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How Does Alcohol Affect Athletic Performance?

By Jiří Kaloč

Have you ever wondered how a hangover affects your performance? Do you think a night of heavy drinking will affect your handling ability on the bike? Will it cause dehydration if you have a beer after a ride? And what about recovery? You are about to find out.

It impairs your handling ability

The usual limit for driving in European countries is 50 mg of alcohol in 100 ml of blood, in the US its 80mg. There was an experiment which tested how alcohol affects bike handling. Cyclists were slaloming between poles, riding in a straight line along a narrowing track, and circling clockwise and anti-clockwise. Even at very low blood alcohol levels, their riding ability was somewhat affected and by the time it reached 80mg there was a significant increase in “gross motoric disturbances”. At 140mg, not a single rider could match their cycling performance when sober.


It makes it harder to lose or even maintain weight

Most foods are required to display nutritional and caloric values on the label. With alcohol there’s no such thing as if it somehow didn’t count. It does count. Alcohol has approximately 7 calories per gram, almost double what carbohydrates have. The average 0,5 l (17 oz.) of beer contains about 150 kcal, amount equivalent to 3-4 slices of bread. So, a reasonable night out can easily give your body more calories than a big meal. And what’s worse, these are pretty much empty calories and your body will be left hungry for nutrients. That, along with the fact that alcohol impairs the body’s’ fat-burning ability, makes it an enemy of weight loss.


It causes dehydration

Alcohol suppresses the anti-diuretic hormone vasopressin, which results in water loss through urine. The amount of dehydration depends on the alcohol content. A study found that the effects start being noticeable with alcohol concentration of 4% (most beers range from 4 – 6 %). Another study looked at athletes who were given either water or beer followed by water to rehydrate after an hour of exercise. They found no differences in hydration status between them. Another study has also shown that up to 660 ml of beer after a ride does not cause dehydration. So, if you want to avoid dehydration, stick to moderation, low-alcoholic content, and always add water.


It ruins your recovery

Significant alcohol consumption after training will have a negative impact on your recovery. There are several factors at play here.

1. Studies have shown that alcohol consumption in large amounts decreases protein synthesis by 15-20%. Protein is needed to repair and grow muscle, so this will slow down the recovery process and could affect performance in the long run.
2. Liver enzymes prioritize getting rid of the alcohol toxins and glycogen replenishment stops as a result. Glucose cannot be converted to glycogen, so your muscles and liver reserves will stay empty until the alcohol is out of your system.
3. The stress hormone cortisol increases when you drink alcohol. Increased cortisol negatively affects testosterone production and reduces levels of human growth hormone by as much as 70%. This vastly reduces your ability to repair and grow muscle.
4. Alcohol negatively affects sleep quality. It disrupts sleep patterns, making it harder to fall into deep REM sleep which means less production of growth hormone and loss of performance in the long run.