Impact of acute weight loss and/or thermal stress on rowing ergometer performance.
OBJECTIVE
The impact of acute weight loss on rowing performance was assessed when generous nutrient intake was provided in 2 h of recovery after making weight.


METHODS
Competitive rowers (N = 17) completed four ergometer trials, each separated by 48 h. Two trials were performed after a 4% body mass loss in the previous 24 h (WT) and two were performed after no weight restrictions, that is, unrestricted (UNR). In addition, two trials (1 x WT, 1 x UNR) were in a thermoneutral environment (NEUTRAL, mean 21.1 +/- SD 0.7 degrees C, 29.0 +/- 4.5% RH) and two were in the heat (HOT 32.4, +/- 0.4 degrees C, 60.4 +/- 2.7% RH). Trials were performed in a counterbalanced fashion according to a Latin square design. Aggressive nutritional recovery strategies (WT 2.3 g x kg(-1) carbohydrate, 34 mg x kg(-1) Na, 28.4 mL x kg(-1) fluid; UNR ad libitum) were employed in the 2 h after weigh-in.


RESULTS
Both WT (mean 2.1, 95% CI 0.7-3.4 s; P = 0.003) and HOT (4.1, 2.7 - 5.4 s; P < 0.001) compromised 2000-m time-trial performance. Whereas WT resulted in hypohydration, the associated reduction in plasma volume explained only part of the performance compromise observed (0.2 s for every 1% decrement) Moreover, WT did not influence core temperature or indices of cardiovascular function.


CONCLUSIONS
Acute weight loss compromised performance, despite generous nutrient intake in recovery, although the effect was small. Performance decrements were further exacerbated when exercise was performed in the heat.
Slater
Gary J
GJ
Department of Physiology, Australian Institute of Sport, Belconnen, Australian Capital Territory, Australia. gary.slater@ausport.gov.au
Rice
Anthony J
AJ
Sharpe
Ken
K
Tanner
Rebecca
R
Jenkins
David
D
Gore
Christopher J
CJ
Hahn
Allan G
AG
D001315:Australia; D001831:Body Temperature; D001835:Body Weight; D004032:Diet; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010953:Plasma Volume; D014867:Water; D015431:Weight Loss
D014867:Water; D019344:Lactic Acid