Neural Contributions to Physical Activity: From the Brain to the Muscle and Back Again

The thesis aims to explore the neural contribution to physical activity. The work is divided into two chapters containing research conducted in Italy, France or both states. The first chapter includes four behavioural studies aimed at evaluating the reciprocal relationship between physical activity and cognition. The second chapter contains two neurophysiological studies aimed at investigating the muscle length and the type of contraction's contribution to the activity of the motor system. Chapter one investigates how motor condition influences cognitive processes and vice versa. Several studies suggested that engaging in physical activity programs elicits a wide range of neural changes. One of those is enhancing cognitive performance (e.g., working memory or information processing speed). On the other side, specific cognitive interventions (e.g., action observation or motor imagery) can ameliorate motor performance. This reciprocal interaction could produce adverse effects if people exceed one of these two activities, which induce a fatiguing state. Chapter two looks into the activity of the corticomotor system as a function of muscle length and type of contraction. After a general introduction exploring previous studies investigating the role of muscle length (in static and dynamic form) on the corticomotor system, the chapter will present two studies. The first study examined the influence of muscle length on neuromuscular function and corticospinal excitability. The second study investigated the difference in primary motor cortex excitability when preparing concentric and eccentric contractions.