ABSTRACT
Purpose: The purpose of this study was to examine if the timing of a carbohydrate/protein supplement would have an effect on post resistance exercise muscle damage, function and soreness. Methods: Twenty one untrained male subjects were given a supplement before or after a bout of resistance exercise. Subjects were randomly assigned to three groups. The pre exercise group (Pre, n=7) received a carbohydrate/protein drink immediately before the exercise bout and a placebo drink immediately after. The post exercise group (Post, n=7) received a placebo drink immediately before the exercise bout and a carbohydrate/protein drink after. The control group (Con, n=7) received a placebo drink before and after the bout of exercise. Subjects performed 50 eccentric quadriceps contractions on an isokinetic dynamometer. Tests for serum creatine kinase (CK), maximal voluntary contraction (MVC) and muscle soreness scores were recorded before the exercise bout then again at six, 24, 48, 72, and 96 hours post exercise. Repeated measures ANOVA (3 x 6 group x time) were used to analyze dependent measures. Significance was accepted at P¡Ü0.05. Results: There were no group by time interactions for any of the measured parameters; however, there were time main effects. Serum CK increased for all groups (P<0.01) when compared to pre exercise values (103¡À45U/L) reaching its peak at 72 (1156¡À1990U/L) and 96 hours (1047¡À1438U/L) post exercise. Maximal voluntary contraction (MVC) was significantly reduced (P<0.01) on average for all groups by 29.5¡À12% at six hours then dropped to 31.3¡À15% at 24 hours before gradually returning to pre exercise values. Muscle soreness scores were also significantly increased (P<0.01) from pre exercise values peaking at 48 hours post exercise. Conclusion: These findings suggest that the eccentric resistance exercise protocol caused significant muscle damage, soreness and loss of strength in all groups. However, the timing or ingestion of the carbohydrate/protein supplement had no effect on those variables.
