Alcohol ingestion impairs maximal post-exercise rates of myofibrillar protein synthesis following a single bout of concurrent training

Abstract

Introduction: The culture in many team sports involves consumption of large amounts of alcohol after training/competition. The effect of such a practice on recovery processes underlying protein turnover in human skeletal muscle are unknown. We determined the effect of alcohol intake on rates of myofibrillar protein synthesis (MPS) following strenuous exercise with carbohydrate (CHO) or protein ingestion.

Methods: In a randomized cross-over design, 8 physically active males completed three experimental trials comprising resistance exercise (8×5 reps leg extension, 80% 1 repetition maximum) followed by continuous (30 min, 63% peak power output (PPO)) and high intensity interval (10×30 s, 110% PPO) cycling. Immediately, and 4 h post-exercise, subjects consumed either 500 mL of whey protein (25 g; PRO), alcohol (1.5 g·kg body mass⁻¹), 12±2 standard drinks) co-ingested with protein (ALC-PRO), or an energy-matched quantity of carbohydrate also with alcohol (25 g maltodextrin; ALC-CHO). Subjects also consumed a CHO meal (1.5 g CHO·kg body mass⁻¹) 2 h post-exercise. Muscle biopsies were taken at rest, 2 and 8 h post-exercise.

Results: Blood alcohol concentration was elevated above baseline with ALC-CHO and ALC-PRO throughout recovery (P<0.05). Phosphorylation of mTOR(Ser2448) 2 h after exercise was higher with PRO compared to ALC-PRO and ALC-CHO (P<0.05), while p70S6K phosphorylation was higher 2 h post-exercise with ALC-PRO and PRO compared to ALC-CHO (P<0.05). Rates of MPS increased above rest for all conditions (∼29-109%, P<0.05). However, compared to PRO, there was a hierarchical reduction in MPS with ALC-PRO (24%, P<0.05) and with ALC-CHO (37%, P<0.05).

Conclusion: We provide novel data demonstrating that alcohol consumption reduces rates of MPS following a bout of concurrent exercise, even when co-ingested with protein. We conclude that alcohol ingestion suppresses the anabolic response in skeletal muscle and may therefore impair recovery and adaptation to training and/or subsequent performance.

Figure 1. Schematic representation of the experimental trial.

Subjects reported to the laboratory after an overnight fast where a constant infusion of L-[ring-¹³C₆] phenylalanine was commenced (3 h in first trial; 1 h in trial 2/3), and subjects completed the concurrent exercise (8×5 repetitions at 80% one repetition maximum (1RM), 5 min rest, 30 min cycling at ∼63% peak power output (PPO), 2 min rest, 10×30 s high intensity intervals at ∼110% PPO). Immediately after exercise completion, and 4 h later, subjects consumed 500-mL of protein (25 g whey) or carbohydrate (25 g maltodextrin).

Figure 2. Blood alcohol levels after alcohol intake during recovery following a single bout of concurrent training.

Data were analysed using a 2-way ANOVA with repeated measures and Student-Newman-Keuls post hoc analysis. Values are mean ± SD. Significant effect of treatment (P = 0.02), time (P<0.01) with no interaction (P = 0.20). Significantly different (P<0.05) vs. (a) rest, and (*) between treatments (ALC-CHO vs. ALC-PRO).

Figure 3. Blood glucose concentrations before and duringrecovery following a single bout of concurrent training.

Drink  =  25 g of whey protein (PRO and ALC-PRO) or 25 g maltodextrin (ALC-CHO); Meal  =  1.5 g·kg⁻¹ BM. Data were analysed using a 2-way ANOVA with repeated measures and Student-Newman-Keuls post hoc analysis. Values are mean ± SD. Significant effect of treatment, time and interaction (all P<0.01). Significantly different (P<0.05) (d) from 1 h within treatment, (j) from 5 h within treatment, ($) between treatments (ALC-CHO vs. ALC-PRO, PRO). (†) between treatments (ALC-CHO vs. PRO), (‡) between treatments (ALC-CHO vs. ALC-PRO).

Figure 4. Plasma EAA (A), BCAA (B), leucine (C) concentration following a single bout of concurrent training.

EAA – essential amino acids; BCAA – branched-chain amino acids. Data were analysed using a 2-way ANOVA with repeated measures and Student-Newman-Keuls post hoc analysis. Values are mean ± SD. Significant effect of treatment, time and interaction (all P<0.01) for (A), (B), and (C). Significantly different (P<0.05) vs. (#) all timepoints for ALC-CHO and ALC-PRO treatments, (*) vs. rest within treatments, and ($) compared to ALC-CHO.

Figure 5. mTOR^Ser2448 (A), p70S6K^Thr389 (B), eEF2^Thr56 (C), 4E-BP1^Thr37/46 (D) phosphorylation at rest and following a single bout of concurrent training.

Images are representative blots for each protein from the same subject and values are expressed relative to α-tubulin and presented in arbitary units. Data were analysed using a 2-way ANOVA with repeated measures with Student-Newman-Keuls post hoc analysis. Values are mean ± SD. Significant effect of time (P<0.01) and interaction (P = 0.02) but not treatment (P = 0.22) for (A); time (P<0.01) and interaction (P = 0.02) but not treatment (P = 0.46) for (B); time (P<0.01) but not treatment (P = 0.14) or interaction (P = 0.56) for (C); no treatment (P = 0.86), time (P = 0.24), or interaction (P = 0.77) effects for (D). Significantly different (P<0.05) vs. (a) rest, (e) ACL-PRO 8 h, (f) PRO 2 h, (g) PRO 8 h, and (*) 2 h between treatments.

Figure 6. MuRF-1 (A), Atrogin-1 (B) mRNA abundance at rest and following a single bout of concurrent training.

Values are expressed relative to GAPDH and presented in arbitrary units (mean ± SD, n = 7). Data were analysed using a 2-way repeated measures ANOVA with Student-Newman-Keuls post hoc analysis. Significantly different (P<0.05) vs. (a) rest, (c,e,g) 8 h within treatments, and (b,d,f) 2 h within treatments.

Figure 7. Myofibrillar fractional synthetic rate (FSR) throughout 2–8 h recovery following a single bout of concurrent training.

Data were analysed using a 1-way repeated measures ANOVA with Student-Newman-Keuls post hoc analysis. Values are mean ± SD expressed as % h⁻¹, n = 8. Significantly different (P<0.05) vs. (a) rest, (b) ALC-CHO, (c) ALC-PRO.