Alcohol ingestion impairs maximal post-exercise rates of myofibrillar protein synthesis following a single bout of concurrent training.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 24533082 · doi:10.1371/journal.pone.0088384
What was done
Eight physically active males completed three experimental trials in a randomized crossover design. Each trial involved concurrent exercise: resistance exercise (8×5 repetitions of leg extensions at 80% 1RM) followed by continuous cycling (30 min at 63% peak power output) and high-intensity interval cycling (10×30 s at 110% peak power output). Immediately and 4 hours post-exercise, participants consumed either 25 g whey protein alone (PRO), alcohol (1.5 g/kg body mass, ~12±2 standard drinks) co-ingested with 25 g protein (ALC-PRO), or an energy-matched amount of carbohydrate co-ingested with alcohol (25 g maltodextrin; ALC-CHO). All participants also consumed a carbohydrate meal (1.5 g/kg) 2 hours post-exercise. Muscle biopsies were taken at rest, 2 hours, and 8 hours post-exercise to measure myofibrillar protein synthesis (MPS) rates and intracellular signaling.
What was found
Blood alcohol concentration remained elevated above baseline throughout recovery in ALC-CHO and ALC-PRO (P<0.05). Phosphorylation of mTOR(Ser2448) at 2 hours post-exercise was higher with PRO compared to ALC-PRO and ALC-CHO (P<0.05), while p70S6K phosphorylation was higher at 2 hours with PRO and ALC-PRO compared to ALC-CHO (P<0.05). MPS rates increased above rest across all conditions (~29-109%, P<0.05). However, compared to PRO, MPS rates were hierarchically reduced by 24% with ALC-PRO (P<0.05) and by 37% with ALC-CHO (P<0.05).
Why it matters
This study shows that binge-level alcohol intake directly suppresses skeletal muscle myofibrillar protein synthesis following exercise, an impairment that protein co-ingestion only partially mitigates.
Limits
The sample size was very small (n=8) and exclusively comprised young, physically active males. The alcohol dose was very high (~12 standard drinks), precluding conclusions about moderate or lower consumption. Only acute 8-hour recovery and molecular markers were evaluated, leaving chronic adaptations, muscle growth, and functional recovery unmeasured.
Cited by
- supports In physically active men, consuming 12 standard drinks after resistance training reduced muscle protein synthesis by 24% despite 25g whey protein ingestion, and by 37% without protein.
- supports Alcohol consumption disrupts the activation of mTOR, impairing the signaling pathway that stimulates muscle protein synthesis.