A good diet for an athlete is dependent upon the sport, age of the athlete, fitness and freedom from injury. Modern sport, football, rugby, athletics, cycling, American football, tennis and hockey are now so competitive that previously unsuspected demands on physical fitness and strength are expected.
Metabolic needs —
The metabolic needs of endurance athletes (long distance runners, distance swimmers and cyclists) are different from intermittent activity athletes (football, hockey, cricket and golf) and sports of short but intense duration, e.g. sprinters and wing three-quarters at rugby. Body-building sportsman such as weight lifters have yet different needs (Figure 44.2).
To perform well endurance athletes must establish a store of readily retrievable energy in a frame which is light in weight. The typical long-distance runner or cyclist is a lean individual packed with large stores of glycogen. A first-class football player may run 10 miles during a game, yet a goalkeeper may be required to perform intermittently in a gymnastic manner. Sprinters over the range of 100–800 metres will rapidly expend energy over short periods of 10 seconds up to 2 minutes. Other sports such as cricket, baseball and golf which are coordination sports, require relaxation concentration. The nutritional needs of a fast bowler at cricket will be different from those of a golfer. It is unlikely that the nutritional needs of this group are likely to differ from the prudent advice offered to the population of their age. The strength sports, e.g. weight lifters, prop-forwards in rugby, heavy-weight boxers and American footballers, build massive muscle structure to perform deeds of strength.
There is therefore a range of requirements including:
1. The provision of energy over an extended period from a modest muscle mass meeting the need to sustain speed for long periods.
2. The development of a strong physique able to push and pull massive loads and, during the same game, to run considerable distances.
3. The requirement for bursts of energy over very brief periods of time, e.g. sprinters, whether these are athletes or wingers in rugby.
A well-balanced diet should contain 50–60% of the calorie intake as carbohydrate, fats no more than 35% and protein approximately 15%. In addition, there should be sufficient amounts of fibre, vitamins and minerals (as suggested for the population in general) but possibly increased pro rata to energy intake. Some sports will require modest increases of a particular nutrient, e.g. carbohydrate for endurance athletes and protein for strength sport. It is important that such diets are sensible and within the overall concept of a balanced diet.
Alcohol is a continuing problem in sport. Athletes are strong, vigorous, young people sometimes with time on their hands. Victories are to be celebrated. Many athletes have taken an undue amount of alcohol and paid the price.
1. The diet of athletes must meet their energy requirements and the demands posed by the speed and duration of exercise. Sports requiring coordination have no special dietary needs. Increased protein calorie intake may be required in the body-building sports whereas a high carbohydrate diet is required by endurance runners.
2. Sport makes demands on biochemical and mechanical efficiency. Mechanical efficiency declines with the amount of work involved in the sport.
3. Skeletal muscle consists of two types of fibre: type 1 is for aerobic metabolism and is resistant to fatigue; type 2 is for anaerobic metabolism.
4. Endurance runners require stores of glycogen to complete their prolonged activity. The glycogen is stored in muscles, the storage capacity being increased by training. Increased carbohydrate intake is required during such training periods.
5. In endurance sports, water is lost and must be replaced during the run or severe and life threatening consequences result.
6. Energy requirements vary from sport to sport; the most demanding is the Tour de France cycle race. Protein requirements are modestly and carbohydrate massively increased in endurance sports. Fat has no merit in stamina provision.
7. There is little evidence that other nutrients are required in amounts in excess of the non exercising population of the same age.
8. It is possible artificially, but both dangerously and illegally, to increase athletic performance with amphetamine- and steroid-type drugs.