Milot Marie-Hélène, Nadeau Sylvie, Gravel Denis, Bourbonnais Daniel
Faculté de Médecine, Ecole de réadaptation, Université de Montréal and Centre de recherche interdisciplinaire en réadaptation (CRIR), Institut de réadaptation de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Que., Canada H3C 3J7.
Clin Biomech (Bristol). 2008 May;23(4):415-23. doi: 10.1016/j.clinbiomech.2007.11.003. Epub 2007 Dec 20.
Following a stroke, strength gain of the trained affected lower-limb muscles has been observed to result in a change in gait speed, but its effect on other variables related to gait performance has scarcely been studied. The aim of this study was to assess the effect of strength gain of the affected plantarflexors and hip flexors on bilateral levels of effort during gait, in the sagittal plane of movement.
The levels of effort of 24 chronic hemiparetic participants (mean (standard deviation (SD)): 57.3 (SD 15.5) years), who had strength gains in the ankle and hip muscles following a strengthening programme, were estimated with the muscular utilization ratio during self-selected and maximal speeds. The ratio relates the net moment in gait relative to the muscle's maximal capability. The peak value and the area under the curve of the ratio were used as main outcome measures.
Regardless of speed, strength gains have been noted to cause a significant 12-17% decrease in the peak value of the ratio of the affected plantarflexors and hip flexors with a reduction of the area under the curve of the affected hip flexors' ratio and a trend toward a decrease for the affected plantarflexors at maximal speed. A significant, albeit small increase in self-selected and maximal gait speeds (P<0.05) was also observed post-training. Regardless of assessment time, the peak value of the affected plantarflexors' ratio was greater than that of the affected hip flexors at self-selected speed (P=0.006) and the area under the curve of the affected hip flexors' ratio was greater than that of the affected plantarflexors (P=0.007) at maximal speed. Generally, negative associations (-0.32
The decrease in the peak value of the ratio could be explained by the increase in strength. Becoming stronger, hemiparetic participants favoured a reduction of their levels of effort during walking instead of substantially increasing their gait speed.
中风后，已观察到训练的患侧下肢肌肉力量增加会导致步态速度改变，但其对与步态表现相关的其他变量的影响鲜有研究。本研究的目的是评估患侧跖屈肌和髋屈肌力量增加对矢状面运动步态中双侧用力水平的影响。
对24名慢性偏瘫参与者（平均（标准差）：57.3（标准差15.5）岁）进行研究，这些参与者在强化训练后踝关节和髋关节肌肉力量增加，通过自定速度和最大速度下的肌肉利用率来估计其用力水平。该比率将步态中的净力矩与肌肉的最大能力相关联。比率的峰值和曲线下面积用作主要结局指标。
无论速度如何，均发现力量增加导致患侧跖屈肌和髋屈肌比率的峰值显著降低12 - 17%，患侧髋屈肌比率曲线下面积减小，且在最大速度时患侧跖屈肌有减小趋势。训练后还观察到自定速度和最大步态速度有显著但微小的增加（P<0.05）。无论评估时间如何，在自定速度下患侧跖屈肌比率的峰值大于患侧髋屈肌（P = 0.006），在最大速度时患侧髋屈肌比率曲线下面积大于患侧跖屈肌（P = 0.007）。一般而言，比率峰值变化与力量之间存在负相关（-0.32 < r > -0.83），但与步态速度变化之间无负相关。
比率峰值的降低可以用力量增加来解释。偏瘫参与者变得更强壮后，在行走时倾向于减少用力水平，而不是大幅提高步态速度。
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