ORCID Profile
0000-0003-4334-608X
Current Organisation
Bond University
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Publisher: Human Kinetics
Date: 2020
Abstract: It is the position of Sports Dietitians Australia (SDA) that exercise in hot and/or humid environments, or with significant clothing and/or equipment that prevents body heat loss (i.e., exertional heat stress), provides significant challenges to an athlete’s nutritional status, health, and performance. Exertional heat stress, especially when prolonged, can perturb thermoregulatory, cardiovascular, and gastrointestinal systems. Heat acclimation or acclimatization provides beneficial adaptations and should be undertaken where possible. Athletes should aim to begin exercise euhydrated. Furthermore, preexercise hyperhydration may be desirable in some scenarios and can be achieved through acute sodium or glycerol loading protocols. The assessment of fluid balance during exercise, together with gastrointestinal tolerance to fluid intake, and the appropriateness of thirst responses provide valuable information to inform fluid replacement strategies that should be integrated with event fuel requirements. Such strategies should also consider fluid availability and opportunities to drink, to prevent significant under- or overconsumption during exercise. Postexercise beverage choices can be influenced by the required timeframe for return to euhydration and co-ingestion of meals and snacks. Ingested beverage temperature can influence core temperature, with cold/icy beverages of potential use before and during exertional heat stress, while use of menthol can alter thermal sensation. Practical challenges in supporting athletes in teams and traveling for competition require careful planning. Finally, specific athletic population groups have unique nutritional needs in the context of exertional heat stress (i.e., youth, endurance/ultra-endurance athletes, and para-sport athletes), and specific adjustments to nutrition strategies should be made for these population groups.
Publisher: Human Kinetics
Date: 06-2022
Abstract: Purpose: The effect of acetaminophen (ACT, also known as paracetamol) on endurance performance in hot and humid conditions has been shown previously in recreationally active populations. The aim of this study was to determine the effect of ACT on physiological and perceptual variables during steady-state and time-trial cycling performance of trained triathletes in hot and humid conditions. Methods: In a randomized, double-blind crossover design, 11 triathletes completed ∼60 minutes steady-state cycling at 63% peak power output followed by a time trial (7 kJ·kg body mass −1 , ∼30 min) in hot and humid conditions (∼30°C, ∼69% relative humidity) 60 minutes after consuming either 20 mg·kg body mass −1 ACT or a color-matched placebo. Time-trial completion time, gastrointestinal temperature, skin temperature, thermal sensation, thermal comfort, rating of perceived exertion, and fluid balance were recorded throughout each session. Results: There was no difference in performance in the ACT trial compared with placebo ( P = .086, d = 0.57), nor were there differences in gastrointestinal and skin temperature, thermal sensation and comfort, or fluid balance between trials. Conclusion: In conclusion, there was no effect of ACT (20 mg·kg body mass −1 ) ingestion on physiology, perception, and performance of trained triathletes in hot and humid conditions, and existing precooling and percooling strategies appear to be more appropriate for endurance cycling performance in the heat.
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: Human Kinetics
Date: 12-2017
Abstract: Immediate postexercise access to fruit/fluid via a recovery “station” is a common feature of mass participation sporting events. Yet little evidence exists examining their impact on subsequent dietary intake. The aim of this study was to determine if access to fruit/water/sports drinks within a recovery station significantly alters dietary and fluid intakes in the immediate postexercise period and influences hydration status the next morning. 127 (79 males) healthy participants ( M ± SD , age = 22.5 ± 3.5y, body mass (BM) = 73 ± 13kg) completed two self-paced morning 10km runs separated by 1 week. Immediately following the first run, participants were randomly assigned to enter (or not) the recovery station for 30min. All participants completed the alternate recovery option the following week. Participants recorded BM before and after exercise and measured Urine Specific Gravity (U SG ) before running and again the following morning. For both trial days, participants also completed 24h food and fluid records via a food diary that included photographs. Paired-s le t tests were used to assess differences in hydration and dietary outcome variables (Recovery vs. No Recovery). No difference in preexercise U SG or BM change from exercise were observed between treatments ( p ’s .05). Attending the recovery zone resulted in a greater total daily fluid (Recovery = 3.37 ± 1.46L, No Recovery = 3.16 ± 1.32L, p = .009) and fruit intake (Recovery = 2.37 ± 1.76 servings, No Recovery = 1.55 ± 1.61 servings, p .001), but had no influence on daily total energy (Recovery = 10.15 ± 4.2MJ, No Recovery = 10.15 ± 3.9MJ), or macronutrient intakes ( p .05). Next morning U SG values were not different between treatments (Recovery = 1.018 ± 0.007, No Recovery = 1.019 ± 0.009, p .05). Recovery stations provide an opportunity to modify dietary intake which promote positive lifestyle behaviors in recreational athletes.
Publisher: Human Kinetics
Date: 10-2014
Abstract: It is the position of Sports Dietitians Australia (SDA) that adolescent athletes have unique nutritional requirements as a consequence of undertaking daily training and competition in addition to the demands of growth and development. As such, SDA established an expert multidisciplinary panel to undertake an independent review of the relevant scientific evidence and consulted with its professional members to develop sports nutrition recommendations for active and competitive adolescent athletes. The position of SDA is that dietary education and recommendations for these adolescent athletes should reinforce eating for long term health. More specifically, the adolescent athlete should be encouraged to moderate eating patterns to reflect daily exercise demands and provide a regular spread of high quality carbohydrate and protein sources over the day, especially in the period immediately after training. SDA recommends that consideration also be given to the dietary calcium, Vitamin D and iron intake of adolescent athletes due to the elevated risk of deficiency of these nutrients. To maintain optimal hydration, adolescent athletes should have access to fluids that are clean, cool and supplied in sufficient quantities before, during and after participation in sport. Finally, it is the position of SDA that nutrient needs should be met by core foods rather than supplements, as the recommendation of dietary supplements to developing athletes over-emphasizes their ability to manipulate performance in comparison with other training and dietary strategies.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2017
Publisher: MDPI AG
Date: 07-12-2022
DOI: 10.3390/NU14245203
Abstract: Triathlon is a physically demanding sport, requiring athletes to make informed decisions regarding their daily food and fluid intake to align with daily training. With an increase in uptake for online learning, remotely delivered education programs offer an opportunity to improve nutritional knowledge and subsequent dietary intake in athletes. This single-arm observational study aimed to evaluate the effectiveness of a remotely delivered nutrition education program on sports nutrition knowledge and the dietary intake of junior elite triathletes (n = 21 female n = 9 male n = 12 18.9 ± 1.6 y). A total of 18 participants completed dietary intake assessments (4-day food diary via Easy Diet DiaryTM) and 14 participants completed an 83-question sports nutrition knowledge assessment (Sports Nutrition Knowledge Questionnaire (SNKQ)) before and after the 8-week program. Sports nutrition knowledge scores improved by 15% (p 0.001, ES = 0.9) following the program. Male participants reported higher energy intakes before (3348 kJ, 95% CI: 117–6579 p = 0.043) and after (3644 kJ, 95% CI: 451–6836 p = 0.028) the program compared to females. Carbohydrate intake at breakfast (p = 0.022), daily intakes of fruit (p = 0.033), dairy (p = 0.01) and calcium (p = 0.029) increased following nutrition education. Irrespective of gender, participants had higher intakes of energy (p 0.001), carbohydrate (p = 0.001), protein (p = 0.007), and fat (p = 0.007) on heavy training days compared to lighter training days before and after the program with total nutrition knowledge scores negatively correlated with discretionary food intake (r = −0.695, p = 0.001). A remotely delivered nutrition education program by an accredited sports nutrition professional improved sports nutrition knowledge and subsequent dietary intake of junior elite triathletes, suggesting remote delivery of nutrition education may prove effective when social distancing requirements prevent face-to-face opportunities.
Publisher: The Royal Australian College of General Practitioners
Date: 2020
Publisher: Human Kinetics
Date: 12-2016
Abstract: We examined the relationship between the regain of body mass (BM) after weigh-in and success in real-life judo competition. Eighty-six (36 females, 50 males) senior judoka volunteered for this observational study of an international judo competition. Subjects were weighed at the official weigh-in and one hour before their first competition fight (15–20 hr later). Regain in BM after weigh-in was compared between medal winners and nonmedalists, winners and losers of each fight, males and females and across weight isions. Heavyweights were excluded from analysis. Prefight BM was greater than BM at official weigh-in for both males and females, with % BM gains of 2.3 ± 2.0 ( p ≤ .0001 ES= 1.59 CI95% [1.63, 2.98]) and 3.1 ± 2.2 ( p ≤ .0001 ES = 2.03 CI95% [2.30, 3.89]), respectively. No significant differences were found between weight isions for post weigh-in BM regain. Differences in post weigh-in BM regain were significantly higher in medal winners than nonmedalists for males and females combined (1.4 ± 0.4% BM p = .0026 ES= 0.69 CI95% [0.05, 2.34]) and for males alone (1.5 ± 0.6% BM p = .017 ES= 0.74 CI95% [0.02, 2.64]), but not for females (1.2 ± 0.7% BM p = .096 ES = 0.58 CI95% [-0.02, 2.31]). Differences in BM regain after weigh-in between winners and losers were significant across all fights (0.9 ± 0.3% BM p = .0021 ES= 0.43 CI95% [0.31, 1.41]) but not for first round fights (0.8 ± 0.5% BM p = .1386, ES = 0.38 CI95% [-0.26, 1.86]). Winners showed a greater regain in BM post weigh-in than losers. This may reflect the greater magnitude of the BM loss needed to achieve weigh-in targets which also relates to the experience level of successful athletes.
