Many athletes like to consume a last protein shake just before turning in for the night. This provides their muscles with extra amino acids while they sleep, and that’s good for muscle growth, they say. And they’re right too: Dutch nutritionists confirmed the theory in Medicine & Science in Sports & Exercise.
Study
The research was carried out by sports nutritionist Peter Res [website], and is a first. It’s the first scientific study that’s been done on the effect of a nocturnal protein shake on athletes’ muscles, and thus differs from all the studies that look at the effect of protein or amino acid intake just before or after a workout.
The researchers did their experiment with 16 reasonably active – but not weight-trained – males in their twenties. During the day the men ate normally and trained their legs in the evening under lab conditions: they did eight sets on a leg-extension machine and another eight sets on a leg-press machine. Immediately after their training session the subjects were given a shake containing 60 g fast carbohydrates and 20 g whey.
Around midnight, just before going to bed, the men drank 450 ml fluid. The fluid that the men in the control group drank contained nothing apart from some colouring agents and flavouring [PLA]. The fluid that the men in the experimental group drank contained 40 g casein, a protein that is digested slowly [PRO].
The protein in the shake was radioactive, which meant that the researchers could track the amino acids in the men’s bodies.
Results
The men in the PRO group had noticeably higher levels of essential amino acids in their blood during their sleep than the men in the PLA group.
The researchers were able to follow the comings and goings of amino acid in the sleepers’ blood. The researchers also took small samples of leg muscle tissue before the men went to sleep and when they woke up. This is how the researchers found out that the intake of extra casein led to an increase in muscle protein synthesis and more muscle tissue growth.
Conclusion
“Protein ingested immediately before sleep is effectively digested and absorbed, thereby stimulating muscle protein synthesis and improving whole-body protein balance during postexercise overnight recovery”, the researchers write.
Amino acid supplementation increases lean body mass, basal muscle protein synthesis, and insulin-like growth factor-I expression in older women.
Abstract
CONTEXT:
Inadequate dietary protein intake has been implicated in sarcopenia.
OBJECTIVE AND DESIGN:
The objectives of this study were to determine whether: 1) chronic essential amino acid (EAA) supplementation improves postabsorptive muscle protein fractional synthesis rate (FSR), lean body mass (LBM), and one-repetition maximum muscle strength, and androgen receptor and IGF-I muscle protein expression; and 2) the acute anabolic response to EAA ingestion is preserved after a 3-month supplementation period. Using a randomized, double-blinded, placebo-controlled design, older women (68 +/- 2 yr) were assigned to receive either placebo (n = 7), or 15 g EAA/d [supplemented treatment group (SUP)] (n = 7) for 3 months. Metabolic outcomes were assessed in association with stable isotope studies conducted at 0 and 3 months.
SETTING:
The study was performed at The University of Texas Medical Branch General Clinical Research Center.
RESULTS:
Ingestion of 7.5 g EAA acutely stimulated FSR in both groups at 0 months (P < 0.05). Basal FSR at 3 months was increased in SUP only. The magnitude of the acute response to EAA was unaltered after 3 months in SUP. LBM increased in SUP only (P < 0.05). One-repetition maximum strength remained unchanged in both groups. Basal IGF-I protein expression increased in SUP after 3 months (P = 0.05), with no changes in androgen receptor or total and phosphorylated Akt, mammalian target of rapamycin, S6 kinase, and 4E-binding protein.
CONCLUSIONS:
EAA improved LBM and basal muscle protein synthesis in older individuals. The acute anabolic response to EAA supplementation is maintained over time and can improve LBM, possibly offsetting the debilitating effects of sarcopenia.
Potential application of essential amino Acid supplementation to treat sarcopenia in elderly people. [J Clin Endocrinol Metab. 2009]
PMID: 19208731 [PubMed - indexed for MEDLINE] PMCID: PMC2684480
Source: http://www.ncbi.nlm.nih.gov/pubmed/19208731
