Step length asymmetry (SLA) is common in most stroke survivors. Several studies have shown that factors such as paretic propulsion can explain between-subjects differences in SLA. However, whether the factors that account for between-subjects variance in SLA are consistent with those that account for within-subjects, stride-by-stride variance in SLA has not been determined. SLA direction is heterogeneous, and different impairments likely contribute to differences in SLA direction. Here, we identified common predictors between-subjects that explain within-subjects variance in SLA using sparse partial least squares regression (sPLSR). We determined whether the SLA predictors differ based on SLA direction and whether predictors obtained from within-subjects analyses were the same as those obtained from between-subjects analyses. We found that for participants who walked with longer paretic steps paretic double support time, braking impulse, peak vertical ground reaction force, and peak plantarflexion moment explained 59% of the within-subjects variance in SLA. However the within-subjects variance accounted for by each individual predictor was less than 10%. Peak paretic plantarflexion moment accounted for 4% of the within-subjects variance and 42% of the between-subjects variance in SLA. In participants who walked with shorter paretic steps, paretic and non-paretic braking impulse explained 18% of the within-subjects variance in SLA. Conversely, paretic braking impulse explained 68% of the between-subjects variance in SLA, but the association between SLA and paretic braking impulse was in the opposite direction for within-subjects vs. between-subjects analyses. Thus, the relationships that explain between-subjects variance might not account for within-subjects stride-by-stride variance in SLA.

中文翻译：

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不同的生物力学变量解释了中风后步长不对称的受试者内与受试者间差异


步长不对称（SLA）在大多数中风幸存者中很常见。多项研究表明，诸如麻痹推进力等因素可以解释受试者之间 SLA 的差异。然而，尚未确定解释受试者间 SLA 差异的因素是否与解释受试者内部 SLA 逐步方差的因素一致。 SLA 方向是异构的，不同的损伤可能会导致 SLA 方向的差异。在这里，我们使用稀疏偏最小二乘回归 (sPLSR) 确定了受试者之间的常见预测因子，这些预测因子可以解释 SLA 中受试者内的方差。我们根据 SLA 方向确定 SLA 预测变量是否不同，以及从受试者内分析获得的预测变量是否与从受试者间分析获得的预测变量相同。我们发现，对于以较长麻痹步数行走的参与者，麻痹双支撑时间、制动脉冲、峰值垂直地面反作用力和峰值跖屈力矩解释了 SLA 受试者内差异的 59%。然而，每个个体预测变量所解释的受试者内方差小于 10%。峰值麻痹跖屈力矩占 SLA 受试者内方差的 4% 和受试者间方差的 42%。在以较短的麻痹步伐行走的参与者中，麻痹和非麻痹制动冲动解释了 SLA 受试者内部差异的 18%。相反，麻痹制动冲动解释了 SLA 受试者间差异的 68%，但在受试者内部与受试者间分析中，SLA 和麻痹制动冲动之间的关联方向相反。 因此，解释受试者间方差的关系可能无法解释受试者内 SLA 中的逐步方差。