Publisher: Cambridge University Press (CUP)
Date: 22-09-2021
DOI: 10.1017/S0007114520003694
Abstract: Nutrition education programmes for athletes aim to enhance nutrition knowledge and more importantly support positive dietary change to enhance performance, health and well-being. This systematic review assessed changes in the dietary intakes of athletes in response to nutrition education programmes. A search was conducted which included studies providing quantitative dietary intake assessment of athletes of any calibre aged between 12 and 65 years in response to a nutrition education programme. Standardised differences (effect sizes) were calculated (when possible) for each dietary parameter. The search yielded 6285 papers with twenty-two studies (974 participants (71·9 % female)) eligible for inclusion. Studies described athletes competing at high school ( n 3) through to college level or higher ( n 19). Study designs were either single arm with an intervention-only group (twelve studies n 241) or double arm including an intervention and control group (ten studies n 689). No control groups received an alternative or ‘sham’ intervention. Face-to-face lectures (9/22) and in idual nutrition counselling (6/22) were the most common education interventions. Non-weighed, 3-d diet records (10/22) were the most frequently utilised dietary assessment method. Although 14/22 studies ( n 5 single and n 9 double) reported significant change in at least one nutrition parameter, dietary changes were inconsistent. Poor study quality and heterogeneity of methods prohibit firm conclusions regarding overall intervention success or superior types of educational modalities. Of note, carbohydrate intakes ‘post-intervention’ when assessed often failed to meet recommended guidelines (12/17 studies). Given the substantial investment made in nutrition education interventions with athletes, there is a need for well-designed and rigorous research to inform future best practice.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2019
Publisher: Springer Science and Business Media LLC
Date: 03-09-2015
DOI: 10.1007/S00421-015-3252-3
Abstract: To examine the effects of 24-h controlled carbohydrate intake on next day pre- and post-exercise inflammatory and hepcidin responses. In a crossover design, 12 well-trained endurance athletes (Ht 181.08 ± 7.68 cm Wt 74.8 ± 11.5 kg, VO 2peak 68.9 ± 7.2 ml kg(-1) min(-1)) completed two experimental (2-day) trials. On day 1, participants completed a glycogen depletion task, including a 16-km run (80 % vVO 2peak) and 5 × 1 min efforts (130 % vVO 2peak) separated by 2-min recovery. Subsequently, strict dietary control was enforced for 24 h, where low carbohydrate (LCHO 3 g kg(-1)) or high carbohydrate (HCHO 10 g kg(-1)) diets were provided. Twenty-four hours later, participants completed an 8 × 3 min interval running session at 85 % vVO 2peak followed by 3-h monitored recovery. Venous blood s les were collected pre-, immediately post- and 3-h post-exercise, which were analyzed for interleukin-6, serum iron, ferritin and hepcidin. Interleukin-6 was elevated (p < 0.001) immediately post-exercise compared to baseline in both conditions, but was lower in HCHO (p = 0.015). Hepcidin levels were also lower at baseline (p = 0.049) in HCHO, and a large effect (d = 0.72) indicated a trend for lower levels at 3-h post-exercise compared to LCHO. Serum iron was increased post-exercise for both trials (p = 0.001), whereas serum ferritin remained unchanged. Twenty-four hours of controlled low carbohydrate intake resulted in higher baseline hepcidin levels and post-exercise IL-6 responses than a high carbohydrate intake. Such hormone increases may be induced by gluconeogenic signaling of the liver, and may negatively impact an athlete's iron metabolism.
Publisher: Human Kinetics
Date: 02-2017
Abstract: Following exercise-induced muscle damage (EIMD), masters athletes take longer to recover than younger athletes. The purpose of this study was to determine the effect of higher than recommended postexercise protein feedings on the recovery of knee extensor peak isometric torque (PIT), perceptions of recovery, and cycling time trial (TT) performance following EIMD in masters triathletes. Eight masters triathletes (52 ± 2 y, V̇O 2max , 51.8 ± 4.2 ml•kg -1 •min -1 ) completed two trials separated by seven days in a randomized, doubleblind, crossover study. Trials consisted of morning PIT testing and a 30-min downhill run followed by an eight-hour recovery. During recovery, a moderate (MPI 0.3 g•kg -1 •bolus -1 ) or high (0.6 g•kg -1 •bolus -1 ) protein intake (HPI) was consumed in three bolus feedings at two hour intervals commencing immediately postexercise. PIT testing and a 7 kJ•kg -1 cycling TT were completed postintervention. Perceptions of recovery were assessed pre- and postexercise. The HPI did not significantly improve recovery compared with MPI ( p .05). However, comparison of within-treatment change shows the HPI provided a moderate beneficial effect ( d = 0.66), attenuating the loss of afternoon PIT (-3.6%, d = 0.09) compared with the MPI (-8.6%, d = 0.24). The HPI provided a large beneficial effect ( d = 0.83), reducing perceived fatigue over the eight-hour recovery ( d = 1.25) compared with the MPI ( d = 0.22). Despite these effects, cycling performance was unchanged (HPI = 2395 ± 297 s vs. MPI = 2369 ± 278 s d = 0.09). In conclusion, doubling the recommended postexercise protein intake did not significantly improve recovery in masters athletes however, HPI provided moderate to large beneficial effects on recovery that may be meaningful following EIMD.
Publisher: No publisher found
Date: 2020
Publisher: CRC Press
Date: 15-10-2014
DOI: 10.1201/B17541-8
Publisher: Informa UK Limited
Date: 02-01-2023
Publisher: Informa UK Limited
Date: 07-08-2018
DOI: 10.1080/02640414.2017.1364404
Abstract: This investigation examined the effect of beetroot juice (BR) supplementation, a source of dietary nitrate (NO
Publisher: Wiley
Date: 03-05-2021
DOI: 10.1002/HUP.2792
Abstract: This study aimed to determine if belief in caffeine's ergogenic potential influences choice reaction time (CRT) and/or running performance. Twenty‐nine healthy in iduals (23.7 ± 5 years, 16 males) completed two trials (one week apart). Before the trials, participants indicated their “belief” in caffeine's ergogenic effects and previous “experience” using caffeine for performance. On arrival, participants randomly received either sham “Low (100mg LD)” or “High (300mg HD)” dose caffeine capsules 30‐min before commencing the CRT test, followed by a 10km run. Paired s les t ‐tests determined differences between trials for CRT latency ( Ex‐Gaussian analysis μ‐, σ‐ and τ‐) and running performance using the entire cohort and sub‐groups exhibiting strong “beliefs”+/−“experience”. Sham caffeine dose did not influence CRT (μ‐, σ‐ and τ‐respectively, LD: 400 ± 53ms vs. HD: 388 ± 41ms LD: 35 ± 18ms vs. HD: 34 ± 17ms LD: 50 ± 24ms vs. HD: 52 ± 19ms, all p 's 0.05). Neither belief ( n = 6), nor belief + experience ( n = 4), influenced this effect. Furthermore, caffeine dose did not influence run time (LD: 49.05 ± 3.75min vs. HD: 49.06 ± 3.85min, p = 0.979). Belief ( n = 9) (LD: 48.93 ± 3.71min vs. HD: 48.9 ± 3.52min, p = 0.976), and belief + experience ( n = 6) (LD: 48.68 ± 1.87min vs. HD: 49.55 ± 1.75min, p = 0.386) didn't influence this effect. A dose‐response to sham caffeine ingestion was not evident on cognitive or endurance performance in healthy in iduals, regardless of their convictions about caffeine's ergogenicity.
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.JSAMS.2019.06.004
Abstract: Skin tattoos have been shown to reduce localised sweat rate and increase sweat sodium concentration ([Na Unblinded, within-participant control, single trial. Twenty-two healthy in iduals (25.1±4.8 y (Mean±SD), 14 males) with a unilateral tattoo ≥11.4cm Tattoo vs. Non-Tattoo: Neither sweat rate (Mean±SD: 0.92±0.37 vs. 0.94±0.43mg·cm Skin tattoos do not appear to alter the rate or [Na
Publisher: Human Kinetics
Date: 06-2010
Abstract: This study investigated the effects of sodium bicarbonate (NaHCO 3 ) ingestion on simulated water polo match performance. Twelve elite players from the Australian National Women’s Water Polo Squad (age 23.7 ± 3.0 yr, height 1.73 ± 0.05 m, body mass 75.7 ± 8.0 kg) participated in the study. In a randomized cross-over double-blind design, players ingested 0.3 g/kg of NaHCO 3 or placebo 90 min before performing a 59-min match-simulation test (MST) that included 56 × 10-m maximal-sprint swims as the performance measure. Capillary blood s les were obtained preingestion, pre- and post-warm-up, and after each quarter of the MST. Preexercise ingestion of NaHCO 3 was effective in enhancing extracellular pH from baseline levels of 7.41 ±0.01 ( M ±90% confidence limits) to 7.49 ±0.01 and bicarbonate levels from 24.4 ±0.3 to 28.5 ±0.5 mmol/L. The percentage difference in mean sprint times between trials showed no substantial effects of NaHCO 3 (0.4 ±1.0, effect size = 0.09 ±0.23 p = .51). These findings are contrary to those of previous NaHCO 3 studies on simulated team-sport performance, but this investigation is unique in that it examined highly trained athletes performing sport-specific tasks. In conclusion, water polo players should not expect substantial enhancement in intermittent-sprint performance from NaHCO 3 supplementation.
Publisher: Canadian Science Publishing
Date: 09-2014
Abstract: This systematic review examines the efficacy of carbohydrate (CHO) supplementation on exercise performance of varying durations. Included studies utilized an all-out or endurance-based exercise protocol (no team-based performance studies) and featured randomized interventions and placebo (water-only) trial for comparison against exclusively CHO trials (no other ingredients). Of the 61 included published performance studies (n = 679 subjects), 82% showed statistically significant performance benefits (n = 50 studies), with 18% showing no change compared with placebo. There was a significant (p = 0.0036) correlative relationship between increasing total exercise time and the subsequent percent increase in performance with CHO intake versus placebo. While not mutually exclusive, the primary mechanism(s) for performance enhancement likely differs depending on the duration of the exercise. In short duration exercise situations (∼1 h), oral receptor exposure to CHO, via either mouthwash or oral consumption (with enough oral contact time), which then stimulates the pleasure and reward centers of the brain, provide a central nervous system-based mechanism for enhanced performance. Thus, the type and (or) amount of CHO and its ability to be absorbed and oxidized appear completely irrelevant to enhancing performance in short duration exercise situations. For longer duration exercise ( h), where muscle glycogen stores are stressed, the primary mechanism by which carbohydrate supplementation enhances performance is via high rates of CHO delivery ( g/h), resulting in high rates of CHO oxidation. Use of multiple transportable carbohydrates (glucose:fructose) are beneficial in prolonged exercise, although in idual recommendations for athletes should be tailored according to each athlete’s in idual tolerance.
