]) greater than continuous CWI during the immersion component ( P = .02). There was a significant effect of CWI temperature during the immersion component ( P = .05), where reductions in water temperature of 1°C resulted in decreases in ΔΔ T c of 0.03°C (0.01°C). Similarly, the effect of CWI duration was significant during the immersion component ( P = .01), where every 1 min of immersion resulted in a decrease in ΔΔ T c of 0.02°C (0.01°C). The peak difference in T c between the CWI and CON interventions during the postimmersion component occurred at 60 min postintervention. Conclusions : Variations in CWI mode, duration, and temperature may have a significant effect on the extent of change in T c . Careful consideration should be given to determine the optimal amount of core cooling before deciding which combination of protocol factors to prescribe.
Publisher: Oxford University Press (OUP)
Date: 25-11-2013
Abstract: Demand for Australian mined iron ore has increased employment within this sector, thus exposing increased numbers of workers to the harsh Australian climate. This study examined the influence of hot (>30°C wet bulb globe temperature) environmental temperatures, consistent with working in North Western Australia, on iron ore mining staff. Core temperature, hydration status, perceived exertion, mood, and fatigue state were measured in 77 participants at three time points (pre-, mid-, and post-shift) during a normal 12-h shift at an open-cut iron ore mining rocessing site (n = 31 Site1) and an iron ore processing/shipping site (n = 46 Site2). A significant effect for time was observed for core temperature with greater mean core temperatures measured mid-shift (37.5±0.4°C) and post-shift (37.6±0.3°C) compared with pre-shift values (37.0±0.5°C). All mean core temperature measures were lower than ISO7933 thresholds (38°C) for thermal safety. Mean hydration measures [urine-specific gravity (USG)] were greater at Site1 (1.029±0.006) compared with those at Site2 (1.021±0.007). Furthermore, both pre- and post-shift measures from Site1 and the post-shift measures from Site2 were greater than the threshold for dehydration (USG = 1.020). No differences were observed for mood or perceived exertion over time however, measures of fatigue state were greater post-shift compared with pre- and mid-shift values for both sites. Our findings indicate that the majority of mine workers in North Western Australia are able to regulate work rate in hot environments to maintain core temperatures below ISO safety guidelines however, 22% of workers reached or exceeded the safety guidelines, warranting further investigation. Furthermore, hydration practices, especially when off-work, appear inadequate and could endanger health and safety.
Publisher: Springer Science and Business Media LLC
Date: 20-11-2013
DOI: 10.1038/MP.2012.162
Abstract: Western countries are experiencing aging populations and increased longevity thus, the incidence of dementia and Alzheimer's disease (AD) in these countries is projected to soar. In the absence of a therapeutic drug, non-pharmacological preventative approaches are being investigated. One of these approaches is regular participation in physical activity or exercise. This paper reviews studies that have explored the relationship between physical activity and cognitive function, cognitive decline, AD/dementia risk and AD-associated biomarkers and processes. There is now strong evidence that links regular physical activity or exercise to higher cognitive function, decreased cognitive decline and reduced risk of AD or dementia. Nevertheless, these associations require further investigation, more specifically with interventional studies that include long follow-up periods. In particular, relatively little is known about the underlying mechanism(s) of the associations between physical activity and AD neuropathology clearly this is an area in need of further research, particularly in human populations. Although benefits of physical activity or exercise are clearly recognised, there is a need to clarify how much physical activity provides the greatest benefit and also whether people of different genotypes require tailored exercise regimes.
Publisher: Wiley
Date: 19-10-2017
Publisher: Wiley
Date: 28-07-2016
DOI: 10.1111/CPF.12380
Abstract: This study compared the effect of postexercise water immersion (WI) at different temperatures on common femoral artery blood flow (CFA), muscle (total haemoglobin tHb) and skin perfusion (cutaneous vascular conductance CVC), assessed by Doppler ultrasound, near-infrared spectroscopy (NIRS) and laser Doppler flowmetry, respectively. Given that heat stress may influence the vascular response during cooling, nine men cycled for 25 min at the first ventilatory threshold followed by intermittent 30-s cycling at 90% peak power until exhaustion at 32·8 ± 0·4°C and 32 ± 5% RH. They then received 5-min WI at 8·6 ± 0·2°C (WI
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2014
Publisher: Springer Science and Business Media LLC
Date: 23-09-2018
DOI: 10.1007/S40279-017-0787-Y
Abstract: A large body of epidemiological and experimental data exploring the relationship between physical activity (PA) and Alzheimer's disease (AD) are now available. Despite observational evidence supporting a role for PA in delaying the onset of AD, randomised controlled trials have reported mixed findings, likely due to the heterogeneity in study cohorts, outcome measures, and the adopted PA intervention. The primary objective of this narrative review is to evaluate the extant evidence on the relationship between PA, cognitive decline and AD in older populations. The interaction between PA and the putative mechanisms underlying AD progression, including genetic factors and amyloid-β levels will be explored. In this context, particular attention will be given to studies assessing PA in the early clinical and preclinical, asymptomatic stages of AD. Based on current evidence, clinical considerations for implementation of exercise-based interventions are discussed, along with limitations of previous research and directions for future studies.
Publisher: Informa UK Limited
Date: 23-05-2019
DOI: 10.1080/17461391.2019.1617789
Abstract: This study examined the acute performance, cardiovascular and local muscular responses to perceived exertion-based high-intensity interval exercise using either double- or single-leg cycling. Fifteen healthy middle-aged adults completed, on separate occasions, ten 30-s double-leg intervals interspersed with 60 s passive recovery and twenty (ten with each leg) 30-s single-leg intervals interspersed with 60 s passive recovery. Impedance cardiography, blood pressure, muscle oxygenation and total haemoglobin content (near-infrared spectroscopy), oxygen consumption and power output were measured throughout each session. Normalised to the lean mass used during each trial, single-leg cycling resulted in lower power output (single-leg: 8.92 ± 1.74 W kg
Publisher: Informa UK Limited
Date: 08-2009
DOI: 10.1080/02640410903207424
Abstract: This study compared the effect of 5, 10 and 20 min of cold-water (14 degrees C) immersion on rectal and muscle temperature and neuromuscular function. Twelve cyclists performed four cycling time-to-exhaustion trials in hot conditions (40 degrees C and 40%rh), followed 25 min later by cold-water immersion for 5, 10 or 20 min or 20 min in room temperature (24 degrees C control). Rectal temperature was measured continuously, and muscle temperature was measured before, immediately after and 45 min after the time-to-exhaustion-test, as well as before and after water immersion. Sixty-second maximal voluntary isometric torque and isokinetic torque of the knee extensors were measured before, immediately after and 55 min after time-to-exhaustion-test. A greater rate of decrease in rectal temperature was observed in all water immersion conditions 45-80 min after time-to-exhaustion-test compared with control. Compared with control, muscle temperature 45 min after time-to-exhaustion-test was lower for all water immersion conditions however, muscle temperature was lower for the 10- and 20-min conditions compared with 5 min. Isometric torque measured 55 min after time-to-exhaustion-test was lower for all conditions. Isokinetic torque was lower for all conditions immediately and 55-min post-time-to-exhaustion-test. Of the durations measured, 5 min of cold-water immersion appeared as the most appropriate duration for reducing rectal temperature but limiting decreases in muscle temperature.
Publisher: World Scientific Pub Co Pte Lt
Date: 12-2006
DOI: 10.1142/S021895770600187X
Abstract: Background: The influence of water immersion on neuromuscular function is of importance to a number of disciplines however, the reliability of surface electromyography (SEMG) following water immersion is not known. This study examined the reliability of SEMG litude during maximal voluntary isometric contractions (MVICs) of the vastus lateralis following water immersion. Methods: Using a Biodex isokinetic dynamometer and in a randomized order, 12 healthy male subjects performed four MVICs at 60° knee flexion on both the dominant and nondominant kicking legs, and the SEMG was recorded. Each subject's dominant and nondominant kicking leg was then randomly assigned to have SEMG electrodes removed or covered during 15 min of water immersion (20°C–25°C). Following water immersion, subjects performed a further four MVICs. Results: Intraclass correlation coefficient (ICC) and the relative standard error of measurement (%SEM) of SEMG litude showed moderate to high trial-to-trial reliability when electrodes were covered (0.93% and 2.79%) and removed (0.95% and 2.10%, respectively). Conclusions: The results of the this study indicate that SEMG litude of the vastus lateralis may be accurately determined during maximal voluntary contractions following water immersion if electrodes are either removed or covered with water-resistive tape during the immersion.
