Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, MS 39216, USA.
J Appl Physiol (1985). 2011 Nov;111(5):1290-5. doi: 10.1152/japplphysiol.00462.2011. Epub 2011 Sep 1.
We tested the hypothesis that force variability and error during maintenance of submaximal isometric knee extension are greater in subacute stroke patients than in controls and are related to motor impairments. Contralesional (more-affected) and ipsilesional (less-affected) legs of 33 stroke patients with sufficiently high motor abilities (62 ± 13 yr, 16 ± 2 days postinjury) and the dominant leg of 20 controls (62 ± 10 yr) were tested in sitting position. After peak knee extension torque [maximum voluntary contraction (MVC)] was established, subjects maintained 10, 20, 30, and 50% of MVC as steady and accurate as possible for 10 s by matching voluntary force to the target level displayed on a monitor. Coefficient of variation (CV) and root-mean-square error (RMSE) were used to quantify force variability and error, respectively. The MVC was significantly smaller in the more-affected than less-affected leg, and both were significantly lower than in controls. The CV was significantly larger in the more-affected than less-affected leg at 20 and 50% MVC, whereas both were significantly larger compared with controls across all force levels. Both more-affected and less-affected legs of patients showed significantly greater RMSE than controls at 30 and 50% MVC. The CV and RMSE were not related to the Fugl-Meyer motor score or to the Rivermead Mobility Index. The CV negatively correlated with MVC in controls but only in the less-affected leg of patients. It is concluded that isometric knee extension strength and force control are bilaterally impaired soon after stroke but more so in the more-affected leg. Future studies should examine possible mechanisms and the evolution of these changes.
我们检验了以下假说，即在亚急性脑卒中患者中，与对照相比，维持次最大等长膝伸展过程中的力变异性和误差更大，且与运动障碍相关。33 例脑卒中患者（62±13 岁，损伤后 16±2 天）具有足够高的运动能力，其患侧（更受影响）和健侧（较不受影响）腿以及 20 例对照的优势腿在坐姿下进行了测试。在确定最大膝伸扭矩（最大随意收缩（MVC））后，受测者通过将自愿用力与显示器上显示的目标水平相匹配，尽可能稳定和准确地维持 10、20、30 和 50%的 MVC 10s。变异系数（CV）和均方根误差（RMSE）分别用于量化力变异性和误差。患侧腿的 MVC 明显小于健侧腿，且均明显低于对照组。在 20%和 50%MVC 时，患侧腿的 CV 明显大于健侧腿，而在所有力水平下，两者均明显大于对照组。与对照组相比，患者的患侧和健侧腿在 30%和 50%MVC 时的 RMSE 均显著更大。CV 和 RMSE 与 Fugl-Meyer 运动评分或 Rivermead 移动指数均无关。CV 与对照组的 MVC 呈负相关，但仅在患者的健侧腿中存在。因此，等长膝伸展强度和力控制在脑卒中后不久即双侧受损，但在更受影响的腿中更为明显。未来的研究应该检查这些变化的可能机制和演变。
