Protein Ingestion before Sleep Increases Muscle Mass and Strength Gains during Prolonged Resistance-Type Exercise Training in Healthy Young Men.
BACKGROUND
It has been demonstrated that protein ingestion before sleep increases muscle protein synthesis rates during overnight recovery from an exercise bout. However, it remains to be established whether dietary protein ingestion before sleep can effectively augment the muscle adaptive response to resistance-type exercise training.


OBJECTIVE
Here we assessed the impact of dietary protein supplementation before sleep on muscle mass and strength gains during resistance-type exercise training.


METHODS
Forty-four young men (22 ± 1 y) were randomly assigned to a progressive, 12-wk resistance exercise training program. One group consumed a protein supplement containing 27.5 g of protein, 15 g of carbohydrate, and 0.1 g of fat every night before sleep. The other group received a noncaloric placebo. Muscle hypertrophy was assessed on a whole-body (dual-energy X-ray absorptiometry), limb (computed tomography scan), and muscle fiber (muscle biopsy specimen) level before and after exercise training. Strength was assessed regularly by 1-repetition maximum strength testing.


RESULTS
Muscle strength increased after resistance exercise training to a significantly greater extent in the protein-supplemented (PRO) group than in the placebo-supplemented (PLA) group (+164 ± 11 kg and +130 ± 9 kg, respectively; P < 0.001). In addition, quadriceps muscle cross-sectional area increased in both groups over time (P < 0.001), with a greater increase in the PRO group than in the PLA group (+8.4 ± 1.1 cm(2) vs. +4.8 ± 0.8 cm(2), respectively; P < 0.05). Both type I and type II muscle fiber size increased after exercise training (P < 0.001), with a greater increase in type II muscle fiber size in the PRO group (+2319 ± 368 μm(2)) than in the PLA group (+1017 ± 353 μm(2); P < 0.05).


CONCLUSION
Protein ingestion before sleep represents an effective dietary strategy to augment muscle mass and strength gains during resistance exercise training in young men. This trial was registered at clinicaltrials.gov as NCT02222415.
['Snijders|Tim|T|', 'Res|Peter T|PT|', 'Smeets|Joey S J|JS|', 'van Vliet|Stephan|S|', 'van Kranenburg|Janneau|J|', 'Maase|Kamiel|K|', 'Kies|Arie K|AK|', 'Verdijk|Lex B|LB|', 'van Loon|Luc J C|LJ|']
D015502:Absorptiometry, Photon D001823:Body Composition D015930:Diet Records D004044:Dietary Proteins D004311:Double-Blind Method D002149:Energy Intake D006801:Humans D008297:Male D018656:Muscle Fibers, Fast-Twitch D053580:Muscle Strength D009752:Nutritional Status D052097:Quadriceps Muscle D055070:Resistance Training D012890:Sleep D055815:Young Adult
protein muscle mass strength exercise training fiber size