The first aim of this proposal is to investigate the post-prandial muscle protein synthesis rates in young and elderly men in response to a meal-like protein bolus after a period of rest or physical activity (study A). The rest trial (REST) will act as a proof-of-principle study to examine the blunted protein synthetic response in the elderly, and as a control trial in comparison with the exercise trial (EXC) to establish the surplus value of physical activity prior to protein intake on muscle protein synthesis.