The effect of milk on recovery from exercise in females

Abstract

It is well established that strenuous physical activity places both mechanical and metabolic stress on participants, resulting in fatigue, increased muscle soreness, reduced muscle function and performance. Post-exercise nutritional interventions aim to minimise the negative effects of exercise participation while maximising recovery. Milk has become a popular post-exercise drink in this context, though exploration of milk’s effect on recovery from varied types of exercise has been minimal. Furthermore there is a dearth of research examining the effects of post-exercise nutritional interventions on female athletes. Therefore the overarching aim of this thesis is to explore the effect of the post-exercise consumption of 500ml of milk on recovery from a range of exercise activities in female athletes. These were an isolated eccentric hamstring protocol (Study 1), an isolated concentric cycling protocol designed to mimic the metabolic demands of team sport (Study 2), repeated jumping and sprinting (Study 3) and a repeated simulated team game (STG) circuit which was repeated following 48h recovery (Study 4). Generally for the protocols with a high eccentric loading (Study 1, 3, 4) milk had a beneficial effect in attenuating losses in peak torque, sprint performance and perceptions of stress, though the likelihood and magnitude of benefit varied. Effects on other variables were less conclusive. The effects of milk on oxidative stress are unknown (Study 2 and Study 4), though this is because oxidative stress was not observed. Milk also had no clear effect on inflammation and CK and minimal impact on muscle soreness and tiredness. When the protocol had no eccentric loading, little effect of milk was observed (Study 2). Interestingly, in study 4 while milk benefited recovery, analysis of STG variables were trivial (HR, CMJ) and unclear (5m sprint, 15m sprint, lap-time, RPE). Of interest, in study 4 the second STG had little impact on variables measures. Overall the findings of this thesis suggest that milk is a beneficial recovery drink for female athletes. The greatest benefits are following exercise with eccentric loading. Further investigation is warranted to determine if these benefits are carried through to subsequent exercise performance.