Tamura Masaki, Aso Takuya, Takahashi Tomoyuki, Furuyama Shumpei, Inoue Shunya, Maeda Takuya, Noguchi Yu, Horike Yoichi, Furuya Kanji, Sambe Takeyuki, Nishinaka Naoya
Showa University Research Institute for Sport and Exercise Sciences: 2-1-1 Fujigaoka Aoba-ku, Yokohama-shi, Kanagawa 227-8518, Japan.
Department of Rehabilitation, Showa University Fujigaoka Rehabilitation Hospital, Japan.
J Phys Ther Sci. 2025 Aug;37(8):384-390. doi: 10.1589/jpts.37.384. Epub 2025 Aug 1.
[Purpose] This study aimed to examine the association among zero-position external rotation muscle strength, shoulder horizontal abduction angle, and humeral head alignment. We hypothesized that individuals who cannot exert zero-position external rotation strength may adopt a horizontal abduction position and have difficulty maintaining a centripetal position for humeral head alignment. [Participants and Methods] Eighteen professional baseball players were included in the study. A handheld dynamometer was used to measure zero-position external rotation muscle strength. The isometric shoulder zero-position external rotation muscle strength was measured, and the weight ratio of the average value of the three trials was calculated. The shoulder horizontal abduction angle and anterior and posterior glenohumeral distances were measured using magnetic resonance imaging in the abduction external rotation position. The glenohumeral distance ratios were also calculated. We investigated the relationship between zero-position external rotation strength and shoulder horizontal abduction angle, anterior and, posterior glenohumeral distances, and glenohumeral distance ratios. [Results] Zero-position external rotation strength, shoulder horizontal abduction angle, and glenohumeral distance ratio were significantly negatively correlated. [Conclusion] Athletes who cannot exert zero-position external rotation strength may have a large horizontal shoulder abduction and glenohumeral distance ratio on magnetic resonance imaging.
[目的] 本研究旨在探讨零位外旋肌力、肩部水平外展角度和肱骨头对线之间的关联。我们假设无法施加零位外旋力量的个体可能会采取水平外展姿势，并且在维持肱骨头对线的向心位置方面存在困难。[参与者与方法] 本研究纳入了18名职业棒球运动员。使用手持测力计测量零位外旋肌力。测量等长肩部零位外旋肌力，并计算三次试验平均值的重量比。在外展外旋位使用磁共振成像测量肩部水平外展角度以及肱骨头前后距离。还计算了肱骨头距离比。我们研究了零位外旋力量与肩部水平外展角度、肱骨头前后距离以及肱骨头距离比之间的关系。[结果] 零位外旋力量、肩部水平外展角度和肱骨头距离比之间存在显著负相关。[结论] 无法施加零位外旋力量的运动员在磁共振成像上可能会有较大的肩部水平外展和肱骨头距离比。
