A study was conducted to clarify changes in the body's defense mechanism and differences among individuals under endurance training in mice. Four-weeks old inbred C57 BL/ 6 Cr mice were used in this experiment. The percentage of cells, helper T cells, suppressor T cells and B cells in blood due to treadmill running exercise were studied over a six-weeks period. Speed, slope and duration of endurance running were changed in a stepwise manner. Initial running speed, duration time, and the slope of the treadmill were 5 m/min, 30 min and 0 degree, respectively. The workload was then gradually increased to give final parameters of 28 m/min, 60 min and 12 degrees respectively.
　The number of lymphocytes in blood was not influenced by endurance exercise in either the control or the training group, or in either male or female mice. The proportions of Thy 1.2⁺, L3 T4⁺ and Lyt 2⁺ in blood in the training group tended to increase after long-term running. However Ig⁺, a marker of B cells tended to decrease. These results suggest that the responses of the cellular and humoral immune systems to long-term exercise differ. The propotion of Thy 1.2⁺ in blood in male mice was higher than that in female mice suggesting a possible sex difference in the response of the cellular immune system.

DESCENTE SPORTS SCIENCE Vol.13/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE