Physical Therapy Department and Graduate Institute of Rehabilitation Science, Chang Gung University, 259, Wen-Hwa 1st Rd, Kweishan, Tao-Yuan, Taiwan.
Sensors (Basel). 2010;10(1):796-807. doi: 10.3390/s100100796. Epub 2010 Jan 21.
Interpolated twitch technique (ITT) is a non-invasive method for assessing the completeness of muscle activation in clinical settings. Voluntary activation level (VA), measured by ITT and estimated by a conventional linear model, was reported to have a non-linear relationship with true voluntary contraction force at higher activation levels. The relationship needs to be further clarified for the correct use by clinicians and researchers. This study was to established a modified voluntary activation (modified VA) and define a valid range by fitting a non-linear logistic growth model. Eight healthy male adults participated in this study. Each subject performed three sets of voluntary isometric ankle plantar flexions at 20, 40, 60, 80 and 100% maximal voluntary contraction (MVC) with real-time feedback on a computer screen. A supramaximal electrical stimulation was applied on tibia nerve at rest and during contractions. The estimated VA was calculated for each contraction. The relationship between the estimated VA and the actual voluntary contraction force was fitted by a logistic growth model. The result showed that according to the upper and lower limit points of the logistic curve, the valid range was between the 95.16% and 10.55% MVC. The modified VA estimated by this logistic growth model demonstrated less error than the conventional model. This study provided a transfer function for the voluntary activation level and defined the valid range which would provide useful information in clinical applications.
插值抽搐技术（ITT）是一种在临床环境中评估肌肉激活完整性的非侵入性方法。通过 ITT 测量的自愿激活水平（VA）和通过传统线性模型估计的 VA 被报道在较高激活水平下与真实自愿收缩力呈非线性关系。为了正确供临床医生和研究人员使用，需要进一步阐明这种关系。本研究旨在通过拟合非线性逻辑增长模型来建立一种改良的自愿激活（改良 VA）并定义有效范围。八名健康男性成年人参加了这项研究。每位受试者在计算机屏幕上实时反馈的情况下，以 20%、40%、60%、80%和 100%最大自愿收缩（MVC）的三个组进行自愿等长踝关节跖屈运动。在休息和收缩期间，对胫骨神经施加超最大电刺激。为每次收缩计算估计的 VA。通过逻辑增长模型拟合估计的 VA 与实际自愿收缩力之间的关系。结果表明，根据逻辑曲线的上限和下限点，有效范围在 95.16%和 10.55%MVC 之间。通过这种逻辑增长模型估计的改良 VA 比传统模型误差更小。本研究提供了一种自愿激活水平的传递函数，并定义了有效范围，这将在临床应用中提供有用的信息。
