IEEE Trans Neural Syst Rehabil Eng. 2021;29:690-698. doi: 10.1109/TNSRE.2021.3070468. Epub 2021 Apr 14.
Functional Electrical Stimulation (FES) may be used in rehabilitation and assistance of people with Spinal Cord Injury (SCI). One significant application is facilitating physical exercise, mainly when combining FES with mechanical platforms, such as tricycles. However, there are still technical challenges in FES cycling protocols, such as improving control and cycling performance. Here we show how passive elements in knee orthoses during FES cycling could increase the average cadence, taking advantage of the cycling movement. Our approach is twofold. First, we simulated the forward dynamics of a detailed musculoskeletal model with passive elements over the knees. Simulations showed that specific spring stiffness ranges increased the crankset speed during cycling by more than 50%. Using parameters found in simulations, we built a pair of passive orthoses and performed experiments with one individual with SCI. During two days, the volunteer cycled with similar stimulation magnitude with and without the passive elements. We observed that the average crankset speed was higher by more than 10% when the springs were attached to the passive orthoses. These results show the potential of using passive elements to increase cycling speed for FES cycling with similar or even lower stimulation magnitude, leading to longer exercise duration.
功能性电刺激（FES）可用于脊髓损伤（SCI）患者的康复和辅助。一个重要的应用是促进体育锻炼，主要是将 FES 与机械平台（如三轮车）结合使用。然而，在 FES 自行车运动协议中仍然存在技术挑战，例如提高控制和骑行性能。在这里，我们展示了在 FES 自行车运动中，膝关节矫形器中的无源元件如何利用自行车运动来增加平均踏频。我们的方法有两种。首先，我们模拟了具有膝关节无源元件的详细肌肉骨骼模型的前向动力学。模拟表明，特定的弹簧刚度范围使曲柄速度在自行车运动中提高了 50%以上。使用模拟中找到的参数，我们制造了一对无源矫形器，并对一名 SCI 患者进行了实验。在两天的时间里，志愿者在刺激幅度相似的情况下，使用和不使用无源元件进行了自行车运动。我们观察到，当弹簧连接到无源矫形器时，曲柄速度的平均值提高了 10%以上。这些结果表明，使用无源元件可以提高 FES 自行车运动的速度，同时使用相似甚至更低的刺激幅度，从而延长运动时间。
