J Sport Rehabil. 2019 Mar 1;28(3):229-235. doi: 10.1123/jsr.2017-0110. Epub 2018 Oct 1.
The infraspinatus muscle plays a particularly important role in producing primary external rotation (ER) torque and dynamic stability of the shoulder joint. Previous studies have reported that prone external rotation with horizontal abduction (PER), side-lying wiper exercise (SWE), and standing external rotation (STER) were effective exercises for strengthening the infraspinatus. However, we do not have enough knowledge about changes in muscle strength and dynamic muscle activity in each exercise under dynamic conditions.
To compare the ER muscle strength, muscle activity among exercise methods and between muscle contraction types during 3 different exercises.
Repeated measures design in which ER muscle strength and muscle activities data were collected from subjects under 3 exercise conditions.
Outpatient clinic.
A total of 15 healthy men with no shoulder, neck, or upper-extremity pain were participated.
The subjects performed 3 different exercises randomly in concentric and eccentric using a Biodex dynamometer at an angular velocity of 60°/s.
The ER peak torque (PT) data was collected and surface electromyography was used to measure the activity of the infraspinatus and posterior deltoid muscles and infraspinatus to posterior deltoid muscle activity ratio.
There was significant main effect for muscle contraction type in ER PT (P < .05). The concentric PT was greater during PER (P < .05) and SWE (P < .05) compared with eccentric. The main effect for exercise was found in ER PT and muscle activity (P < .05). The ER PT and infraspinatus muscle activity were the largest increased during PER whereas the lowest during STER in both concentric and eccentric (P < .05).
The results of this study suggest that PER is an exercise for strengthening the infraspinatus muscle effectively.
冈下肌在产生肩部主要外旋（ER）扭矩和动态稳定性方面起着特别重要的作用。之前的研究报告称，仰卧外展水平外旋（PER）、侧卧擦拭练习（SWE）和站立外旋（STER）是加强冈下肌的有效练习。然而，我们对于动态条件下每种练习的肌肉力量和动态肌肉活动的变化知之甚少。
比较 3 种不同运动方式下 ER 肌肉力量、肌肉活动，并比较肌肉收缩类型之间的差异。
在 3 种运动条件下，对受试者进行重复测量设计，以收集 ER 肌肉力量和肌肉活动数据。
门诊。
共有 15 名无肩部、颈部或上肢疼痛的健康男性参加。
受试者以 60°/s 的角速度在同心和离心两种情况下随机进行 3 种不同的运动。
收集 ER 峰值扭矩（PT）数据，并使用表面肌电图测量冈下肌和后三角肌的活动以及冈下肌与后三角肌的活动比。
在 ER PT 方面，肌肉收缩类型存在显著的主效应（P < .05）。与离心相比，PER（P < .05）和 SWE（P < .05）的同心 PT 更大。在 ER PT 和肌肉活动方面，运动存在显著的主效应（P < .05）。在同心和离心两种情况下，PER 的 ER PT 和冈下肌肌肉活动增加最大，而 STER 则最小（P < .05）。
本研究结果表明，PER 是一种有效增强冈下肌力量的运动。
