Reversing age-associated immunosenescence via exercise.

Decreases in immune responsiveness with age are thought to contribute to the increased incidence and severity of infectious disease among the elderly. Several interventions, including exercise, have been proposed to restore immune function in older populations. The findings from some, but not all studies, support the possibility that exercise may attenuate immunosenescence. In recent years, the role of exercise in modulating immune response has been examined using models that may have clinical relevance, such as the response to vaccines and novel antigens. Taken together, the accumulated data suggest that exercise may be an efficacious therapy for restoring immune function in the elderly. In general, long term exercise interventions appear to show the most promise. Exercise related improvements have been reported with respect to antibody titre, T cell function, macrophage response, alterations of the T(H)1/T(H)2 cytokine balance, the level of pro-inflammatory cytokines, and changes in naïve/memory cell ratio. However, current data is minimal, and many questions remain including: the mechanisms that are involved, the potential clinical impact, the appropriate type or dose of exercise, and whether the benefits extend to all populations including frail, older adults. This review summarizes the major findings of these studies and proposes directions for future exploration.