Publisher: Springer Science and Business Media LLC
Date: 12-09-2016
DOI: 10.1038/SREP33244
Abstract: Manual therapy is suggested as a potentially therapeutic intervention that may improve pulmonary function. However, this form of therapy is largely based on clinical observations and hypothetical models rather than mechanistic knowledge. This study examined the influence of a single session of manual therapy applied to the thoracic spine and thorax on dynamic pulmonary function over an extended time frame in healthy adults. 21 healthy in iduals (14 males) aged 19–35 (mean [SD] age = 23 [3.9], BMI [SD] = 22.97 [2.41]) completed one experimental testing session consisting of five pulmonary function tests and the delivery of a manual therapy intervention. Pulmonary function was measured at baseline and 1 minute, 10 minutes, 20 minutes and 30 minutes following the intervention. Baseline mean (SD) forced vital capacity (FVC), forced expired volume in 1 second (FEV 1 ) and maximal voluntary ventilation (MVV) were 5.55(1.23 L), 4.64(0.92 L) and 165.7(40.0L min −1 ) respectively. The mean (SD) FEV 1 /FVC ratio was 0.84(0.07). There were no statistically significant changes in any of the pulmonary function measures following the manual therapy intervention. Our findings do not support the use of manual therapy to provide a short-term benefit in respiratory function to healthy adults.
Publisher: American Physiological Society
Date: 04-2008
DOI: 10.1152/JAPPLPHYSIOL.00683.2007
Abstract: The aim of the present study was to determine the effect of carbohydrate (CHO sucrose) ingestion and environmental heat on the development of fatigue and the distribution of power output during a 16.1-km cycling time trial. Ten male cyclists (V̇o 2max = 61.7 ± 5.0 ml·kg −1 ·min −1 , mean ± SD) performed four 90-min constant-pace cycling trials at 80% of second ventilatory threshold (220 ± 12 W). Trials were conducted in temperate (18.1 ± 0.4°C) or hot (32.2 ± 0.7°C) conditions during which subjects ingested either CHO (0.96 g·kg −1 ·h −1 ) or placebo (PLA) gels. All trials were followed by a 16.1-km time trial. Before and immediately after exercise, percent muscle activation was determined using superimposed electrical stimulation. Power output, integrated electromyography (iEMG) of vastus lateralis, rectal temperature, and skin temperature were recorded throughout the trial. Percent muscle activation significantly declined during the CHO and PLA trials in hot (6.0 and 6.9%, respectively) but not temperate conditions (1.9 and 2.2%, respectively). The decline in power output during the first 6 km was significantly greater during exercise in the heat. iEMG correlated significantly with power output during the CHO trials in hot and temperate conditions ( r = 0.93 and 0.73 P 0.05) but not during either PLA trial. In conclusion, cyclists tended to self-select an aggressive pacing strategy (initial high intensity) in the heat.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2019
DOI: 10.1519/JSC.0000000000003007
Abstract: Hughes, LJ, Banyard, HG, Dempsey, AR, Peiffer, JJ, and Scott, BR. Using load-velocity relationships to quantify training-induced fatigue. J Strength Cond Res 33(3): 762–773, 2019—The purpose of this study was to investigate using load-velocity relationships to quantify fluctuations in maximal strength (1 repetition maximum [1RM]), which occur as a result of training-induced fatigue. The 19 well-trained men (age: 24.3 ± 2.9 years, height: 180.1 ± 5.9 cm, body mass: 84.2 ± 10.5 kg, and squat 1RM: 151.1 ± 25.7 kg) who were recruited for this study attended 5 sessions. After baseline strength testing, in idual load-velocity relationships were established using mean concentric velocity during visits 2, 4, and 5, with visit 3 consisting of a bout of fatiguing exercise (5 sets of squats performed to muscular failure with 70% 1RM). Predicted 1RM values were calculated using the minimal velocity threshold (1RM MVT ), load at zero velocity (1RM LD0 ), and force-velocity (1RM FV ) methods. Measured 1RM, maximal voluntary contractions, and perceived muscle soreness were used to examine the effects of fatigue in relation to the predicted 1RM scores. The 1RM MVT and 1RM LD0 demonstrated very strong and strong correlations with measured 1RM during each of the sessions ( r = 0.90–0.96 and r = 0.77–0.84, respectively), while no strong significant correlations were observed for the 1RM FV . Further analysis using Bland-Altman plots demonstrated substantial interin idual variation associated with each method. These results suggest that load-velocity–based 1RM predictions are not accurate enough to be used for daily training load prescription, as has been previously suggested. Nevertheless, these predictions are practical to implement during an in idual's warm-up and may be useful to indicate general fluctuations in performance potential, particularly if used in conjunction with other common monitoring methods.
Publisher: Human Kinetics
Date: 08-2018
Abstract: Context : Night games are a regular occurrence for team-sport athletes, yet sleep complaints following night competitions are common. The mechanisms responsible for reported sleep difficulty in athletes are not understood. Methods : An observational crossover design investigating a night netball game and a time-matched rest day in 12 netball athletes was conducted to ascertain differences in physiological (core temperature), psychometric (state and trait), and neuroendocrine (adrenaline, noradrenaline, and cortisol) responses. Results : Following the night game, athletes experienced reduced sleep durations, lower sleep efficiency, early awakenings, and poorer subjective sleep ratings compared with the rest day. No differences were found between core temperature, state psychometric measures, and cortisol at bedtime. Adrenaline and noradrenaline concentrations were elevated compared with the time-matched rest day prior to (26.92 [15.88] vs 12.90 [5.71] and 232.6 [148.1] vs 97.83 [36.43] nmol/L, respectively) and following the night game (18.67 [13.26] vs 11.92 [4.56] and 234.1 [137.2] vs 88.58 [54.08] nmol/L, respectively) however, the concentrations did not correlate to the sleep variables (duration, efficiency, and sleep-onset latency). A correlation ( r s = −.611) between sleep efficiency and hyperarousal (trait psychometric measure) was found. Conclusions : Athletes experienced poor sleep following a night game. Furthermore, results suggest that athletes who have a tendency toward a high trait arousal may be more susceptible to sleep complaints following a night game. These data expand knowledge and refute frequently hypothesized explanations for poor sleep following night competition. The results may also help support staff and coaches target strategies for in idual athletes at a higher risk of sleep complaints.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-09-2014
Publisher: American Physiological Society
Date: 10-2018
DOI: 10.1152/JAPPLPHYSIOL.00499.2018
Abstract: Although complex in nature, a number of metabolites have been implicated in the onset of exercise-induced fatigue. The purpose of this study was to identify changes in the plasma metabolome and specifically, to identify candidate metabolites associated with the onset of fatigue during prolonged cycling. Eighteen healthy and recreationally active men (mean ± SD age: 24.7 ± 4.8 yr mass 67.1 ± 6.1 kg body mass index: 22.8 ± 2.2 peak oxygen uptake: 40.9 ± 6.1 ml·kg −1 ·min −1 ) were recruited to this study. Participants performed a prolonged cycling time-to-exhaustion (TTE) test at an intensity corresponding to a fixed blood lactate concentration (3 mmol/l). Plasma s les collected at 10 min of exercise, before fatigue (last s le before fatigue min before fatigue), immediately after fatigue (point of exhaustion), and 20 min after fatigue were assessed using a liquid chromatography-mass spectrometry-based metabolomic approach. Eighty metabolites were putatively identified, with 68 metabolites demonstrating a significant change during the cycling task (duration: ~80.9 ± 13.6 min). A clear multivariate structure in the data was revealed, with the first principal component (36% total variance) describing a continuous increase in metabolite concentration throughout the TTE trial and recovery, whereas the second principal component (14% total variance) showed an increase in metabolite concentration followed by a recovery trajectory, peaking at the point of fatigue. Six clusters of correlated metabolites demonstrating unique metabolite trajectories were identified, including significant separation in the metabolome between prefatigue and postfatigue time points. In accordance with our hypothesis, free-fatty acids and tryptophan contributed to differences in the plasma metabolome at fatigue. NEW & NOTEWORTHY Metabolites have long been implicated in the onset of fatigue. This study applied a metabolomic approach to track 80 plasma-borne metabolites during a cycle to fatigue task. Of these, 68 metabolites demonstrated significant change, with the plasma metabolome at fatigue being clearly distinguishable from other time points. Six unique clusters of metabolites were identified, and free fatty acids were strongly associated with fatigue onset therein lending support to the central fatigue hypothesis.
Publisher: Springer Science and Business Media LLC
Date: 17-07-2017
DOI: 10.1038/S41598-017-05953-2
Abstract: Common estimates of external training intensity for resistance exercise do not incorporate inter-set recovery duration, and might not reflect the overall demands of training. This study aimed to assess novel metrics of exercise density (ED) during resistance exercise, and how these related to a physiological marker of internal training intensity as well as traditional measures of external training intensity and volume. Thirteen males and seven females performed two bouts of resistance exercise focused on developing strength (5 sets of 5 repetitions with 5-repetition maximum 180 s recovery) and hypertrophy (3 sets of 10 repetitions with 10-repetition maximum 60 s recovery). Blood lactate concentration was measured to quantify internal training intensity. Specific metrics of external volume (mechanical work, volume load and total repetitions) and intensity (average weight lifted and ED) were calculated. Despite lower average weights and no difference in mechanical work or volume load, blood lactate was greater following hypertrophy compared with the strength condition. This finding was consistent with higher measures of ED in the hypertrophy compared with the strength condition. Greater ED during hypertrophy resistance exercise, along with the significant association with changes in blood lactate, indicates that ED metrics are reflective of the sessional intensity for resistance exercise.
