**Disclaimer** I enjoy alcoholic beverages when I’m not in a competition prep. In no way am I judging those that drink. However, like most things in life – the key is moderation and proper timing. Explanation to follow.
It is generally accepted that Alcohol consumption in moderate to large quantities is unhealthy. Hard liquors are erroneously seen as empty calories and consumption of beer can quickly lead to over-consumption of carbohydrates. A typical downfall of those beginning to diet is “drinking their calories.” You have to take into account all caloric intake, not simply solid foods. Beyond the total caloric impact (7 cal/g), however, there have been some significantly detrimental findings against alcohol intake.
Burke and colleagues found that consumption of alcohol inhibited glucose uptake into skeletal muscle, decreased exercises effect on glucose uptake, and impaired glucose utilization as a whole. What does this mean? Glucose uptake is necessary for repair of muscular micro-tears post exertion; therefore, the minimization of this phenomenon would decrease muscular repair and progressive growth. Furthermore, notably decreased glycogen storage will decrease stored energy available in power/strength based movements.1
1) Effect of alcohol intake on muscle glycogen storage after prolonged exercise
Louise M. Burke, Greg R. Collier, Elizabeth M. Broad, Peter G. Davis, David T. Martin, Andrew J. Sanigorski, Mark Hargreaves
Journal of Applied Physiology Sep 2003, 95 (3) 983-990
Proteolysis/Decreased Protein Synthesis
Protein synthesis is an ongoing process; however the rate of synthesis is increased post-exercise. As touched on previously, this is for repair and adaptive hypertrophy of the fibers. This time period should, therefore, be optimized for best results. Acute alcohol ingestion in this post-exercise period, however, decreases muscle protein synthesis in a dose and time dependent manner. Meaning both the quantity consumed and time post completion of exercise are both significant. When alcohol is consumed post-exercise, the natural metabolite cascade that initiates protein synthesis is inhibited. On top of the decreased protein synthesis is the upregulation (increase) of muscular ligases which serve to promote muscle atrophy.2 It should be specifically noted that alcohol’s effects on protein metabolism are greater in type II (fast-twitch) fibers than type I (slow twitch).3
2) Alcohol, Athletic Performance and Recovery. Luke D. Vella and David Cameron Smith. Nutrients. July 2010. 2(8). 781-789.
3) Studies on the Time-Course of Ethanol’s Acute Effects on Skeletal Muscle Protein Synthesis: Comparison with Acute Changes in Proteolytic Activity. Matthew E. Reilly, David Mantle, Peter J. Richardson, et al. Alcoholism: Clinical and Experimental Research. Aug 1997. 21(5). 792-798.
Decreased Peak Strength
Barnes et al. studied the effects of alcohol consumption muscular adaptation post eccentric based exercise. The study measured max isokinetic torque and isometric torque generated across the knee, plasma creatine kinase concentration, and subjective muscular soreness at both 36 and 60 hours post exercise. Both the group consuming alcohol post-exercise and those consuming a calorically identical placebo had significantly decreased peak strength loss at both time periods. However, there was a significant difference in the loss of strength. The alcohol group showed 22%, 12%, and 15% less strength in the above measures when compared to the non-alcohol group. Plasma creatine and muscular soreness were not affected. The results of this study indicate that acute consumption of alcohol post-exercise can have lasting effects on strength up to a minimum of 60 hours post-exercise.
4) Acute alcohol consumption aggravates the decline in muscle performance following strenuous eccentric exercise. Matthew J. Barnes, Toby Mundel, Stephen R. Stannard. Journal of Science and Medicine in Sport. Jan 2010. 13(1). 189-193.
· Alcohol consumption post-exercise minimizes glucose utilization for muscular repair and energy availability in resulting exercise bouts
· Increased protein breakdown, paired with decreases muscular synthesis found
· Decreases in peak muscular strength up to 60 hours post-exercise observed