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Alcohol consumption and hormonal alterations related to muscle hypertrophy: a review

  • Published: Thursday, 12 June 2014 00:00
  • Alex Leaf
  • Hits: 725

Abstract (provisional)

Detrimental effects of acute and chronic alcohol (ethanol) consumption on human physiology are well documented in the literature. These adversely influence neural, metabolic, cardiovascular, and thermoregulatory functions. However, the side effects of ethanol consumption on hormonal fluctuations and subsequent related skeletal muscle alterations have received less attention and as such are not entirely understood. The focus of this review is to identify the side effects of ethanol consumption on the major hormones related to muscle metabolism and clarify how the hormonal profiles are altered by such consumption.

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PLAGERISM ALERT! While initially researching this paper to compile the discussion that follows, I discovered that much of the information of this review was stolen word-for-word from Examine’s page on alcohol. This is apparent because the copied section was last updated in 2012 judging from the edited history on Examine, and the review at hand was published last Friday (June 6, 2014). I informed Examine of this atrocity and they are taking action as they see fit. That said, I feel that this is still an important topic and have decided to include it in the newsletter regardless. Just note that credit for this paper should go to the team at Examine.com and not the authors of this review.

Alex’s Notes: According to the dictionary, a poison is “a substance that is capable of causing the illness or death of a living organism when introduced or absorbed.” Ethanol (drinking alcohol) is a poison. That cold beer on a hot summer day? Poison. The lovely glass of wine during a romantic evening? Poison. The shots of vodka during your college-party days? Poison. Fortunately, it’s the dose that makes the poison, and we are equipped to handle moderate amounts of alcohol at the expense of our liver.

Interestingly, one area that doesn’t receive much mainstream attention with regards to alcohol consumption is muscle hypertrophy. Granted most people in the world are sedentary and probably don’t care, but we aren’t most people; we are Super Humans. The free review at hand aimed to understand some of the biological mechanisms behind muscle hypertrophy and then look to see how ethanol consumption influenced them. It is short, sweet, and provides an essential insight into how that drink may be affecting your fitness progress.

Okay, we know that muscle hypertrophy requires protein synthesis (MPS) to exceed breakdown (MPB), and muscle proteins are constantly being replaced every 7-15 days. The most important pathways to accomplish this involve kinase or phosphatase activity, with exercise activating numerous pathways at any given time. One such pathway is the activation of protein kinase mechanistic target of rapamycin (mTOR), which triggers a cascade of responses that eventually lead to hypertrophy. Other hypertrophic mechanisms are hormonally related with the two most anabolic hormones being testosterone and growth hormone. Testosterone acts directly on cells to induce growth, while growth hormone acts through insulin-like growth factor 1 (IGF-1).

Ethanol and its metabolic byproducts have been shown to directly affect protein synthesis in skeletal muscle tissue with a preference for fast-twitch (type-II) muscle fibers. This has been demonstrated in human trials as well, with one such trial showing a reduction of muscle protein synthesis by 24-37% after an acute bout of resistance training and high intensity interval training (HIT). That same study also found mTOR phosphorylation to be about 54% lower than without ethanol, which suggests that at least part of the MPS suppression is via inhibition of exercise-induced mTOR. It’s worse for alcoholics, because chronic ethanol consumption increases the myostatin mRNA content of skeletal muscle. Put simply, myostatin controls cell differentiation and is one of the strongest inhibitors of skeletal muscle growth. Interestingly, ethanol also reduces leucine oxidation which is an often used indicator of muscle breakdown, when ingested alongside a meal, but it still isn’t enough to overcome the suppression of MPS that the meal itself stimulated. This was all confirmed in another study that concluded that

“An elevation of blood ethanol concentrations to the levels observed in social drinking results in a net anticatabolic effect (diminished leucine oxidation) when ethanol is administered alone. However, during administration of other nutritional substrates, the anticatabolic effect was not detectable, possibly because ethanol enhanced nutrient-induced thermogenesis.”

So if you go party, don’t eat… and don’t train either since you will inhibit your body’s repair ability.

As for hormones, testosterone in resistance trained men isn’t affected by acute ingestion of the equivalent of 3-4 beers of ethanol immediately after exercise. Another study in Rugby players confirms this with a slightly higher dosage (about five beers), but there was a decrease in power output. However, higher doses of ethanol may suppress the natural circadian rise in testosterone for upwards of 16 hours after ingestion, and growth hormone is not only significantly suppressed but the entire circadian pulse rhythm gets screwed up. Also, testosterone’s nemesis – cortisol – spikes four hours after acute ethanol consumption and remains elevated for upwards of 24 hours. For completeness, estrogen is unaffected by ethanol consumption and women may actually have a rise in testosterone.

So what does all this mean? What are the practical applications? Well, the dose makes the poison. Assuming that a can of beer is around 12 oz. (355 ml) and on average its alcohol content is between 4.5 and 6%, detrimental effects on MPS and hormones can be seen with as little as 5-6 beers for a 154 lb (70 kg) person. Now assuming you can’t control yourself, two things appear prudent with the weekend party in mind. First, don’t train within 48 hours of drinking because your body will still be recovering from the workout and you wouldn’t want to impair that growth and development would you? Second, try and aim to have the last meal come five or so hours beforehand so that you have absorbed its nutrients are beginning to fast again because alcohol may be somewhat anti-catabolic when consumed without food.

 

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