Dept of Physiotherapy, University of Limerick, Limerick, Ireland.
J Sport Rehabil. 2011 May;20(2):174-86. doi: 10.1123/jsr.20.2.174.
Functional subdivisions are proposed to exist in the gluteus medius (GM) muscle. Dysfunction of the GM, in particular its functional subdivisions, is commonly implicated in lower limb pathologies. However, there is a lack of empirical evidence examining the role of the subdivisions of the GM.
To compare the activation of the functional subdivisions of the GM (anterior, middle, and posterior) during isometric hip contractions.
Single-session, repeated-measures observational study.
University research laboratory.
Convenience sample of 15 healthy, pain-free subjects.
Subjects performed 3 maximal voluntary isometric contractions for hip abduction and internal and external rotation on an isokinetic dynamometer with simultaneous recording of surface electromyography (sEMG) activity of the GM subdivisions.
sEMG muscle activity for each functional subdivision of the GM during each hip movement was analyzed using a 1-way repeated-measures ANOVA (post hoc Bonferroni).
The response of GM subdivisions during the 3 different isometric contractions was significantly different (interaction effect; P = .003). The anterior GM displayed significantly higher activation across all 3 isometric contractions than the middle and posterior subdivisions (main effect; both P < .001). The middle GM also demonstrated significantly higher activation than the posterior GM across all 3 isometric contractions (main effect; P = .027). There was also significantly higher activation of all 3 subdivisions during both abduction and internal rotation than during external rotation (main effect; both P < .001).
The existence of functional subdivisions in the GM appears to be supported by the findings. Muscle activation was not homogeneous throughout the entire muscle. The highest GM activation was found in the anterior GM subdivision and during abduction and internal rotation. Future studies should examine the role of GM functional subdivisions in subjects with lower limb pathologies.
臀中肌（GM）存在功能亚区。GM 功能障碍，尤其是其功能亚区的功能障碍，通常与下肢疾病有关。然而，目前缺乏关于 GM 亚区作用的实证证据。
比较等长髋关节收缩时 GM 的功能亚区（前、中、后）的激活情况。
单次、重复测量的观察性研究。
大学研究实验室。
15 名健康、无痛的受试者。
受试者在等速测力计上进行 3 次最大自主等长髋关节外展和内收、外旋收缩，同时记录 GM 亚区的表面肌电图（sEMG）活动。
分析 GM 各功能亚区在每次髋关节运动中的 sEMG 肌肉活动，采用单因素重复测量方差分析（事后 Bonferroni 检验）。
GM 亚区在 3 种不同等长收缩中的反应存在显著差异（交互效应；P =.003）。前 GM 在所有 3 种等长收缩中的激活均显著高于中、后 GM（主效应；均 P <.001）。中 GM 在所有 3 种等长收缩中的激活也显著高于后 GM（主效应；P =.027）。在所有 3 种等长收缩中，外展和内收时 GM 所有 3 个亚区的激活均显著高于外旋时（主效应；均 P <.001）。
研究结果支持 GM 存在功能亚区的观点。整个肌肉的肌肉激活并非均匀分布。GM 激活最高的部位在前 GM 亚区，且在髋关节外展和内收时。未来的研究应探讨 GM 功能亚区在下肢疾病患者中的作用。
