Exercise-induced changes in the blood concentration of leukocyte populations in teenage athletes

Neutrophilia following exercise is well described in adults and children. However, the effects of exercise on less concentrated leukocyte populations, such as circulating colony forming unit-granulocyte macrophage (CFU-GM), CFU-granulocyte, erythrocyte, megakaryocyte, macrophage (CFU-GEMM), and the various lymphocyte subsets, is not clear. To obtain this information, members of a high school track team were asked to run flights of stairs at their most rapid pace for 10 min. Prior to and 5 min following the exercise, blood concentrations of various leukocyte populations were measured. As expected, the circulating neutrophil concentration increased following exercise (26% increase). However, the largest postexercise increases were in eosinophils (139% increase) and lymphocytes (67% increase). The increase in blood lymphocytes was primarily due to an increase in total T-cells (52% increase) and T-suppressor cells (49% increase), with no significant elevation in T-helper cell or B-cell populations. The exercise did not induce an increase in the immature/total neutrophil ratio or in the number of circulating CFU-GM or CFU-GEMM.