Publisher: Human Kinetics
Date: 09-2017
Abstract: To examine the influence of manipulating aerobic contribution after whole-blood removal on pacing patterns, performance, and energy contribution during self-paced middle-distance cycling. Seven male cyclists (33 ± 8 y) completed an incremental cycling test followed 20 min later by a 4-min self-paced cycling time trial (4MMP) on 6 separate occasions over 42 d. The initial 2 sessions acted as familiarization and baseline testing, after which 470 mL of blood was removed, with the remaining sessions performed 24 h, 7 d, 21 d, and 42 d after blood removal. During all 4MMP trials, power output, oxygen uptake, and aerobic and anaerobic contribution to power were determined. 4MMP average power output significantly decreased by 7% ± 6%, 6% ± 8%, and 4% ± 6% at 24 h, 7 d, and 21 d after blood removal, respectively. Compared with baseline, aerobic contribution during the 4MMP was significantly reduced by 5% ± 4%, 4% ± 5%, and 4% ± 10% at 24 h, 7 d, and 21 d, respectively. The rate of decline in power output on commencement of the 4MMP was significantly attenuated and was 76% ± 20%, 72% ± 24%, and 75% ± 35% lower than baseline at 24 h, 21 d, and 42 d, respectively. Removal of 470 mL of blood reduces aerobic energy contribution, alters pacing patterns, and decreases performance during self-paced cycling. These findings indicate the importance of aerobic energy distribution during self-paced middle-distance events.
Publisher: BMJ
Date: 06-06-2010
Abstract: This study examined the effect of a 5-min cold-water immersion (14 degrees C) recovery intervention on repeated cycling performance in the heat. 10 male cyclists performed two bouts of a 25-min constant-paced (254 (22) W) cycling session followed by a 4-km time trial in hot conditions (35 degrees C, 40% relative humidity). The two bouts were separated by either 15 min of seated recovery in the heat (control) or the same condition with 5-min cold-water immersion (5th-10th minute), using a counterbalanced cross-over design (CP(1)TT(1) --> CWI or CON --> CP(2)TT(2)). Rectal temperature was measured immediately before and after both the constant-paced sessions and 4-km timed trials. Cycling economy and Vo(2) were measured during the constant-paced sessions, and the average power output and completion times were recorded for each time trial. Compared with control, rectal temperature was significantly lower (0.5 (0.4) degrees C) in cold-water immersion before CP(2) until the end of the second 4-km timed trial. However, the increase in rectal temperature (0.5 (0.2) degrees C) during CP(2) was not significantly different between conditions. During the second 4-km timed trial, power output was significantly greater in cold-water immersion (327.9 (55.7) W) compared with control (288.0 (58.8) W), leading to a faster completion time in cold-water immersion (6.1 (0.3) min) compared with control (6.4 (0.5) min). Economy and Vo(2) were not influenced by the cold-water immersion recovery intervention. 5-min cold-water immersion recovery significantly lowered rectal temperature and maintained endurance performance during subsequent high-intensity exercise. These data indicate that repeated exercise performance in heat may be improved when a short period of cold-water immersion is applied during the recovery period.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Elsevier BV
Date: 2015
DOI: 10.1016/J.JSAMS.2014.02.007
Abstract: Anecdotally many athletes report worse sleep in the nights prior to important competitions. Despite sleep being acknowledged as an important factor for optimal athletic performance and overall health, little is understood about athlete sleep around competition. The aims of this study were to identify sleep complaints of athletes prior to competitions and determine whether complaints were confined to competition periods. Cross-sectional study. A s le of 283 elite Australian athletes (129 male, 157 female, age 24±5 y) completed two questionnaires Competitive Sport and Sleep questionnaire and the Pittsburgh Sleep Quality Index. 64.0% of athletes indicated worse sleep on at least one occasion in the nights prior to an important competition over the past 12 months. The main sleep problem specified by athletes was problems falling asleep (82.1%) with the main reasons responsible for poor sleep indicated as thoughts about the competition (83.5%) and nervousness (43.8%). Overall 59.1% of team sport athletes reported having no strategy to overcome poor sleep compared with in idual athletes (32.7%, p=0.002) who utilised relaxation and reading as strategies. In idual sport athletes had increased likelihood of poor sleep as they aged. The poor sleep reported by athletes prior to competition was situational rather than a global sleep problem. Poor sleep is common prior to major competitions in Australian athletes, yet most athletes are unaware of strategies to overcome the poor sleep experienced. It is essential coaches and scientists monitor and educate both in idual and team sport athletes to facilitate sleep prior to important competitions.
Publisher: Georg Thieme Verlag KG
Date: 04-03-2011
Abstract: This study examined the reliability/validity of power output measured using the Fortius Virtual Reality cycle trainer. 10 cyclists (age: 28±6 years V˙O (2)max: 60.9±7.2 ml · kg (-1) · min (-1) peak power: 393±82 W) completed three 20 km time trials on a Fortius cycle trainer. During each time trial, power output was measured at 1 Hz using the Fortius internal software and a PowerTap power monitor. Validity calculated for the Fortius trainer Pearson correlation coefficient (r=0.99 95% CI: 0.98-0.99 p<0.01) and typical error of estimate (3.5% 95% CI: 3.2-3.9%), was similar to other established laboratory ergometers. No differences (F (2,16)=0.32 p=0.73) in mean 20 km power were observed between trial 1 (253±46 W), 2 (258±49 W), or 3 (255±50 W). Test-retest reliability (intraclass correlation coefficient (ICC) and coefficient of variation (CV)) was better between trial 2 and 3 (ICC=1.00 (CI: 0.98-1.00) CV: 1.6% (CI: 1.1-3.3%)) compared with trial 1 and 2 (ICC=0.98 (CI: 0.91-1.00) CV: 3.3% (CI: 2.2-6.4%)). The Fortius cycle trainer is a valid and reliable device for the measurement of power output in cyclists, thus providing an alternative to larger more expensive laboratory ergometers.
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.JSAMS.2016.08.018
Abstract: Research is equivocal regarding endurance performance benefits of external nasal dilators, and currently research focusing on internal nasal dilators is non-existent. Both devices are used within competitive cycling. This study examined the influence of external and internal nasal dilation on cycling economy of motion and 20-km time trial performance. The study utilized a randomized, counterbalanced cross-over design. Fifteen trained cyclists completed three exercise sessions consisting of a 15min standardized warm up and 20-km cycling time trial while wearing either a Breathe Right No differences were observed for mean 20-km power output between the internal (270±45W) or external dilator (271±44W) and control (272±44W). No differences in the economy of motion were observed throughout the 15-min warm up between conditions. The Turbine
Publisher: Springer Science and Business Media LLC
Date: 26-10-2008
DOI: 10.1007/S00421-007-0598-1
Abstract: We investigated the influence of rectal temperature on the immune system during and after exercise. Ten well-trained male cyclists completed exercise trials (90 min cycling at 60% VO(2max) + 16.1 - km time trial) on three separate occasions: once in 18 degrees C and twice in 32 degrees C. Twenty minutes after the trials in 32 degrees C, the cyclists sat for approximately 20 min in cold water (14 degrees C) on one occasion, whereas on another occasion they sat at room temperature. Rectal temperature increased significantly during cycling in both conditions, and was significantly higher after cycling in 32 degrees C than in 18 degrees C (P < 0.05). Leukocyte counts increased significantly during cycling but did not differ between the conditions. The concentrations of serum interleukin (IL)-6, IL-8 and IL-10, plasma catecholamines, granulocyte-colony stimulating factor, myeloperoxidase and calprotectin increased significantly following cycling in both conditions. The concentrations of serum IL-8 (25%), IL-10 (120%), IL-1 receptor antagonist (70%), tumour necrosis factor-alpha (17%), plasma myeloperoxidase (26%) and norepinephrine (130%) were significantly higher after cycling in 32 degrees C than in 18 degrees C. During recovery from exercise in 32 degrees C, rectal temperature was significantly lower in response to sitting in cold water than at room temperature. However, immune changes during 90 min of recovery did not differ significantly between sitting in cold water and at room temperature. The greater rise in rectal temperature during exercise in 32 degrees C increased the concentrations of serum IL-8, IL-10, IL-1ra, TNF-alpha and plasma myeloperoxidase, whereas the greater decline in rectal temperature during cold water immersion after exercise did not affect immune responses.
Publisher: Bentham Science Publishers Ltd.
