Kennedy Sean M, Myers Natalie L, Conway John E, Garrison J Craig, Guffey Thomas, Bailey Lane B, Arnold Amanda J
Memorial Hermann Health, Rockets Sports Medicine Institute, Houston, Texas.
University of Texas Health Sciences Center, McGovern School of Medicine, Houston, Texas.
Sports Health. 2025 Apr 14:19417381251329929. doi: 10.1177/19417381251329929.
Arm injuries in baseball continue to rise. Previous studies have confirmed relationships between shoulder strength, injury risk, and performance in baseball athletes. Shoulder strength measures vary considerably within and among baseball players and are influenced heavily by anthropometric measures. Presently, the normalization of shoulder strength measures has not been tested adequately to meet necessary statistical assumptions.
At least 1 shoulder strength normalization method would meet 2 statistical assumptions: the intercept assumption and correlation assumption.
Cross-sectional study.
Level 3.
Isometric shoulder strength was tested in a cohort of uninjured baseball athletes on the dominant limb via handheld dynamometry: external rotation (ER), internal rotation (IR), and scapular plane abduction (SCAP). Five normalization methods were assessed using 2 statistical assumptions to determine the most appropriate normalization method for each shoulder strength measure: first, the regression line between a participant characteristic (body mass, height, ulnar length, and their respective combinations) and the unnormalized strength measure passes through the origin; second, normalizing shoulder strength eliminates its correlation with the participant characteristics. Statistical significance was set a priori at < 0.05.
Body mass normalization was the only normalization method that satisfied the intercept and correlation assumptions for ER, IR, and SCAP strength ( > .05).
Normalizing shoulder ER, IR, and SCAP strength in uninjured baseball athletes using body mass satisfied both statistical assumptions. When clinicians seek to compare shoulder strength in baseball athletes of differing anthropometric make-up, using body mass as the denominator is the most appropriate method for normalization.
The utilization of a statistically supported shoulder strength normalization method is warranted to account for anthropometric differences when comparing strength between athletes. This study adds a clinically relevant and reproducible method for normalizing isometric shoulder strength in uninjured baseball players.
棒球运动中的手臂损伤持续增加。先前的研究已经证实了棒球运动员肩部力量、受伤风险和运动表现之间的关系。肩部力量测量值在棒球运动员内部和之间差异很大，并且受到人体测量指标的严重影响。目前，肩部力量测量值的标准化尚未得到充分测试，无法满足必要的统计假设。
至少有一种肩部力量标准化方法能够满足两个统计假设：截距假设和相关性假设。
横断面研究。
3级。
通过手持测力计对一组未受伤的棒球运动员的优势肢体进行等长肩部力量测试：外旋（ER）、内旋（IR）和肩胛平面外展（SCAP）。使用两个统计假设评估了五种标准化方法，以确定每种肩部力量测量的最合适标准化方法：第一，参与者特征（体重、身高、尺骨长度及其各自组合）与未标准化力量测量之间的回归线通过原点；第二，标准化肩部力量消除其与参与者特征的相关性。统计显著性预先设定为<0.05。
体重标准化是唯一满足ER、IR和SCAP力量截距和相关性假设的标准化方法（>.05）。
使用体重对未受伤的棒球运动员的肩部ER、IR和SCAP力量进行标准化，满足了两个统计假设。当临床医生试图比较不同人体测量构成的棒球运动员的肩部力量时，以体重作为分母是最合适的标准化方法。
在比较运动员之间的力量时，有必要使用统计学支持的肩部力量标准化方法来考虑人体测量差异。本研究增加了一种临床相关且可重复的方法，用于对未受伤的棒球运动员的等长肩部力量进行标准化。
