1 University of Southern California, Los Angeles, CA, USA.
Neurorehabil Neural Repair. 2018 Aug;32(8):701-713. doi: 10.1177/1545968318787913. Epub 2018 Jul 12.
Changes in the control of the lower extremities poststroke lead to persistent biomechanical asymmetries during walking. These asymmetries are associated with an increase in energetic cost, leading to the possibility that reducing asymmetry can improve walking economy. However, the influence of asymmetry on economy may depend on the direction and cause of asymmetry. For example, impairments with paretic limb advancement may result in shorter paretic steps, whereas deficits in paretic support or propulsion result in shorter nonparetic steps. Given differences in the underlying impairments responsible for step length asymmetry, the capacity to reduce asymmetry and the associated changes in energetic cost may not be consistent across this population. Here, we identified factors explaining individual differences in the capacity to voluntarily reduce step length asymmetry and modify energetic cost during walking. A total of 24 individuals poststroke walked on a treadmill, with visual feedback of their step lengths to aid explicit modification of asymmetry. We found that individuals who took longer paretic steps had a greater capacity to reduce asymmetry and were better able to transfer the effects of practice to overground walking than individuals who took shorter paretic steps. In addition, changes in metabolic cost depended on the direction of asymmetry, baseline cost of transport, and reductions in specific features of spatiotemporal asymmetry. These results demonstrate that many stroke survivors retain the residual capacity to voluntarily walk more symmetrically on a treadmill and overground. However, whether reductions in asymmetry reduce metabolic cost depends on individual differences in impairments affecting locomotor function.
脑卒中后下肢控制的改变导致步行时持续存在生物力学不对称。这些不对称与能量消耗增加有关，因此减少不对称性可能会改善步行经济性。然而，不对称性对经济性的影响可能取决于不对称性的方向和原因。例如，由于瘫痪肢体前进的障碍，可能导致瘫痪侧步长变短，而瘫痪侧支撑或推进的缺陷则导致非瘫痪侧步长变短。鉴于导致步长不对称的潜在损伤不同，自愿减少不对称性的能力以及相关的能量消耗变化在该人群中可能不一致。在这里，我们确定了可解释个体在自愿减少步长不对称性和修改步行时能量消耗的能力方面的差异的因素。共有 24 名脑卒中后患者在跑步机上行走，同时提供步长的视觉反馈以帮助明确修改不对称性。我们发现，与步长较短的患者相比，步长较长的患者具有更大的减少不对称性的能力，并且能够更好地将练习的效果转移到地面行走中。此外，代谢成本的变化取决于不对称性的方向、基础运输成本以及时空不对称性特定特征的减少。这些结果表明，许多脑卒中幸存者在跑步机和地面上仍然保留着自愿更对称行走的剩余能力。然而，减少不对称性是否会降低代谢成本取决于影响运动功能的损伤的个体差异。
