Physical Activity, Aging and Immune Function

The extent to which exercise training or long-term physical activity influences poorly regulated immune function in the elderly is unclear. Preliminary evidence suggests that exercise training may improve various immune function measures in older adults. Although such findings have the potential to be of substantial public health importance, the majority of studies have suffered from small sample sizes, inadequate measurement of physical fitness, and weak research designs.

This study is designed to overcome these limitations by employing a longitudinal randomized controlled trial examining the effect of exercise training on clinically relevant immune function measures in older adults (65-80 years). Moreover, relationships between several factors known to be altered by exercise training and changes in immune function will be assessed. As such, there are two specific aims to be addressed. In Aim 1, a 10-month exercise trial will determine whether moderate intensity aerobic exercise training can improve immune function in previously sedentary older adults. In Aim 2, the role played by physiological, behavioral, and psychosocial factors in the relationship between exercise training and improved immune function will be examined.

150 sedentary participants will be randomly assigned to either a 10-month moderate aerobic exercise training program or a sedentary control group. Clinically relevant measures of immune function including the delayed-type hypersensitivity (DTH) response to a battery of antigens and the antibody response to tetanus toxoid and influenza virus vaccination will be assessed before, during and after the intervention. We hypothesize that exercise training will result in improved immune responses including higher peak antibody titers and DTH responses, and sustained levels of protective antibodies.