The Effects of 3 versus 7 Days of Creatine Supplementation on Intramuscular Creatine and Thermoregulation in the Heat

The Effects of 3 versus 7 Days of Creatine Supplementation on Intramuscular Creatine and Thermoregulation in the Heat

Many thermoregulation studies associated with creatine supplementation have utilized a pre/post-supplementation protocol. Additionally, investigations have not measured intramuscular creatine (MCR) levels to ensure increases in MCR while examining thermoregulation. The aim of this investigation was to determine the effects of 3 and 7 d of creatine supplementation (0.3 g.kg.d-1 total body weight) on MCR and thermoregulation while exercising in the heat. Ten subjects participated in two thermoregulation sessions following 3 and 7 d of creatine supplementation. Subjects ran for 60 min at 65-70% of VO2max in the heat (temp = 32.85 + 0.91°C; hum = 17.10 + 3.50%). Pre- and post-test exercise measures included nude body weight (NBW), urine specific gravity (USG), serum creatinine levels (SCR), and MCR. Total body water (TBW), extracellular water (ECW), and intracellular water (ICW) were measured preexercise. Core temperature (Tc) was assessed at 5 min intervals during exercise. Regardless of condition, Tc was not significantly different (p ≥ 0.05) from 0-5 min after which Tc increased throughout exercise. There was no significant difference or interaction (p ≥ 0.05) for TBW, ECW, and ICW. NBW was greater (p<0.05) preexercise versus post exercise for both conditions. There was no significant difference or interaction (p ≥ 0.05) between conditions for SCR.