Alcohol is a key factor in many social events and situations. It is socially acceptable to have alcoholic beverages with friends or family. Even one glass of alcohol for women and up to two drinks for men is promoted as safe and having possible health benefits. However, for athletes, does alcohol affect athletic performance? Does alcohol kill muscle gains? In this article, I’ll discuss the metabolism of alcohol in the body and its effect on glycogen storage. Then summarize multiple research studies involving the consequences of alcohol on athletic performance. I’ll also breakdown how drinking effects the body, hydration, inflammation, and hormones.
Metabolism of Alcohol
The form of alcohol that humans consume is called ethanol. Once a person begins drinking alcohol, it absorbs immediately in the gastrointestinal tract. It reaches peak concentration in a persons blood within 30 minutes. However, food in the stomach will delay absorption. The liver will oxidize most alcohol. The remainder excretes through the lungs and urine. Most adults metabolize 7-10 g of alcohol per hour, equivalent to one drink.
How Does Alcohol Affect the Body?
Alcohol impacts the body in many ways. Alcohol is a Central Nervous System Depressent (CNS). Sleepiness, slurred speech, ataxia, impaired judgment, and reduced anxiety are consequences of drinking too much alcohol. There may be decrease in myocardial contractility, which is the ability of the heart to contract. With prolonged alcohol abuse, liver disease can develop. Persons can become psychologically dependent on alcohol and also physically dependent. The neurotransmitters in the brain, such as serotonin and dopamine are involved in the brain reward system. Serotonin and dopamine increase when drinking, which can lead to alcoholism and addiction.
Alcohol Use Among Athletes
Alcohol is detrimental both physiologically and psychologically. Therefore, it seems reasonable to assume there would be negative consequences when using alcohol during athletic training and competition.
The athletic population is unique. An athlete competes in one or more sports and cycles through pre-season training, in-season competition, and an off-season. There is often a strong camaraderie between team-mates. Close friendships are easy to form due to common schedules and stressors.
Research studies have found athletes tend to have higher alcohol usage than non-athletes. However, many of these studies were conducted on collegiate athletes. College students tend to overall have a higher alcohol intake. The highest rate of alcohol usage is among males.
There are several theories based on research studies as to why athletes drink more alcohol.
- Positive reinforcement. This involves a reinforcing stimulus after a behavior. Perhaps every time the athlete drinks alcohol, the behavior is reinforced due to a feeling of euphoria after consuming the substance.
- Group mentality. When it becomes socially acceptable to drink alcohol, it becomes easier for a person to participate in drinking. Especially surrounding a group social activity. Drinking may make the athlete feel part of the team.
- Sport-related stress. Playing a sport for competition is stressful. The athlete has the constant stress of keeping up with training. There is often competition pressure. And other life stressors, such as school, work, or family.
All of these factors perhaps are contributors to an athlete consuming alcohol. Given the high prevalence of alcohol use among athletes, it is important to understand the physiological changes and consequences alcohol may have on performance.
Alcohol and Glycogen Storage
Glycogen is the storage unit of carbohydrates in the body. The majority of glycogen is found in the liver and skeletal muscle. The body uses glycogen during training and competition as a source of energy. Alcohol can affect the building up of glycogen reserves in the body. Therefore, the athlete may have less energy to pull from during training and competition.
Animal studies show liver and skeletal muscle glycogen forming impairment in the presence of even relatively low amounts of alcohol. But, no impact on type 2 muscle fibers, also known as fast twitch muscle fibers. These are the muscles associated with resistance training.
A study on human cyclers found a decrease in carbohydrate stores after alcohol consumption. It’s important to note that much of glycogen storage and metabolism effects are based on food. What an athlete eats or does not eat in addition to alcohol will provide different results related to glycogen storage.
When consuming alcohol, many end up replacing a meal with an alcoholic beverage. If a high carbohydrate diet is eaten along with the intake of alcohol, then there is no reduction in glycogen storage. However, if alcohol is consumed in place of carbohydrates, then there is a decrease in glycogen storage. According to the research study, “The effect of alcohol on athletic performance”, muscle glycogen storage was reduced by almost 50% at 8 hours and 16% at 24 hours when alcohol replaced food.
If alcohol was consumed before exercise, it appears that alcohol has little or no effect on the re-synthesis of muscle glycogen after exercise.
