Interactions between nutrition and exercise: diet, supplementation and sports performance

This Doctor of Philosophy (Ph.D.) thesis presents five papers I have worked on in these three years, related to the topic “nutrition, supplementation and sports performance”, and to the interactions between these. The thesis could be ideally divided in three main topics: 1. The effects of physical exercise on dietary behaviours; 2. The contribution of the sports supplements for the sports performance; 3. The prevalence of weight-control practices for the performance optimisation. Specifically, in the first two chapters of the thesis, an experimental, and a longitudinal observational study are presented, which both of them aimed to investigate the influence of physical exercise on dietary behaviours. In the first one, a sample of college students was involved in a specific training period lasted for nine weeks, during which their diet was daily monitored. In the second one, the effect of self-administered exercise on food choices has been explored during the Covid-19 lockdown. On chapters three and four, the focus moved to the topic of ‘sports supplements’. A cross-sectional study is presented which explored the supplements consumption in professional and recreational beach volley athletes, taking part in a national championship. Then, in a randomized-controlled trial, we aimed to investigate the performance-enhancing effect of a commercially available supplement, mainly containing carbohydrates and branched-chain amino acids. Lastly, in chapter five is presented an observational study which explored the rapid weight-loss strategies applied by a sample of professional and amateurs boxers, in order to lose weight before the competition. Some future research questions have risen, that will likely bring toward a better understanding of these complex relationships, with a common goal: improve health and optimise sports performance.