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The Effects of Alcohol Ingestion on Myofibrillar Protein Synthesis

STUDY TITLE:

Alcohol Ingestion Impairs Maximal Post-Exercise Rates of Myofibrillar Protein Synthesis following a Single Bout of Concurrent Training

STUDY AUTHORS: 

Evelyn B. Parr, Donny M. Camera, Jose´ L. Areta, Louise M. Burke, Stuart M. Phillips,John A. Hawley, Vernon G. Coffey

STUDY SPOTLIGHT BY: 

Cody Haun, PhD, MA, CSCS

 

PURPOSE:

Due to the prevalence of alcohol consumption in popular and sport culture, the authors of this study sought to determine the effect of alcohol intake on rates of myofibrillar protein synthesis (MPS) following strenuous exercise accompanied by carbohydrate (CHO) or protein ingestion (PRO).

 

DESIGN: 8 physically active males completed three separate trials (in a random order) which included resistance exercise (8 sets ×5 reps leg extension at 80% 1 repetition maximum) followed by continuous (30 minutes at 63% peak power output (PPO)) and high intensity interval (10 intervals of 30 seconds at 110% PPO) cycling.

 

Immediately after training was over subjects consumed either 25 grams of whey protein or (PRO), or 25 grams of carbohydrate (CHO) and again 4 hours after training.

 

Since this was a randomized crossover design, all subjects completed three separate trials in a randomized order (i.e., PRO, ALC-PRO, and ALC-CHO). The visit where protein alone was consumed was deemed PRO. The visit where protein and alcohol were consumed was deemed ALC-PRO, and the visit where carbohydrate and alcohol was consumed was deemed ALC-CHO.

 

Subjects also consumed a meal primarily composed of CHO (1.5 grams of CHO per kilogram body mass) 2 hours after exercise each separate visit.

 

For the PRO visit, subjects consumed 500 mL of whey protein (25 grams; [PRO]).

 

For the ALC-PRO visit, subjects consumed alcohol (1.5 grams per kilogram body mass, [i.e., ~12 ± 2 standard drinks]) co-ingested with protein (ALC-PRO).

 

For the ALC-CHO visit, subjects consumed an energy-matched amount of carbohydrate with alcohol (25 grams of maltodextrin; [ALC-CHO]).

 

The alcohol ingestion protocol began 1 h post-exercise and was consumed in 6 equal volumes of 1 part vodka (∼60 mL) to four parts orange juice (∼240 mL, 1.8 grams of CHO per kg body mass) during a 3 h period.

 

For the PRO condition, orange juice was consumed with a matched volume of water in place of the alcohol. Subjects ingested the beverages within 5 min every 30 min.

 

Muscle biopsies were taken at rest, 2 hours and 8 hours after exercise.

 

RESULTS: Blood alcohol concentration was elevated above baseline levels with ALC-CHO and ALC-PRO throughout recovery.

 

 

Phosphorylation of mTOR 2 hours after exercise was higher with PRO compared to ALC-PRO and ALC-CHO, while p70S6K phosphorylation was higher 2 hours after exercise with ALC-PRO and PRO compared to ALC-CHO.

Rates of MPS increased above rest for all conditions by between ∼30-100%.

However, compared to PRO, there was a hierarchical reduction in MPS with ALC-PRO (~25 %) and with ALC-CHO (~35 %).

AUTHOR’S CONCLUSIONS:

The authors concluded that alcohol consumption reduces rates of MPS following a bout of concurrent exercise, even when co-ingested with protein.

 

The authors noted that alcohol ingestion suppresses the anabolic response in skeletal muscle and may therefore impair recovery and adaptation to training and/or subsequent performance.

 

MY INTERPRETATION:

Genes in your DNA are transcribed to messenger RNA (mRNA) molecules which are translated into proteins by organelles in the cell called ribosomes. These proteins provide structure and function to cells. Muscle protein synthesis is the term used to describe this process in muscle, and particularly relates to the process of translating muscle mRNA molecules into muscle proteins. This is measured in laboratory settings by infusing subjects with special tracer molecules than can be incorporated into synthesized muscle proteins. These tracer molecules can be detected in muscle samples collected by performing muscle biopsies and calculating the amount of the tracer molecule in the sample. Myofibrillar protein synthesis (e.g., the process of synthesizing proteins comprising myofibrils of muscle cells) is often expressed as a fractional synthesis rate (FSR) per hour. This is a simple statistic which refers to the fraction of myofibril proteins, relative to the total amount of myofibril proteins, that are synthesized per hour. This is often an acute measurement used to gain insight into the expected muscle growth response from a supplemental or training stimulus. Muscle protein breakdown is measured differently, but conceptually, methodology is similar and the overarching point to be made here is that the consistent difference between muscle protein synthesis (MPS) and muscle protein breakdown (MPB) can result in notable changes in muscle cell size since muscle cells are primarily composed of water and protein.

