Knocking Yourself Out
Elite athletes and their coaches dread the "competition flu" -- a catchall term for a variety of persistent respiratory illnesses and fatigue syndromes that seem to plague athletes as the competitive season progresses. Sebastian Coe, for example, a British runner and a 1984 Olympic gold medalist, was so debilitated by a respiratory infection during the 1988 Olympic trials that he failed to make the British team. Skaters, gymnasts, cyclists, swimmers, runners, and skiers all train intensely for national and international meets, only to find their performance hampered by the onset of some infectious disease. Although moderate exercise is known to promote health, evidence is mounting that intense exercise may actually lower the body's resistance to disease, thereby making the elite athlete -- as well as the dedicated amateur -- more susceptible to colds and other infectious diseases. In fact, reported L. Fitzgerald in the June 1991 issue of the International Journal of Sports Medicine, Sebastian Coe's malady, first described to the press as "glandular fever," was later diagnosed as toxoplasmosistan opportunistic infection typically seen in those with artificially induced immunosuppression. In U.S. schools, infectious diseases have been shown to hit hardest among those students involved in athletic activities. In a 1982 article in JAMA, the journal of the American Medical Association, R.C. Baron described an outbreak of aseptic meningitis at one high school. Football players were twice as likely to come down with the infection as were other members of the student body. When polio developed at a Connecticut school where none of the staff or students had been vaccinated, all nine students who contracted the disease were actively participating in strenuous sports, according to L. Weinstein in a 1973 article in the New England Journal of Medicine. At a Texas college, a hepatitis outbreak affected 90 out of the 97 members of the football team, while no other students were affected, wrote L.J. Morse in a 1972 report in JAMA. By looking at the actual components of the immune system, medical studies have begun to show that these kinds of observations are not just the results of coincidence. The immune system consists of humoral and cellular "arms"; the humoral arm is made up of B cells, which make antibodies that fight bacteria and bacterial toxins, while the cellular arm consists of T and NK cells, which kill the body's own cells that have become cancerous or virus-infected. When tested, members of the U.S. cross-country ski team were found to have lower antibody levels than the normal population, and those levels decreased even further after a meet, according to T.B. Tomasi, writing in the Journal of Clinical Immunology in 1982. Finnish runners were found to have decreased T-cell function after a race, reported J. Eskola in a 1978 issue of Clinical and Experimental Immunology; in a study published in a 1987 issue of Advances in Experimental Medicine and Biology, Mackinnon found that cyclists were shown to have post-race reductions in NK function and antibody levels. As they reported in a 1983 issue of South African Medical Journal, E.M. Peters and E.D. Bateman questioned 150 runners at the end of a 56 km race; those with the highest weekly training mileages had the lowest levels of T-cell function and the highest rate of respiratory disease. Long-distance runners tested at the end of the competitive season had lower antibody levels, and even lower numbers of T cells, than non runners reported Fitzgerald in 1988 in Immunology Today. And even non athletes showed the same kinds of decreases in immune function, when exercised to exhaustion in the laboratory, according to L.S. Berk in a 1985 report in Medicine and Science in Sports and Exercise. How does intense exercise cause the immune system to malfunction? There are several possible explanations, according to Fitzgerald. Exercise stimulates the release of a variety of hormones and chemicals, many of which effect different components of the immune system -- chronic intense exercise may bombard the "targets" for those hormones until they no longer respond correctly. Intense physical exertion inevitably causes some tissue damage; long-term strenuous training may result in chronic inflammation which could potentially result in lowered immune responsiveness. The psychological stress that is part of world-class competition almost certainly contributes as well. Exactly what part each of these factors may play has yet to be unraveled, however. In the meantime, what are the lessons for the athlete? Although elite athletes have brought the problem to the attention of the medical community, anyone with a strenuous training program is at risk as well. And although serious health problems are unlikely to result from overtraining, nobody wants more colds and flus either. So let's look at what dedicated amateur athletes can do to maximize their exercise efficiency and optimize the health benefits from their efforts. * Pay attention to your body's signals. If you feel like you're coming down with something, forgo the exercise for a day or two. Fitzgerald found that exercising during the incubation period of an infection may cause more severe illness. * Take your vitamins. Intense exercise requires very rapid cellular metabolism, which may deplete cellular stores. A regular supplement will help ensure adequate levels, suggests Fitzgerald. * Avoid social contact as much as possible for a few hours after exercising, Fitzgerald further warns. The most pronounced dip in immune function occurs shortly after a workout; levels then rise again to approach normal. This provides a window of opportunity for viruses or other microorganisms to invade and, without attack by normal defense mechanisms, establish infection. Avoiding being around a lot of people, especially people known to be sick, may help ward off illness. * Take a day or two off after a major meet or race. After a single strenuous exercise session, immune function levels dip but then rebound, reported D. Keast in a 1988 issue of Sports Medicine. Reporting in a 1981 issue of the Annals of Allergy, R.L. Green found that at the end of their competitive season, long-distance runners had lower levels than normal controls -- even without exercising. With repeated intense exercise, apparently, immune function levels don't have time to return to normal. No one yet knows how long it takes for the body to fully recover immunocompetence, but a day or two is better than nothing. * Avoid tobacco and alcohol, eat sensibly, and get enough sleep. Malnutrition, not getting enough sleep, and alcohol and tobacco use can all impair immune function on their own. Exercise improves muscle tone, increases energy, benefits the cardiovascular system, and helps an individual maintain the proper body weight -- but like anything else, can be too much of a good thing. Train sensibly and follow the guidelines above to ensure that your exercise program enhances, rather than diminishes, your overall physical health.