The current double blind, randomized, placebo-controlled trial (NL7550) aimed to assess the impact of whey protein supplementation on recovery of muscle function and muscle soreness following eccentric exercise. During a 9-day period, forty recreationally active males received twice daily supplementation with either whey protein (PRO; 60 g/day) or an iso-energetic amount of carbohydrate (CON).

Muscle function and soreness were assessed before, and 0, 3, 24, 48, and 72 h after performing 100 drop jumps on day 5 of the supplementation period. Recovery of maximal voluntary isometric contraction did not significantly differ between groups (time x treatment, P=0.56). In contrast, the recovery of maximal voluntary isokinetic contraction at 90°·s^-1 was faster in CON as opposed to PRO (time x treatment interaction, P=0.044).

Recovery of maximal voluntary isokinetic contraction at 180°·s^-1 was also faster in CON as opposed to PRO (time x treatment interaction, P=0.011). Recovery of countermovement jump performance did not differ between groups (time x treatment interaction, P=0.52). Muscle soreness, CK and CRP showed a transient increase over time (time effect, P<0.001), with no differences between groups. In conclusion, whey protein supplementation does not accelerate recovery of muscle function or attenuate muscle soreness and inflammation during 3 days of recovery from a single bout of eccentric exercise.