The effect of a moderate aerobic training program on T, B, and natural killer cell number and function in normal adults, normal children, and children with cancer

grantor: University of TorontoA moderate intensity aerobic training program was hypothesized to produce enduring changes in the immune response, both at rest and to an exercise stimulus. To test this hypothesis, 3 separate populations each underwent 12 weeks of aerobic exercise training at an intensity of 70-85% of their maximal heart rates. Blood samples were drawn before and after training during an immune exercise challenge at 60% of each individual's aerobic power. The groups studied were comprised of 18 sedentary male university students, 11 healthy pre-adolescents, and 6 children with a history of cancer. Children also completed the Piers-Harris Children's Self Concept Scale questionnaire in an attempt to discern the changes in general well-being associated with chronic exercise in this population. Following the aerobic training program, adults showed a significant increase in maximal oxygen consumption. Immunological results included a decreased hemoglobin concentration equivalent to a 12.6% blood volume expansion, an increased absolute number of monocytes, NK, and IL-2 alpha receptor positive cells, but a decreased number of pan T cells with no change in the helper/suppressor ratio. These changes suggest an enhancement rather than a harming of immune function. Despite a high initial fitness level in healthy children, there was a 6% increase in absolute maximal oxygen consumption following training, and a trend toward improvement in overall self-concept, particularly anxiety. Adults and children were found to have similar percentages of lymphocyte subsets at rest, and responded to acute exercise with similar patterns. The main exception to this is a greater number of CD3+ and CD8+ cells in children, likely linked to the onset of thymic regression in adolescence. Children, like adults, had a decreased number of pan T cells and no change in mitogen responsiveness or NK cell function following training. There was, however, an increased percentage of T helper cells with a trend toward an increased helper/suppressor ratio. From these results there is nothing to suggest that a program of moderate aerobic exercise, such as that experienced in a school physical education setting, causes immune suppression in healthy children. A population of children undergoing routine chemotherapy and radiation treatment for cancer were able to support a moderate intensity chronic exercise program. Benefits included improvement of an initially low fitness level while preventing the decreasing work capacity seen in non-exercising peers. There was also improvement in an elevated anxiety level on the Piers-Harris Self Concept Questionnaire. Immunological results from the exercise training program were difficult to separate from the effects of chemotherapy. While close monitoring is necessary in this immunologically compromised population, an aerobic exercise program may be helpful in preventing some of the debilitating side effects of this disease and treatment regime. In conclusion, there is a similarity in both the resting immune profile and the response to acute exercise across populations of adults and children. As hypothesized, there were changes in the immune response following a 12 week aerobic exercise training program. We perceive these as beneficial to immune function. (Abstract shortened by UMI.)Ph.D