Abstract

This study examined the effects of heavy training on cell-mediated immunity in highly trained runners. Ten men (29.8 y; VO2max, 65.3 ml/kg/min; personal best 10-km race time, 32 min, 43 s) were evaluated following 3 weeks of normal baseline training (B1), 3 weeks of deliberately heavy training (Ht), and another 3 weeks of baseline training (B2). At each laboratory evaluation, the subjects ran on a treadmill for 30 min at 80 of VO2max. Antecubital samples of venous blood were taken immediately before and 5 and 30 min after exercise. Cell-mediated immune function was assessed by two in vitro measurements: (a) stimulation of lymphocyte proliferation with the mitogens phytohemagglutinin (PHA) and concanavalin (Con-A), and (b) assessment of subpopulations of lymphocytes (B cells, T cells, helper cells (CD4+ or H), and suppressor cells (CD8+ or S)). Following HT, resting blood samples indicated trends for increased proliferation of peripheral blood mononuclear cells and a decrease in the H/S ratio compared with values for B1. Submaximal exercise did not alter proliferation at either B1 or B2. The acute bout of HT exercise produced a significant 18 suppression of PHA-induced lymphocyte proliferaiton, with a similar but not significant 12 suppression of Con-A response. However, the exercise-induced decrease of the H/S ratio was larger at B1 and B2 than following HT. Thus, we conclude that the apparent impact of heavy training on cell-mediated immunity is strongly dependent on the chosen in vitro measure of immune function. Verf.-Referat