Immune function in marathon runners versus sedentary controls

Abstract

Ectively) and height, the marathon runners were significantly leaner and possessed a VO2max 60% higher than that of the controls. Neutrophil counts tended to be lower in the group of marathoners, while other leukocyte and lymphocyte subsets were similar to controls. Mitogen-induced lymphocyte proliferation did not differ between groups. Natural killer cell cytotoxic activity (NKCA) was significantly higher in the marathoners versus controls (373 ± 38 vs 237 ± 41 total lytic units, respectively, a 57% difference, P = 0.02). For all subjects combined (N = 40) and within the group of marathon runners (N = 22), percent body fat was negatively correlated with NKCA (r = −0.48, P = 0.002; r = −0.49, P = 0.019, respectively), and age was negatively correlated with Con A-induced lymphocyte proliferation (r = −0.41, P = 0.009; r = −0.53, P = 0.011, respectively). These data indicate that NKCA but not mitogen-induced lymphocyte proliferation is higher in marathon runners relative to sedentary controls. ©1995The American College of Sports Medicine...