Shitara Hitoshi, Tajika Tsuyoshi, Ichinose Tsuyoshi, Sasaki Tsuyoshi, Hamano Noritaka, Kamiyama Masataka, Miyamoto Ryosuke, Nakase Kurumi, Ino Fukuhisa, Kachi Takuma, Hatori Yuhei, Yanai Koichiro, Yamamoto Atsushi, Takagishi Kenji, Chikuda Hirotaka
Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
Orthop J Sports Med. 2025 Jun 27;13(6):23259671251349721. doi: 10.1177/23259671251349721. eCollection 2025 Jun.
Differences in shoulder range of motion (ROM), shoulder muscle strength, and humeral torsion between left- and right-handed high school baseball pitchers remain poorly characterized.
Similar differences in shoulder ROM, strength, and humeral torsion between right-handed pitchers (RHPs) and left-handed pitchers (LHPs) observed in professionals will also be present in high school pitchers, with potential variations due to developmental stages.
Cross-sectional study; Level of evidence, 3.
The authors included 921 high school baseball pitchers (706 RHPs and 215 LHPs) and evaluated their age, height, weight, body mass index, baseball experience, shoulder ROM, and muscle strength. Humeral torsion was measured in 211 RHPs and 57 LHPs. The Mann-Whitney test was performed to determine the differences between the RHPs and LHPs and between the dominant and nondominant sides in each group. Pearson correlation analysis was performed to test the relationship between humeral torsion and shoulder ROM. Logistic regression analysis was conducted to determine the independent factors associated with LHP.
LHPs exhibited increased nondominant external rotation (ER) (103.1° vs 100.0°; = .004), dominant horizontal adduction (HA) (23.0° vs 19.6°; = .015), and side-to-side ratio in prone internal rotation (PIR) strength (107.6% vs 98.3%; < .001) compared with RHPs. Additionally, LHPs were shorter (171.4 vs 172.9 cm; = .002) with lower side-to-side differences in ER (5.7° vs 8.9°; < .001) and HA (-6.5° vs -11.3°; < .001), dominant prone ER (PER) strength (15.4 vs 16.8 kgf; = .040), side-to-side ratio in PER strength (93.1% vs 103.7%; < .001), and side-to-side differences in humeral torsion (5.8° vs 9.9°; = .011) compared with RHPs. After adjusting for confounding factors, a smaller side-to-side ratio in PER strength ( < .001; OR, 0.911) and larger side-to-side ratio in PIR strength ( < .001; OR, 1.031) were independent factors associated with being an LHP.
LHPs have a decreased side-to-side ratio in PER strength and increased side-to-side ratio in PIR strength compared with RHPs. These findings suggest that shoulder-related biomechanical differences between right- and left-handed pitchers are evident in high school athletes.
左、右利手的高中棒球投手在肩部活动范围（ROM）、肩部肌肉力量和肱骨扭转方面的差异仍未得到充分描述。
在职业投手中观察到的右投手（RHP）和左投手（LHP）之间在肩部ROM、力量和肱骨扭转方面的类似差异也会出现在高中投手中，并且可能因发育阶段而有所不同。
横断面研究；证据等级，3级。
作者纳入了921名高中棒球投手（706名RHP和215名LHP），并评估了他们的年龄、身高、体重、体重指数、棒球经验、肩部ROM和肌肉力量。对211名RHP和57名LHP测量了肱骨扭转。采用曼-惠特尼检验来确定RHP和LHP之间以及每组优势侧和非优势侧之间的差异。进行Pearson相关性分析以检验肱骨扭转与肩部ROM之间的关系。进行逻辑回归分析以确定与LHP相关的独立因素。
与RHP相比，LHP的非优势侧外旋（ER）增加（103.1°对100.0°；P = 0.004），优势侧水平内收（HA）增加（23.0°对19.6°；P = 0.015），以及俯卧位内旋（PIR）力量的左右侧比值增加（107.6%对98.3%；P < 0.001）。此外，与RHP相比，LHP更矮（171.4对172.9厘米；P = 0.002），ER的左右侧差异更小（5.7°对8.9°；P < 0.001），HA的左右侧差异更小（-6.5°对-11.3°；P < 0.001），优势侧俯卧位ER（PER）力量更小（15.4对16.8千克力；P = 0.040），PER力量的左右侧比值更小（93.1%对103.7%；P < 0.001），以及肱骨扭转的左右侧差异更小（5.8°对9.9°；P = 0.011）。在调整混杂因素后，PER力量的左右侧比值更小（P < 0.001；OR，0.911）和PIR力量的左右侧比值更大（P < 0.001；OR，1.031）是与成为LHP相关的独立因素。
与RHP相比，LHP的PER力量左右侧比值降低，PIR力量左右侧比值增加。这些发现表明，右投手和左投手之间与肩部相关的生物力学差异在高中运动员中很明显。
