How Drinking Alcohol Affects Running Performance
There are many behaviors in which athletes engage that can detract from their overall performance. The most common include lack of sleep and poor diet. But, what about the activities in which we do as part of societal norms? Is that happy hour drink, cocktail at brunch, or participation in a beer mile hurting your running performance? The ways in which drinking affect a person’s running ability and the science behind these facts are discussed below.
Alcohol causes a number of muscular weaknesses and malfunctions because it can inhibit the manner in which muscles typically behave. For instance, calcium is a necessary nutrient for regulating muscular contractions. When alcohol has been consumed, calcium is unable to adequately transport1 through muscle tissue, which decreases the relative output of strength and power.
In addition, alcohol has been linked to increased levels of creatine kinase2 in the bloodstream, which similarly occurs as a result of muscular damage or inflammation. While the mechanism of creatine kinase release is unknown, it is believed to lead to loss of coordination, weakness, and muscle cramping.
Alcohol is a well-known diuretic, so it should be no surprise that alcohol consumption can impair athletic performance by causing dehydration. By itself, dehydration is known to impair performance in an athlete; in fact, only 1% dehydration3 can lead to perceptible performance flaws.
Alcoholic beverages greater than 4% alcohol by volume (ABV) have been shown to cause excessive urine production at a rate of 10 mL urine4 for every 1 gram of ethanol consumed. To put this in perspective, a 16 oz beer that is 5% ABV contains approximately 24 grams of ethanol, which will lead to 240 mL of additional urine production, or roughly 0.5 lbs. For a 150 lb person, three draft beers that are 5% ABV will cause enough urine loss to inhibit running performance.
A common misconception is that alcohol consumption can be considered carbohydrate loading, since ethanol – particularly beer – is high in carbohydrates. However, the body is unable to store alcohol as energy in the muscles, and instead it is stored in the liver as fat5. Excess fat storage can negatively affect the conversion of muscular glycogen to glucose, which will ultimately adversely affect an athlete’s performance during an endurance event.
When alcoholic drinks are stored as fat they can increase the amount of fat stored in the body, and increase caloric consumption by 100 – 200 calories per drink. For runners trying to achieve “race weight,” the additional calories, the storage of fat, and the associated inflammation can make weight maintenance difficult.
Alcohol produces hypoglycemia, so it should be avoided during long periods of effort (e.g., marathons or ultramarathons).
Even though alcohol can give you the “warm fuzzies,” a complication of alcohol misuse is decreased ability to regulate body temperature during physical exertion. Alcohol inhibits thermoregulatory mechanisms within the body, leading to increased chance of heat stroke or hypothermia during extreme weather conditions.
For endurance athletes competing on warm days, this effect is exacerbated by the fact that core body temperature is known to rise as much as 6 degrees, meaning that work tolerance at even moderate temperatures can be negatively impacted.
Central Nervous System
As a depressant, alcohol strongly affects the central nervous system6, resulting in reduced reflexes, coordination, and accuracy of motor skills, among others. In addition, impairment of the central nervous system has also been suggested to affect a person’s quality of sleep7 by reducing time spent in the REM stage.
For runners, these neurological effects will hinder performance by decreasing reaction times (particularly important for sprinters), and leading to the feeling of overall sluggishness. Decreased quality of sleep will negatively affect recovery, as muscle repair primarily occurs during periods of REM.
Endurance athletes pride themselves on their cardiovascular function, and while moderate alcohol use may actually improve heart health8, excessive alcohol consumption can be harmful. A recent study9 showed that participants who completed a 5 mile time trial immediately after consuming 3 shots of whiskey did not exhibit significant changes in performance versus the same group that performed the time trial without the alcohol.
When alcohol is regularly consumed, blood pressure and blood lipids increase10, both of which can lead to impaired performance by forcing the cardiovascular system to compensate in order to operate optimally under stress.
There is nothing like a post-race celebration, but, research warns athletes should hold off on post-run imbibing unless celebrating the end of the season. Alcohol impairs muscle recovery and has been shown to increase the circulation of pro-inflammatory11 biomarkers in the blood.
Abundant research has shown the effects of inflammation on all factors of athletic performance – particularly how chronic inflammation can adversely affect the body’s ability to repair muscular damage. In addition, alcohol inhibits muscle protein synthesis12, leading to delayed recovery and longer periods of muscle soreness. For athletes that consumed alcohol immediately following exercise in concentrations of 1 gram alcohol per kilogram body weight (approximately three 16 oz beers at 5% ABV for a 150 lb person), significant loss of isometric, concentric, and eccentric muscular strength was observed 36 hours later.
Another factor that vilifies alcohol consumption in the eyes of athletes is the subsequent immune system response. Alcohol is well known for impairing host defence13 by causing the immune system to attack healthy cells. Common diseases linked to alcohol abuse include Pneumonia and Tuberculosis.
When combined with the already-weakened immune system of endurance athletes, alcohol can decrease performance by drastically increasing the risk of disease.
Fortunately for many of us, alcohol consumption is not all bad. For instance, it has been shown to improve cardiovascular health when consumed moderately, thanks to the antioxidant content in wine or dark beers. Other favorable effects include increase in HDL14 (good cholesterol), decreased risk of blood clots15, and lower chance of total mortality16.
Studies have even indicated that light beer post-race17 may improve recovery, and that a beer the night before a race may improve performance for women. The key to the positive effects of alcohol lie in moderation.
One the same note, this study18 found that “alcoholic beer intake reduced plasma Na+ and increased plasma K+ during exercise, which may negatively affect health and physical performance, and finally, the consumption of water before exercise could induce decreases of Na+ in plasma during exercise”.
Ultimately, it’s your decision.
How Much Alcohol is Too Much?
For the majority of scientific studies, both human and animal, alcohol was administered in excessive doses greater than would presumably be consumed by an athlete either before or after exercise. Drinking moderately is roughly defined as one drink for women and two drinks for men per night; however, athletes may not fit the common norm put forth by scientists.
For instance, alcohol concentrations as low as 1 g per kg of body weight have been found to have detrimental effects on muscle recovery. For a 120 lb runner, this level can easily be met in only 1.5 draft beers that are 7% ABV. In addition, even a moderate amount of alcohol can negatively affect energy conversion, which is perhaps the single greatest factor in endurance performance from a biochemical level.
When should athletes abstain from alcohol consumption?
Runners should avoid consuming more than 1 – 2 alcoholic drinks within 36 hours of competition to avoid negative effects. After competition, runners that wish to celebrate with a drink should do so after properly refueling and rehydrating, in order to avoid deleterious effects to muscle recovery and hydration levels.
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