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What does alcohol actually do to a runner’s body?

A look at what actually happens to your body after a night of overindulgence

As runners, we’re told to consume alcohol in moderation and avoid excessive intake around key competition dates. But what does consuming alcohol actually do to your body from a performance standpoint, and why are we recommended to skip it leading up to a goal race?

Beer and Wine

Rachel Hannah is a registered dietitian and marathoner. She says, “Alcohol isn’t providing any nutritional value, but you have to think of the whole person.”

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What the experts say

The United States Olympic Committee sport nutrition team says that regular consumption of alcohol in moderation may have some health benefits in terms of disease risk reduction, especially cardiovascular disease, but the association is not as convincing as is sometimes assumed. “There are reasons to believe that acute alcohol intake may impair performance of endurance exercise because of effects on metabolic, cardiovascular and thermoregulatory function, and that its neurological actions may affect performance of skilled tasks because of effects on reaction time, fine motor control, levels of arousal, and judgment.”

Draft Beer Machine

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What happens physiologically 

According to the USOC, all processes in the liver shut down to accommodate the metabolism of alcohol. This causes low blood sugar and impairs the use of fat as fuel, which also inhibits training adaptation. In the brain, alcohol consumption can impair motor skills, balance and reaction time. 

In terms of your muscle tissue, alcohol consumption impairs blood flow, which in turns reduces muscle strength. And shockingly, the USOC reports that the prevalence of musculoskeletal injury is 30 per cent higher in athletes who drink versus those who do not. Hormonally, when runners drink, testosterone decreases and estrogen increases. This hormone change causes fluid retention and fat deposition that can lead to weight gain. 

Finally, after a night of drinking, sleep quality is compromised. The disturbed sleep cycles means that muscles repair and synthesis isn’t happening at the same rate it would otherwise. 

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If you’ve over-indulged a bit the night before training, make sure you hydrate and consider a short nap or early bedtime the following evening to make up for lost sleep. Hannah’s opinion is that, “Alcohol intake should be avoided during key training and racing periods for runners, but can be enjoyed in moderation during holidays or during the off-season.”