Publisher: Human Kinetics
Date: 08-2016
Abstract: Postexercise nutrition is a critical component of an athlete’s recovery from training and competition. However, little is known about athletes’ postexercise dietary practices or knowledge of dietary recommendations, particularly among masters athletes. The purpose of this study was to compare and contrast the knowledge of postexercise nutritional recommendations, and typical postexercise intakes of carbohydrate and protein, between masters and younger triathletes. 182 triathletes (Male = 101, Female = 81) completed an online survey distributed by Triathlon Australia . Knowledge of postexercise nutrition recommendations for protein and carbohydrate intake were assessed as a group, and contrasted between subgroups of masters (≥50 years) and younger triathletes (≤30 years). Using dietary recall, postexercise intakes of carbohydrate and protein were examined and contrasted between masters and younger triathletes. As a group, 43.1% and 43.9% of all triathletes answered, “I don’t know” when asked to identify the recommended postexercise carbohydrate and protein intakes, respectively. Dietary analysis revealed masters triathletes consumed significantly less carbohydrate (0.7 ± 0.4 g.kg -1 ) postexercise than recommended (1.0 g.kg -1 p = .001), and in comparison with younger triathletes (1.1 ± 0.6 g.kg -1 p = .01). Postexercise protein intakes were similar between masters (19.6 ± 13.5 g) and younger (26.4 ± 15.8 g) triathletes. However, relative to body mass, masters triathletes consumed significantly less protein (0.3 ± 0.2 g.kg -1 ) than younger triathletes (0.4 ± 0.2 g.kg -1 p = .03), and consumed significantly less energy postexercise (22.7 ± 11.7 kJ.kg -1 ) than younger triathletes (37.8 ± 19.2 kJ.kg -1 p = .01). The present data suggests triathletes have poor knowledge of recommendations for postexercise carbohydrate and protein intakes. Furthermore, low postexercise intakes of carbohydrate and protein by masters athletes may impair acute recovery.
Publisher: SAGE Publications
Date: 30-08-2022
DOI: 10.1177/00315125221124369
Abstract: In this study we investigated the effects of variously derived sources of low-dose caffeine on mood/arousal and cognitive performance. Twenty-two participants (15 men, 7 women M age: 28.2, SD = 9.0 years) undertook five randomized, crossover trials in which they consumed either a water control (CON) or 80 mg of caffeine from one of four sources (coffee [COF], energy drink [END], capsule [CAP], and dissolvable mouth strip [STR]). We measured the participants’ perceived efficacy of these varied caffeine sources pre-treatment and we measured mood/arousal at pre-treatment, and again at 15 and 45 minutes post-treatment. We also measured choice reaction-time at 15 and 45 minutes post-treatment, and participants completed the psychomotor vigilance task (PVT) 45 minutes post-treatment. Caffeine increased participant ratings of alertness and decreased their ratings of tiredness irrespective of source ( p’s .05), and all sources of caffeine decreased reaction time on the PVT ( p’s .05), with ex-Gaussian distributional analysis localizing this to the tau-parameter, indicating lower variability. However, only the COF source was associated with improved ‘overall mood’ ( p’s .05). Participants expected to perform better on the PVT with COF compared to CON, but there were no other significant associations between source expectancy and performance. In sum, a modest dose of caffeine, regardless of source, positively impacted mood/arousal and cognitive performance, and these effects did not appear to be influenced by expectations.
Publisher: Canadian Science Publishing
Date: 10-2021
Abstract: This study examined the impact of varying the holding time following an ad libitum laboratory breakfast on acute dietary behaviour and subsequent intake. Twenty-four participants (20 females (age: 23.4 ± 6.3 years body mass index: 23.9 ± 3.9 kg·m –2 , mean ± SD)) completed 3 trials following a quasi-randomised, crossover design. Each trial (7-day separation) incorporated a defined post-prandial delay (DPD) period of either zero (no delay), 1 or 3 hours following a buffet breakfast consumed over 30 minutes. Dietary intake outcomes included energy, macronutrient and core food group intakes. On completion of the DPD period, participants left the laboratory and recorded all food/beverages consumed for the remainder of the day. One-way repeated-measures ANOVA assessed all outcomes, with post hoc analysis conducted on significant main effects. Energy and carbohydrate intakes were significantly lower on no delay vs. 1-hour (p = 0.014) and 3-hour (p = 0.06) DPD trials (energy intake: 1853 ± 814 kJ vs. 2250 ± 1345 kJ vs. 1948 ± 1289 kJ carbohydrates: 68 ± 34 g vs. 77 ± 44 vs. 69 ± 43 g respectively). DPD periods did not influence the time to consume next meal or energy, macronutrient and core food group intakes for the remainder of the day. Delaying participants from leaving a laboratory alters dietary intake at an ad libitum test meal. The post-meal holding period is an important methodological consideration when planning laboratory studies to assess appetite. Novelty: Delaying participants from leaving a laboratory alters dietary intake at ad libitum breakfast meals. The length of the delay period did not affect dietary intake at ad libitum breakfast meals.
Publisher: Human Kinetics
Date: 06-2015
Abstract: We assessed the ingestion of a beetroot juice supplement (BR) on 4-min laboratory-based kayak performance in national level male ( n = 6) athletes (Study A), and on 500 m on-water kayak time-trial (TT) performance in international level female ( n = 5) athletes (Study B). In Study A, participants completed three laboratory-based sessions on a kayak ergometer, including a 7 × 4 min step test, and two 4 min maximal effort performance trials. Two and a half hours before the warm-up of each 4 min performance trial, athletes received either a 70 ml BR shot containing ~4.8 mmol of nitrate, or a placebo equivalent (BR PLA ). The distance covered over the 4 min TT was not different between conditions however, the average VO 2 over the 4 min period was significantly lower in BR ( p = .04), resulting in an improved exercise economy ( p = .05). In Study B, participants completed two field-based 500 m TTs, separated by 4 days. Two hours before each trial, athletes received either two 70 ml BR shots containing ~9.6 mmol of nitrate, or a placebo equivalent (BR PLA ). BR supplementation significantly enhanced TT performance by 1.7% ( p = .01). Our results show that in national-level male kayak athletes, commercially available BR shots (70 ml) containing ~4.8 mmol of nitrate improved exercise economy during laboratory-based tasks predominantly reliant on the aerobic energy system. Furthermore, greater volumes of BR (140 ml ~9.6 mmol nitrate) provided to international-level female kayak athletes resulted in enhancements to TT performance in the field.
Publisher: Informa UK Limited
Date: 03-2008
Publisher: Springer Science and Business Media LLC
Date: 04-05-2019
DOI: 10.1007/S00421-019-04157-Y
Abstract: Iron plays a significant role in the body, and is specifically important to athletes, since it is a dominant feature in processes such as oxygen transport and energy metabolism. Despite its importance, athlete populations, especially females and endurance athletes, are commonly diagnosed with iron deficiency, suggesting an association between sport performance and iron regulation. Although iron deficiency is most common in female athletes (~ 15-35% athlete cohorts deficient), approximately 5-11% of male athlete cohorts also present with this issue. Furthermore, interest has grown in the mechanisms that influence iron absorption in athletes over the last decade, with the link between iron regulation and exercise becoming a research focus. Specifically, exercise-induced increases in the master iron regulatory hormone, hepcidin, has been highlighted as a contributing factor towards altered iron metabolism in athletes. To date, a plethora of research has been conducted, including investigation into the impact that sex hormones, diet (e.g. macronutrient manipulation), training and environmental stress (e.g. hypoxia due to altitude training) have on an athlete's iron status, with numerous recommendations proposed for consideration. This review summarises the current state of research with respect to the aforementioned factors, drawing conclusions and recommendations for future work.
Publisher: Human Kinetics
Date: 09-1996
DOI: 10.1123/IJSN.6.3.307
Abstract: Fluid losses (measured by body weight changes) and voluntary fluid intakes were measured in elite basketball, netball, and soccer teams during typical summer and winter exercise sessions to determine fluid requirements and the degree of fluid replacement. Each subject was weighed in minimal clothing before and immediately after training, weights, and competition sessions fluid intake, duration of exercise, temperature and humidity, and opportunity to drink were recorded. Sweat rates were greatest during competition sessions and significantly lower during weights sessions for all sports. Seasonal variation in dehydration (%DH) was not as great as may have been expected, particularly in sports played indoors. Factors influencing fluid replacement during exercise included provision of an in idual water bottle, proximity to water bottles during sessions, encouragement to drink, rules of the game, duration and number of breaks or substitutions, and awareness of personal sweat rates. Guidelines for optimizing fluid intakes in these three sports are provided.
Publisher: Wiley
Date: 12-07-2021
DOI: 10.1111/JHN.12897
Abstract: With increasing pressure on the Earth's finite resources, there is significant demand for environmentally sustainable practices in foodservice. A shift to sustainable foodservice operations can decrease its environmental impact and may align with consumer expectations. This systematic review explored consumer expectations (attitudes pre‐intervention) and responses (behaviour, cognitive attitudes and affective attitudes post‐intervention) towards environmentally sustainable initiatives of foodservice operations. A systematic search following PRISMA guidelines was conducted across MEDLINE, EMABASE, CINAHL and Web of Science databases. English and full‐text research articles published up to November 2019 were identified. Consumers’ expectations and responses to interventions were extracted. The quality of the studies was assessed using the Mixed Methods Appraisal Tool (MMAT). Thirty‐three studies were included and, given the heterogeneity of the studies, the results were synthesised narratively. The main outcomes analysed included changes in behaviour and attitudes (cognitive and affective), including knowledge and satisfaction. Intervention strategies were interpreted and categorised into three groups: food waste reduction, single‐use item and packaging waste reduction, and initiatives related to menu, messaging and labelling. Most studies resulted in significant pro‐environmental changes towards decreasing food waste, decreasing single use‐item and packaging waste, as well as engaging consumers in sustainable eating. There are a range of successful environmentally sustainable strategies that when implemented by foodservices can have a mostly positive impact on consumer attitudes and responses. However, positive consumer attitudes did not always translate to changes in behaviour. Foodservices should carefully consider implementing interventions that support changes in consumer behaviour.
