title: The effects of acute heat exposure on muscular strength, muscular endurance, and muscular power in the euhydrated athlete.
abstract: 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.
authors.affiliation: Faculty of Health Sciences, The University of Sydney, Lidcombe, New South Wales, Australia 2059.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Hedley
authors.forename: Mike
authors.initials: M
authors.lastname: Climstein
authors.forename: Ross
authors.initials: R
authors.lastname: Hansen
mesh_terms: 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