Date: 11-05-2016
DOI: 10.2174/1567205013666160315112151
Abstract: Alzheimer's disease (AD) is a degenerative brain disorder and is the most common form of dementia. Minimally invasive approaches are required that combine biomarkers to identify in iduals who are at risk of developing mild cognitive impairment (MCI) and AD, to appropriately target clinical trials for therapeutic discovery as well as lifestyle strategies aimed at prevention. Buccal mucosa cells from the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing cohort (n=60) were investigated for cytological markers that could be used to identify both MCI and AD in iduals. Visual scoring of the buccal cytome demonstrated a significantly lower frequency of basal and karyorrhectic cells in the MCI group compared with controls. A high content, automated assay was developed using laser scanning cytometry to simultaneously measure cell types, nuclear DNA content and aneuploidy, neutral lipid content, putative Tau and amyloid-β (Aβ) in buccal cells. DNA content, aneuploidy, neutral lipids and Tau were similar in all groups. However, there was significantly lower Tau protein in both basal and karyolytic buccal cell types compared with differentiated buccal cells. Aβ, as measured by frequency of cells containing Aβ signal, as well as area and integral of Aβ signal, was significantly higher in the AD group compared with the control group. Buccal cell Aβ was correlated with mini-mental state examination (MMSE) scores (r = -0.436, P=0.001) and several blood-based biomarkers. Combining newly identified biomarkers from buccal cells with those already established may offer a potential route for more specific biomarker panels which may substantially increase the likelihood of better predictive markers for earlier diagnosis of AD.
Publisher: American Physiological Society
Date: 05-2011
DOI: 10.1152/JAPPLPHYSIOL.01247.2010
Abstract: Single-leg cycling may enhance the peripheral adaptations of skeletal muscle to a greater extent than double-leg cycling. The purpose of the current study was to determine the influence of 3 wk of high-intensity single- and double-leg cycle training on markers of oxidative potential and muscle metabolism and exercise performance. In a crossover design, nine trained cyclists (78 ± 7 kg body wt, 59 ± 5 ml·kg −1 ·min −1 maximal O 2 consumption) performed an incremental cycling test and a 16-km cycling time trial before and after 3 wk of double-leg and counterweighted single-leg cycle training (2 training sessions per week). Training involved three (double) or six (single) maximal 4-min intervals with 6 min of recovery. Mean power output during the single-leg intervals was more than half that during the double-leg intervals (198 ± 29 vs. 344 ± 38 W, P 0.05). Skeletal muscle biopsy s les from the vastus lateralis revealed a training-induced increase in Thr 172 -phosphorylated 5′-AMP-activated protein kinase α-subunit for both groups ( P 0.05). However, the increase in cytochrome c oxidase subunits II and IV and GLUT-4 protein concentration was greater following single- than double-leg cycling ( P 0.05). Training-induced improvements in maximal O 2 consumption (3.9 ± 6.2% vs. 0.6 ± 3.6%) and time-trial performance (1.3 ± 0.5% vs. 2.3 ± 4.2%) were similar following both interventions. We conclude that short-term high-intensity single-leg cycle training can elicit greater enhancement in the metabolic and oxidative potential of skeletal muscle than traditional double-leg cycling. Single-leg cycling may therefore provide a valuable training stimulus for trained and clinical populations.
Publisher: Informa UK Limited
Date: 22-08-2023
DOI: 10.1080/17461391.2022.2107436
Abstract: This study investigated whether walking with blood flow restriction (BFR) increases acute cardio-respiratory demands to the point that it can be considered an alternative for jogging. Sixteen physically active adults completed five experimental sessions (order randomised), comprising 10 min of treadmill exercise. Two sessions included unrestricted walking, two sessions required walking with BFR cuffs positioned on the lower limbs inflated to 60% of in idualised arterial occlusion pressure, and one session was conducted at a jogging pace. Comfortable walking and jogging speeds were calculated during the familiarisation session. Walking speeds were in idualised to either 100% (speed: 6.0 ± 0.3km·h-1[low-intensity]) or 120% (speed: 7.2 ± 0.3km·h-1[moderate-intensity]) of comfortable walking speed. The jogging session was unrestricted (speed: 9.1 ± 0.7km·h-1). Initial analysis compared walking conditions across heart rate, left cardiac work index, systolic blood pressure, relative oxygen consumption, minute ventilation, rating of perceived exertion and limb discomfort. Secondary analysis compared the walking session with the highest cardio-respiratory demands to jogging. Initial analysis identified that moderate-intensity with BFR induced the highest cardio-respiratory and perceptual responses compared with any other walking sessions (
Publisher: Informa UK Limited
Date: 26-11-2017
DOI: 10.1080/17461391.2017.1405077
Abstract: This review evaluated the effects of precooling via cold water immersion (CWI) and ingestion of ice slurry/slushy or crushed ice (ICE) on endurance performance measures (e.g. time-to-exhaustion and time trials) and psychophysiological parameters (core [T
Publisher: Frontiers Media SA
Date: 10-2018
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.JSAMS.2018.01.013
Abstract: Blood flow restriction (BFR) during interval cycling may stimulate aerobic and anaerobic adaptations. However, acute physiological responses to BFR interval cycling have not been extensively investigated. Eighteen males completed low-intensity (LI), low-intensity with BFR (LI During LI BP, HR, CO, V˙O LI
Publisher: Human Kinetics
Date: 06-2023
Abstract: Purpose : This study examined the influence of blood-flow restriction (BFR) on the distribution of pace, physiological demands, and perceptual responses during self-paced cycling. Methods : On separate days, 12 endurance cyclists/triathletes were instructed to produce the greatest average power output during 8-minute self-paced cycling trials with BFR (60% arterial occlusion pressure) or without restriction (CON). Power output and cardiorespiratory variables were measured continuously. Perceived exertion, muscular discomfort, and cuff pain were recorded every 2 minutes. Results : Linear regression analysis of the power output slope was statistically significant (ie, deviated from the intercept) for CON (2.7 [3.2] W·30 s −1 P = .009) but not for BFR (−0.1 [3.1] W·30 s −1 P = .952). Absolute power output was ∼24% (12%) lower at all time points ( P .001) during BFR compared with CON. Oxygen consumption (18% [12%] P .001), heart rate (7% [9%] P .001), and perceived exertion (8% [21%] P = .008) were reduced during BFR compared with CON, whereas muscular discomfort (25% [35%] P = .003) was greater. Cuff pain was rated as “strong” (5.3 [1.8] au 0–10 scale) for BFR. Conclusion : Trained cyclists adopted a more even distribution of pace when BFR was applied compared with a negative distribution during CON. By presenting a unique combination of physiological and perceptual responses, BFR is a useful tool to understand how the distribution of pace is self-regulated.
Publisher: Springer Science and Business Media LLC
Date: 20-11-2012
DOI: 10.1038/TP.2012.118
Publisher: Informa UK Limited
Date: 08-08-2023
Publisher: Wiley
Date: 11-2018
DOI: 10.1113/EP087159
Publisher: Elsevier BV
Date: 2010
DOI: 10.1016/J.JSAMS.2008.08.003
Abstract: This study examined the effect of a short cold water immersion (CWI) intervention on rectal and muscle temperature, isokinetic strength and 1-km cycling time trial performance in the heat. Ten male cyclists performed a 1-km time trial at 35.0+/-0.3 degrees C and 40.0+/-3.0% relative humidity, followed by 20 min recovery sitting in either cold water (14 degrees C) for 5 min or in 35 degrees C air (control) a second 1-km time trial immediately followed. Peak and mean cycling power output were recorded for both time trials. Rectal and muscle temperature, and maximal isokinetic concentric torque of the knee extensors were measured before and immediately after the first and second time trials. Rectal temperature was not different between cold water immersion and control conditions at any time points. After the second time trial, however, muscle temperature was significantly lower (-1.3+/-0.7 degrees C) in cold water immersion compared with the control trial. While peak and mean power decreased from the first to second time trial in both conditions (-86+/-54 W and -24+/-16 W, respectively), maximal isokinetic concentric torque was similar between conditions at all time points. The 5 min cold water immersion intervention lowered muscle temperature but did not affect isokinetic strength or 1-km cycling performance.
Publisher: Georg Thieme Verlag KG
Date: 07-08-2015
Abstract: The aim of this study was to quantify the demands of road competitions ending with sprints in male professional cycling. 17 races finished with top-5 results from 6 male road professional cyclists (age, 27.0±3.8 years height, 1.76±0.03 m weight, 71.7±1.1 kg) were analysed. SRM power meters were used to monitor power output, cadence and speed. Data were averaged over the entire race, different durations prior to the sprint (60, 10, 5 and 1 min) and during the actual sprint. Variations in power during the final 10 min of the race were quantified using exposure variation analysis. This observational study was conducted in the field to maximize the ecological validity of the results. Power, cadence and speed were statistically different between various phases of the race (p<0.001), increasing from 316±43 W, 95±4 rpm and 50.5±3.3 km·h(-1) in the last 10 min, to 487±58 W, 102±6 rpm and 55.4±4.7 km·h(-1) in the last min prior to the sprint. Peak power during the sprint was 17.4±1.7 W·kg(-1). Exposure variation analysis revealed a significantly greater number of short-duration high-intensity efforts in the final 5 min of the race, compared with the penultimate 5 min (p=0.010). These findings quantify the power output requirements associated with high-level sprinting in men's professional road cycling and highlight the need for both aerobic and anaerobic fitness.