Publisher: Human Kinetics
Date: 09-2020
Abstract: Purpose : To compare the metabolic cost of paddling on different commercially available kayak ergometers using a standardized kayak incremental exercise protocol. Methods : Six male sprint kayak athletes undertook an incremental exercise protocol on 3 different kayak ergometers utilizing a randomized counterbalanced pair-matched design. Results : Mean maximal aerobic power on the WEBA ergometer (265 [14] W) was significantly higher than on the Dansprint (238 [9] W) and KayakPro ® (247 [21] W, P .01, effect size [ES] = 0.80). At the fifth stage, absolute oxygen consumption on the WEBA (3.82 [0.25] L·min −1 ) was significantly lower ( P 0.05, ES = 0.20) than KayakPro and Dansprint (4.10 [0.28] and 4.08 [0.27] L·min −1 , respectively). Blood lactate concentration response at the sixth stage was significantly lower for the WEBA (3.5 [0.8] mmol·L −1 ), compared with KayakPro and Dansprint (5.4 [1.2] and 5.6 [1.5] mmol·L −1 , P = .012, ES = 0.20). Stroke rate was significantly higher, without any effect of pacing during the submaximal stages for the Dansprint, compared with the WEBA ( P .001, ES = 0.28) and KayakPro ( P .001, ES = 0.38). A pacing effect was present at the maximal stage for all ergometers. Conclusions : This study demonstrated that paddling on different kayak ergometers when controlling power output elicits different metabolic and work outputs. It is recommended that scientists and coaches avoid testing on different ergometers and regularly calibrate these devices. Moreover, when an ergometer has been calibrated against a first principle device, it is necessary to consider calibration of various drag settings, due to their impact on stroke rate. Further research should explore the relationship between drag settings and stroke rate.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.PHYSBEH.2018.12.013
Abstract: This study investigated the effect of consuming either water or a carbohydrate (CHO)-electrolyte sports beverage ('Sports Drink') ad libitum with food during a 4 h post-exercise recovery period on fluid restoration, nutrient provision and subsequent endurance cycling performance. On two occasions, 16 endurance-trained cyclists 8 male [M] (age: 31 ± 9 y VO
Publisher: Informa UK Limited
Date: 28-05-2019
DOI: 10.1080/17461391.2019.1616826
Abstract: Physique traits of a range of elite athletes have been identified however, few detailed investigations of Olympic combat sports (judo, wrestling, taekwondo and boxing) exist. This is surprising given the importance of body composition in weight category sports. We sought to develop a descriptive database of Olympic combat sport athletes, compare variables relative to weight ision and examine differences within and between sports. Additionally, we investigated the appropriateness of athletes' self-selected weight classes compared to an internationally recognised classification system (the NCAA minimum wrestling weight scheme used to identify minimum 'safe' weight). Olympic combat sport athletes (56♂, 38♀) had body mass (BM), stretch stature and dual-energy X-ray absorptiometry derived body composition assessed within 7-21 days of competition. Most athletes were heavier than their weight ision. Sport had an effect (
Publisher: Elsevier BV
Date: 02-2003
Abstract: Dietary fatty acids may be important in regulating gene expression. However, little is known about the effect of changes in dietary fatty acids on gene regulation in human skeletal muscle. The objective was to determine the effect of altered dietary fat intake on the expression of genes encoding proteins necessary for fatty acid transport and beta-oxidation in skeletal muscle. Fourteen well-trained male cyclists and triathletes with a mean (+/- SE) age of 26.9 +/- 1.7 y, weight of 73.7 +/- 1.7 kg, and peak oxygen uptake of 67.0 +/- 1.3 mL x kg(-1) x min(-1) consumed either a high-fat diet (HFat: > 65% of energy as lipids) or an isoenergetic high-carbohydrate diet (HCho: 70-75% of energy as carbohydrate) for 5 d in a crossover design. On day 1 (baseline) and again after 5 d of dietary intervention, resting muscle and blood s les were taken. Muscle s les were analyzed for gene expression [fatty acid translocase (FAT/CD36), plasma membrane fatty acid binding protein (FABPpm), carnitine palmitoyltransferase I (CPT I), beta-hydroxyacyl-CoA dehydrogenase (beta-HAD), and uncoupling protein 3 (UCP3)] and concentrations of the proteins FAT/CD36 and FABPpm. The gene expression of FAT/CD36 and beta -HAD and the gene abundance of FAT/CD36 were greater after the HFat than after the HCho diet (P < 0.05). Messenger RNA expression of FABPpm, CPT I, and UCP-3 did not change significantly with either diet. A rapid and marked capacity for changes in dietary fatty acid availability to modulate the expression of mRNA-encoding proteins is necessary for fatty acid transport and oxidative metabolism. This finding is evidence of nutrient-gene interactions in human skeletal muscle.
Publisher: Human Kinetics
Date: 07-2019
Abstract: This study assessed voluntary dietary intake when different beverages were provided within a recovery area following recreational exercise. Participants completed two 10-km runs 1 week apart. Immediately after the first run, “beer drinkers” ( n = 54 mean ± SD : age = 23.9 ± 5.8 years, body mass [BM] = 76 ± 13 kg) randomly received low-alcohol beer (Hahn Ultra ® [Lion Co.], 0.9% alcohol by volume) or sports drink (SD Gatorade ® [PepsiCo]), whereas “nonbeer drinkers” ( n = 78 age = 21.8 ± 2.2 years, BM = 71 ± 13 kg) received water or SD. Participants remained in a recovery area for 30–60 min with fluid consumption monitored. The following week, participants received the alternate beverage. Participants recorded all food/fluid consumed for the remainder of both trial days (diary and photographs). Fluid balance was assessed via BM change and urine specific gravity. Paired t tests were used to assess differences in hydration and dietary variables. No differences were observed in preexercise urine specific gravity (∼1.01) or BM loss (∼2%) between intervention groups ( p s .05). Water versus SD: No difference in acute fluid intake was noted (water = 751 ± 259 ml, SD = 805 ± 308 ml, p = .157). SD availability influenced total energy and carbohydrate intakes (water = 5.7 ± 2.5 MJ and 151 ± 77 g, SD = 6.5 ± 2.7 MJ and 187 ± 87 g, energy p = .002, carbohydrate p .001). SD versus beer: SD availability resulted in greater acute fluid intake (SD = 1,047 ± 393 ml, beer = 850 ± 630 ml p = .004), which remained evident at the end of trial days (SD = 3,337 ± 1,100 ml, beer = 2,982 ± 1,191 ml p .01). No differences in dietary variables were observed. Next day, urine specific gravity values were not different between water versus SD. However, a small difference was detected between SD versus beer (SD = 1.021 ± 0.009, beer = 1.016 ± 0.008, p = .002). Consuming calorie-containing drinks postexercise appears to increase daily energy and carbohydrate intake but has minimal impact on next-day hydration.
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.JSAMS.2019.03.009
Abstract: To determine if a 4 d period of high carbohydrate intake can supercompensate muscle glycogen and exercise work capacity on back-to-back occasions. Seven trained cyclists (6 male, VO A resting muscle biopsy was obtained prior to each trial consisting of 2 min work intervals (90-60% peak power output) interspersed with 2 min recovery (40% peak power output) repeated until exhaustion. Each 72-h period between trial days included two days of low volume cycling and a rest day. Resting muscle glycogen and total work completed was determined for each trial day. Baseline muscle glycogen on day 1 (583.6 ± 111.0 mmol kg A 4 d high carbohydrate feeding strategy is sufficient to repeatedly supercompensate muscle glycogen content following exhaustive exercise and results in enhanced work capacity.
Publisher: No publisher found
Date: 2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2002
DOI: 10.1097/00005768-200201000-00014
Abstract: Five days of a high-fat diet produce metabolic adaptations that increase the rate of fat oxidation during prolonged exercise. We investigated whether enhanced rates of fat oxidation during submaximal exercise after 5 d of a high-fat diet would persist in the face of increased carbohydrate (CHO) availability before and during exercise. Eight well-trained subjects consumed either a high-CHO (9.3 g x kg(-1) x d(-1) CHO, 1.1 g x kg(-1) x d(-1) fat HCHO) or an isoenergetic high-fat diet (2.5 g x kg(-1) x d(-1) CHO, 4.3 g x kg(-1) x d(-1) fat FAT-adapt) for 5 d followed by a high-CHO diet and rest on day 6. On day 7, performance testing (2 h steady-state (SS) cycling at 70% peak O(2) uptake [VO(2peak)] + time trial [TT]) of 7 kJ x kg(-1)) was undertaken after a CHO breakfast (CHO 2 g x kg(-1)) and intake of CHO during cycling (0.8 g x kg(-1) x h(-1)). FAT-adapt reduced respiratory exchange ratio (RER) values before and during cycling at 70% VO(2peak) RER was restored by 1 d CHO and CHO intake during cycling (0.90 +/- 0.01, 0.80 +/- 0.01, 0.91 +/- 0.01, for days 1, 6, and 7, respectively). RER values were higher with HCHO (0.90 +/- 0.01, 0.88 +/- 0.01 (HCHO > FAT-adapt, P FAT-adapt, P < 0.05)). On day 7, fat oxidation remained elevated (73 +/- 4 g vs 45 +/- 3 g, P < 0.05), whereas CHO oxidation was reduced (354 +/- 11 g vs 419 +/- 13 g, P < 0.05) throughout SS in FAT-adapt versus HCHO. TT performance was similar for both trials (25.53 +/- 0.67 min vs 25.45 +/- 0.96 min, NS). Adaptations to a short-term high-fat diet persisted in the face of high CHO availability before and during exercise, but failed to confer a performance advantage during a TT lasting approximately 25 min undertaken after 2 h of submaximal cycling.
