Dehydration has been shown to hinder performance of sustained exercise in the heat. Consuming fluids before exercise can result in hyperhydration, delay the onset of dehydration during exercise and improve exercise performance. However, humans normally drink only in response to thirst, which does not result in hyperhydration. Thirst and voluntary fluid consumption have been shown to increase following oral ingestion or infusion of sodium into the bloodstream. We measured the effects of acute sodium ingestion on voluntary water consumption and retention during a 2-hr hydration period before exercise. Subjects then performed a 60-min submaximal dehydration ride (DR) followed immediately by a 200 kJ performance time trial (PTT) in a warm (30 °C) environment. Water consumption and retention during the hydration period was greater following sodium ingestion (1380 ± 580 mL consumed, 821 ± 367 ml retained) compared with placebo (815 ± 483 ml consumed, 244 ± 402 mL retained) and no treatment (782 ± 454 ml consumed, 148 ± 289 mL retained). Dehydration levels following the DR were significantly less after sodium ingestion (0.7 ± 0.6%) compared with placebo (1.3 ± 0.7%) and no treatment (1.6 ± 0.4%). Time to complete the PTT was significantly less following sodium consumption (773 ± 158 s) compared with placebo (851 ± 156 s) and no treatment (872 ± 190 s). These results suggest that voluntary hyperhydration can be induced by acute consumption of sodium and has a favorable effect on hydration status and performance during subsequent exercise in the heat.
David M. Morris, Joshua R. Huot, Adam M. Jetton, Scott R. Collier and Alan C. Utter
Dru A. Henson, David C. Nieman, Andy D. Blodgett, Diane E. Butterworth, Alan Utter, J. Mark Davis, Gerald Sonnenfeld, Darla S. Morton, Omar R. Fagoaga and Sandra L. Nehlsen-Cannarella
The influence of exercise mode and 6% carbohydrate (C) versus placebo (P) beverage ingestion on lymphocyte proliferation, natural killer cell cytotoxicily (NKCA), Interleukin (IL)-1ß production, and hormonal responses to 2.5 hr of intense running and cycling (~75%
Alessandro Moura Zagatto, Jorge Vieira de Mello Leite, Marcelo Papoti and Ralph Beneke
To test the hypotheses that the metabolic profile of table tennis is dominantly aerobic, anaerobic energy is related to the accumulated duration and intensity of rallies, and activity and metabolic profile are interrelated with the individual fitness profile determined via table tennis–specific tests.
Eleven male experienced table tennis players (22 ± 3 y, 77.6 ± 18.9 kg, 177.1 ± 8.1 cm) underwent 2 simulated table tennis matches to analyze aerobic (WOXID) energy, anaerobic glycolytic (WBLC) energy, and phosphocreatine breakdown (WPCr); a table tennis–specific graded exercise test to measure ventilatory threshold and peak oxygen uptake; and an exhaustive supramaximal table tennis effort to determine maximal accumulated deficit of oxygen.
WOXID, WBLC, and WPCr corresponded to 96.5% ± 1.7%, 1.0% ± 0.7%, and 2.5% ± 1.4%, respectively. WOXID was interrelated with rally duration (r = .81) and number of shots per rally (r = .77), whereas match intensity was correlated with WPCr (r = .62) and maximal accumulated oxygen deficit (r = .58).
The metabolic profile of table tennis is predominantly aerobic and interrelated with the individual fitness profile determined via table tennis–specific tests. Table tennis–specific ventilatory threshold determines the average oxygen uptake and overall WOXID, whereas table tennis–specific maximal accumulated oxygen deficit indicates the ability to use and sustain slightly higher blood lactate concentration and WBLC during the match.
Eliseo Iglesias-Soler, Eduardo Carballeira, Tania Sánchez-Otero, Xian Mayo and Miguel Fernández-del-Olmo
To analyze performance during the execution of a maximum number of repetitions (MNR) in a cluster-set configuration.
Nine judokas performed 2 sessions of parallel squats with a load corresponding to 4-repetition maximum (4RM) with a traditional-training (TT) and cluster-training (CT) set configuration. The TT consisted of 3 sets of repetitions leading to failure and 3 min of rest between sets. In the CT the MNR was performed with a rest interval between repetitions (45.44 ± 11.89 s). The work-to-rest ratio was similar for CT and TT.
