Effects of oral creatine supplementation on muscular strength and body composition.

PURPOSE The purpose of this investigation was to examine the effects of 6 wk of oral creatine supplementation during a periodized program of arm flexor strength training on arm flexor IRM, upper arm muscle area, and body composition. METHODS Twenty-three male volunteers with at least 1 yr of weight training experience were assigned in a double blind fashion to two groups (Cr, N = 10; Placebo, N = 13) with no significant mean pretest one repetition maximum (IRM) differences in arm flexor strength. Cr ingested 5 g of creatine monohydrate in a flavored, sucrose drink four times per day for 5 d. After 5 d, supplementation was reduced to 2 g x d(-1). Placebo ingested a flavored, sucrose drink. Both drinks were 500 mL and made with 32 g of sucrose. IRM strength of the arm flexors, body composition, and anthropometric upper arm muscle area (UAMA) were measured before and after a 6-wk resistance training program. Subjects trained twice per week with training loads that began at 6RM and progressed to 2RM. RESULTS IRM for Cr increased (P < 0.01) from (mean +/- SD) 42.8 +/- 17.7 kg to 54.7 +/- 14.1 kg, while IRM for Placebo increased (P < 0.01) from 42.5 +/- 15.9 kg to 49.3 +/- 15.7 kg. At post-test IRM was significantly (P < 0.01) greater for Cr than for Placebo. Body mass for Cr increased (P < 0.01) from 86.7 +/- 14.7 kg to 88.7 +/- 13.8 kg. Fat-free mass for Cr increased (P < 0.01) from 71.2 +/- 10.0 kg to 72.8 +/- 10.1 kg. No changes in body mass or fat-free mass were found for Placebo. There were no changes in fat mass and percent body fat for either group. UAMA increased (P < 0.01) 7.9 cm2 for Cr and did not change for Placebo. CONCLUSION Creatine supplementation during arm flexor strength training lead to greater increases in arm flexor muscular strength, upper arm muscle area, and fat-free mass than strength training alone.