Self-selected step length asymmetry is not explained by energy cost minimization in individuals with chronic stroke
Self-selected step length asymmetry is not explained by energy cost minimization in individuals with chronic stroke
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DOI：
10.1186/s12984-020-00733-y
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发表时间：
2020-08-26
影响因子：
5.1
通讯作者：
Torres-Oviedo, Gelsy
中科院分区：
文献类型：
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作者：
Nguyen, Thu M.;Jackson, Rachel W.;Torres-Oviedo, Gelsy
背景中风后步态不对称与活动能力下降有关，然而慢性中风患者尽管能够更对称地行走，但通常会自我选择不对称步态。本研究的目的是测试自我选择的不对称性是否可以解释为能源成本最小化。我们假设短期偏离自我选择的不对称性会导致代谢能量消耗增加，尽管与长期康复益处相关。其他研究发现，在慢性中风患者中，不同程度的强制不对称的代谢率没有差异，但使用的方法留下了一些不确定性有待解决。方法在这项研究中，10名慢性中风患者在跑步机上以参与者特有的速度行走，同时自愿改变步长不对称。我们只纳入了临床相关的自我选择的不对称谁能够显着改变不对称使用视觉生物反馈的参与者。条件包括瞄准零不对称、自选不对称和自选不对称的两倍。参与者在一次会议上接受生物反馈系统的培训，并在随后的三次会议上重复测量收集数据。自我选择的不对称性是一致的跨会话。在未受损的参与者中进行了类似的协议。结果慢性中风患者使用生物反馈显著改变了步长不对称性，但这并不影响代谢率（ANOVA，p = 0.68）。在未受损的参与者中，自我选择的步长不对称接近于零，对应于最低的代谢能量成本（ANOVA，p = 6 e-4）。虽然未受损步态的对称性可能是能量成本最小化的结果，但慢性卒中患者的自我选择步长不对称性不能用类似的最小努力驱动来解释。结论通过控制代谢能量消耗来鼓励改变步长不对称性的干预措施可能是有效的，因为这些疗法不必克服改变不对称性的代谢惩罚。
Background Asymmetric gait post-stroke is associated with decreased mobility, yet individuals with chronic stroke often self-select an asymmetric gait despite being capable of walking more symmetrically. The purpose of this study was to test whether self-selected asymmetry could be explained by energy cost minimization. We hypothesized that short-term deviations from self-selected asymmetry would result in increased metabolic energy consumption, despite being associated with long-term rehabilitation benefits. Other studies have found no difference in metabolic rate across different levels of enforced asymmetry among individuals with chronic stroke, but used methods that left some uncertainty to be resolved. Methods In this study, ten individuals with chronic stroke walked on a treadmill at participant-specific speeds while voluntarily altering step length asymmetry. We included only participants with clinically relevant self-selected asymmetry who were able to significantly alter asymmetry using visual biofeedback. Conditions included targeting zero asymmetry, self-selected asymmetry, and double the self-selected asymmetry. Participants were trained with the biofeedback system in one session, and data were collected in three subsequent sessions with repeated measures. Self-selected asymmetry was consistent across sessions. A similar protocol was conducted among unimpaired participants. Results Participants with chronic stroke substantially altered step length asymmetry using biofeedback, but this did not affect metabolic rate (ANOVA,p = 0.68). In unimpaired participants, self-selected step length asymmetry was close to zero and corresponded to the lowest metabolic energy cost (ANOVA,p = 6e-4). While the symmetry of unimpaired gait may be the result of energy cost minimization, self-selected step length asymmetry in individuals with chronic stroke cannot be explained by a similar least-effort drive. Conclusions Interventions that encourage changes in step length asymmetry by manipulating metabolic energy consumption may be effective because these therapies would not have to overcome a metabolic penalty for altering asymmetry.