MNR in CT was 45.5 ± 32 repetitions and was 9.33 ± 1.87 times the volume in TT. There was a tendency for the average mean propulsive velocity (MPV) to be higher in CT (0.39 ± 0.04 vs 0.36 ± 0.04 m/s for CT and TT, respectively, P = .054, standardized mean difference [d] = 0.57). The average MPV was higher in CT for a similar number of repetitions (0.44 ± 0.08 vs 0.36 ± 0.04 m/s for CT and TT, respectively, P = .006, d = 1.33). The number of repetitions in TT was correlated with absolute 4RM load (r = –.719, P = .031) but not in CT (r = –.273, P = .477).
A cluster-set configuration allows for a higher number of repetitions and improved sustainability of mechanical performance. CT, unlike TT, was not affected by absolute load, suggesting an improvement of training volume with high absolute loads.
Mindy L. Millard-Stafford, Kirk J. Cureton, Jonathan E. Wingo, Jennifer Trilk, Gordon L. Warren and Maxime Buyckx
Caffeine is regarded as a diuretic despite evidence that hydration is not impaired with habitual ingestion. The purpose of this study was to determine whether a caffeinated sports drink impairs fluid delivery and hydration during exercise in warm, humid conditions (28.5 °C, 60% relative humidity). Sixteen cyclists completed 3 trials: placebo (P), carbohydrate-electrolyte (CE), and caffeinated (195 mg/L) sports drink (CAF+CE). Subjects cycled for 120 min at 60–75%VO2max followed by 15 min of maximal-effort cycling. Heart rate and rectal temperature were similar until the final 15 min, when these responses and exercise intensity were higher with CAF+CE than with CE and P. Sweat rate, urine output, plasma-volume losses, serum electrolytes, and blood deuterium-oxide accumulation were not different. Serum osmolality was higher with CAF+CE vs. P but not CE. The authors conclude that CAF+CE appears as rapidly in blood as CE and maintains hydration and sustains cardiovascular and thermoregulatory function as well as CE during exercise in a warm, humid environment.
Martin D. Hoffman and Carol A. Parise
This work longitudinally assesses the influence of aging and experience on time to complete 161-km ultramarathons.
From 29,331 finishes by 4066 runners who had completed 3 or more 161-km ultramarathons in North America from 1974 through 2010, independent cohorts of men (n = 3,092), women (n = 717), and top-performing men (n = 257) based on age-group finish place were identified. Linear mixed-effects regression was used to assess the effects of aging and previous 161-km finish number on finish time adjusted for the random effects of runner, event, and year.
Men and women up to 38 y of age slowed by 0.05–0.06 h/y with advancing age. Men slowed 0.17 h/y from 38 through 50 y and 0.23 h/y after 50 y. Women slowed 0.20–0.23 h/y with advancing age from 38 y. Top-performing men under 38 y did not slow with increasing age but slowed by 0.26 and 0.39 h/y from 38 through 50 y and after 50 y, respectively. Finish number was inversely associated with finish time for all 3 cohorts. A 10th or higher finish was 1.3, 1.7, and almost 3 h faster than a first finish for men, women, and top-performing men, respectively.
High-level performances in 161-km ultramarathoners can be sustained late into the 4th decade of life, but subsequent aging is associated with declines in performance. Nevertheless, the adverse effects of aging on performance can be offset by greater experience in these events.
Jonathan Esteve-Lanao, Eneko Larumbe-Zabala, Anouar Dabab, Alberto Alcocer-Gamboa and Facundo Ahumada
The aim of this study was to describe the pacing distribution during 6 editions of the world cross-country championships.
Data from the 768 male runners participating from 2007 to 2013 were considered for this study. Blocks of 10 participants according to final position (eg, 1st to 10th, 11 to 20th, etc) were considered.
Taking data from all editions together, the effect of years was found to be significant (F 5,266 = 3078.69, P < .001, ω2 = 0.31), as well as the effect of blocks of runners by final position (F 4,266 = 957.62, P < .001, ω2 = 0.08). A significant general decrease in speed by lap was also found (F 5,1330 = 2344.02, P < .001, ω2 = 0.29). Post hoc analyses were conducted for every edition where several pacing patterns were found. All correlations between the lap times and the total time were significant. However, each lap might show different predicting capacity over the individual outcome.
Top athletes seem to display different strategies, which allow them to sustain an optimal speed and/or kick as needed during the critical moments and succeed. After the first group (block) of runners, subsequent blocks always displayed a positive pacing pattern (fast to slow speed). Consequently, a much more stable pacing pattern should be considered to maximize final position.
Top-10 finishers in the world cross-country championships tend to display a more even pace than the rest of the finishers, whose general behavior shows a positive (fast-to-slow) pattern.
Jeanne Dekerle and James Paterson
To examine muscle fatigue of the shoulder internal rotators alongside swimming biomechanics during long-duration submaximal swimming sets performed in 2 different speed domains.