Publisher: Wiley
Date: 11-05-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 30-05-2019
DOI: 10.1249/MSS.0000000000002053
Abstract: Regular exercise can reduce the risk of developing cardiovascular disease through risk factor modification, with high-intensity exercise and more recently small muscle mass training providing alternatives to moderate-intensity exercise. This study randomly assigned 53 healthy middle-age adults (age, 62 ± 6 yr) to complete 24 sessions (8 wk 3 d·wk −1 ) of exercise training, using either high-intensity double-leg cycling ( n = 17 HIT DL ), high-intensity single-leg cycling ( n = 18 HIT SL ), or moderate-intensity double-leg cycling ( n = 18 MCT DL ). Biomarkers of cardiovascular risk (total cholesterol, triglycerides, HDL-c, LDL-c, apo-B48, and glucose), anthropometry measures (body mass, body mass index, waist circumference, and waist-to-hip ratio), resting blood pressure, and aerobic capacity were assessed pre- and postintervention. Total work completed was greater ( P 0.01) in MCT DL (5938 ± 1462 kJ) compared with the HIT DL (3462 ± 1063 kJ) and HIT SL (4423 ± 1875 kJ). Pre- to posttraining differences were observed for waist-to-hip ratio (0.84 ± 0.09 vs 0.83 ± 0.09 P 0.01), resting systolic blood pressure (129 ± 11 vs 124 ± 12 mm Hg P 0.01), total cholesterol (5.87 ± 1.17 vs 5.55 ± 0.98 mmol·L −1 P 0.01), and LDL-c (3.70 ± 1.04 vs 3.44 ± 0.84 mmol·L −1 P 0.01), with no differences between conditions. In addition, aerobic capacity increased after training (22.3 ± 6.4 vs 24.9 ± 7.6 mL·kg −1 ·min −1 P 0.01), with no differences between conditions. These findings suggest that all three modes of exercise can be prescribed to achieve cardiovascular risk reduction in an aging population.
Publisher: Informa UK Limited
Date: 14-05-2023
DOI: 10.1080/17461391.2022.2062056
Abstract: This study examined cardiovascular, perceptual and neuromuscular fatigue characteristics during and after cycling intervals with and without blood flow restriction (BFR). Fourteen endurance cyclists/triathletes completed four 4-minute self-paced aerobic cycling intervals at the highest sustainable intensity, with and without intermittent BFR (60% of arterial occlusion pressure). Rest interval durations were six, four and four minutes, respectively. Power output, cardiovascular demands and ratings of perceived exertion (RPE) were averaged over each interval. Knee extension torque and
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.BBR.2019.01.013
Abstract: Higher cardiorespiratory fitness has been associated with better cognitive function in older adults yet, this relationship demonstrates a degree of variability across the older adult population. Thus, it is hypothesised that variation in genetic factors may influence the relationship between fitness and cognitive health. One such genetic factor is the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism, which has previously been shown to moderate the relationship between self-reported physical activity and memory performance. In this study we aim to investigate the interaction between BDNF Val66Met polymorphism and objectively-measured cardiorespiratory fitness on performance on tasks assessing verbal and visuospatial memory. Data from ninety-nine cognitively normal men and women aged 60-80 years were used. Fitness was assessed by peak oxygen consumption, and verbal and visuospatial memory were evaluated using well-validated measures. Participants were categorised into: lower-fit Met carriers, higher-fit Met carriers, lower-fit Val/Val, or higher-fit Val/Val. Higher-fit in iduals performed better on a task assessing visuospatial memory, compared with lower-fit in iduals. Furthermore, an interaction between BDNF Val66Met and fitness was observed in terms of visuospatial memory performance on a continuous paired associate learning task whereby lower-fit Met carriers performed 1 standard deviation worse than higher-fit Met carriers. No differences were observed between the higher-fit and lower-fit Val/Val homozygotes. Future intervention studies should evaluate the effect of structured exercise on cognitive health between BDNF Val66Met carriers and Val/Val homozygotes.
Publisher: American Physiological Society
Date: 02-2010
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.JSAMS.2019.06.013
Abstract: High-intensity exercise is a potential therapeutic tool to postpone or prevent the onset of cognitive decline. However, there is a lack of sufficient evidence regarding the longitudinal effects of structured resistance training on cognitive function in healthy adults. The purpose of this study was to investigate the effect of two ecologically valid, intense 12-week resistance training programs on cognitive function in late middle-aged adults. Single-site parallel randomised controlled trial at the Department of Exercise Science strength and conditioning laboratory. Groups allocated by minimisation randomisation. Forty-five healthy adults (age range=41-69 years) were enrolled and randomised into (A) high-load, long rest resistance training (n=14), or (B) moderate-load, short rest resistance training (n=15) twice per week for 12 weeks, or a non-exercising control (n=16). Follow-up within seven days. Data were collected September 2016-December 2017. Cognitive function assessed using the CogState computerised battery. Assessors were blinded to participant group allocation. Secondary outcomes were maximal muscle strength and body composition. Forty-four participants were analysed in 2018. Delayed verbal memory performance was improved (p=0.02) in resistance training groups (g=0.67-0.79) when compared to the control group, with no differences between training groups. Likewise, increases in maximal muscle strength were observed (p<0.01) in resistance training groups when compared to the control group, with no differences between training groups. No differences in body composition were observed. There were no adverse events or side-effects of the intervention. 12 weeks of intense resistance training improves delayed verbal memory irrespective of training design (i.e., high-load vs. moderate-load). This study is registered at www.anzctr.org.au ACTRN12616000690459.
Publisher: Elsevier BV
Date: 11-2014
Publisher: Center for Open Science
Date: 11-01-2019
Abstract: Transcranial direct current stimulation (tDCS) to the primary motor cortex (M1) and dorsolateral prefrontal cortex (DLPFC) have separately been shown to increase performance during fixed-work time-to-exhaustion tasks. No studies have examined application of tDCS to these cortical sites in a single study or during self-paced tasks. Objectives: This study examined the influence of anodal-tDCS (A-tDCS) applied to M1 and DLPFC on cycling performance during a self-paced 16.1-km time trial (TT). Design: randomised cross-over design. Methods: Ten cyclists received 20 min of A-tDCS (1.5 mA) applied to M1, DLPFC or the visual cortex (V1 control), followed by a standardised 10-min warmup and a 16.1-km cycling TT. During the TT, heart rate and power output were continuously recorded and mean values for each quartile of the total TT duration were calculated. Ratings of perceive exertion (RPE) were collected at four, eight, 12 and 16.1 km. RESULTS: No differences were observed for the time-to-complete (p=0.07 BF10=1.24) or mean power output (p=0.09 BF10=1.11) during the 16.1-km TT between the M1 (1443.7±81.0 s and 274±44 W), DLPFC (1428.4±80.0 s and 280±39 W) and V1 (1434.8±9.6 s and 279±44 W) conditions. Both HR and RPE progressively increased from the first quartile of the TT with no differences observed between A-tDCS conditions. CONCLUSION: A-tDCS does not represents a viable method to decrease the physiological and perceptual stress during or enhance the performance of a self-paced cycling TT. Nevertheless, these findings should be viewed with respect to the inherent complexities between performance, fatigue and the brain.
Publisher: Cold Spring Harbor Laboratory
Date: 24-02-2023
DOI: 10.1101/2023.02.24.529869
Abstract: Double-stranded DNA viruses utilise machinery, made of terminase proteins, to package viral DNA into the capsid. For cos bacteriophage, a defined signal, recognised by small terminase, flanks each genome unit. Here we present the first structural data for a cos virus DNA packaging motor, assembled from the bacteriophage HK97 terminase proteins, procapsids encompassing the portal protein, and DNA containing a cos site. The cryo-EM structure is consistent with the packaging termination state adopted after DNA cleavage, with DNA density within the large terminase assembly ending abruptly at the portal protein entrance. Retention of the large terminase complex after cleavage of the short DNA substrate suggests that motor dissociation from the capsid requires headful pressure, in common with pac viruses. Interestingly, the clip domain of the 12-subunit portal protein does not adhere to C 12 symmetry, indicating asymmetry induced by binding of the large terminase/DNA. The motor assembly is also highly asymmetric, showing a ring of 5 large terminase monomers, tilted against the portal. Variable degrees of extension between N- and C-terminal domains of in idual subunits suggest a mechanism of DNA translocation driven by inter-domain contraction and relaxation.
