| PURPOSE: The purpose of this study was to examine the effect of
creatine supplementation in conjunction with resistance training on
physiological adaptations including muscle fiber hypertrophy and
muscle creatine accumulation. METHODS: Nineteen healthy resistance-
trained men were matched and then randomly assigned in a double-blind
fashion to either a creatine (N = 10) or placebo (N = 9) group.
Periodized heavy resistance training was performed for 12 wk.
Creatine or placebo capsules were consumed (25 g x d(-1)) for 1 wk
followed by a maintenance dose (5 g x d(-1)) for the remainder of the
training. RESULTS: After 12 wk, significant (P < or = 0.05) increases
in body mass and fat-free mass were greater in creatine (6.3% and
6.3%, respectively) than placebo (3.6% and 3.1%, respectively)
subjects. After 12 wk, increases in bench press and squat were
greater in creatine (24% and 32%, respectively) than placebo (16% and
24%, respectively) subjects. Compared with placebo subjects, creatine
subjects demonstrated significantly greater increases in Type I (35%
vs 11%), IIA (36% vs 15%), and IIAB (35% vs 6%) muscle fiber cross-
sectional areas. Muscle total creatine concentrations were unchanged
in placebo subjects. Muscle creatine was significantly elevated after
1 wk in creatine subjects (22%), and values remained significantly
greater than placebo subjects after 12 wk. Average volume lifted in
the bench press during training was significantly greater in creatine
subjects during weeks 5-8. No negative side effects to the
supplementation were reported. CONCLUSION: Creatine supplementation
enhanced fat-free mass, physical performance, and muscle morphology
in response to heavy resistance training, presumably mediated via
higher quality training sessions.
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