Abstract
Anabolic resistance, consisting of a diminished ability of aging muscle to respond to anabolic stimuli such as exercise and protein intake, is a key contributor to age-related declines in muscle mass. However, diseases and lifestyle factors associated with aging, including insulin resistance states, overweight/obesity, persistent inflammation and specifically-as a focus herein-physical inactivity and inadequate dietary protein-intake habits, might interact with chronological impairments in muscle anabolism. In this context, master athletes, as individuals who have engaged in lifelong structured exercise, including regular training and sports participation, offer a valuable model for studying processes of chronological vs. inactivity-related aging. While these lifelong exercisers may present improved body composition parameters and other potential benefits in terms of muscle mass and function, it remains unclear whether exercise practice throughout life can prevent the development of anabolic resistance associated with aging. Albeit limited, evidence has indicated that even in lifelong-trained older individuals there is a blunted post-exercise muscle anabolic response compared to younger athletes. However, there is a paucity of data to systematically understand the differences in postprandial anabolic response to varying protein doses in older vs. young athletes. In lieu of the above, it seems reasonable that master athletes may benefit from increasing protein intake closer to the upper limit of current recommendations (1.6-2.0 g/kg/day). In addition, supplementing their diet with ingredients that have established anabolic potential, including branched chain amino acids (BCAAs) such as leucine, the leucine metabolite β-hydroxy-β-methylbutyrate (HMB), and n3-polyunsaturated fatty acids (n3-PUFA), may potentiate the anabolic response to protein and exercise.