Publisher: Public Library of Science (PLoS)
Date: 27-02-2019
Publisher: Georg Thieme Verlag KG
Date: 06-02-2009
Abstract: The purpose of this study was to determine the influence of starting strategy on time trial performance in the heat. Eleven endurance trained male cyclists (30+/-5 years, 79.5+/-4.6 kg, VO(2max) 58.5+/-5.0 ml x kg x (-1) min(-1)) performed four 20-km time trials in the heat (32.7+/-0.7 degrees C and 55% relative humidity). The first time trial was completed at a self-selected pace (SPTT). During the following time trials, subjects performed the initial 2.5-km at power outputs 10% above (10% ATT), 10% below (10% BTT) or equal (ETT) to that of the average power during the initial 2.5-km of the self-selected trial the remaining 17.5-km was self-paced. Throughout each time trial, power output, rectal temperature, skin temperature, heat storage, pain intensity and thermal sensation were taken. Despite significantly (P<0.05) greater power outputs for 10% BTT (273+/-45W) compared with the ETT (267+/-48W) and 10% ATT (265+/-41W) during the final 17.5-km, overall 20-km performance time was not significantly different amongst trials. There were no differences in any of the other measured variables between trials. These data show that varying starting power by +/-10% did not affect 20 km time trial performance in the heat.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 28-06-2022
DOI: 10.1519/JSC.0000000000004079
Abstract: Smith, NDW, Scott, BR, Girard, O, and Peiffer, JJ. Aerobic training with blood flow restriction for endurance athletes: potential benefits and considerations of implementation. J Strength Cond Res 36(12): 3541–3550, 2022—Low-intensity aerobic training with blood flow restriction (BFR) can improve maximal oxygen uptake, delay the onset of blood lactate accumulation, and may provide marginal benefits to economy of motion in untrained in iduals. Such a training modality could also improve these physiological attributes in well-trained athletes. Indeed, aerobic BFR training could be beneficial for those recovering from injury, those who have limited time for training a specific physiological capacity, or as an adjunct training stimulus to provide variation in a program. However, similarly to endurance training without BFR, using aerobic BFR training to elicit physiological adaptations in endurance athletes will require additional considerations compared with nonendurance athletes. The objective of this narrative review is to discuss the acute and chronic aspects of aerobic BFR exercise for well-trained endurance athletes and highlight considerations for its effective implementation. This review first highlights key physiological capacities of endurance performance. The acute and chronic responses to aerobic BFR exercise and their impact on performance are then discussed. Finally, considerations for prescribing and monitoring aerobic BFR exercise in trained endurance populations are addressed to challenge current views on how BFR exercise is implemented.
Publisher: Informa UK Limited
Date: 21-09-2016
DOI: 10.1080/02640414.2016.1235790
Abstract: This study examined the test-retest reliability of near-infrared spectroscopy (NIRS), laser Doppler flowmetry (LDF) and Doppler ultrasound to assess exercise-induced haemodynamics. Nine men completed two identical trials consisting of 25-min submaximal cycling at first ventilatory threshold followed by repeated 30-s bouts of high-intensity (90% of peak power) cycling in 32.8 ± 0.4°C and 32 ± 5% relative humidity (RH). NIRS (tissue oxygenation index [TOI] and total haemoglobin [tHb]) and LDF (perfusion units [PU]) signals were monitored continuously during exercise, and leg blood flow was assessed by Doppler ultrasound at baseline and after exercise. Cutaneous vascular conductance (CVC PU/mean arterial pressure (MAP)) was expressed as the percentage change from baseline (%CVC
Publisher: Human Kinetics
Date: 04-2017
Abstract: To describe the within-season external workloads of professional male road cyclists for optimal training prescription. Training and racing of 4 international competitive professional male cyclists (age 24 ± 2 y, body mass 77.6 ± 1.5 kg) were monitored for 12 mo before the world team-time-trial ch ionships. Three within-season phases leading up to the team-time-trial world ch ionships on September 20, 2015, were defined as phase 1 (Oct–Jan), phase 2 (Feb–May), and phase 3 (June–Sept). Distance and time were compared between training and racing days and over each of the various phases. Times spent in absolute ( , 100–300, 400–500, W) and relative (0–1.9, 2.0–4.9, 5.0–7.9, W/kg) power zones were also compared for the whole season and between phases 1–3. Total distance (3859 ± 959 vs 10911 ± 620 km) and time (240.5 ± 37.5 vs 337.5 ± 26 h) were lower ( P .01) in phase 1 than phase 2. Total distance decreased ( P .01) from phase 2 to phase 3 (10911 ± 620 vs 8411 ± 1399 km, respectively). Mean absolute (236 ± 12.1 vs 197 ± 3 W) and relative (3.1 ± 0 vs 2.5 ± 0 W/kg) power output were higher ( P .05) during racing than training, respectively. Volume and intensity differed between training and racing over each of 3 distinct within-season phases.
Publisher: Human Kinetics
Date: 08-2022
Abstract: This study compared training loads and internal:external load ratios from an aerobic interval session at the highest perceptually sustainable intensity with and without blood flow restriction (BFR). On separate days, 14 endurance cyclists/triathletes completed four 4-minute self-paced aerobic cycling intervals at their highest sustainable intensity, with and without BFR (60% of arterial occlusion pressure). Internal training load was quantified using 3 training impulses (TRIMP Banister, Lucia, and Edwards) and sessional ratings of perceived exertion. External load was assessed using total work done (TWD). Training load ratios between all internal loads were calculated relative to TWD. Lucia TRIMP was lower for the BFR compared with non-BFR session (49 [9] vs 53 [8] arbitrary units [au], P = .020, dz = -0.71). No between-conditions differences were observed for Banister TRIMP (P = .068), Edwards TRIMP (P = .072), and training load in sessional ratings of perceived exertion (P = .134). The TWD was lower for the BFR compared with non-BFR session (223 [52] vs 271 [58] kJ, P < .001, dz = -1.27). Ratios were greater for the BFR session compared with non-BFR for Lucia TRIMP:TWD (0.229 [0.056] vs 0.206 [0.056] au, P < .001, dz = 1.21), Edwards TRIMP:TWD (0.396 [0.105] vs 0.370 [0.088] au, P = .031, dz = 0.66), and training load in sessional ratings of perceived exertion:TWD (1.000 [0.266] vs 0.890 [0.275] au, P = .044, dz = 0.60), but not Banister TRIMP:TWD (P = .306). Practitioners should consider both internal and external loads when monitoring BFR exercise to ensure the demands are appropriately captured. These BFR-induced changes were reflected by the Lucia TRIMP:TWD and Edwards TRIMP:TWD ratio, which could be used to monitor aerobic BFR training loads. The Lucia TRIMP:TWD ratio likely represents BFR-induced changes more appropriately compared with ratios involving either Edwards or Banister TRIMP.
Publisher: Springer Science and Business Media LLC
Date: 14-08-2013
DOI: 10.1038/MP.2012.107
Abstract: Previous studies suggest physical activity improves cognition and lowers Alzheimer's disease (AD) risk. However, key AD pathogenic factors that are thought to be influenced by physical activity, particularly plasma amyloid-β (Aβ) and Aβ brain load, have yet to be thoroughly investigated. The objective of this study was to determine if plasma Aβ and amyloid brain deposition are associated with physical activity levels, and whether these associations differed between carriers and non-carriers of the apolipoprotein E (APOE) ε4 allele. Five-hundred and forty six cognitively intact participants (aged 60-95 years) from the Australian Imaging, Biomarkers and Lifestyle Study of Ageing (AIBL) were included in these analyses. Habitual physical activity levels were measured using the International Physical Activity Questionnaire (IPAQ). Serum insulin, glucose, cholesterol and plasma Aβ levels were measured in fasting blood s les. A subgroup (n=116) underwent (11)C-Pittsburgh compound B (PiB) positron emission tomography (PET) scanning to quantify brain amyloid load. Higher levels of physical activity were associated with higher high density lipoprotein (HDL) (P=0.037), and lower insulin (P<0.001), triglycerides (P=0.019) and Aβ1-42/1-40 ratio (P=0.001). After stratification of the cohort based on APOE ε4 allele carriage, it was evident that only non-carriers received the benefit of reduced plasma Aβ from physical activity. Conversely, lower levels of PiB SUVR (standardised uptake value ratio) were observed in higher exercising APOE ε4 carriers. Lower plasma Aβ1-42/1-40 and brain amyloid was observed in those reporting higher levels of physical activity, consistent with the hypothesis that physical activity may be involved in the modulation of pathogenic changes associated with AD.
Publisher: Springer Science and Business Media LLC
Date: 08-2019
DOI: 10.1007/S00421-019-04202-W
Abstract: There is growing evidence for a preventative effect of resistance training on cognitive decline through physiological mechanisms yet, the effect of resistance training on resting growth factors and homocysteine levels is incompletely understood. This study aimed to investigate the effect of intense resistance training, for 12 weeks, on changes in peripheral growth factors and homocysteine in late middle-aged adults. 45 healthy adults were enrolled into the single-site parallel groups' randomized-controlled trial conducted at the Department of Exercise Science, Strength and Conditioning Laboratory, Murdoch University. Participants were allocated to the following conditions: (1) high-load resistance training (n = 14), or (2) moderate-load resistance training (n = 15) twice per week for 12 weeks or (3) non-exercising control group (n = 16). Data were collected from September 2016 to December 2017. Fasted blood s les were collected at baseline and within 7 days of trial completion for the analysis of resting serum brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1, vascular endothelial growth factor, and plasma homocysteine levels. No differences in baseline to post-intervention change in serum growth factors or plasma homocysteine levels were observed between groups. A medium effect was calculated for BDNF change within the high-load condition alone (+ 12.9%, g = 0.54). High-load or moderate-load resistance training twice per week for 12 weeks has no effect on peripheral growth factors or homocysteine in healthy late middle-aged adults. Australian New Zealand Clinical Trials Registry: ACTRN12616000690459.
