【論文摘要】The Relationship Between Lateral Abdominal Muscle Asymmetry and Bat Swing Velocity in High School Baseball Players

【論文摘要】高中棒球選手外腹肌不對稱性和揮棒速度之間的關係

陳銘陽(Ming-Yang Chen) ； 郭怡良(Yi-Liang Kuo)

《物理治療》 45卷4期 (2020/12) Pp. 346-347

https://doi.org/10.6215/FJPT.202012.P42

摘要

Background and Purpose: Bat swing velocity is one of the most important factors in achieving successful baseball batting performance. Elite baseball players spend hours practicing baseball swing. Repetitive and unidirectional rotational movement of the trunk could result in asymmetric hypertrophy of lateral abdominal muscles. Lateral abdominal muscle asymmetry seems necessary for the demands of baseball batting, but may influence control of the lumbopelvic-hip complex and lead to inferior athletic performance. No study has examined the relationship between lateral abdominal muscle asymmetry and bat swing velocity in adolescent baseball players. The purposes of this study were to compare the thickness of lateral abdominal muscles on both sides of the trunk and to investigate whether lateral abdominal muscle asymmetry was correlated with bat swing velocity in high school baseball players. Methods: Fifteen high school position players from a Division I baseball team (right-handed batting and throwing; aged 16.0 ± 1.1 years, height 172.6 ± 5.0 cm, weight 73.3 ± 10.8 kg) participated in this study. Bat swing velocity was measured by a swing sensor during tee batting. Thickness of the external abdominal oblique (EO), internal abdominal oblique (IO), and transverse abdominis (TA) muscles were measured by the Siemens ultrasound system (ACUSON NX3^(TM), Siemens Medical Solution Inc., Issaquah, WA) using a linear transducer of 4-12 MHz set in B mode in the crook-lying position. Absolute thickness of each lateral abdominal muscle on the dominant and non-dominant sides were compared using paired t-tests. The relationship between the asymmetry ratio (the difference of the muscle thickness between both sides expressed as a percentage of the muscle thickness on the dominant side) and bat swing velocity was analyzed using Spearman correlation coefficient. Results: The EO was significantly thicker in the dominant side than in the non-dominant side (6.85 ± 1.13 vs. 5.05 ± 1.46 mm, p ＜ 0.001), and the TA was significantly thicker in the non-dominant side than in the dominant side (4.21 ± 0.85 vs. 3.49 ± 0.60 mm, p = 0.003). No significant difference was found in the IO (11.77 ± 2.43 vs. 11.55 ± 1.86 mm, p = 0.655). The asymmetry ratio of the EO was also significantly correlated with the bat swing velocity (r = -0.74, p = 0.002). Conclusion: High school baseball players demonstrate lateral abdominal asymmetry in the EO and TA. The significant negative correlation found in the EO indicates that a greater side-to-side asymmetry of the EO thickness is highly related to decreased bat swing velocity. Clinical Relevance: High school baseball players may benefit from exercises to correct asymmetric thickness of the EO.