Consuming alcohol after a workout can cancel out any physiological gains received from the activity. Long term alcohol use diminishes protein synthesis resulting in a decrease in muscle build-up and short-term alcohol use can impede muscle growth.
•Because of alcohol's effect on sleep, your body is deprived of a chemical called human growth hormone or HGH. HGH is part of the normal muscle building and repair process. Alcohol, however, can decrease the secretion of HGH by as much as 70%.
•Alcohol triggers the production of a substance in your liver that is directly toxic to testosterone. Testosterone is essential for the development and recovery of your muscles. As alcohol is absorbed through your stomach and small intestine and into your cells, it can disrupt the water balance in muscle cells, altering their ability to produce adenosine triphosphate (ATP), which is your muscles' source of energy. ATP provides the fuel necessary for your muscles to contract.
•Speeding the recovery of sore muscles and injuries is essential to the gains from a workout. On occasion, when a student is injured or sore and doesn't work out, they may see this as an opportunity to use alcohol. The use of alcohol causes dehydration and slows your body's ability to heal itself.
Source: McDonald Center