Eight trained swimmers (mean ± SD 20.5 ± 0.9 y, 173 ± 10 cm, 71.3 ± 10.0 kg) raced over 3 distances (200-, 400-, 800-m races) for determination of critical speed (CS; slope of the distance–time relationship). After a familiarization with muscle isokinetic testing, they subsequently randomly performed 2 constant-speed efforts (6 × 5-min blocks, 2.5-min recovery) 5% above (T105) and 5% below CS (T95) with maximal voluntary contractions recorded between swimming blocks.
Capillary blood lactate concentration ([La]), rating of perceived exertion (RPE), peak torque, stroke length, and stroke rate were maintained throughout T95 (P < .05). [La], RPE, and stroke rate increased alongside concomitant decreases in maximal torque and stroke length during T105 (P < .05) with incapacity of the swimmers to maintain the pace for longer than ~20 min. For T105, changes in maximal torque (35.0 ± 14.9 to 25.8 ± 12.1 Nm) and stroke length (2.66 ± 0.36 to 2.23 ± 0.24 m/cycle) were significantly correlated (r = .47, P < .05).
While both muscle fatigue (shoulder internal rotators) and task failure occur when swimming at a pace greater than CS, the 2.5-min recovery period during the sub-CS set possibly alleviated the development of muscle fatigue for the pace to be sustainable for 6 × 5 min at 95% of CS. A causal relationship between reduction in stroke length and loss of muscle strength should be considered very cautiously in swimming.
Michael L. Newell, Angus M. Hunter, Claire Lawrence, Kevin D. Tipton and Stuart D. R. Galloway
In an investigator-blind, randomized cross-over design, male cyclists (mean± SD) age 34.0 (± 10.2) years, body mass 74.6 (±7.9) kg, stature 178.3 (±8.0) cm, peak power output (PPO) 393 (±36) W, and VO2max 62 (±9) ml·kg−1min−1 training for more than 6 hr/wk for more than 3y (n = 20) completed four experimental trials. Each trial consisted of a 2-hr constant load ride at 95% of lactate threshold (185 ± 25W) then a work-matched time trial task (~30min at 70% of PPO). Three commercially available carbohydrate (CHO) beverages, plus a control (water), were administered during the 2-hr ride providing 0, 20, 39, or 64g·hr−1 of CHO at a fluid intake rate of 1L·hr−1. Performance was assessed by time to complete the time trial task, mean power output sustained, and pacing strategy used. Mean task completion time (min:sec ± SD) for 39g·hr−1 (34:19.5 ± 03:07.1, p = .006) and 64g·hr−1 (34:11.3 ± 03:08.5 p = .004) of CHO were significantly faster than control (37:01.9 ± 05:35.0). The mean percentage improvement from control was −6.1% (95% CI: −11.3 to −1.0) and −6.5% (95% CI: −11.7 to −1.4) in the 39 and 64g·hr−1 trials respectively. The 20g·hr−1 (35:17.6 ± 04:16.3) treatment did not reach statistical significance compared with control (p = .126) despite a mean improvement of −3.7% (95% CI −8.8−1.5%). No further differences between CHO trials were reported. No interaction between CHO dose and pacing strategy occurred. 39 and 64g·hr−1 of CHO were similarly effective at improving endurance cycling performance compared with a 0g·hr−1 control in our trained cyclists.
Dean Ritchie, Will G. Hopkins, Martin Buchheit, Justin Cordy and Jonathan D. Bartlett
Training volume, intensity, and distribution are important factors during periods of return to play.
To quantify the effect of injury on training load (TL) before and after return to play (RTP) in professional Australian Rules football.
Perceived training load (RPE-TL) for 44 players was obtained for all indoor and outdoor training sessions, while field-based training was monitored via GPS (total distance, high-speed running, mean speed). When a player sustained a competition time-loss injury, weekly TL was quantified for 3 wk before and after RTP. General linear mixed models, with inference about magnitudes standardized by between-players SDs, were used to quantify effects of lower- and upper-body injury on TL compared with the team.
While total RPE-TL was similar to the team 2 wk before RTP, training distribution was different, whereby skills RPE-TL was likely and most likely lower for upper- and lower-body injury, respectively, and most likely replaced with small to very large increases in running and other conditioning load. Weekly total distance and high-speed running were most likely moderately to largely reduced for lower- and upper-body injury until after RTP, at which point total RPE-TL, training distribution, total distance, and high-speed running were similar to the team. Mean speed of field-based training was similar before and after RTP compared with the team.
Despite injured athletes’ obtaining comparable TLs to uninjured players, training distribution is different until after RTP, indicating the importance of monitoring all types of training that athletes complete.