Creatine Supplementation: Effect on Supramaximal Exercise Performance at Two Levels of Acute Hypohydration

Sixteen men performed 5, 5-second maximal sprints on a cycle ergometer in an environmental chamber maintained at similar to 32 degrees C and 50% RH. They were then supplemented with either creatine monohydrate (CR; 20 g.d(-1) for 5 days) or a placebo (PL). After 5 days of supplementation, subjects again performed 5, 5-second maximal cycling sprints on the cycle, which was immediately followed by a 75-minute exercise session to facilitate an acute loss of body water. After completion of the 75 minutes of exercise, subjects again performed 5, 5-second sprints on the cycle followed by a second 75 minutes of exercise in order to facilitate a further loss of body water The CR group demonstrated a significant increase in body mass compared with the PL group (CR, 1.1 +/- 0.2; PL, 0.7 +/- 0.5%; p \u3c 0.01); however, this was not associated with any significant percent change in plasma volume (%Delta PV). The two 75-minute exercise sessions elicited significant losses in body mass (similar to-2.5 and similar to-4%) and plasma volume (similar to-7 and similar to-9%), which were not significantly different between groups. No differences were reported for any measures of work or power. Occurrences of skeletal muscle tightness and/or cramping were reported in both groups, although it tvas nothing that would suggest a greater incidence associated with creatine supplementation. Although creatine supplementation does not appear to negatively impact hydration status, neither is it associated with an improvement in exercise performance