Modification of immune responses to exercise by carbohydrate, glutamine and anti-oxidant supplements

Immunosuppression in athletes involved in heavy training is undoubtedly mul tifactorial in origin. Training and competitive surroundings may increase t he athlete's exposure to pathogens and provide optimal conditions for patho gen transmission. Heavy prolonged exertion is associated with numerous horm onal and biochemical changes, many of which potentially have detrimental ef fects on immune function. Furthermore, improper nutrition can compound the negative influence of heavy exertion on immunocompetence. An athlete exerci sing in a carbohydrate-depleted state experiences larger increases in circu lating stress hormones and a greater perturbation of several immune functio n indices. The poor nutritional status of some athletes may predispose them to immunosuppression. For example, dietary deficiencies of protein and spe cific micronutrients have long been associated with immune dysfunction. Alt hough it is impossible to counter the effects of all of the factors that co ntribute to exercise-induced immunosuppression, it has been shown to be pos sible to minimize the effects of many factors. Athletes can help themselves by eating a well-balanced diet that includes adequate protein and carbohyd rate, sufficient to meet their energy requirements. This will ensure a more than adequate intake of trace elements without the need for special supple ments. Consuming carbohydrate (but not glutamine or other amino acids) duri ng exercise attenuates rises in stress hormones, such as cortisol, and appe ars to limit the degree of exercise-induced immunosuppression, at least for non-fatiguing bouts of exercise. Evidence that high doses of anti-oxidant vitamins can prevent exercise-induced immunosuppression is also lacking.