Publisher: Human Kinetics
Date: 08-2017
Abstract: Combat-sport athletes acutely reduce body mass (BM) before weigh-in in an attempt to gain a size/strength advantage over smaller opponents. Few studies have investigated these practices among boxers and none have explored the impact of this practice on competitive success. One hundred (30 women, 70 men) elite boxers participating in the Australian national ch ionships were weighed at the official weigh-in and 1 h before each competition bout. Regain in BM after weigh-in was compared between finalists and nonfinalists, winners and losers of each fight, men and women, and weight isions. Boxers were surveyed on their pre- and post-weigh-in nutrition practices. The lightest men’s weight category displayed significantly greater relative BM regain than all other isions, with no difference between other isions. BM prebout was higher than official weigh-in for men (2.12% ± 1.62% P .001 ES = 0.13) and women (1.49% ± 1.65% P .001 ES = 0.11). No differences in BM regain were found between finalists and nonfinalists, winners and losers of in idual bouts, or between preliminary or final bouts. BM regain was significantly greater (0.37% BM, P .001 ES = 0.25) before an afternoon bout compared with a morning bout. Boxers engage in acute BM-loss practices before the official competition weigh-in, but this does not appear to affect competition outcomes, at least when weight regain between weigh-in and fighting is used as a proxy for the magnitude of acute loss. While boxers recognize the importance of recovering after weigh-in, current practice is not aligned with best-practice guidance.
Publisher: Springer Science and Business Media LLC
Date: 03-08-2019
DOI: 10.1007/S00421-019-04199-2
Abstract: To determine the impact of altering dietary sodium intake for 3 days preceding exercise on sweat sodium concentration [Na Fifteen male endurance athletes (runners n = 8, cyclists n = 7) consumed a low (LNa, 15 mg kg UNa on days 2-3 pre-exercise [mean (95% CI) LNa 16 (12-19) mg kg Three day altered sodium intake influenced urinary sodium excretion and sweat [Na
Publisher: Springer Science and Business Media LLC
Date: 2001
DOI: 10.2165/00007256-200131040-00003
Abstract: Official dietary guidelines for athletes are unanimous in their recommendation of high carbohydrate (CHO) intakes in routine or training diets. These guidelines have been criticised on the basis of a lack of scientific support for superior training adaptations and performance, and the apparent failure of successful athletes to achieve such dietary practices. Part of the problem rests with the expression of CHO intake guidelines in terms of percentage of dietary energy. It is preferable to provide recommendations for routine CHO intake in grams (relative to the body mass of the athlete) and allow flexibility for the athlete to meet these targets within the context of their energy needs and other dietary goals. CHO intake ranges of 5 to 7 g/kg/day for general training needs and 7 to 10 g/kg/day for the increased needs of endurance athletes are suggested. The limitations of dietary survey techniques should be recognised when assessing the adequacy of the dietary practices of athletes. In particular, the errors caused by under-reporting or undereating during the period of the dietary survey must be taken into account. A review of the current dietary survey literature of athletes shows that a typical male athlete achieves CHO intake within the recommended range (on a g/kg basis). In idual athletes may need nutritional education or dietary counselling to fine-tune their eating habits to meet specific CHO intake targets. Female athletes, particularly endurance athletes, are less likely to achieve these CHO intake guidelines. This is due to chronic or periodic restriction of total energy intake in order to achieve or maintain low levels of body fat. With professional counselling, female athletes may be helped to find a balance between bodyweight control issues and fuel intake goals. Although we look to the top athletes as role models, it is understandable that many do not achieve optimal nutrition practices. The real or apparent failure of these athletes to achieve the daily CHO intakes recommended by sports nutritionists does not necessarily invalidate the benefits of meeting such guidelines. Further longitudinal studies of training adaptation and performance are needed to determine differences in the outcomes of high versus moderate CHO intakes. In the meantime, the recommendations of sports nutritionists are based on plentiful evidence that increased CHO availability enhances endurance and performance during single exercise sessions.
Publisher: Springer Science and Business Media LLC
Date: 05-07-2016
DOI: 10.1007/S00421-016-3426-7
Abstract: This investigation examined if a high carbohydrate (CHO) diet, maintained across a seven-day training period, could attenuate post-exercise interleukin-6 (IL-6) and serum hepcidin levels. Twelve endurance-trained male athletes completed two seven-day running training blocks whilst consuming either a high (8 g kg(-1)) versus a low (3 g kg(-1)) CHO isoenergetic diet. Each training block consisted of five running sessions performed on days 1, 2, 4, 5, and 7, with the intensity and duration of each session matched between training weeks. Serum levels of Interleukin-6 (IL-6) and hepcidin were measured pre- and either immediately (IL-6) or 3-h (hepcidin) post-exercise on days 1 and 7 of each training week. During each training week, the immediate post-exercise IL-6 and 3-h post-exercise serum hepcidin levels were significantly elevated (both p = 0.001) from pre-exercise on days 1 and 7. These increases were not different between trials. These results suggest that the ingestion of a high (compared to low) CHO diet over a seven-day training period is ineffective in attenuating post-exercise IL-6 and hepcidin responses. Such results may be due to the modest training load, the increased protein intake in the low-CHO trial, and a 48 h recovery period prior to s le collection on day 7, allowing a full recovery of muscle glycogen status between exercise sessions.
Publisher: BMJ
Date: 03-2019
DOI: 10.1136/BJSPORTS-2018-099889
Abstract: To determine the effects of multi-ingredient protein (MIP) supplements on resistance exercise training (RT)-induced gains in muscle mass and strength compared with protein-only (PRO) or placebo supplementation. Systematic search of MEDLINE, Embase, CINAHL and SPORTDiscus. Randomised controlled trials with interventions including RT ≥6 weeks in duration and a MIP supplement. Random effects meta-analyses were conducted to determine the effect of supplementation on fat-free mass (FFM), fat mass, one-repetition maximum (1RM) upper body and 1RM lower body muscular strength. Subgroup analyses compared the efficacy of MIP supplementation relative to training status and chronological age. The most common MIP supplements included protein with creatine (n=17) or vitamin D (n=10). Data from 35 trials with 1387 participants showed significant (p .05) increases in FFM (0.80 kg (95% CI 0.44 to 1.15)), 1RM lower body (4.22 kg (95% CI 0.79 to 7.64)) and 1RM upper body (2.56 kg (95% CI 0.79 to 4.33)) where a supplement was compared with all non-MIP supplemented conditions (means (95% CI)). Subgroup analyses indicated a greater effect of MIP supplements compared with all non-MIP supplements on FFM in untrained (0.95 kg (95% CI 0.51 to 1.39), p .0001) and older participants (0.77 kg (95% CI 0.11 to 1.43), p=0.02) taking MIP supplements was also associated with gains in 1RM upper body (1.56 kg (95% CI 0.80 to 2.33), p=0.01) in older adults. When MIP supplements were combined with resistance exercise training, there were greater gains in FFM and strength in healthy adults than in counterparts who were supplemented with non-MIP. MIP supplements were not superior when directly compared with PRO supplements. The magnitude of effect of MIP supplements was greater (in absolute values) in untrained and elderly in iduals undertaking RT than it was in trained in iduals and in younger people. CRD42017081970.
Publisher: Springer Science and Business Media LLC
Date: 22-01-2018
DOI: 10.1007/S00421-018-3809-Z
Abstract: This study investigated whether reported improvements in blood flow distribution, and the possible related effects on thermoregulation during exercise following supplementation with beetroot juice (BR), a rich source of dietary nitrate (NO 12 male endurance-trained cyclists (age 27 ± 6 years, VO Salivary NO This investigation shows that the ergogenic effects and health benefits of BR supplementation, such as augmented cutaneous blood flow, reduced MAP, increased muscle oxygenation, and improved aerobic efficiency may be attenuated when exercise is performed in hot conditions.
Publisher: Human Kinetics
Date: 06-2003
Abstract: A routine activity for a sports dietitian is to estimate energy and nutrient intake from an athlete’s self-reported food intake. Decisions made by the dietitian when coding a food record are a source of variability in the data. The aim of the present study was to determine the variability in estimation of the daily energy and key nutrient intakes of elite athletes, when experienced coders analyzed the same food record using the same database and software package. Seven-day food records from a dietary survey of athletes in the 1996 Australian Olympic team were randomly selected to provide 13 sets of records, each set representing the self-reported food intake of an endurance, team, weight restricted, and sprint ower athlete. Each set was coded by 3–5 members of Sports Dietitians Australia, making a total of 52 athletes, 53 dietitians, and 1456 athlete-days of data. We estimated within- and between- athlete and dietitian variances for each dietary nutrient using mixed modeling, and we combined the variances to express variability as a coefficient of variation (typical variation as a percent of the mean). Variability in the mean of 7-day estimates of a nutrient was 2- to 3-fold less than that of a single day. The variability contributed by the coder was less than the true athlete variability for a 1-day record but was of similar magnitude for a 7-day record. The most variable nutrients (e.g., vitamin C, vitamin A, cholesterol) had ~3-fold more variability than least variable nutrients (e.g., energy, carbohydrate, magnesium). These athlete and coder variabilities need to be taken into account in dietary assessment of athletes for counseling and research.
Publisher: Informa UK Limited
Date: 02-03-2018
DOI: 10.1080/02640414.2017.1298828
Abstract: This study investigated the effects of aerobic exercise, fluid loss and rehydration on cognitive performance in well-trained athletes. Ten endurance-trained males (25 ± 5 years 175 ± 5 cm 70.35 ± 5.46 kg VO
Publisher: Georg Thieme Verlag KG
Date: 19-02-2010
Publisher: Human Kinetics
Date: 08-2014
Abstract: Water polo is an aquatic team sport that requires endurance, strength, power, swimming speed, agility, tactical awareness, and specific technical skills, including ball control. Unlike other team sports, few researchers have examined the nutritional habits of water polo athletes or potential dietary strategies that improve performance in water polo match play. Water polo players are typically well muscled, taller athletes female players display higher levels of adiposity compared with their male counterparts. Positional differences exist: Center players are heavier and have higher body fat levels compared with perimeter players. Knowledge of the physical differences that exist among water polo players offers the advantage of player identification as well as in idualizing nutrition strategies to optimize desired physique goals. In idual dietary counseling is warranted to ensure dietary adequacy, and in cases of physique manipulation. Performance in games and during quality workouts is likely to improve by adopting strategies that promote high carbohydrate availability, although research specific to water polo is lacking. A planned approach incorporating strategies to facilitate muscle glycogen refueling and muscle protein synthesis should be implemented following intensified training sessions and matches, particularly when short recovery times are scheduled. Although sweat losses of water polo players are less than what is reported for land-based athletes, specific knowledge allows for appropriate planning of carbohydrate intake strategies for match play and training. Postgame strategies to manage alcohol intake should be developed with input from the senior player group to minimize the negative consequences on recovery and player welfare.
