Myocontrol holds great promise because it has the potential to provide flexible and accurate prosthetic control that approaches the quality of normal movement. Speed and accuracy are important factors to consider when applying myoelectric signals to external devices. Fitts's law can be used to assess the speed-accuracy trade-off. We hypothesized that speed is affected not only by accuracy as prescribed by Fitts's law, but also by target distances independent of target size. A total of 12 healthy adult subjects were studied. Subjects controlled the vertical movement of a computer cursor by contracting their dominant first dorsal interosseus muscle to reach targets as quickly as possible. We manipulated twenty-five different target distances in order to obtain five indices of difficulty, as defined by Fitts's law, combined with five target widths. We tested the relationship between movement time and the index of difficulty as predicted by Fitts's law among different combinations of target distance and widths. Results showed a significant linear regression for all conditions, with the exception of a significantly longer movement time than predicted for targets close to the start point. Movements to these targets showed significantly higher relative variance during stabilization, higher overshoot, and lower success. Therefore, we found that with comparable index of difficulty, small distance movements had a higher variability, slower movement, and higher rates of error compared to larger distance movements. Our results are consistent with our hypothesis that low muscle activation required for short distances results in higher variability and low controllability in reaching the target as required by the task demand. Neurophysiological mechanisms underlying the violation of the Fitts's law relationship are discussed. These results have significance for myocontrol applications, and we suggest that such applications require control signals with sufficient recruitment to reduce variability at lower levels of muscle activation.

Myocontrol具有广阔的前景，因为它有潜力提供接近正常运动质量的灵活而准确的义肢控制。将肌电信号应用于外部设备时，速度和准确性是要考虑的重要因素。菲茨定律可用于评估速度精度的权衡。我们假设速度不仅受Fitts定律规定的精度的影响，还受到与目标大小无关的目标距离的影响。共研究了12名健康成人受试者。受试者通过收缩其支配的第一背骨间第一肌以尽快达到目标，来控制计算机光标的垂直移动。根据菲茨定律，我们操纵了25个不同的目标距离，以获得5个难度指标，结合五个目标宽度 我们测试了根据目标距离和宽度的不同组合，根据费茨定律预测的运动时间与难度指数之间的关系。结果显示在所有条件下均具有显着的线性回归，但运动时间明显长于接近起点的目标所预测的时间。向这些目标的移动显示出稳定过程中的相对方差明显更高，超调次数更高，成功率更低。因此，我们发现，与较大的距离运动相比，在具有可比较的难度指标的情况下，较小的距离运动具有较高的可变性，较慢的运动和较高的错误率。我们的结果与我们的假设是一致的，即，短距离所需的低肌肉激活导致任务要求所要求的达到目标的更高可变性和较低可控性。讨论了违反菲茨定律关系的神经生理机制。这些结果对于肌控应用具有重要意义，我们建议此类应用需要具有足够募集功能的控制信号，以降低较低水平的肌肉激活时的变异性。