The purpose of this study was to elucidate the improvement of physical capacities with effective training utilizing weighted sports wear in baseball players. Nineteen male athletes (aged:19±2) participated in the study. They were divided into two groups : 9 subjects carried out training utilizing weighted sports wear (1.5kg) under their uniforms during routine baseball practice (experimental group, EG), and 10 subjects did not utilize weighted wear during training (control group, CG). Subjects participated in each training session every day for 6 weeks. Results showed that, heart rates during running with weighted wear showed 20 bpm (17%) increase a the speed of 8 km/h and 13 bpm (7%) increase a the speed of 12 km/h, compared with the use of only baseball uniforms. Body weight in EG after the training with the weighted wear for 6 weeks was significantly lower than that before the training. Body composition of body fat in total body, legs, trunk and arms was significantly less after 6 weeks. No significant differences were found in lean body mass, bone mass and bone mineral density of the athletes total body, legs, trunk and arms between prior to and after 6 weeks in both EG and CG. Grip strength, whole body reaction time and sit-ups in EG improved after 6 weeks. Anaerobic threshold also significantly improved after 6 weeks in EG.
　These results suggest that training utilizing weighted sports wear during routine (skill) baseball practice sessions was effective for the improvement of physical capacities and had beneficial effects for body fat reduction.

DESCENTE SPORTS SCIENCE Vol.26/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE