A study was conducted to investigate the effects of voluntary exercise training, and the relationship hbetween the quantity of training exercise and immunocytes, in mice. Sixty four six-weeks old inbred C57BL/6 mice used for the experiments were divided into four groups : sedentary controls, and mice taking voluntry exercise training on running wheels ; a) 7/weeks training group, b) 4/weeks training group, c) 1/weeks training group. The period of exercise toraing was 6 and 36 weeks. Beginning at the age of 6 weeks, the number of wheel rotaions was measured as the quantity of exercise.
Body weights of mice in training groups tended to decrease. The weights of thymus, spleen and lymph nodes per body weight were unchanged in 36 weeks training compared with the control group.
The percentages of immunocytes in blood, thymus and spleen did not show a certain trend, but the immunocytes in lymph nodes changed significantly in 6 weeks and 36 weeks training grops.
These results suggest that the response of the immune system to voluntary exercise training might be different from each organ regardless of the period of training.