Impact of Protein Supplements on Muscle Recovery After Exercise-induced Muscle Soreness

The intent of this study was to determine whether nutritional supplements [protein (0.4 g·kg−1) vs. carbohydrate (0.4 g·kg−1) vs. placebo] would affect muscle recovery differently after eccentric exercise-induced muscle soreness in untrained healthy young men (n = 21) aged 20-28 years. During this double-blind randomized block study design, each subject completed three, 3-day trials (separated by = 2 weeks), identical except for treatment, with each subject serving as his own control. Trials began with a bout of right-leg eccentric exercise (Biodex), followed directly by treatment. At 0 (baseline), 24 and 48 hours, data were collected: creatine phosphokinase from pre-exercise blood samples, subjective muscle soreness questions, and strength tests (power, torque, work). ANOVA indicated that exercise caused mild muscle damage, as evidenced by an overall day effect (p = 0.0001) for muscle soreness, with the lowest median values (0-10 scale) on day 1 (0.7), increasing (p = 0.0001) on day 2 (3.2), and remaining elevated on day 3 (3.4). We also noted an overall day effect (p = 0.0001) for creatine phosphokinase, with the lowest median values on day 1 (136 U·L-1), increasing (p = 0.0001) on day 2 (235 U·L-1), and remaining elevated on day 3 (189 U·L-1). ANOVA revealed no significant treatment effect on indicators of soreness or damage during recovery. Our results indicated that protein or carbohydrate supplement after exercise that caused mild muscle damage did not facilitate muscle recovery in adequately nourished, healthy young men.