Department of Orthopedics and Traumatology, Policlinico San Pietro, Ponte San Pietro, Bergamo, Italy.
Transalpine Center of Pediatric Sports Medicine and Surgery, University of Milano-Bicocca, Monza, Monza-Brianza, Italy.
J Sports Med Phys Fitness. 2023 Nov;63(11):1138-1145. doi: 10.23736/S0022-4707.23.14912-7. Epub 2023 Aug 4.
Volleyball is an exceptionally popular global sport that involves repetitive, rapid, powerful and wide overhead movements, which can seriously alter normal shoulder kinematics. A recognized hallmark of shoulder muscle balance is the ratio of shoulder external (ER) and internal (IR) rotators. By extension, objective measurement of shoulder muscles' strength could help identify at risk athletes and preempt those injuries by engaging in prescriptive strength training programs.
This cross-sectional study measured the isometric strengths of 1) shoulder internal and external rotator muscles, as well as the 2) supraspinatus, 3) rhomboid, and 4) middle and inferior trapezius muscles, in addition to calculation of ER:IR ratios, in professional volleyball players as well as in non-athletes. Measurements were made for dominant- and non-dominant upper limbs, in different position of the body (supine and orthostatic) and in different position of upper limb (adducted and abducted position). Our subject population included 11 male professional volleyball players as well as 14 healthy male orthopedic interns from Orthopedics and Trauma school of University of Milano Bicocca. Strengths were assessed by a handheld dynamometer. Each subject's isometric strength was assessed in triplicate in each limb position through a "make test" procedure; the greatest of each triplicate value was the accepted measure of isometric strength.
We observed a gradient in muscle strength in the scapulothoracic complex in both groups; the rhomboid, middle trapezius, and lower trapezius ranked from greatest to least strength, respectively. The data suggest also that intrarotators are stronger in rotation adducted position than in rotation abducted position; however, extrarotators seem to be weaker in rotation adducted position than in rotation abducted position. There is also some indication that force development is enhanced in the supine position compared with the orthostatic position.
Our findings indicate a scapulothoracic strength gradient with a rank order of strength of the rhomboid>middle trapezius>lower trapezius. The data further suggest that volleyball players have stronger intrarotation in rotation adducted position than in the rotation abducted position, while extra rotation shows the opposite trend. Finally, our data suggest that force development is greater in the supine position compared to the orthostatic position.
排球是一项在全球范围内非常流行的运动，涉及重复、快速、有力和广泛的头顶动作，这可能会严重改变正常的肩部运动学。肩部肌肉平衡的一个公认标志是肩部外旋（ER）和内旋（IR）旋转肌的比例。通过扩展，肩部肌肉力量的客观测量可以帮助识别有风险的运动员，并通过进行规定的力量训练计划来预防这些损伤。
这项横断面研究测量了职业排球运动员和非运动员的 1）肩部内、外旋肌，以及 2）冈上肌、3）菱形肌和 4）中、下斜方肌的等长力量，以及 ER：IR 比值的计算。测量在不同的身体位置（仰卧位和直立位）和不同的上肢位置（内收位和外展位）进行，分别为优势侧和非优势侧上肢。我们的研究对象包括 11 名男性职业排球运动员和 14 名来自米兰比可卡大学矫形和创伤外科的健康男性骨科实习生。力量由手持测力计评估。每个受试者在每个肢体位置的三次重复“用力测试”过程中评估等长力量；三次重复中的最大值为可接受的等长力量测量值。
我们观察到两组肩胛胸复合体的肌肉力量呈梯度分布；菱形肌、中斜方肌和下斜方肌的力量依次递减。数据还表明，内旋肌在旋转内收位的力量大于在旋转外展位的力量；然而，外旋肌在旋转内收位的力量似乎小于在旋转外展位的力量。还有一些迹象表明，与直立位相比，仰卧位的力发展增强。
我们的发现表明，肩胛胸复合体存在力量梯度，力量顺序为菱形肌>中斜方肌>下斜方肌。数据进一步表明，排球运动员在旋转内收位的内旋力量大于在旋转外展位的内旋力量，而外旋则相反。最后，我们的数据表明，与直立位相比，仰卧位的力发展更大。