Publisher: Human Kinetics
Date: 03-2002
Abstract: This study investigated the effects of acute creatine (Cr) supplementation on the performance of elite female soccer players undertaking an exercise protocol simulating match play. On two occasions, 7 days apart, 12 players performed 5 X 11-min exercise testing blocks interspersed with 1 min of rest. Each block consisted of 11 all-out 20-m running sprints, 2 agility runs, and 1 precision ball-kicking drill, separated by recovery 20-m walks, jogs, and runs. After the initial testing session, subjects were assigned to either a CREATINE (5 g of Cr, 4 times per day for 6 days) or a PLACEBO group (same dosage of a glucose polymer) using a double-blind research design. Body mass (BM) increased (61.7 ± 8.9 to 62.5 ± 8.9 kg, p .01) in the CREATINE group however, no change was observed in the PLACEBO group (63.4 ± 2.9 kg to 63.7 ± 2.5 kg). No overall change in 20-m sprint times and agility run times were observed, although the CREATINE group achieved faster post-supplementation times in sprints 11, 13, 14, 16, 21, 23, 25, 32, and 39 ( p .05), and agility runs3,5,and8 ( p .05). The accuracy of shooting was unaffected in both groups. In conclusion, acute Cr supplementation improved performance of some repeated sprint and agility tasks simulating soccer match play, despite an increase in BM.
Publisher: Human Kinetics
Date: 08-2011
Abstract: The aim of this case study was to describe the race nutrition practices of a female runner who completed her first 100-km off-road ultraendurance running event in 12 hr 48 min 55 s. Food and fluid intake during the race provided 10,890 kJ (736 kJ/hr) and 6,150 ml (415 ml/hr) of fluid. Hourly reported carbohydrate intake was 44 g, with 34% provided by sports drink. Hourly carbohydrate intake increased in the second half (53 g/hr) compared with the first half (34 g/h) of the race, as the athlete did not have access to in idualized food and fluid choices at the early checkpoints and felt satiated in the early stages of the race after consuming a prerace breakfast. Mean sodium intake was 500 mg/hr (52 mmol/L), with a homemade savory broth and sports drink (Gatorade Endurance) being the major contributors. The athlete consumed a variety of foods of varying textures and tastes with no complaints of gastrointestinal discomfort. Despite thinking she would consume sweet foods exclusively, as she had done in training, the athlete preferred savory foods and fluids at checkpoints during the latter stages of the race. This case study highlights the importance of the sports nutrition team in educating athletes about race-day nutrition strategies and devising a simple yet effective system to allow them to manipulate their race-day food and fluid intake to meet their nutritional goals.
Publisher: Canadian Science Publishing
Date: 2019
Abstract: This study investigated the effect of consuming different commercial beverages with food ad libitum after exercise on fluid, energy, and nutrient recovery in trained females. On 4 separate occasions, 8 females (body mass (BM): 61.8 ± 10.7 kg maximal oxygen uptake: 46.3 ± 7.5 mL·kg −1 ·min −1 ) lost 2.0% ± 0.3% BM cycling at ∼75% maximal oxygen uptake before completing a 4-h recovery period with ad libitum access to 1 of 4 beverages: Water, Powerade (Sports Drink), Up & Go Reduced Sugar (Lower Sugar (LS)-MILK) or Up & Go Energize (Higher Protein (HP)-MILK). Participants also had two 15-min opportunities to access food within the first 2 h of the recovery period. Beverage intake, total water/nutrient intake, and indicators of fluid recovery (BM, urine output, plasma osmolality), gastrointestinal tolerance and palatability were assessed periodically. While total water intake (from food and beverage) (Water: 1918 ± 580 g Sports Drink: 1809 ± 338 g LS-MILK: 1458 ± 431 g HP-MILK: 1523 ± 472 g p = 0.010) and total urine output (Water: 566 ± 314 g Sports Drink: 459 ± 290 g LS-MILK: 220 ± 53 g HP-MILK: 230 ± 117 g p = 0.009) differed significantly by beverage, the quantity of ingested water retained was similar across treatments (Water: 1352 ± 462 g Sports Drink: 1349 ± 407 g LS-MILK: 1238 ± 400 g HP-MILK: 1293 ± 453 g p = 0.691). Total energy intake (from food and beverage) increased in proportion to the energy density of the beverage (Water: 4129 ± 1080 kJ Sports Drink: 5167 ± 643 kJ LS-MILK: 6019 ± 1925 kJ HP-MILK: 7096 ± 2058 kJ p = 0.014). When consumed voluntarily and with food, different beverages promote similar levels of fluid recovery, but alter energy/nutrient intakes. Providing access to food and understanding the longer-term dietary goals of female athletes are important considerations when recommending a recovery beverage.
Publisher: Wiley
Date: 18-08-2006
Publisher: Human Kinetics
Date: 12-2016
Abstract: This case study describes the nutrition plans, intakes and experiences of five ultra-marathon runners who completed the Marathon des Sables in 2011 and 2013 age 37 (28–43) y, height 184 (180–190) cm, body mass 77.5 (71–85.5) kg, marathon personal best 3:08 (2:40–3:32). MdS is a 7-day, six-stage ultra-running stage race held in the Sahara Desert (total distance of timed stages 1–5 was 233.2 km in 2011, 223.4 km in 2013). Competitors are required to carry all equipment and food (except water) for the race duration, a minimum of 8,360 kJ/day and total pack weight of 6.5–15 kg. Total food mass carried was 4.2 (3.8–4.7) kg or 0.7 (0.5–1.1) kg/day. Planned energy (13,550 (10,323–18,142) kJ/day), protein (1.3 (0.8–1.8) g/kg/day), and carbohydrate (6.2 (4.3–9.2) g/kg/day) intakes on the fully self-sufficient days were slightly below guideline recommendations, due to the need to balance nutritional needs with food mass to be carried. Energy density was 1,636 (1,475–1,814) kJ/100g. 98.5% of the planned food was consumed. Fluid consumption was ad libitum with no symptoms or medical treatment required for dehydration or hyponatremia. During-stage carbohydrate intake was 42 (20–64) g/hour. Key issues encountered by runners included difficulty consuming foods due to dry mouth, and unpalatability of sweet foods (energy gels, sports drinks) when heated in the sun. Final classification of the runners ranged from 11th to 175th of 970 finishers in 2013, and 132nd of 805 in 2011. The described pattern of intake and macronutrient quantities were positively appraised by the five runners.
Publisher: Elsevier BV
Date: 09-2002
DOI: 10.1016/S1440-2440(02)80003-2
Abstract: Calculated sweat rates (measured by body mass changes) and voluntary fluid intakes were monitored in elite level water polo players and swimmers during normal exercise sessions to determine fluid requirements to maintain fluid balance, and the degree of fluid replacement of these athletes. Data were collected from training and competition sessions for male water polo players (n = 23) and training sessions only for swimmers (n = 20 females n = 21 males). The calculated average sweat rate and fluid intake rate during training sessions for male water polo players was 287 ml/h and 142 ml/h, respectively, with a rate of 786 ml/h and 380 ml/h during matches. During training sessions for male swimmers, the calculated average sweat rate and fluid intake rate per kilometre was 138 ml/km and 155 ml/km, respectively and for female swimmers, 107 ml/km and 95 ml/km. There was a wide in idual variation in fluid intake and sweat loss of both water polo players and swimmers. Dehydration experienced by athletes in this study was less than typically reported for "land-based" athletes. Errors inherent in the technique used in this study are acknowledged and may be significant in the calculation of reported sweat losses and levels of fluid balance in aquatic athletes.
Publisher: Human Kinetics
Date: 08-2010
Abstract: The aim of this study was to investigate the prerace and during-race carbohydrate intakes of elite-level triathletes contesting draft-legal Olympic-distance triathlon (ODT) events. Self-reported prerace and during-race nutrition data were collected at 3 separate ODT events from 51 elite senior and under-23 triathletes. One hundred twenty-nine observations of food and fluid intake representing actual prerace ( n = 62) and during-race ( n = 67) nutrition practices from 36 male and 15 female triathletes were used in the final analysis of this study. Female triathletes consumed significantly more carbohydrate on the morning before race start when corrected for body mass and race start time than their male counterparts ( p .05). Male and female triathletes consumed 26% more energy (kJ/kg) and 24% more carbohydrate (g/kg) when commencing a race after midday (1:00–1:30 p.m.) than for a late morning (11:00–11:15 a.m.) race start. During the race, triathletes consumed less than 60 g of carbohydrate on 66% of occasions, with average total race intakes of 48 ± 25 and 49 ± 25 g carbohydrate for men and women, respectively. Given average race times of 1:57:07 hr and 2:08:12 hr, hourly carbohydrate intakes were ~25 g and ~23 g for men and women, respectively. Although most elite ODT triathletes consume sufficient carbohydrate to meet recommended prerace carbohydrate intake guidelines, during-race carbohydrate intakes varied considerably, with many failing to meet recommended levels.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2019
Publisher: Springer International Publishing
Date: 07-11-2019
Publisher: Human Kinetics
Date: 2020
Abstract: Sleeping with low carbohydrate (CHO) availability is a dietary strategy that may enhance training adaptation. However, the impact on an athlete’s health is unclear. This study quantified the effect of a short-term “sleep-low” dietary intervention on markers of iron regulation and immune function in athletes. In a randomized, repeated-measures design, 11 elite triathletes completed two 4-day mixed cycle run training blocks. Key training sessions were structured such that a high-intensity training session was performed in the field on the afternoon of Days 1 and 3, and a low-intensity training (LIT) session was performed on the following morning in the laboratory (Days 2 and 4). The ingestion of CHO was either ided evenly across the day (HIGH) or restricted between the high-intensity training and LIT sessions, so that the LIT session was performed with low CHO availability (LOW). Venous blood and saliva s les were collected prior to and following each LIT session and analyzed for interleukin-6, hepcidin 25, and salivary immunoglobulin-A. Concentrations of interleukin-6 increased acutely after exercise ( p .001), but did not differ between dietary conditions or days. Hepcidin 25 increased 3-hr postexercise ( p .001), with the greatest increase evident after the LOW trial on Day 2 (2.5 ± 0.9 fold increase ±90% confidence limit). The salivary immunoglobulin-A secretion rate did not change in response to exercise however, it was highest during the LOW condition on Day 4 ( p = .046). There appears to be minimal impact to markers of immune function and iron regulation when acute exposure to low CHO availability is undertaken with expert nutrition and coaching input.
