What physiological effects does alcohol have on sports performance?

Whether you’re a competitive athlete or a recreational athlete, a gym goer or participate in regular matches or events, alcohol could be the factor that is preventing you from reaching your goals.  Alcohol consumption impairs all aspects of exercise, from performance to recovery, affecting skeletal muscle, metabolism, thermoregulation and neural systems.

 

Short-term:

Dehydration and reduced glucose production are immediate effects of alcohol consumption:

Dehydration:

Alcohol dehydrates the body through excess urine production and vasodilation, hence why you feel nauseous and have a headache the morning after a big night!  Whilst exercising, you sweat in order to prevent increases in body temperature – this results in fluid loss and therefore further dehydration.  Combining alcohol with exercise increases the risk of dehydration, this leads to diminished blood flow and therefore reduced circulation of oxygen and nutrients, which are essential to fuel and repair the muscles.  Water is required to regulate body temperature and therefore if dehydrated when exercising there is a high chance of overheating.

 

Blood sugar:

If the liver has to break down excess alcohol then it is less able to produce glucose (the primary fuel used by the muscles).  Depleted glucose means the body has to rely on fat metabolism for energy, resulting in feelings of lethargy and slower movement.  Low blood sugar will have adverse affects on the intensity and duration of exercise, as well as reduced concentration, reaction speed, coordination and dexterity.  It is well documented that availability of glucose is a key factor in aerobic performance, as well as muscle repair and recovery.  In addition, if the liver has to concentrate on removing the toxins from alcohol, lactic acid clearance will be less efficient, leading to lactic acid build up and rapid fatigue.

Therefore consuming alcohol before exercise will lead to reduced performance due to excess dehydration as well as decreased blood sugar and depleted lactic acid clearance.  Similarly, drinking alcohol post-exercise isn’t advisable as it will compromise hydration status as well as ability to recover efficiently.

Long-term:

In the long-term, alcohol has adverse affects on metabolism:

·         Alcohol is extremely high in calories (7 calories/g), almost as high as pure fat. 

·         Alcohol reduces the number of calories you are able to burn whilst exercising.

·         The body isn’t designed to store alcohol and therefore tries to expel the toxins as fast as possible – this gets in the way of other processes, such as the absorption of essential nutrients and fat metabolism.

Although the mechanisms of action are yet to be fully understood, in terms of skeletal muscle, alcohol misuse has adverse affects on muscle cramps, muscle pain and proprioception. Furthermore, by disrupting sleep patterns and hormone concentrations (testosterone and growth hormone), alcohol reduces muscle synthesis and therefore the ability to build muscle.

Summary:

The effects of alcohol in regards to human physiology and consequently, exercise performance are multi-factorial and extremely complex.  However, evidence is clear that athletes who want to achieve their maximum potential should refrain from alcohol consumption, especially in excess.

This article was expertly written by nutrition writer Samantha Innes.