Purpose of review: Whereas diet and exercise have been shown to influence whole-body protein utilization, little is known about the impact of these factors on skeletal-muscle protein turnover. We highlight the role of dietary protein in modulating skeletal-muscle protein turnover in response to endurance exercise. Effects of endurance exercise on skeletal-muscle protein metabolism are presented and the influence of habitual protein intake on exercise-related protein responses is discussed.
Recent findings: Skeletal-muscle protein turnover increases in response to endurance exercise training and following a single endurance exercise bout. Nutritional supplementation postexercise favorably affects skeletal-muscle protein synthesis and demonstrates amino acid availability as pivotal to the skeletal-muscle synthetic response following exercise. The level of habitual protein intake influences postexercise skeletal-muscle protein turnover.
Summary: Dietary protein and exercise are powerful stimuli affecting protein turnover. Since variation in habitual protein intake influences skeletal-muscle protein turnover postexercise, investigations are needed to determine what role protein intake has in regulating skeletal-muscle protein metabolism. Long-term, well controlled diet and exercise intervention studies are essential for clarification of the relation between protein intake, endurance exercise, and skeletal-muscle protein turnover. Studies designed to characterize this relationship should be attentive to habitual macronutrient and energy intakes.