Bilateral level of effort of the plantar flexors, hip flexors, and extensors during gait in hemiparetic and healthy individuals

Background and Purpose-Muscle weakness is recognized as a key factor in gait performance of poststroke individuals, but its impact on lower-limb muscular effort has been scarcely studied. The aims of this study were to compare the level of effort of the lower limbs of hemiparetic and able-bodied individuals and to assess the effect of side, cadence, and muscle group.Methods-Seventeen chronic hemiparetic participants (7 females and 10 males) with a mean age of 60.5 +/- 13.4 years were assessed when walking. They were compared with a group of 14 able-bodied individuals. The level of effort was estimated from the muscular utilization ratio (MUR), which relates the walking moment of a given muscle group to its maximal potential moment. Peak MUR and MURarea were used as main outcome measures.Results-Hemiparetic individuals showed greater peak MUR values (45% to 78%) than the able-bodied subjects matched for cadence (24% to 63%). For both groups, the peak MUR values were similar between sides and increased with cadence. At self-selected cadence, the plantar flexors showed greater peak MUR values, whereas at maximal cadence, levels of effort for all muscles were equivalent. The MURarea values at the hip joint were greater for the hemiparetic group, and both groups had values that increased with cadence. Differences between sides and muscle groups were noted for the hemiparetic and healthy individuals, respectively. Large peak MUR values were associated with high MURarea values.Conclusions-For a similar cadence, the levels of effort of hemiparetic individuals were greater than those of the able-bodied. In the presence of muscle weakness, similar bilateral levels of effort could mean that hemiparetic individuals relied on their sense of effort while walking.

背景与目的——肌肉无力被认为是卒中后个体步态表现的关键因素，但其对下肢肌肉用力的影响却鲜有研究。本研究的目的是比较偏瘫患者和健康个体下肢的用力水平，并评估侧别、步频和肌群的影响。 方法——对17名平均年龄为60.5±13.4岁的慢性偏瘫患者（7名女性和10名男性）在行走时进行评估，并与14名健康个体组成的一组进行比较。用力水平通过肌肉利用率（MUR）来估算，该比率将特定肌群的行走力矩与其最大潜在力矩相关联。峰值MUR和MUR面积被用作主要的结果测量指标。 结果——偏瘫患者的峰值MUR值（45% - 78%）比步频匹配的健康受试者（24% - 63%）更高。对于两组而言，两侧的峰值MUR值相似，且随步频增加。在自选步频下，跖屈肌的峰值MUR值更高，而在最大步频下，所有肌肉的用力水平相当。偏瘫组髋关节的MUR面积值更大，且两组的值均随步频增加。偏瘫患者和健康个体分别在侧别和肌群方面存在差异。较大的峰值MUR值与较高的MUR面积值相关。 结论——在步频相似的情况下，偏瘫患者的用力水平高于健康个体。在存在肌肉无力的情况下，相似的双侧用力水平可能意味着偏瘫患者在行走时依赖其用力的感觉。