Publisher: Springer Science and Business Media LLC
Date: 18-06-2015
DOI: 10.1007/S00421-015-3202-0
Abstract: Carbohydrate ingestion prior and during exercise attenuates exercise-induced interleukin-6. This investigation examined if an analogous effect was evident for interleukin-6 and hepcidin response when carbohydrates were ingested post-exercise. In a crossover design, 11 well-trained endurance athletes completed two experimental trials. Participants completed an 8 × 3 min interval running session at 85 % vVO2peak followed by 5 h of monitored recovery. During this period, participants were provided with two 1.2 g kg(-1) carbohydrate beverages at either an early feeding time (immediately post-exercise and 2 h post-exercise) or delayed feeding time (2 h post-exercise and 4 h post-exercise). Venous blood s les were collected pre-, immediately post-, 3 and 5 h post-exercise. S les were analysed for Interleukin-6, serum iron, serum ferritin and hepcidin. Interleukin-6 was significantly elevated (p = 0.004) immediately post-exercise compared to baseline for both trials. Hepcidin levels were significantly elevated at 3 h post-exercise (p = 0.001) and 5 h post-exercise (p = 0.002) compared to baseline levels in both trials, with no significant difference between the two conditions and any time point. Serum iron was significantly increased from baseline to immediately post-exercise (p = 0.001) for both trials, with levels decreasing by 3 h (p = 0.025) and 5 h post-exercise (p = 0.001). Serum ferritin levels increased immediately post-exercise compared to baseline (p = 0.006) in both conditions. The timing and ingestion of post-exercise carbohydrate ingestion do not appear to impact post-exercise interleukin-6 and hepcidin responses this is likely a result of the interval running task inducing an inflammatory response and subsequent up-regulation of hepcidin.
Publisher: American Physiological Society
Date: 07-2010
DOI: 10.1152/JAPPLPHYSIOL.00950.2009
Abstract: We determined the effects of varying daily carbohydrate intake by providing or withholding carbohydrate during daily training on endurance performance, whole body rates of substrate oxidation, and selected mitochondrial enzymes. Sixteen endurance-trained cyclists or triathletes were pair matched and randomly allocated to either a high-carbohydrate group (High group n = 8) or an energy-matched low-carbohydrate group (Low group n = 8) for 28 days. Immediately before study commencement and during the final 5 days, subjects undertook a 5-day test block in which they completed an exercise trial consisting of a 100 min of steady-state cycling (100SS) followed by a 7-kJ/kg time trial on two occasions separated by 72 h. In a counterbalanced design, subjects consumed either water (water trial) or a 10% glucose solution (glucose trial) throughout the exercise trial. A muscle biopsy was taken from the vastus lateralis muscle on day 1 of the first test block, and rates of substrate oxidation were determined throughout 100SS. Training induced a marked increase in maximal citrate synthase activity after the intervention in the High group (27 vs. 34 μmol·g −1 ·min −1 , P 0.001). Tracer-derived estimates of exogenous glucose oxidation during 100SS in the glucose trial increased from 54.6 to 63.6 g ( P 0.01) in the High group with no change in the Low group. Cycling performance improved by ∼6% after training. We conclude that altering total daily carbohydrate intake by providing or withholding carbohydrate during daily training in trained athletes results in differences in selected metabolic adaptations to exercise, including the oxidation of exogenous carbohydrate. However, these metabolic changes do not alter the training-induced magnitude of increase in exercise performance.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2020
Publisher: Springer London
Date: 24-12-2008
Publisher: Human Kinetics
Date: 03-2020
Abstract: This study investigated the effect of drinking rate on fluid retention of milk and water following exercise-induced dehydration. In Part A, 12 male participants lost 1.9% ± 0.3% body mass through cycle exercise on four occasions. Following exercise, plain water or low-fat milk equal to the volume of sweat lost during exercise was provided. Beverages were ingested over 30 or 90 min, resulting in four beverage treatments: water 30 min, water 90 min, milk 30 min, and milk 90 min. In Part B, 12 participants (nine males and three females) lost 2.0% ± 0.3% body mass through cycle exercise on four occasions. Following exercise, plain water equal to the volume of sweat lost during exercise was provided. Water was ingested over 15 min (DR15), 45 min (DR45), or 90 min (DR90), with either DR15 or DR45 repeated. In both trials, nude body mass, urine volume, urine specific gravity and osmolality, plasma osmolality, and subjective ratings of gastrointestinal symptoms were obtained preexercise and every hour for 3 hr after the onset of drinking. In Part A, no effect of drinking rate was observed on the proportion of fluid retained, but milk retention was greater ( p .01) than water (water 30 min: 57% ± 16%, water 90 min: 60% ± 20%, milk 30 min: 83% ± 6%, and milk 90 min: 85% ± 7%). In Part B, fluid retention was greater in DR90 (57% ± 13%) than DR15 (50% ± 11%, p .05), but this was within test–retest variation determined from the repeated trials (coefficient of variation: 17%). Within the range of drinking rates investigated the nutrient composition of a beverage has a more pronounced impact on fluid retention than the ingestion rate.
Publisher: Human Kinetics
Date: 11-2018
Abstract: Novel methods of acute weight loss practiced by combat sport athletes include “water loading,” the consumption of large fluid volumes for several days prior to restriction. We examined claims that this technique increases total body water losses, while also assessing the risk of hyponatremia. Male athletes were separated into control ( n = 10) and water loading ( n = 11) groups and fed a standardized energy-matched diet for 6 days. Days 1–3 fluid intake was 40 and 100 ml/kg for control and water loading groups, respectively, with both groups consuming 15 ml/kg on Day 4 and following the same rehydration protocol on Days 5 and 6. We tracked body mass (BM), urine sodium, urine specific gravity and volume, training-related sweat losses and blood concentrations of renal hormones, and urea and electrolytes throughout. Physical performance was assessed preintervention and postintervention. Following fluid restriction, there were substantial differences between groups in the ratio of fluid input/output (39%, p .01, effect size = 1.2) and BM loss (0.6% BM, p = .02, effect size = 0.82). Changes in urine specific gravity, urea and electrolytes, and renal hormones occurred over time ( p .05), with an interaction of time and intervention on blood sodium, potassium, chloride, urea, creatinine, urine specific gravity, and vasopressin ( p .05). Measurements of urea and electrolyte remained within reference ranges, and no differences in physical performance were detected over time or between groups. Water loading appears to be a safe and effective method of acute BM loss under the conditions of this study. Vasopressin-regulated changes in aquaporin channels may potentially partially explain the mechanism of increased body water loss with water loading.
Publisher: Elsevier BV
Date: 2010
Publisher: American Physiological Society
Date: 12-2000
DOI: 10.1152/JAPPL.2000.89.6.2413
Abstract: For 5 days, eight well-trained cyclists consumed a random order of a high-carbohydrate (CHO) diet (9.6 g · kg −1 · day −1 CHO, 0.7 g · kg −1 · day −1 fat HCHO) or an isoenergetic high-fat diet (2.4 g · kg −1 · day −1 CHO, 4 g · kg −1 · day −1 fat Fat-adapt) while undertaking supervised training. On day 6,subjects ingested high CHO and rested before performance testing on day 7 [2 h cycling at 70% maximal O 2 consumption (SS) + 7 kJ/kg time trial (TT)]. With Fat-adapt, 5 days of high-fat diet reduced respiratory exchange ratio (RER) during cycling at 70% maximal O 2 consumption this was partially restored by 1 day of high CHO [0.90 ± 0.01 vs. 0.82 ± 0.01 ( P 0.05) vs. 0.87 ± 0.01 ( P 0.05), for day 1, day 6, and day 7, respectively]. Corresponding RER values on HCHO trial were [0.91 ± 0.01 vs. 0.88 ± 0.01 ( P 0.05) vs. 0.93 ± 0.01 ( P 0.05)]. During SS, estimated fat oxidation increased [94 ± 6 vs. 61 ± 5 g ( P 0.05)], whereas CHO oxidation decreased [271 ± 16 vs. 342 ± 14 g ( P 0.05)] for Fat-adapt compared with HCHO. Tracer-derived estimates of plasma glucose uptake revealed no differences between treatments, suggesting muscle glycogen sparing accounted for reduced CHO oxidation. Direct assessment of muscle glycogen utilization showed a similar order of sparing (260 ± 26 vs. 360 ± 43 mmol/kg dry wt P = 0.06). TT performance was 30.73 ± 1.12 vs. 34.17 ± 2.48 min for Fat-adapt and HCHO ( P = 0.21). These data show significant metabolic adaptations with a brief period of high-fat intake, which persist even after restoration of CHO availability. However, there was no evidence of a clear benefit of fat adaptation to cycling performance.
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.COIS.2018.12.004
Abstract: If we are to fully comprehend the evolution of insect ersity at a genomic level we need to understand how natural selection can alter genetically encoded characters within populations. Genetic association panels have the potential to be standard bearers in this endeavour. They enable the mapping of phenotypes to genotypes at unprecedented resolution while simultaneously providing population genomic s les that can be interrogated for the tell-tale signs of selection. Analyses of these panels promise to elucidate the entanglement of gene ontologies, pathways, developmental processes and evolutionary constraints, and inform how these are shaped by adaptation.
Publisher: Human Kinetics
Date: 08-2014
Abstract: Competitive ing involves grace, power, balance, and flexibility, which all require satisfying daily energy and nutrient needs. Divers are short, well-muscled, and lean, giving them a distinct biomechanical advantage. Although little ing-specific nutrition research on performance and health outcomes exists, there is concern that ers are excessively focused on body weight and composition, which may result in reduced dietary intake to achieve desired physique goals. This will result in low energy availability, which may have a negative impact on their power-to-weight ratio and health risks. Evidence is increasing that restrictive dietary practices leading to low energy availability also result in micronutrient deficiencies, premature fatigue, frequent injuries, and poor athletic performance. On the basis of daily training demands, estimated energy requirements for male and female ers are 3,500 kcal and 2,650 kcal, respectively. Divers should consume a diet that provides 3–8 g/kg/day of carbohydrate, with the higher values accommodating growth and development. Total daily protein intake (1.2–1.7 g/kg) should be spread evenly throughout the day in 20 to 30 g amounts and timed appropriately after training sessions. Divers should consume nutrient-dense foods and fluids and, with medical supervision, certain dietary supplements (i.e., calcium and iron) may be advisable. Although sweat loss during indoor training is relatively low, ers should follow appropriate fluid-intake strategies to accommodate anticipated sweat losses in hot and humid outdoor settings. A multidisciplinary sports medicine team should be integral to the daily training environment, and suitable foods and fluids should be made available during prolonged practices and competitions.
