CREATINE SUPPLEMENTATION ENHANCES MAXIMUM VOLUNTARY ISOMETRIC FORCE AND ENDURANCE CAPACITY IN RESISTANCE TRAINED MEN

The present study examined the hypothesis that creatine (Cr) supplemen tation can increase the performance of isometric exercise in subjects engaged in a strength training program. Ten male subjects were tested in three experimental trials 7 days apart (days 1.8 and 15). In each t rial the subjects' maximum voluntary force of contraction (MVC) was me asured in both legs and isometric endurance capacity at 80, 60, 40 and 20% of MVC of their stronger leg (knee extensor group) was measured w ith a 4-min rest between contractions. Additionally, the subjects' iso metric endurance capacity at 80% of MVC of their weaker leg was measur ed in 10 repeated bouts interspersed with 2-min rest. A double-blind c ross-over design was adopted for administering Cr or placebo. Subjects were randomized into either the Cr-placebo (Group A: clays 2-6. 10 g day(-1) of Cr; days 9-13: 10 g day(-1) of glucose polymers) or the pla cebo-Cr group (Group B reverse supplementation order). The daily diet was analysed, and urine samples from 24-h collections were subjected t o Cr and creatinine analysis. In each subject. approximate to 18 g (35 %) of Cr was eliminated in the urine during the Cr supplementation per iod. MVC increased by about 10% (P < 0.01 in the weaker leg, P < 0.05 in the stronger leg) and body mass increased by 1.7 +/- 0.4 kg (2.3%. P < 0.01) and 1.8 +/- 0.3 kg (2.1%, P < 0.01) in groups A and B, respe ctively, after Cr supplementation, while energy intake and diet compos ition remained constant throughout the study. The subjects' endurance capacity increased (P < 0.05) in all the bouts after Cr supplementatio n. Muscle hypertrophy in response to Cr supplementation and weight tra ining may explain the findings of the present study.