Exercise, immune function and HIV infection

The implications of HIV infection for exercise and sport are reviewed. HIV infection leads to impairment in a number of key elements of immune function, most obviously a progressive decline in the numbers of CD4+ T helper/inducer lymphocytes. Nevertheless, patients with early through moderately advanced HIV-1 infection can engage in moderate sport and exercise without risk to themselves or other participants; the resulting gains of aerobic power and muscle strength are similar to those observed in healthy individuals of comparable initial fitness. In fully developed AIDS, the ability to exercise may be compromised by deteriorations in cardiorespiratory and neuromuscular function. Given the impairment of resting immune function, the potential immunosuppression from very intensive bouts of competitive exercise must be avoided. Review of all published papers to date provides a relatively limited data base. During a bout of moderate physical activity, HIV seropositive individuals apparently have an impaired ability to mobilize neutrophils, NK and LAK cells into the circulation. Nevertheless, programmes of moderate training can be sustained without any large change in CD4+ count or CD4+/CD8+ ratio. In some studies, training has also attenuated psychological stress, possibly for this reason checking the anticipated fall in CD4+ count. However, further large-scale randomized and long-term studies of HIV are needed, comparing the therapeutic value of exercise alone with that of psychotherapy or a combined programme of exercise and psychotherapy.