女子野球選手のバットスイング速度に関連する体力要素

抄録

Previous studies reported significant positive correlations between physical variables such as lower-limb muscular power and annual hitting records in baseball players. Thus, physical variable factors may contribute to batting performance. This study examined the relationship between physical fitness or body composition and bat swing speed in female baseball players. Thirty-two Japanese female professional baseball players (21.9 ± 3.2 years) participated in this study. Height, body mass, lean body mass (upper-limb, trunk, lower-limb, and whole body), grip strength, back strength, knee extension strength, hamstring extensibility, vertical jump height, reaction time, and bat swing speed were measured at preseason. Body mass index was calculated by dividing weight by height squared. Vertical jump index was calculated by multiplying the vertical jump height by weight. Lean body mass showed significant positive correlations with bat swing speed [upper-limb (r = 0.415), trunk (r = 0.390), lower-limb (r = 0.376), and whole body (r = 0.408): P < 0.05]. Similarly, age (r = 0.537：P = 0.002), knee (extension strength (r = 0.415:P = 0.018), and vertical jump index (r = 0.442:P = 0.013) were significantly correlated with bat swing speed. When partial correlation analysis was performed with age as control variable, these correlations were found to become weaker and insignificant. Vertical jump index, however, showed the highest partial correlation of 0.359 (P = 0.052), which is close to critical value of significance but did not reach the significant level. This study showed that skeletal muscle mass, lower-limb strength, lower-limb muscle power, and age were related to bat swing speed in female baseball players. Age can be interpreted as a term of competitive and training experiences, which has both positive (e.g., improvement of performance skill) and negative (e. g., increase in injury risk) aspects for players. However, this study cannot clearly conclude a relationship between age and bat swing speed. Improvement of body composition and physical function may positively affect batting performance and thus hitting performance in women baseball players.