Alcohol and Hydration Status
Hydration status is an essential part of any sport or exercise. The goal during any competition or training session is to prevent dehydration. When the body is dehydrated, performance suffers. The consumption of alcohol can lead to dehydration if one isn’t focusing on rehydrating.
Alcohol increases urinary output. It does this through the inhibition of the hormone, vasopressin. This means that when drinking alcoholic beverages, one will need to pee more often. This leads to dehydration because water doesn’t have the chance to get absorbed fast enough.
The influence of alcohol on the hydration status of an athlete depends on several factors. If a person is hyper-hydrated, the diuretic effect may be eliminated, with no impact on performance. Additionally, hypo-hydration, not drinking enough water in general, also negatively affects performance and training.
In one study, .92g of alcohol/kg body weight significantly increased urinary output, reducing the recovery of blood volume, and delaying recovery from dehydration. This ultimately impacts athletic performance.
Alcohol and Body Temperature Regulation
Thermoregulation, the ability of the body to regulate its temperature may be affected by alcohol. This makes performances in extreme heat or cold more difficult. A study found that drinking 2.5mL/kg of alcohol before exercise lasting longer than 3 hours in the cold can increase heat loss. It seems that alcohol may impair adaptation to cold and heat, negatively affecting an athlete.
Alcohol and the Immune System
A healthy immune system is critical to an athlete. Even a minor illness, such as a cold, can create unfavorable results in training and competition. Alcohol can upset the balance of normal inflammatory processes. The imbalance increases the risk of sickness or infection. Additionally, alcohol may limit blood flow to an injury when it comes to trauma. When there is a limit to blood flow, recovery from an injury will take longer to heal.
Alcohol and Hormone Balance
Alcohol impacts hormonal balance. For males, when consuming large quantities of alcohol (1.5 g alcohol/kg BW), there is a decrease in testosterone production. This may lead to feminizing effects such as gynecomastia, the increase in breast tissue in males. And, testicular atrophy, the shrinking of the testicles. The decrease in testosterone could affect muscle growth, impacting performance, training, and muscle gains.
A higher percentage of male athletes engage in drinking. Many male athletes compete in high-contact sports, such as football. The injury prevalence in football players who habitually drink alcohol is higher (55%) than in nondrinkers (24%). Additionally, there is the risk of injury outside of training or competition—for instance, a fall from lack of coordination when drinking.
Alcohol and Protein Synthesis (Muscle Growth)
Protein synthesis is the process in which cells make protein. Protein synthesis may decrease with alcohol consumption, leading to a decline in muscle gains. Although, studies are conflicting. One research study found no difference in measures of creatine kinase, muscle soreness, isometric strength, or range of motion with alcohol intake. Another study found the opposite, a decrease in muscle function. The study, “Impact of Sports Performance and Recovery in Male Athletes”, found skeletal muscle protein synthesis decreases by 75% for at least 24 hours post-alcohol consumption.
Overall Recommendations for Alcohol and Maximizing Athletic Performance
When it comes to endurance performance, low to moderate doses of alcohol decrease endurance. However, drinking alcohol does not seem to affect muscular strength as strongly as it can reduce endurance performance. One thing is for certain. Studies show there are no benefits of alcohol consumption on performance and training for the athlete.
The American College of Sports Medicine (ACSM) states using alcohol in sports may negatively affect physical performance. The undesirable effects of consuming alcohol may have consequences on the athlete’s strength, power, muscular endurance, speed, and cardiovascular endurance. Therefore, the limit alcohol to maximize athletic performance.
Barnes, M. J. (2014). Alcohol: Impact on Sports Performance and Recovery in Male Athletes. Sports Medicine,44(7), 909-919. doi:10.1007/s40279-014-0192-8
Brenner, J. W., Metz, S. M., Entriken, J., & Brenner, C. J. (2014). Experiences and Attitudes of Collegiate Athletic Trainers Regarding Alcohol-Related Unintentional Injury in Athletes. Journal of Athletic Training,49(1), 83-88. doi:10.4085/1062-6050-48.6.02
Dodge, T., Clarke, P., & Dwan, R. (2016). The Relationship Between Physical Activity and Alcohol Use Among Adults in the United States. American Journal of Health Promotion,31(2), 97-108. doi:10.1177/0890117116664710
Katzung, B. (2-18). Pharmacology: Examination & Board Review(12th ed.). New York, NY: McGraw-Hill. doi:http://accessmedicine.mhmedical.com.proxy.library.kent.edu/content.aspx?bookid=2465§ionid=197944079
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