The effects of acute heat exposure on muscular strength, muscular endurance, and muscular power in the euhydrated athlete.
The purpose of this study was to determine the effects of acute heat exposure upon muscular strength, muscular endurance, and muscular power in euhydrated athletes. Ten healthy, weight-trained men (average age = 23.0 +/- 4.0 years) volunteered for this investigation. Subjects were randomized to normothermic (22.5 degrees C, 65% relative humidity [RH]) or hyperthermic (65-75 degrees C, 15% RH) condition for 30 minutes. Results indicated that all subjects experienced significant (p < 0.05) hemodynamic stress because of the 30 minutes of heat exposure (blood pressure [BP](rest) 124/78 mm Hg to BP(postsauna) 148/60 mm Hg, heart rate [HR](rest) 64 b.min(-1) to HR(postsauna) 122 b.min(-1)). Oral and tympanic temperature measurements correlated strongly (r(2) = 0.904) and increased by 2.48 and 2.71 degrees C, respectively, during sauna exposure. One repetition maximum (1RM) bench press strength did not differ between the 2 conditions, whereas 1RM leg press strength was significantly decreased (p < 0.05) after the hyperthermic protocol. Subjects' muscular endurance decreased significantly (p < 0.05) in both the leg press (29.2%) and bench press (15.8%) after the sauna exposure. In contrast, muscular power (vertical jump) increased significantly (3.1%, p < 0.5) after acute heat exposure. In agreement with previous studies, we concluded that acute heat exposure is detrimental to muscular endurance; however, the areas of strength and power are far less unequivocal.
Hedley
Andrew M
AM
Faculty of Health Sciences, The University of Sydney, Lidcombe, New South Wales, Australia 2059.
Climstein
Mike
M
Hansen
Ross
R
D000328:Adult; D001794:Blood Pressure; D001831:Body Temperature; D018592:Cross-Over Studies; D004326:Drinking; D015444:Exercise / Q000502:physiology*; D006801:Humans; D006813:Humidity; D006979:Hyperthermia, Induced; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance; D029002:Steam Bath