腓肠肌内侧头和外侧头肌肉活动随足部位置的变化
VARIATION IN MEDIAL AND LATERAL GASTROCNEMIUS MUSCLE ACTIVITY WITH FOOT POSITION.
作者信息
Cibulka Michael, Wenthe April, Boyle Zach, Callier Dylan, Schwerdt Adam, Jarman Deidra, Strube Michael J
机构信息
Maryville University, St. Louis, MO, USA.
Washington University, St. Louis, MO.
出版信息
Int J Sports Phys Ther. 2017 Apr;12(2):233-241.
BACKGROUND
The gastrocnemius has two heads, medial gastrocnemius (MG) and lateral gastrocnemius (LG); little is known how they contract with different foot positions. The MG is more frequently strained than the LG; and gastrocnemius activation pattern altered by foot position may play a role in injury. Leg exercises often use a toe-in versus toe-out foot position to isolate one gastrocnemius head over another.
PURPOSE
The purpose of this study was to determine the electromyographic gastrocnemius muscle activity in the toe-out and toe-in foot positions during weight bearing and non-weight bearing activities. The hypothesis was that a toe-out foot position would elicit greater MG than LG activity; while the toe-in position would elicit greater activity in LG than MG in both weight bearing and non-weight bearing (NWB) positions.
STUDY DESIGN
A cross-sectional study of young adults.
METHODS
Thirty-three participants were recruited. Surface electrodes were placed on the bellies of the MG and LG. The gastrocnemius muscle was tested in toe-in and toe-out foot positions using two different tests: a standing heel-rise and resisted knee flexion while prone. Electromyographic activity was normalized against a MVIC during a heel raise with a neutral foot position. A 2x2x2 (Foot Position x Test Position x Muscle) ANOVA was used to determine if differences exist in activity between the MG and LG for toe-in versus toe-out standing and prone test positions.
RESULTS
Significant test position main effect (F [1,32] = 86.9; p < .01), significant muscle main effect (F [1,32]=5.5; p < .01), and significant foot position x muscle interaction (F [1,32] = 14.58; p < .01) were found. Post hoc tests showed differences between MG and LG in toe-out position (t = 3.10; p < .01) but not in the toe-in for both test positions (t = 1.27; p = 0.21).
CONCLUSIONS
With toe-out, the MG was more active than LG in standing and prone; no difference was noted between MG and LG in toe-in for either position.
LEVEL OF EVIDENCE
Level 2.
背景
腓肠肌有两个头，即内侧腓肠肌（MG）和外侧腓肠肌（LG）；关于它们在不同足部位置时如何收缩，人们了解甚少。MG比LG更常出现拉伤；而因足部位置改变的腓肠肌激活模式可能在损伤中起作用。腿部锻炼常采用脚尖内扣与脚尖外展的足部位置来孤立一侧腓肠肌头。
目的
本研究的目的是确定在负重和非负重活动期间，脚尖外展和脚尖内扣足部位置时腓肠肌的肌电图活动。假设是脚尖外展的足部位置会使MG的活动大于LG；而在负重和非负重（NWB）位置时，脚尖内扣的位置会使LG的活动大于MG。
研究设计
对年轻成年人的横断面研究。
方法
招募了33名参与者。将表面电极置于MG和LG的肌腹上。使用两种不同测试在脚尖内扣和脚尖外展的足部位置测试腓肠肌：站立提踵和俯卧位时的抗阻屈膝。在中立足部位置提踵期间，将肌电图活动相对于最大随意等长收缩（MVIC）进行标准化。使用2×2×2（足部位置×测试位置×肌肉）方差分析来确定在脚尖内扣与脚尖外展的站立和俯卧测试位置时，MG和LG之间的活动是否存在差异。
结果
发现显著的测试位置主效应（F [1,32] = 86.9；p <.01）、显著的肌肉主效应（F [1,32] = 5.5；p <.01）以及显著的足部位置×肌肉交互作用（F [1,32] = 14.58；p <.01）。事后检验显示，在脚尖外展位置时MG和LG之间存在差异（t = 3.10；p <.01），但在两个测试位置的脚尖内扣时均无差异（t = 1.27；p = 0.21）。
结论
脚尖外展时，MG在站立和俯卧位时比LG更活跃；在任一位置的脚尖内扣时，MG和LG之间均未发现差异。
证据水平
2级。
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