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Purpose:

We examined the effects of creatine supplementation on the response to repeated bouts of resistance exercise.

Methods:

Young men (24.1 ± 5.2 yr) were divided into Creatine (CM, n = 9) and Placebo (PL, n = 9) groups. On day (D) 1 and D15, subjects performed four sets of bicep curls at 75% 1-RM to concentric failure. On D8-D13, subjects consumed either 20g/d creatine monohydrate or placebo. Muscle soreness and elbow joint range of motion (ROM) were assessed on D1-D5 and D15-D19. Serum creatine kinase activity (CK) was assessed on D1, D3, D5, D15, D17, and D19.

Results:

The first exercise bout produced increases in muscle soreness and CK, and decreases in ROM in both groups (p < .001). The second bout produced lesser rises in serum CK, muscle soreness, and a lesser decrease in ROM (bout effect, p < .01 for all), with greater attenuation of these damage markers in CM than PL. CK levels on D17 were lower (+110% over D15 for CM vs. +343% for PL), muscle soreness from D15–19 was lower (–75% for CM vs. –56% for PL compared with first bout), and elbow ROM was decreased in PL, but not CM on D16 (p < .05 for all).

Conclusions:

Creatine supplementation provides an additive effect on blunting the rise of muscle damage markers following a repeated bout of resistance exercise. The mechanism by which creatine augments the repeated bout effect is unknown but is likely due to a combination of creatine’s multifaceted functions.

Veggi, Machado, Santana, and Oliveira are with the Laboratory of Physiology and Biokinetic, Universidade Iguaçu, Itaperuna, Brazil. Koch is with the Exercise Physiology Laboratory, Lenoir-Rhyne University, Hickory, NC. Stec is with the Dept. of Cell, Developmental, and Integrative Biology, University of Alabama, Birmingham, Birmingham, AL.