Alcohol (ethyl alcohol, ethanol) is a drug, but technically it can also be classified as a nutrient because it provides energy, about 7 kcal per gram. One drink of alcohol is considered to be an amount typically found in 340ml of beer, 114ml of wine or 35ml of 40 per cent (80 proof) spirits. Alcohol affects all cells in the body but the most immediate physiological and psychological effects are on the brain.

These effects are dependent on the blood alcohol concentration (BAC). A number of factors may influence the BAC (eg, body size, body fat content, gender) but for the average male one drink will result in a BAC of about 25mg/L. The table highlights some common effects associated with increasing BAC.

Although alcohol is classified as a depressant drug, it may elicit a transient stimulant effect, and it has been theorised by some authors to be ergogenic for both of these effects.

Potential ergogenic effects
Alcohol may influence both psychological and physiological processes related to physical performance, but most of the theoretical ergogenic benefits have been related to psychological effects. Psychologically, alcohol may benefit performance by increasing self-confidence, decreasing sensitivity to pain, or removing psychological barriers to performance. However, the most prevalent use of alcohol in sports competition is related to its ability to reduce excess anxiety and hand tremor, important considerations for athletes involved in precision sports such as pistol shooting.

Potential ergolytic effects
Alcohol may also influence psychological and physiological processes in an adverse fashion and may lead to deterioration in physical performance. Obviously, many of the adverse psychomotor effects listed in the table could impair performance in sports requiring great skill, but a number of physiological effects could also be detrimental to other types of performance. For example, alcohol may depress heart function, interfere with liver function to cause hypoglycaemia, and lead to dehydration by suppressing the release of antidiuretic hormone.

Effects on psychomotor performance
The table indicates some of the psychomotor effects of alcohol with increasing BAC. Obviously, levels about 100m/L will interfere with almost all types of psychomotor skills. Although research findings are somewhat inconsistent regarding the influence of BAC below 50mg/L upon psychomotor performance, several studies have reported decrements in a variety of psychomotor performance tasks with BAC lower than 50mg/L. Complex psychomotor skills, such as the ability to react quickly to rapidly changing stimuli (eg, in tennis) are most likely to be unpaired at low BAC.

Strength, speed, power and endurance Several major review articles have concluded that alcohol has no beneficial effects on events characterised by maximal force development for short periods of time, such as laboratory tests of muscle strength and short-term muscular endurance, and both laboratory and field tests of speed. In several studies, alcohol actually impaired performance in tests of strength, power and speed. In prolonged aerobic endurance events, major physiological variables such as heart rate and oxygen consumption during submaximal and maximal exercise do not appear to be affected by alcohol, and, in general, neither is performance on tests of aerobic endurance. However, some investigators have reported a detrimental effect on performance in 800 and 1500m races.

Precision shooting sports
Although alcohol might best be used as an ergogenic aid for precision shooting sports, little research has been conducted relative to the effect of alcohol on actual performance. Although the available data are somewhat equivocal, studies supporting the anxiolytic effect of alcohol serve as the basis for banning its use in conjunction with such sports. Melvin H Williams (Sports Science Update)



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