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.
Michael L. Newell, Angus M. Hunter, Claire Lawrence, Kevin D. Tipton and Stuart D. R. Galloway
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.
Jason D. Vescovi and Jaci L. VanHeest
This observational case study examined the association of inter- and intraday energy intake and exercise energy expenditure with bone health, menstrual status and hematological factors in a female triathlete. The study spanned 7 months whereby energy intake and exercise energy expenditure were monitored three times (13 d); 16 blood samples were taken, urinary hormones were assessed for 3 months, and bone mineral density was measured twice. Energy availability tended to be sustained below 30 kcal/kg FFM/d and intraday energy intake patterns were often “back-loaded” with approximately 46% of energy consumed after 6 p.m. Most triiodothyronine values were low (1.1–1.2nmol/L) and supportive of reduced energy availability. The athlete had suppressed estradiol (105.1 ± 71.7pmol/L) and progesterone (1.79 ±1.19nmol/L) concentrations as well as urinary sex-steroid metabolites during the entire monitoring period. Lumbar spine (L1-L4) bone mineral density was low (age-matched Z-score −1.4 to −1.5). Despite these health related maladies the athlete was able to perform typical weekly training loads (swim: 30–40 km, bike: 120–300 km, run 45–70 km) and was competitive as indicated by her continued improvement in ITU World Ranking during and beyond the assessment period. There is a delicate balance between health and performance that can become blurred especially for endurance athletes. Education (athletes, coaches, parents) and continued monitoring of specific indicators will enable evidence-based recommendations to be provided and help reduced the risk of health related issues while maximizing performance gains. Future research needs to longitudinally examine how performance on standardized tests in each discipline (e.g., 800-m swim, 20-km time trial, 5-km run) is impacted when aspects of the female athlete triad are present.
Shane Malone, Mark Roe, Dominic A. Doran, Tim J. Gabbett and Kieran D. Collins
To examine the association between combined session rating of perceived exertion (RPE) workload measures and injury risk in elite Gaelic footballers.
Thirty-seven elite Gaelic footballers (mean ± SD age 24.2 ± 2.9 y) from 1 elite squad were involved in a single-season study. Weekly workload (session RPE multiplied by duration) and all time-loss injuries (including subsequent-wk injuries) were recorded during the period. Rolling weekly sums and wk-to-wk changes in workload were measured, enabling the calculation of the acute:chronic workload ratio by dividing acute workload (ie, 1-weekly workload) by chronic workload (ie, rolling-average 4-weekly workload). Workload measures were then modeled against data for all injuries sustained using a logistic-regression model. Odds ratios (ORs) were reported against a reference group.
High 1-weekly workloads (≥2770 arbitrary units [AU], OR = 1.63–6.75) were associated with significantly higher risk of injury than in a low-training-load reference group (<1250 AU). When exposed to spikes in workload (acute:chronic workload ratio >1.5), players with 1 y experience had a higher risk of injury (OR = 2.22) and players with 2–3 (OR = 0.20) and 4–6 y (OR = 0.24) of experience had a lower risk of injury. Players with poorer aerobic fitness (estimated from a 1-km time trial) had a higher injury risk than those with higher aerobic fitness (OR = 1.50–2.50). An acute:chronic workload ratio of (≥2.0) demonstrated the greatest risk of injury.
These findings highlight an increased risk of injury for elite Gaelic football players with high (>2.0) acute:chronic workload ratios and high weekly workloads. A high aerobic capacity and playing experience appears to offer injury protection against rapid changes in workload and high acute:chronic workload ratios. Moderate workloads, coupled with moderate to high changes in the acute:chronic workload ratio, appear to be protective for Gaelic football players.
Katrien De Bock, Bert O. Eijnde, Monique Ramaekers and Peter Hespel
The purpose of this study was to investigate the effect of acute and 4-week Rhodiola rosea intake on physical capacity, muscle strength, speed of limb movement, reaction time, and attention.
PHASE I: A double blind placebo-controlled randomized study (n = 24) was performed, consisting of 2 sessions (2 days per session). Day 1: One hour after acute Rhodiola rosea intake (R, 200-mg Rhodiola rosea extract containing 3% rosavin + 1% salidroside plus 500 mg starch) or placebo (P, 700 mg starch) speed of limb movement (plate tapping test), aural and visual reaction time, and the ability to sustain attention (Fepsy Vigilance test) were assessed. Day 2: Following the same intake procedure as on day 1, maximal isometric knee-extension torque and endurance exercise capacity were tested. Following a 5-day washout period, the experimental procedure was repeated, with the treatment regimens being switched between groups (session 2). PHASE II: A double blind placebo-controlled study (n = 12) was performed. Subjects underwent sessions 3 and 4, identical to Phase I, separated by a 4-week R/P intake, during which subjects ingested 200 mg R/P per day.
PHASE I: Compared with P, acute R intake in Phase I increased 0 < -05) time to exhaustion from 16.8 ± 0.7 min to 17.2 ± 0.8 min. Accordingly, VO2peak (p < .05) and VCO2peak(p< .05) increased during R compared to P from 50.9 ± 1.8 ml • min-1 • kg−1 to 52.9 ± 2.7 ml • min-1 • kg"’ (VO2peak) and from 60.0 ± 2.3 ml • min-1 • kg-’ to 63.5 ± 2.7 ml • min-1 kg-1 (VCO2peak). Pulmonary ventilation (p = .07) tended to increase more during R than during P(P: 115.9±7.7L/min; R: 124.8 ± 7.7 L/min). All other parameters remained unchanged. PHASE II: Four-week R intake did not alter any of the variables measured.
Acute Rhodiola rosea intake can improve endurance exercise capacity in young healthy volunteers. This response was not altered by prior daily 4-week Rhodiola intake.
360 360 10.1123/ijsn.9.4.345 Influence of Caffeine on Metabolic and Cardiovascular Functions during Sustained Light Intensity Cycling and at Rest Hermann-J. Engels * John C. Wirth * Sueda Celik * Jodee L. Dorsey * 12 1999 9 9 4 4 361 361 370 370 10.1123/ijsn.9.4.361 Ginseng Treatment Improves
Naroa Etxebarria, Megan L. Ross, Brad Clark and Louise M. Burke
tract to these ingredients. 1 This new area of sport nutrition, typically known as “mouth rinsing,” emerged from observations of the performance benefits of carbohydrate (CHO) intake during shorter (∼1 h) protocols of sustained higher-intensity exercise. During these shorter protocols, CHO was unlikely
Mark Kramer, Mark Watson, Rosa Du Randt and Robert W. Pettitt
consequently introduced which represented the maximum work rate that could be sustained for prolonged periods without fatigue and was characterized by the asymptote of the power–time ( P – t ) relationship. 8 The P – t relationship also revealed an “energy store” parameter, termed W ′, which denoted a
Robert McCunn, Hugh H.K. Fullagar, Sean Williams, Travis J. Halseth, John A. Sampson and Andrew Murray
The potential for physical injury is an accepted risk that differs in size across all sports. The cost of sustaining an injury is multifaceted and the burden is shared among numerous parties, not least the athlete themselves. Consequences incorporate financial, 1 long-term health, 2 emotional
Rachael L. Thurecht and Fiona E. Pelly
values and beliefs If the food aligns with my values for animal welfare (i.e., no animal products/vegan, cruelty-free raised animals) −0.02 0.01 0.06 −0.14 −0.19 0.05 0.79 −0.02 −0.13 0.71 My religious food beliefs −0.03 0.04 −0.01 0.06 0.20 −0.01 0.79 −0.21 0.08 0.72 If the food is sustainably produced