CREATINE SUPPLEMENTATION ENHANCES MUSCULAR PERFORMANCE DURING HIGH-INTENSITY RESISTANCE EXERCISE

Objective This study was undertaken to investigate the influence of or al supplementation with creatine monohydrate on muscular performance d uring repeated sets of high-intensity resistance exercise. Subjects/de sign Fourteen active men were randomly assigned in a double-blind fash ion to either a creatine group (n=7) or a placebo group (n=7). Both gr oups performed a bench press exercise protocol (5 sets to failure usin g each subject's predetermined 10-repetition maximum) and a jump squat exercise protocol (5 sets of 10 repetitions using 30% of each subject 's 1-repetition maximum squat) on three different occasions (T1, T2, a nd T3) separated by 6 days. Intervention Before T1, both groups receiv ed no supplementation. From T1 to T2, both groups ingested placebo cap sules. From T2 to T3, the creatine group ingested 25 g creatine monohy drate per day, and the placebo group ingested an equivalent amount of placebo. Main outcome measures Total repetitions for each set of bench presses and peak power output for each set of jump squats were determ ined. Other measures included assessment of diet, body mass, skinfold thickness, and preexercise and 5-minute postexercise lactate concentra tions. Results Lifting performance was not altered for either exercise protocol after ingestion of the placebos. Creatine supplementation re sulted in a significant improvement in peak power output during all 5 sets of jump squats and a significant improvement in repetitions durin g all 5 sets of bench presses. After creatine supplementation, postexe rcise lactate concentrations were significantly higher after the bench press but not the jump squat. A significant increase in body mass of 1.4 kg (range= 0.0 to 2.7 kg) was observed after creatine ingestion. C onclusion One week of creatine supplementation (25 g/day) enhances mus cular performance during repeated sets of bench press and jump squat e xercise.