Intramuscular temperatures during exercise in the heat following pre-cooling and pre-heating

✍ Scribed by John D. Booth; Bradley R. Wilsmore; Andrea D. MacDonald; Annerieke Zeyl; Len H. Storlien; Nigel A.S. Taylor

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 291 KB
• Volume: 29
• Category: Article
• ISSN: 0306-4565
• DOI: 10.1016/j.jtherbio.2004.08.044

✦ Synopsis

Pre-cooling improves heat tolerance and time to exhaustion in the heat. We tested the possibility that reduced tissue temperatures may explain this phenomenon, using three whole-body treatments: pre-cooling, thermoneutral (control) and pre-heating. Pre-cooling reduced muscle temperature (T m ) by 6.3 1C while pre-heating increased T m 3.4 1C, relative to control. Despite this offset, T m climbed towards a common asymptote, with pre-cooling offering no thermal protection beyond $40 min. Following pre-cooling, exercising oesophageal temperature (T es ) initially increased at 0.09 1C min À1 , being significantly faster than control (0.05 1C min À1 ) and pre-heated conditions (0.03 1C min À1 ). Precooling lowered the sweat threshold and also resulted in a reduced cardiac frequency across the exercise-heat exposure. Our observations do not support the hypothesis that pre-cooling reduces T m at the end of an exercise-heat exposure, thereby delaying the development of fatigue.