Publisher: Informa UK Limited
Date: 06-2012
DOI: 10.1080/02640414.2012.689432
Abstract: AbstThis study examined the relationship between intensity of training and changes in hydration status, core temperature, sweat rate and composition and fluid balance in professional football players training in the heat. Thirteen professional football players completed three training sessions "higher-intensity" (140 min HI140), "lower-intensity" (120 min LI120) and "game-simulation" (100 min GS100). Movement demands were measured by Global Positioning System, sweat rate and concentration were determined from dermal patches and body mass change. Despite similar environmental conditions (26.9 ± 0.1 °C and 65.0 ± 7.0% relative humidity [Rh]), higher relative speeds (m · min(-1)) and increased perceptions of effort and thermal strain were observed in HI140 and GS100 compared with LI120 (P < 0.05). Significantly (P < 0.05) greater sweat rate (L · h(-1)) and electrolyte losses (g) were observed in HI140 and GS100 compared with LI120. Rate of rise in core temperature was correlated with mean speed (r = 0.85), session rating of perceived exertion (sRPE) (r = 0.61), loss of potassium (K+) (r = 0.51) sweat rate (r = 0.49), and total sweat loss (r = 0.53), with mean speed the strongest predictor. Sodium (Na+) (r = 0.39) and K+ (r = 0.50) losses were associated with total distance covered. In hot conditions, in idualised rehydration practices should be adopted following football training to account for differences in sweat rate and electrolyte losses in response to intensity and overall activity within a session.
Publisher: Wiley
Date: 28-07-2018
DOI: 10.1111/CPF.12451
Abstract: This study assessed whether hypoxia during high-load resistance exercise could enhance the acute physiological responses related to muscular development. Twelve trained men performed exercise in three conditions: normoxia (fraction of inspired oxygen [F
Publisher: Human Kinetics
Date: 10-2019
Abstract: Objectives : To examine the associations between physical activity duration and intensity, cardiorespiratory fitness, and executive function in older adults. Methods : Data from 99 cognitively normal adults (age = 69.10 ± 5.1 years n = 54 females) were used in the current study. Physical activity (intensity and duration) was measured with the International Physical Activity Questionnaire, and fitness was measured by analysis of maximal aerobic capacity, VO 2 peak. Executive function was measured comprehensively, including measures of Shifting, Updating, Inhibition, Generativity, and Nonverbal Reasoning. Results : Higher levels of cardiorespiratory fitness were associated with better performance on Generativity ( B = .55 95% confidence interval [.15, .97]). No significant associations were found between self-reported physical activity intensity/duration and executive functions. Discussion : To our knowledge, this study is the first to identify an association between fitness and Generativity. Associations between physical activity duration and intensity and executive function requires further study, using objective physical activity measures and longitudinal observations.
Publisher: BMJ
Date: 20-09-2015
DOI: 10.1136/BJSPORTS-2013-092417
Abstract: Laboratory studies that support the hydration guidelines of leading governing bodies have shown that dehydration to only -2% of body mass can lead to increase in body temperature and heart rate during exercise, and decrease in performance. These studies, however, have been conducted in relatively windless environments (ie, wind speed <12.9 km/h), without participants being blinded to their hydration status. To investigate the effect of blinded hydration status on cycling time-trial performance in the heat with ecologically valid facing wind speed conditions. During three experimental trials, 10 cyclists were dehydrated to -3% body mass by performing 2 h of submaximal exercise (walking and cycling) in the heat, before being reinfused with saline to replace 100%, 33% or 0% of fluid losses, leaving them 0%, -2% or -3% hypohydrated, respectively. Participants then completed a 25 km time trial in the heat (33°C, 40% relative humidity wind speed 32 km/h) during which their starting hydration status was maintained by infusing saline at a rate equal to their sweat rate. The treatment was participant-blinded and the order was randomised. Completion time, power output, heart rate, rectal temperature and perceptual variables were measured. While rectal temperature was higher beyond 17 km of the time trial in the -3% vs 0% conditions (38.9±0.3°C vs 38.6±0.3°C p<0.05), no other differences between trials were shown. When well-trained cyclists performed a 25 km cycling time trial under ecologically valid conditions and were blinded to their hydration status, performance, physiological and perceptual variables were not different between trials. These data do not support the residing basis behind many of the current hydration guidelines.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2018
DOI: 10.1249/MSS.0000000000001553
Abstract: Leg order during sequential single-leg cycling (i.e., exercising both legs independently within a single session) may affect local muscular responses potentially influencing adaptations. This study examined the cardiovascular and skeletal muscle hemodynamic responses during double-leg and sequential single-leg cycling. Ten young healthy adults (28 ± 6 yr) completed six 1-min double-leg intervals interspersed with 1 min of passive recovery and, on a separate occasion, 12 (six with one leg followed by six with the other leg) 1-min single-leg intervals interspersed with 1 min of passive recovery. Oxygen consumption, heart rate, blood pressure, muscle oxygenation, muscle blood volume, and power output were measured throughout each session. Oxygen consumption, heart rate, and power output were not different between sets of single-leg intervals, but the average of both sets was lower than the double-leg intervals. Mean arterial pressure was higher during double-leg compared with sequential single-leg intervals (115 ± 9 vs 104 ± 9 mm Hg, P 0.05) and higher during the initial compared with second set of single-leg intervals (108 ± 10 vs 101 ± 10 mm Hg, P 0.05). The increase in muscle blood volume from baseline was similar between the active single leg and the double leg (267 ± 150 vs 214 ± 169 μM·cm, P = 0.26). The pattern of change in muscle blood volume from the initial to second set of intervals was significantly different ( P 0.05) when the leg was active in the initial (−52.3% ± 111.6%) compared with second set (65.1% ± 152.9%). These data indicate that the order in which each leg performs sequential single-leg cycling influences the local hemodynamic responses, with the inactive muscle influencing the stimulus experienced by the contralateral leg.
Publisher: Springer Science and Business Media LLC
Date: 12-06-2012
DOI: 10.1007/S00421-011-2021-1
Abstract: The purpose of this study was to examine the cardiorespiratory and muscle oxygenation responses to a sprint interval training (SIT) session, and to assess their relationships with maximal pulmonary O(2) uptake [Formula: see text], on- and off- [Formula: see text] kinetics and muscle reoxygenation rate (Reoxy rate). Ten male cyclists performed two 6-min moderate-intensity exercises (≈90-95% of lactate threshold power output, Mod), followed 10 min later by a SIT session consisting of 6 × 30-s all out cycling sprints interspersed with 2 min of passive recovery. [Formula: see text] kinetics at Mod onset ([Formula: see text]) and cessation ([Formula: see text]) were calculated. Cardiorespiratory variables, blood lactate ([La](b)) and muscle oxygenation level of the vastus lateralis (tissue oxygenation index, TOI) were recorded during SIT. Percentage of the decline in power output (%Dec), time spent above 90% of [Formula: see text] (t > 90% [Formula: see text]) and Reoxy rate after each sprint were also recorded. Despite a low mean [Formula: see text] (48.0 ± 4.1% of [Formula: see text]), SIT performance was associated with high peak [Formula: see text] (90.4 ± 2.8% of [Formula: see text]), muscle deoxygenation (sprint ΔTOI = -27%) and [La](b) (15.3 ± 0.7 mmol l(-1)) levels. Muscle deoxygenation and Reoxy rate increased throughout sprint repetitions (P 90% [Formula: see text] versus [Formula: see text] [r = 0.68 (90% CL, 0.20 0.90) P = 0.03], there were no significant correlations between any index of aerobic function and either SIT performance or physiological responses [e.g., %Dec vs. [Formula: see text]: r = -0.41 (-0.78 0.18) P = 0.24]. Present results show that SIT elicits a greater muscle O(2) extraction with successive sprint repetitions, despite the decrease in external power production (%Dec = 21%). Further, our findings obtained in a small and homogenous group indicate that performance and physiological responses to SIT are only slightly influenced by aerobic fitness level in this population.
Publisher: Informa UK Limited
Date: 15-07-2020
Publisher: Wiley
Date: 31-03-2017
DOI: 10.1111/SMS.12685
Abstract: The post-exercise hepcidin response during prolonged (>2 weeks) hypoxic exposure is not well understood. We compared plasma hepcidin levels 3 h after exercise [6 × 1000 m at 90% of maximal aerobic running velocity (vVO
Publisher: Cold Spring Harbor Laboratory
Date: 10-05-2022
DOI: 10.1101/2022.05.10.491410
Abstract: Many essential cellular processes rely on substrate rotation or translocation by a multi-subunit, ring-type NTPase. A large number of double-stranded DNA viruses, including tailed bacteriophages and herpes viruses, use a homomeric ring ATPase to processively translocate viral genomic DNA into procapsids during assembly. Our current understanding of viral DNA packaging comes from three archetypal bacteriophage systems: cos, pac and phi29. Detailed mechanistic understanding exists for pac and phi29, but not for cos . Here we reconstituted in vitro a cos packaging system based on bacteriophage HK97 and provided a detailed biochemical and structural description. We used a photobleaching-based, single-molecule assay to determine the stoichiometry of the DNA-translocating ATPase large terminase. Crystal structures of the large terminase and DNA-recruiting small terminase, a first for both this phage and a cos system, reveal unexpected mechanistic similarities between cos and pac systems. At the same time, mutational and biochemical analyses indicate a new regulatory mechanism for ATPase multimerization and coordination in the HK97 system. This work therefore establishes a framework for studying the evolutionary relationships between ATP-dependent DNA translocation machineries in double-stranded DNA viruses.
