Abstract

In competitive swimming, on-the-ground training, also called “dry-land training,” is performed to improve swimming performance and prevent injury before and after underwater physical activity. This study aimed to elucidate the immediate effects of core muscle training, which is commonly performed by many athletes, on shoulder muscle strength and pull motion in water. Eleven swimmers enrolled in the Japan Intercollegiate Championship Division 1 participated in this study. The participants performed seven types of core training exercises, primarily focusing on abdominal drawing-in and stabilization training. Bilateral shoulder muscle strength was measured before and after core training and the time needed to perform a 15-m swim with pull motion without kicking was monitored. Shoulder muscle strength was measured using a handheld dynamometer in three different positions: catch, pull, and finish. The right and left shoulder muscle strength pre/post core training were, respectively, 15.1±3.5/17.1±4.3 kgf and 14.4±2.9/15.8±3.1 kgf in the catch position, 15.2±3.4/16.8±5.6 kgf and 16.3±3.4/16.7±4.1 kgf in the pull position, and 10.4±2.1/11.1±3.2 kgf and 12.6±1.0/13.0±2.9 kgf in the finish position. Significant improvements in bilateral shoulder muscle strength were observed in the catch position after the core training. Furthermore, the 15-m swim time improved significantly from 11.4±0.7 s to 10.9±0.5 s after core training (p<0.05). These findings suggest that shoulder muscle strength improved immediately after core training. Moreover, the muscle strength in the catch position significantly contributed to the improvement in swimming speed in the pull motion.