THE EFFECTS OF CREATINE LOADING ON THERMOREGULATION AND INTERMITTENT SPRINT EXERCISE PERFORMANCE IN A HOT HUMID ENVIRONMENT

• Published in: Journal of strength and conditioning research Vol. 21; no. 3; pp. 655 - 660
• Main Authors: WRIGHT, GLENN A., GRANDJEAN, PETER W., PASCOE, DAVID D.
• Format: Journal Article
• Language: English
• Published: United States National Strength and Conditioning Association 01.08.2007; Lippincott Williams & Wilkins Ovid Technologies
• Subjects: Adult; Analysis of Variance; Blood Volume; Body Mass Index; Body Temperature; Body Temperature Regulation - drug effects; Body Temperature Regulation - physiology; Body Water - physiology; Body Weight; Creatine - administration & dosage; Creatine - pharmacology; Dietary Supplements; Environmental conditions; Fluid dynamics; Football; Heat; Hot Temperature; Humans; Humidity; Male; Martial arts; Physical fitness; Running - physiology; Sports medicine; Sports training; Studies; Sweating - physiology; Temperature
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/00124278-200708000-00002

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°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.