Kouhzad Mohammadi Hosein, Mehravar Mohammad, Khademi Kalantari Khosro, Naimi Sedighe Sadat, Akbarzadeh Baghban Alireza, Okhovatian Farshad, Rezasoltani Asghar, Mohseni Bandpei Mohammad Ali, Taheri Navid
Musculoskeletal Rehabilitation Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Musculoskeletal Rehabilitation Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
J Bodyw Mov Ther. 2018 Apr;22(2):379-384. doi: 10.1016/j.jbmt.2017.07.004. Epub 2017 Jul 21.
Pronated of the foot is one of the important factors contributing to musculoskeletal problems affecting the lower extremities. It is known that in a pronated foot, excessive mechanical load is applied to the lower limb structures which may result in altered biomechanics and muscle activation patterns. The aim of this study was to determine changes in the muscle activation pattern of the lower extremities in individuals with pronated, compared to normal, feet, using the voluntary response index (VRI).
In this cross sectional study, 15 asymptomatic pronated foot individuals (mean age 23.27 ± 3.28 years) and 15 normal subjects (mean age 23.40 ± 3.11 years) were recruited by simple non-random sampling. Electrical activities of gluteus medius (GM), vastus lateralis (VL), vastus medialis (VM), biceps femoris, semitendinosus (ST), and medial gastrocnemius (MG) muscles were recorded during a forward jump landing task. Voluntary response index (VRI) variables, included similarity index (SI) and magnitude (Mag) were also evaluated.
Muscle activity of VM (p < 0.001) and ST (p = 0.010) were significantly higher but VL (p = 0.039) and MG (p = 0.001) were significantly lower in pronated foot, compared to normal subjects. Similarity index was found to be different (p < 0.001) between pronated foot and healthy individuals. No significant difference was found in terms of Mag between the two groups (p = 0.576).
The altered pattern of lower limb muscle activation identified in the pronated foot during landing may be attributed to the different activation involving VL, VM, MG and ST muscles. Adaptations to the biomechanical effects, due to the pronated foot causing altered activation of VL, VM, MG, and ST muscles, results in an altered pattern of muscle activation. This change in activation pattern may harm the effectiveness of movement control processes; and might also predispose individuals with pronated feet, to injuries. It seems that an altered motor strategy with the aim of minimizing biomechanical changes, predisposes individuals to injuries. However, further large scale studies are needed to support the findings of the present study.
足内翻是导致影响下肢的肌肉骨骼问题的重要因素之一。众所周知，在足内翻的情况下，下肢结构会承受过大的机械负荷，这可能会导致生物力学和肌肉激活模式的改变。本研究的目的是使用自主反应指数（VRI）来确定足内翻个体与正常足个体相比下肢肌肉激活模式的变化。
在这项横断面研究中，通过简单的非随机抽样招募了15名无症状的足内翻个体（平均年龄23.27±3.28岁）和15名正常受试者（平均年龄23.40±3.11岁）。在向前跳跃落地任务期间记录臀中肌（GM）、股外侧肌（VL）、股内侧肌（VM）、股二头肌、半腱肌（ST）和腓肠肌内侧头（MG）的电活动。还评估了自主反应指数（VRI）变量，包括相似性指数（SI）和幅度（Mag）。
与正常受试者相比，足内翻个体的VM（p<0.001）和ST（p=0.010）肌肉活动显著更高，但VL（p=0.039）和MG（p=0.001）显著更低。发现足内翻个体与健康个体之间的相似性指数不同（p<0.001）。两组之间在Mag方面未发现显著差异（p=0.576）。
在落地过程中足内翻个体中发现的下肢肌肉激活模式改变可能归因于VL、VM、MG和ST肌肉的不同激活。由于足内翻导致VL、VM、MG和ST肌肉激活改变而对生物力学效应的适应，导致肌肉激活模式改变。这种激活模式的变化可能会损害运动控制过程的有效性；并且还可能使足内翻个体更容易受伤。似乎旨在最小化生物力学变化的改变的运动策略会使个体更容易受伤。然而，需要进一步的大规模研究来支持本研究的结果。
