Alcohol and exercise should never be mixed, writes Dr Giles Warrington.
MOST EVIDENCE suggests that even small amounts of alcohol taken prior to or during exercise may have an adverse effect on performance. Despite this, alcohol consumption is an integral part of many sports, both in terms of tradition and ritual.
In Ireland this is particularly evident at the recreational level where socialising may be as important as actual sports participation. Within certain competitive sports in Ireland there is often a ritual of alcohol consumption following training and before competition.
Acute responses to excessive alcohol use include impaired reaction time and eye-hand co-ordination, dehydration, reduced blood sugar levels as well as impaired temperature regulation.
Furthermore, these effects may persist for hours after intoxication. Chronic alcohol abuse may induce pathological changes in heart, liver, neural tissue and muscle which may be fatal. Further longer-term responses would include obesity and hypertension among others.
Although alcohol is high in energy content, it differs from carbohydrate and fat, in that the liver can only break it down very slowly. Alcohol cannot, therefore, provide a rapid energy source to the working muscles during exercise.
In effect, alcohol is "empty calories", an excess of energy which is stored in the body as fat. A pint of beer, for example, contains about 180 calories, of which only 12 calories are in the form of carbohydrate. Furthermore, being low in essential nutrients, alcohol takes up the nutrient space in the diet that could be used more effectively.
Alcohol, particularly in concentrated form such as spirits, is a potent diuretic which means it will promote dehydration which may further negatively impact on performance.
A decline in endurance performance has been reported with dehydration levels as low as 2 per cent of body weight and losses in excess of 5 per cent have been shown to decrease work capacity by about 30 per cent. Imagine telling an athlete to "detrain" by 30 per cent before a major competition!
Alcohol does not possess an ergogenic or enhancing effect on sports performance. However, in some highly skilled events such as target shooting, a small amount of alcohol is sometimes taken in the belief that it will relax the mind, raise confidence levels and reduce tremor prior to competition.
However, this is based on weak evidence and there is little or no information to support this contention.
A thorough analysis of the available research investigating the effects of alcohol consumption on performance was conducted by the American College of Sports Medicine with the following conclusions:
• Effects on psychomotor skills: The acute ingestion of alcohol can exert a deleterious effect upon a wide variety of psychomotor skills such as reaction time, hand-eye co-ordination, accuracy, balance and complex co-ordination.
• Effects on physiological functions: Acute ingestion of alcohol will not substantially influence metabolic or physiological functions essential to physical performance such as maximum aerobic capacity, heart rate, muscle blood flow and respiratory dynamics. Alcohol consumption may impair body temperature regulation during prolonged exercise in a cold environment.
• Effects on physical capacity: Acute alcohol ingestion will not improve and may decrease strength, power, local muscular endurance, speed and cardiovascular endurance.
• Use and abuse: Alcohol is the most abused drug in the western world and is a major contributing factor to accidents and their consequences. Also, it has been documented widely that prolonged excessive alcohol consumption can elicit pathological changes in the liver, heart, brain and muscle, which can lead to disability and death.
• Role of education: Serious and continuous efforts should be made to educate athletes, coaches, sports organisations, health and physical educators, trainers, the sports media and the public regarding the effects of acute alcohol ingestion upon human physical performance and on the potential acute and chronic problems of excessive alcohol consumption.
A survey conducted in 1990 by the Australian Sports Drug Agency (ASDA) among athletes from 19 sports revealed some startling results. Many athletes, both elite and non-elite, were unaware of the specific detrimental effects on performance that resulted from the use of "social drugs" such as alcohol. Education of athletes to the possible harmful effects of alcohol is, therefore, clearly essential.
• What's your limit? The issue of what level of alcohol consumption is appropriate in the athletic population is a difficult one to address.
Although it is commonly reported that there is a high incidence of alcohol usage in the athletic community, in reality the majority of serious athletes consume very little if any. Individual tolerance may vary greatly, and probably also from time to time in the same individual.
Maximum recommended alcohol intake is 21 units for men and 14 for women per week. However, it is important to remember that people have different tolerance levels and binge drinking should be avoided at all costs. For athletic populations, alcohol consumption should be less than 5 per cent of total calorific intake and ideally a lot less.
Clearly, drinking alcohol is an integral part of the social aspect of participation in many sports. Among athletes who choose to drink, a moderate amount of alcohol is unlikely to affect athletic performance as long as it is not ingested close to the time of competition. Nevertheless, for the various reasons outlined in this article, for serious athletes, alcohol should contribute only a very small percentage of calorific intake, if any.
Evidence suggests, however, that the level of alcohol consumption, even at the elite level, varies considerably across sporting groups.
Alcohol has been shown to have no positive effects on athletic performance and may have a negative effect on a broad range of activities. Quite apart from its effect on performance, alcohol is an extremely ineffective and inappropriate way to replace bodily fluids after exercise.
From a purely health viewpoint, excessive alcohol consumption can cause serious damage to the liver and may even cause morbidity in the long term.
It is, therefore, important for all those associated with participation in sports to educate both junior and senior athletes against the danger of alcohol consumption in conjunction with athletic training and competition, and discourage its use.
Dr Giles Warrington is a sport and exercise physiologist and lecturer in the School of Health And Human Performance at Dublin City University.