Biomedical Engineering Program, Bainer Hall, University of California, One Shields Avenue, Davis, California 95616, USA.
Muscle Nerve. 2010 Jun;41(6):857-67. doi: 10.1002/mus.21603.
Mathematical prediction of power loss during electrically stimulated contractions is of value to those trying to minimize fatigue and to those trying to decipher the relative contributions of force and velocity. Our objectives were to: (1) develop a model of non-isometric fatigue for electrical stimulation-induced, open-chain, repeated extensions of the leg at the knee; and (2) experimentally validate the model. A computer-controlled stimulator sent electrical pulses to surface electrodes on the thighs of 17 able-bodied subjects. Isometric and non-isometric non-fatiguing and fatiguing leg extension torque and/or angle at the knee were measured. Two existing mathematical models, one of non-isometric force and the other of isometric fatigue, were combined to develop the non-isometric force-fatigue model. Angular velocity and 3 new parameters were added to the isometric fatigue model. The new parameters are functions of parameters within the force model, and therefore additional measurements from the subject are not needed. More than 60% of the variability in the measurements was explained by the new force-fatigue model. This model can help scientists investigate the etiology of non-isometric fatigue and help engineers to improve the task performance of functional electrical stimulation systems.
电刺激收缩过程中功率损耗的数学预测对于那些试图最小化疲劳的人以及那些试图解释力和速度相对贡献的人很有价值。我们的目标是：(1) 开发一种用于膝关节开放式链重复伸展的电刺激诱导的非等长疲劳模型；(2) 对模型进行实验验证。计算机控制的刺激器将电脉冲发送到 17 名健康受试者大腿上的表面电极。测量等长和非等长非疲劳和疲劳时的膝关节伸肌扭矩和/或角度。将两种现有的数学模型（一种是非等长力模型，另一种是等长疲劳模型）结合起来，开发非等长力-疲劳模型。角速度和 3 个新参数被添加到等长疲劳模型中。新参数是力模型中参数的函数，因此不需要来自受试者的额外测量。新的力-疲劳模型解释了测量值的 60%以上的可变性。该模型可以帮助科学家研究非等长疲劳的病因，并帮助工程师提高功能性电刺激系统的任务性能。
