Specifically designed programs of sprint and endurance running were used to comparison of each training effect on muscle fibers and those of capillary supply. Wistar strain male rats (42 days after birth) were trained by treadmill for 10 weeks. The gastrocnemius muscle were histochemically studied. The results obtained were summarized as follows: 1) The body and muscle weight of the rats in both training groups were significantly smaller than those of the control group. 2) The sprint training caused hypertrophy of muscle fiber, but the endurance training did not. 3) The endurance training group showed the higher value in the number of capillaries per fiber (CF ratio), per mm2 (CD), around each fiber type (CC) than control group. And the endurance training group showed the lower value in the distance of diffusion than sprint training group and control group. 4) The sprint training group showed the higher value in CF ratio and CC than control group, but not so high as endurance training group. These results suggest that training effects are specific to the type of training program used.