EFFECT OF HIGH-INTENSITY VERSUS MODERATE-INTENSITY EXERCISE ON LYMPHOCYTE SUBPOPULATIONS AND PROLIFERATIVE RESPONSE

The effect of 45 min of high- (80% VO(2)max) versus moderate- (50% VO(2)max) intensity treadmill exercise on circulating leukocyte and lymphocyte subpopulations, catecholamine and cortisol concentrations, and the mitogen-stimulated lymphocyte proliferative response was investigated in 10 well-conditioned (mean VO(2)max 66.0 +/-1.9 ml/kg/min), young males (mean age 22.1 +/- 1.3 yrs). Blood samples were taken before and immediately after exercise, with three more samples taken during 3.5 h of recovery. Treatment order on the treadmill (graded walking at 7.3 +/- 0.1 km/h, 6.5 +/- 0.6% grade, versus level running at 16.1 +/- 0.3 km/h) was counterbalanced, with subjects acting as their own controls and results analyzed using a 2 x 5 repeated measures ANOVA. The concanavalin A- (Con A) stimulated lymphocyte proliferative response was decreased at 1 h and 2 h post-exercise relative to baseline levels following both exercise-intensity conditions. However, when adjusted on a per-T cell (CD3+) basis to account for the change in number of T cells in the in vitro assay, only the high-intensity exercise condition was associated with a 1-h post-exercise decrease (21 %, p = 0.05) in the proliferative response relative to baseline. Exercise at 80 % versus 50 % VO(2)max resulted in significantly greater increases in cortisol and epinephrine concentrations, providing a physiological rationale for the immediate-post-exercise lymphocytosis, 1- to 3.5-h lymphocytopenia, and the decrease in Con A-stimulated lymphocyte proliferative response (per CD3+ cell) that occurred in greater measure following high-intensity exercise.