LYMPHOCYTE PROLIFERATIVE RESPONSE TO 2.5 HOURS OF RUNNING

The effect of 2.5 h of treadmill running at 75.6 +/- 0.9 % VO2 max on circulating leukocyte and lymphocyte subpopulations, epinephrine and cortisol concentrations, and the Con A-induced lymphocyte proliferative response was investigated in 22 experienced marathon runners (VO2 max 57.9 +/- 1.1 ml . kg(-1) . min(-1), age 38.7 +/- 1.5 yrs). Blood samples were taken 15 min before (07.15 h) and immediately after exercise (10.00 h), with three more samples taken during 6 h of recovery (11.30, 13.00, 16.00 h). Ten sedentary controls (34.7 +/- 1.0 ml . kg(-1) . min(-1), 45.3 +/- 2.3 yrs) sat in the laboratory during testing and had their blood sampled at the same time points. Serum cortisol was elevated relative to controls for more than 3 h post-exercise, and correlated significantly with the 3-h post-exercise elevation of the neutrophil/lymphocyte ratio (r = 0.68, p < 0.001). The concanavalin A- (Con A) induced lymphocyte proliferative response was decreased relative to controls for more than 3 h post-exercise, and except for the immediate post-exercise time point, tended to parallel the decrease in T cell (CD3(+)) concentrations.