Effect of timing of whey protein supplement on muscle damage markers after eccentric exercise

Whey protein is a nutritional supplement commonly ingested for recovery following exercise. However, the timing when whey protein supplement must be ingested after muscle-damaging exercise is debatable. Therefore, the present study investigated the effects of the timing of supplement ingestion on muscle damage markers after eccentric or muscle-damaging exercise. In total, 32 collegiate male students participated in this study; they were randomly assigned to control group (n=8), before supplement group (n=8), after supplement group (n=8), or before and after supplement group (n=8). Eccentric exercise was performed using elbow flexors with a modified preacher curl machine. Subsequently, maximal isometric strength, muscle soreness, range of motion (relaxed and flexed arm angle), and blood markers (creatine kinase and aspartate transaminase) were measured before and after exercise. Repeated-measure analysis of variance was used to analyze the effects of timing of supplement. No significant group by time effects were noted in maximal isometric strength, muscle soreness, range of motion, and blood markers (P>0.05). The timing of whey protein supplement did not affect reduction of muscle damage or recovery following eccentric exercise.