It is well established that consuming protein and/or amino acids is necessary to stimulate post-exercise protein synthesis, thus creating a positive protein balance1-3. In accordance, dietary protein administration with or without carbohydrate ingestion before, during, and/or immediately after exercise has been shown to stimulate net muscle protein accretion during post-exercise recovery which is needed for the accrual of muscle mass.
Most of the research in this area examined the effect of food intake on the muscle protein synthesis response to exercise in an overnight fasted state2,4,5. It is reasonable to assume the limited availability of amino acids prevents a substantial rise in post-exercise muscle protein synthesis rate. This post-absorptive (fasted) condition differs from normal everyday practice in which sport activities are often performed in postprandial (after eating) conditions, such as in the evening. A study evaluated the efficacy of protein ingestion immediately after exercise in the evening on protein synthesis rates during this time period and during subsequent overnight recovery6. Protein synthesis increased during first few hours of post-exercise recovery when protein was ingested, but protein synthesis rates during overnight sleep were very low and were even lower than those observed in normal basal post-absorptive state6. The investigators of this study speculated that the lack of an increase in plasma amino acid and/or insulin concentration prevents muscle protein synthesis rates to be elevated throughout the night.
Recently, a group of scientists from the Netherlands and the United Kingdom assessed whether provision of dietary protein prior to sleep leads to adequate dietary protein digestion and absorption thereby increasing plasma amino acid availability. They also assessed if this proposed increase in amino acid availability throughout the night would stimulate protein synthesis and/or attenuate protein breakdown, thus enhancing protein balance during overnight recovery from exercise7. Their hypothesis was that consuming protein prior to sleep would effectively enhance plasma amino acid availability, stimulate skeletal muscle protein synthesis, and therefore, improve whole-body protein balance during overnight sleep.
Recreationally active young males were studied during an overnight recovery from a single bout of resistance exercise performed in the evening after a full day of dietary standardization. Subjects were given either a bolus of protein (casein) or placebo immediately prior to sleep after which protein digestion and absorption kinetics and subsequent overnight muscle protein synthesis rates were assessed during sleep. This was the first study assessing the effect of protein ingestion immediately prior to sleep as a dietary strategy to stimulate muscle protein synthesis and improve protein balance during post-exercise overnight recovery.
The important findings from this research were that dietary protein ingested immediately prior to sleep: 1) was effectively digested and absorbed, thereby increasing overnight plasma amino acid availability and 2) stimulated muscle protein synthesis rates, thus improving overnight protein balance. This is the first study demonstrating that protein ingested immediately prior to sleep is effectively digested and absorbed, thereby stimulating muscle protein synthesis and improving whole-body protein balance during post-exercise overnight recovery.
References:
1. Biolo G, Tipton KD, Klein S, Wolfe RR. An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein. Am J Physiol 1997;273:E122-9.
2. Koopman R, Wagenmakers AJ, Manders RJ, et al. Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects. Am J Physiol Endocrinol Metab 2005;288:E645-53.
3. Tipton KD, Elliott TA, Cree MG, Aarsland AA, Sanford AP, Wolfe RR. Stimulation of net muscle protein synthesis by whey protein ingestion before and after exercise. Am J Physiol Endocrinol Metab 2007;292:E71-6.
4. Borsheim E, Aarsland A, Wolfe RR. Effect of an amino acid, protein, and carbohydrate mixture on net muscle protein balance after resistance exercise. Int J Sport Nutr Exerc Metab 2004;14:255-71.
5. Borsheim E, Tipton KD, Wolf SE, Wolfe RR. Essential amino acids and muscle protein recovery from resistance exercise. Am J Physiol Endocrinol Metab 2002;283:E648-57.
6. Beelen M, Tieland M, Gijsen AP, et al. Coingestion of carbohydrate and protein hydrolysate stimulates muscle protein synthesis during exercise in young men, with no further increase during subsequent overnight recovery. J Nutr 2008;138:2198-204.
7. Res PT, Groen B, Pennings B, et al. Protein ingestion before sleep improves postexercise overnight recovery. Med Sci Sports Exerc 2012;44:1560-9.
