The effects of creatine loading on thermoregulation and intermittent sprint exercise performance in a hot humid environment.
The purpose of this study was to determine the effects creatine (Cr) loading may have on thermoregulatory responses during intermittent sprint exercise in a hot/humid environment. Ten physically active, heat-acclimatized men performed 2 familiarization sessions of an exercise test consisting of a 30-minute low-intensity warm-up followed by 6 x 10 second maximal sprints on a cycle ergometer in the heat (35 degrees C, 60% relative humidity). Subjects then participated in 2 different weeks of supplementation. The first week, subjects ingested 5 g of a placebo (P, maltodextrin) in 4 flavored drinks (20 g total) per day for 6 days and were retested on day 7. The second week was similar to the first except a similar dose (4 x 5 g/day) of creatine monohydrate (Cr) replaced maltodextrin in the flavored drinks. Six days of Cr supplementation produced a significant increase in body weight (+1.30 +/- 0.63 kg), whereas the P did not (+0.11 +/- 0.52 kg). Compared to preexercise measures, the exercise test in the heat produced a significant increase in core temperature, a loss of body water determined by body weight change during exercise, and a relative change in plasma volume (%PVC); however, these were not significantly different between P and Cr. Sprint performance was enhanced by Cr loading. Peak power and mean power were significantly higher during the intermittent sprint exercise test following 6 days of Cr supplementation. It appears that ingestion of Cr for 6 days does not produce any different thermoregulatory responses to intermittent sprint exercise and may augment sprint exercise performance in the heat.
Wright
Glenn A
GA
Exercise and Sport Science Department, University of Wisconsin-LaCrosse, LaCrossse, Wisconsin 54601, USA. glen@uwlax.edu
Grandjean
Peter W
PW
Pascoe
David D
DD
D000328:Adult; D000704:Analysis of Variance; D001810:Blood Volume; D015992:Body Mass Index; D001831:Body Temperature; D001833:Body Temperature Regulation / Q000187:drug effects* / Q000502:physiology; D001834:Body Water / Q000502:physiology; D001835:Body Weight; D003401:Creatine / Q000008:administration & dosage / Q000494:pharmacology*; D019587:Dietary Supplements; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D008297:Male; D012420:Running / Q000502:physiology*; D013546:Sweating / Q000502:physiology
D003401:Creatine