 

Think of it this way:

 

MPS – MPB = Net Muscle Protein Balance (NMPB)

 

Strategies that tilt the scale in the favor of a positive NMPB are critical to optimize functional and morphological adaptations to training over time. One well-known finding is that resistance training can increase FSR significantly for ~24 hours, on average. The ingestion of dietary protein can also increase FSR at rest.

 

The combination of resistance training and protein ingestion has been shown to result in the highest net muscle protein balancesin the literature, pointing to this strategy to maximize the muscle growth response to training.

 

Parr et al. reported significantly lower FSR rates when alcohol was ingested immediately and 4 hours after training.

 

This seemed to be associated with the initiation of the translation of mRNA into proteins being impaired in the case of alcohol ingestion.

 

Duplanty et al. have reported similar findings, although these authors only dosed alcohol at ~1 gram per kilogram of fat-free body mass ~10 minutes after exercise. Recall, Parr et al. dosed at ~1.5 grams per kilogram body mass. To put this in perspective, if someone weighed 100 kg and was 20 % body fat (~80% fat-free mass [80kg]), Parr et al. would have dosed them at 150 grams over the course of 4 hours. Duplanty et al. would have dosed this same individual at ~80 grams (~½ of the amount of Parr et al.) ~10 minutes after exercise which is likely why findings were somewhat different. Note that subjects consumed quite a bit of alcohol in both studies but certainly in the Parr et al. study (~10 drinks in 4 hours). Stated differently, the subjects were likely quite hammered in the Parr et al. study haha. Although more research is necessary to elucidate specific dose-dependent effects (researchers shouldn’t have too much of an issue recruiting for these studies lol), it does seem that effects are worse with more alcohol ingestion past a certain point.

 

From Duplanty et al.

Duplanty et al. noted a more impaired response in men than women, which was an interesting finding. Although Duplanty et al. did not directly measure muscle protein synthesis, they measured a surrogate anabolic marker that suggests protein synthesis would have been lower in men (i.e., phosphorylation of mTOR at ser2448 site). This suggests men might experience greater impairments in anabolism from drinking compared to women (sorry guys).

 

Let me finish with some practical advice.

 

Avoiding above ~1-2 drinks for the first 6 hours after training is likely a good idea to allow mRNA translation initiation and other signaling processes to increase to near peak levels.

 

After this window of time, keeping drinking at bay is also important, but likely less important by comparison. Either way, drinking within 12 hours of training is suboptimal but is a really bad idea in the case of drinking over 3-4 drinks if maximizing the hypertrophic response is of interest. Although I’m not advising complete abstinence and feel that responsible drinking below these amounts is possible in context of the training process, the following implications can be gleaned from available research:

 

  1. a) avoid drinking within 6 hours after training
  2. b) avoid having above ~3 drinks at once
  3. c) if drinking, try and position ~24-36 hours after training and ~24-36 hours before your next training bout
  4. d) getting intoxicated doesn’t ever fit nicely into a training program, so I recommend against it
  5. e) having an occasional drink or two at the right time after a training bout (~24 hours after) or before your next training bout (~24 hours before) likely won’t do too much damage
  6. f) regular drinking above 1-2 drinks isn’t a great idea for a variety of other reasons in addition to the evidence provided above (e.g., hormonal, cognitive, liver health).

 

 

“I’m a scientist first and a coach second. I have a passion for positively impacting the lives of people through providing critically thought-out, data-driven, scientifically-sound nutrition and training programming services that equip individuals to successfully achieve their performance and/or physique goals. I seek to offer the best service within my power and I am confident, given my background, education, experience, and relentless pursuit of knowledge pertaining to human physiology and the training process, that I can provide you with programming to realize great results. Feel free to contact me with any questions.”

 

Cody Haun, PhD, MA, CSCS
codythaun@gmail.com
-APLYFT Science Consultant
-APLYFT Coach