Publisher: Wiley
Date: 22-05-2007
Publisher: Elsevier BV
Date: 06-2022
DOI: 10.1016/J.JSAMS.2022.02.002
Abstract: To characterise the assessment and management practices employed by Sports Dietitians when assessing and managing athletes at risk of low energy availability (LEA). 55 Sports Dietitians participated in an online questionnaire that captured the typical methods used to identify and manage LEA in athletic populations. The questionnaire consisted of 27 questions which explored common methods used to identify and manage LEA, as well as dietary methods employed and barriers experienced by Sports Dietitians. Broadly, the top 3 nutrition-related priorities for respondents were nutrition strategies to support training, competition, and recovery while 'LEA' was ranked fifth. 'Dietary intake', 'menstrual function' and 'training load (km/week)' were the primary methods used to assess LEA and respondents were 'confident' in their ability to correctly identify athletes at risk. Among support personnel, coaches were rarely a referral source for management of LEA but did present frequent communication difficulties. Respondents indicated athletes have concerns about undesirable changes in body composition when providing recommendations of increased energy intake for LEA management. Sport Dietitians appear to recognise and prioritise LEA management in athletes, but assessments are limited to dietary intake and training load (km/week) with collaborative approaches to LEA management lacking. Sports Dietitian may be overconfident in their ability to identify LEA as only a limited number of assessment methods are commonly used. Access to reliable assessments methods and collaborative management approaches are needed to improve athlete care when suspected of LEA.
Publisher: MDPI AG
Date: 03-10-2021
DOI: 10.3390/NU13103502
Abstract: Tactical personnel (including military, law enforcement, and fire and rescue) are responsible for ensuring national and public safety. Dietary intake is an important consideration to support optimal health and performance. The aims of this systematic review were to: (1) describe the reported free-living dietary intake (energy and macronutrients) of tactical personnel, and (2) describe the practical implications of reported dietary intakes to support the physical and dietary requirements of tactical personnel. A systematic search of databases (MEDLINE, EMBASE, CINAHL and Web of Science) was conducted following the PRISMA guidelines. English and full text research articles were identified and screened against inclusion and exclusion criteria. Demographic and dietary intake data were extracted, tabulated, and synthesized narratively. The quality of the studies was assessed using the Academy of Nutrition and Dietetics Quality Criteria Checklist. Twenty-two studies (15 military, 4 law enforcement, and 2 fire and rescue) were eligible to inform this review. The volume of evidence suggested that tactical personnel met dietary protein and exceeded dietary fat recommendations but failed to meet energy and carbohydrate recommendations. Therefore, practical approaches to support optimized energy, fat and carbohydrate intake in tactical personnel is important.
Publisher: Georg Thieme Verlag KG
Date: 09-07-2008
Abstract: Most studies investigating the effects of acute carbohydrate (CHO) ingestion on post-exercise cytokine responses have involved fasted athletes. This study characterised the effects of acute CHO beverage ingestion preceded by consumption of a CHO-containing pre-exercise meal. Sixteen highly-trained male cyclists/triathletes (age: 30.6 +/- 5.6 y V O (2max): 64.8 +/- 4.7 ml . kg . min (-1) [mean +/- SD]) undertook two cycle ergometry trials involving randomised consumption of a 10 % CHO beverage (15 mL . kg (-1) . hr (-1)) or water (H (2)O). Trials were undertaken 2 h after a breakfast providing 2.1 g CHO . kg (-1) body mass (BM) (48 kJ . kg (-1) BM) and consisted of 100 min steady state cycle ergometry at 70 % V O (2max) followed by a time trial of approximately 30 min duration. Blood s les were collected pre-, post- and 1 h post-exercise for measurement of Interleukin (IL)-6, IL-8, IL-10 and IL-1ra. Time-trial performance was not substantially different between CHO and H (2)O trials (4.5 %, p = 0.42). Neither IL-6 nor IL-8 responses were substantially reduced in the CHO compared to the H (2)O trial. There was a substantial reduction in IL-10 (32 %, p = 0.05) and IL-1ra (43 %, p = 0.02) responses at 1 h post-exercise with CHO compared to H (2)O ingestion. In conclusion, the previously shown attenuating effects of CHO ingestion during exercise on cytokine responses appear reduced when athletes consume a CHO-containing pre-exercise meal.
Publisher: Human Kinetics
Date: 03-2023
Abstract: This review discusses the potential value of tracking interstitial glucose with continuous glucose monitors (CGMs) in athletes, highlighting possible applications and important considerations in the collection and interpretation of interstitial glucose data. CGMs are sensors that provide real time, longitudinal tracking of interstitial glucose with a range of commercial monitors currently available. Recent advancements in CGM technology have led to the development of athlete-specific devices targeting glucose monitoring in sport. Although largely untested, the capacity of CGMs to capture the duration, magnitude, and frequency of interstitial glucose fluctuations every 1–15 min may present a unique opportunity to monitor fueling adequacy around competitive events and training sessions, with applications for applied research and sports nutrition practice. Indeed, manufacturers of athlete-specific devices market these products as a “fueling gauge,” enabling athletes to “push their limits longer and get bigger gains.” However, as glucose homeostasis is a complex phenomenon, extensive research is required to ascertain whether systemic glucose availability (estimated by CGM-derived interstitial glucose) has any meaning in relation to the intended purposes in sport. Whether CGMs will provide reliable and accurate information and enhance sports nutrition knowledge and practice is currently untested. Caveats around the use of CGMs include technical issues (dislodging of sensors during periods of surveillance, loss of data due to synchronization issues), practical issues (potential bans on their use in some sporting scenarios, expense), and challenges to the underpinning principles of data interpretation, which highlight the role of sports nutrition professionals to provide context and interpretation.
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.PHYSBEH.2017.01.009
Abstract: This study compared the effects of ad libitum consumption of different beverages and foods on fluid retention and nutrient intake following exercise. Ten endurance trained males (mean±SD Age=25.3±4.9years, VO Total fluid volume ingested from food and beverages in W1 (2.28±0.42L) and P (2.82±0.80L) trials were significantly greater than SS (1.94±0.54L). Total urine output was not different between trials (W1=644±202mL, W2=602±352mL, P=879±751mL, SS=466±129mL). No significant differences in net body weight change was observed between trials (W1=0.01±0.28kg, W2=0.08±0.30kg, P=-0.02±0.24kg, SS=-0.05±0.24kg). Total energy intake was higher on P (10,179±1484kJ) and SS (10,577±2210kJ) compared to both water trials (W1=7826±888kJ, W2=7578±1112kJ). With the co-ingestion of food, fluid restoration following exercise is tightly regulated and not influenced by the choice of either water, a carbohydrate-electrolyte (sports drink) or a milk-based beverage.
Publisher: Human Kinetics
Date: 07-2019
Abstract: There is little information describing how endurance athletes perceive sodium intake in relation to training and competition. Using an online questionnaire, this study assessed the beliefs, information sources, and intended practices regarding sodium ingestion for training and competition. Endurance athletes ( n = 344) from six English-speaking countries completed the questionnaire and were included for analysis. The most cited information sources were social supports (63%), self-experimentation (56%), and media (48%). Respondents generally believed ( % on electronic visual analog scale) endurance athletes require additional sodium on a daily basis (median 67% [interquartile range: 40–81%]), benefit from increased sodium in the days preceding competition (60% [30–77%]), should replace sodium losses during training (69% [48–83%]) and competition (74% [54–87%]), and would benefit from sweat composition testing (82% [65–95%]). Respondents generally believed sodium ingestion during endurance exercise prevents exercise-associated muscle cr s (75% [60–88%]) and exercise-associated hyponatremia (74% [62–89%]). The majority (58%) planned to consciously increase sodium or total food intake (i.e., indirectly increasing sodium intake) in the days preceding competition. Most (79%) were conscious of sodium intake during competition, but only 29% could articulate a specific intake plan. A small minority (5%) reported using commercial sweat testing services, of which 75% believed it was beneficial. We conclude that endurance athletes commonly perceive sodium intake as important for their sporting activities. Many intend to consciously increase sodium intake in the days preceding and during competition, although these views appear informed mostly by nonscientific and/or non-evidence-based sources.
Publisher: American Physiological Society
Date: 09-2002
DOI: 10.1152/JAPPLPHYSIOL.00249.2002
Abstract: Competitive athletes completed two studies of 2-h steady-state (SS) cycling at 70% peak O 2 uptake followed by 7 kJ/kg time trial (TT) with carbohydrate (CHO) intake before (2 g/kg) and during (6% CHO drink) exercise. In Study A, 12 subjects received either 6 mg/kg caffeine 1 h preexercise (Precaf), 6 × 1 mg/kg caffeine every 20 min throughout SS (Durcaf), 2 × 5 ml/kg Coca-Cola between 100 and 120 min SS and during TT (Coke), or placebo. Improvements in TT were as follows: Precaf, 3.4% (0.2–6.5%, 95% confidence interval) Durcaf, 3.1% (−0.1–6.5%) and Coke, 3.1% (−0.2–6.2%). In Study B, eight subjects received 3 × 5 ml/kg of different cola drinks during the last 40 min of SS and TT: decaffeinated, 6% CHO (control) caffeinated, 6% CHO decaffeinated, 11% CHO and caffeinated, 11% CHO (Coke). Coke enhanced TT by 3.3% (0.8–5.9%), with all trials showing 2.2% TT enhancement (0.5–3.8% P 0.05) due to caffeine. Overall, 1) 6 mg/kg caffeine enhanced TT performance independent of timing of intake and 2) replacing sports drink with Coca-Cola during the latter stages of exercise was equally effective in enhancing endurance performance, primarily due to low intake of caffeine (∼1.5 mg/kg).
No related grants have been discovered for Gregory Cox.