Publisher: American Physiological Society
Date: 02-2009
DOI: 10.1152/AJPHEART.01017.2008
Abstract: The aim of the present study was to assess the effect of cold water immersion (CWI) on postexercise parasympathetic reactivation. Ten male cyclists (age, 29 ± 6 yr) performed two repeated supramaximal cycling exercises (SE 1 and SE 2 ) interspersed with a 20-min passive recovery period, during which they were randomly assigned to either 5 min of CWI in 14°C or a control (N) condition where they sat in an environmental chamber (35.0 ± 0.3°C and 40.0 ± 3.0% relative humidity). Rectal temperature (T re ) and beat-to-beat heart rate (HR) were recorded continuously. The time constant of HR recovery (HRRτ) and a time (30-s) varying vagal-related HR variability (HRV) index (rMSSD 30s ) were assessed during the 6-min period immediately following exercise. Resting vagal-related HRV indexes were calculated during 3-min periods 2 min before and 3 min after SE 1 and SE 2 . Results showed no effect of CWI on T re ( P = 0.29), SE performance ( P = 0.76), and HRRτ ( P = 0.61). In contrast, all vagal-related HRV indexes were decreased after SE 1 ( P 0.001) and tended to decrease even further after SE 2 under N condition but not with CWI. When compared with the N condition, CWI increased HRV indexes before ( P 0.05) and rMSSD 30s after ( P 0.05) SE 2 . Our study shows that CWI can significantly restore the impaired vagal-related HRV indexes observed after supramaximal exercise. CWI may serve as a simple and effective means to accelerate parasympathetic reactivation during the immediate period following supramaximal exercise.
Publisher: Mary Ann Liebert Inc
Date: 02-2010
Abstract: Resistance training programs for older adults (>65 years) are an effective method to counteract the loss of muscle mass, strength, and function associated with aging. Nevertheless, limited normative strength and functional data exist for the comparison and stratification of older adults. Therefore, the purpose of this study was to establish normative strength and functional data for males and females 64-69 years, 70-74 years, and 75+ years old, using commonly available equipment and procedures. At total of 110 males and 191 females completed upper and lower body strength and functional performance testing. Measurements were compared across gender and age groups (65-69, 70-74, and 75+ years). All strength measures, absolute and relative (to body and lean muscle mass), were significantly (p < 0.01) greater in males compared with females. Additionally, younger participants were stronger (p < 0.01) compared with older participants. Similar findings were observed for the functional performance tests. Quartile ranking for relative strength and functional measures provides comparative data for clinical and research assessments. This study provides additional normative data for strength and functional performance in males and females aged 65-69, 70-74, and 75+ years and confirms lower performance in females and with aging even when adjusted for lean muscle mass.
Publisher: Springer Science and Business Media LLC
Date: 09-06-2015
DOI: 10.1007/S40279-015-0344-5
Abstract: Ratings of perceived exertion (RPE) and effort are considered extremely important in the regulation of intensity during self-paced physical activity. While effort and exertion are slightly different constructs, these terms are often used interchangeably within the literature. The development of perceptions of both effort and exertion is a complicated process involving numerous neural processes occurring in various regions within the brain. It is widely accepted that perceptions of effort are highly dependent on efferent copies of central drive which are sent from motor to sensory regions of the brain. Additionally, it has been suggested that perceptions of effort and exertion are integrated based on the balance between corollary discharge and actual afferent feedback however, the involvement of peripheral afferent sensory feedback in the development of such perceptions has been debated. As such, this review examines the possible difference between effort and exertion, and the implications of such differences in understanding the role of such perceptions in the regulation of pace during exercise.
Publisher: Oxford University Press (OUP)
Date: 04-2024
DOI: 10.1093/NAR/GKAC647
Abstract: Many essential cellular processes rely on substrate rotation or translocation by a multi-subunit, ring-type NTPase. A large number of double-stranded DNA viruses, including tailed bacteriophages and herpes viruses, use a homomeric ring ATPase to processively translocate viral genomic DNA into procapsids during assembly. Our current understanding of viral DNA packaging comes from three archetypal bacteriophage systems: cos, pac and phi29. Detailed mechanistic understanding exists for pac and phi29, but not for cos. Here, we reconstituted in vitro a cos packaging system based on bacteriophage HK97 and provided a detailed biochemical and structural description. We used a photobleaching-based, single-molecule assay to determine the stoichiometry of the DNA-translocating ATPase large terminase. Crystal structures of the large terminase and DNA-recruiting small terminase, a first for a biochemically defined cos system, reveal mechanistic similarities between cos and pac systems. At the same time, mutational and biochemical analyses indicate a new regulatory mechanism for ATPase multimerization and coordination in the HK97 system. This work therefore establishes a framework for studying the evolutionary relationships between ATP-dependent DNA translocation machineries in double-stranded DNA viruses.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.ARR.2019.01.003
Abstract: Several prospective cohort studies have reported an association between higher levels of physical activity and decreased risk of cognitive decline and dementia, years later. To support physical activity as a preventative measure against dementia, including Alzheimer's disease (AD the most common form of dementia), evidence regarding the underlying mechanisms is vital. Here, we review previous work examining the role of physical activity in modulating levels of AD pathological hallmarks, beta-amyloid (Aβ) and tau (in the brain, cerebrospinal fluid and blood). Robust evidence from transgenic animal studies suggests that physical activity (voluntary wheel running) and exercise (forced wheel running) are implicated in lowering levels of brain Aβ and tau. Nevertheless, evidence from human studies, utilising measurements from positron emission tomography and cerebrospinal fluid biomarkers, is less consistent. Rigorous randomised controlled trials utilising long exercise interventions are vital to further understand the relationship between physical activity and Alzheimer's disease.
Publisher: Elsevier BV
Date: 2009
DOI: 10.1016/J.JSAMS.2007.10.011
Abstract: Cold water immersion (CWI) is a popular recovery modality, but actual physiological responses to CWI after exercise in the heat have not been well documented. The purpose of this study was to examine effects of 20-min CWI (14 degrees C) on neuromuscular function, rectal (T(re)) and skin temperature (T(sk)), and femoral venous diameter after exercise in the heat. Ten well-trained male cyclists completed two bouts of exercise consisting of 90-min cycling at a constant power output (216+/-12W) followed by a 16.1km time trial (TT) in the heat (32 degrees C). Twenty-five minutes post-TT, participants were assigned to either CWI or control (CON) recovery conditions in a counterbalanced order. T(re) and T(sk) were recorded continuously, and maximal voluntary isometric contraction torque of the knee extensors (MVIC), MVIC with superimposed electrical stimulation (SMVIC), and femoral venous diameters were measured prior to exercise, 0, 45, and 90min post-TT. T(re) was significantly lower in CWI beginning 50min post-TT compared with CON, and T(sk) was significantly lower in CWI beginning 25min post-TT compared with CON. Decreases in MVIC, and SMVIC torque after the TT were significantly greater for CWI compared with CON differences persisted 90min post-TT. Femoral vein diameter was approximately 9% smaller for CWI compared with CON at 45min post-TT. These results suggest that CWI decreases T(re), but has a negative effect on neuromuscular function.
Publisher: Human Kinetics
Date: 10-2018
Abstract: Purpose : To examine the power-output distribution and sprint characteristics of professional female road cyclists. Methods : A total of 31 race files, representing top 5 finishes, were collected from 7 professional female cyclists. Files were analyzed for sprint characteristics, including mean and peak power output, velocity, and duration. The final 20 min before the sprint was analyzed to determine the mean maximal power output (MMP) consistent with durations of 5, 15, 30, 60, 240, and 600 s. Throughout the race, the number of efforts for each duration exceeding 80% of its corresponding final 20-min MMP (MMP 80 ) was determined. The number of 15-s efforts exceeding 80% of the mean final sprint power output (MSP 80 ) was determined. Results : Sprint finishes lasted 21.8 (6.7) s with mean and peak power outputs of 679 (101) and 886 (91) W, respectively. Throughout the race, additional 5-, 15-, and 30-s efforts above MMP 80 were completed in the 5th compared with the 1st–4th quintiles of the race. The 60-s efforts were greater during the 5th quintile compared with the 1st, 2nd, and 4th quintiles, and during the 3rd compared with the 4th quintile. More 240-s efforts were recorded during the 5th compared with the 1st and 4th quintiles. About 82% of the 15-s efforts above MSP 80 were completed in the 2nd, 3rd, and 5th quintiles of the race. Conclusions : These data demonstrate the variable nature of women’s professional cycling and the physical demands necessary for success, thus providing information that could enhance in-race decision making and the development of race-specific training programs.
No related grants have been discovered for Jeremiah Peiffer.