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Study under review: Pre-sleep dietary protein-derived amino acids are incorporated in myofibrillar protein during post-exercise overnight recovery
Introduction
Consuming nutrients, primarily protein, during and around exercise to maximize training adaptations and facilitate repair and recovery has been a heavily investigated[1] topic over the past several decades. This practice is a standard recommendation among sports nutrition authorities like the International Society of Sports Nutrition[2] and American College of Sports Medicine[3].
Nutrient timing strategies vary depending on the athlete and their goals, but the post-exercise period is generally considered to be of special importance due to the depletion of stored energy and damage to muscle fibers that occurs during exercise. Although a single exercise session[4] increases muscle protein synthesis for up to 48 hours, overall muscle protein balance is negative without nutritional intervention. Consuming protein after training has been shown[5] to shift muscle protein balance from a negative to a positive state, as depicted in Figure 1.

Adapted from: Trommelen J & van Loon LJ. Nutrients. 2016 Nov.
However, the muscle-full effect[6] proposes that protein ingestion stimulates muscle protein synthesis for only two to three hours, after which rates begin to decline, even when there is a continuous supply[7] of amino acids. Accordingly, eating multiple meals after training appears necessary to maximize increases in muscle protein synthesis throughout the day. Yet, many people train in the evening after a full day of regular physical activity and food intake, eating only once or twice again before going to sleep and beginning an overnight fast.
Previous research[8] has shown that supplementing with 40 grams of casein before bed results in significant elevations of muscle protein synthesis throughout the night. The study under review is a follow-up study that sought to determine whether a more moderate amount of protein would affect muscle protein synthesis rates.
Nutrient timing is a common and heavily investigated practice among athletes for maximizing training adaptations and facilitating repair and recovery. Consuming protein post-workout has been shown to stimulate muscle protein synthesis, but this effect only lasts for a couple hours, requiring further feeding for further stimulation. The study under review sought to evaluate whether consuming casein protein before sleep would augment overnight rates of muscle protein synthesis.
Who and what was studied?
What were the findings?
What does the study really tell us?
The big picture
Frequently Asked Questions
What should I know?
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