Biomedical Engineering, Rutgers University, Piscataway, NJ 08854, USA.
Med Eng Phys. 2011 May;33(4):464-71. doi: 10.1016/j.medengphy.2010.11.012. Epub 2010 Dec 19.
While surface electromyography (SEMG) can accurately register electrical activity of muscles during gait, there are no methods to estimate muscular force non-invasively. To better understand the mechanical behavior of muscle, we evaluated surface muscle pressure (SMP) in conjunction with SEMG. Changes in anterior thigh radial pressure during isometric contractions and gait were registered by pressure sensors on the limb. During isometric knee extensions by a single subject, SMP waveforms correlated well with SEMG (r=0.97), and SEMG onsets preceded those of SMP by 35-40 ms. SMP and SEMG signals were simultaneously recorded from the quadriceps of 10 healthy subjects during gait at speeds of 0.4, 0.8, 1.1, 1.4 and 2.2m/s. Muscle activity onset and cessation times were objectively determined for both modalities, and results showed high intra-class correlations. SMP waveforms were highly consistent from stride to stride, while SEMG waveforms varied widely. SEMG waveforms were typically brief, while SMP waveforms tended to be biphasic and outlasted the SEMG by approximately 40% of gait cycle at all speeds. These results are consistent with mechanical models of muscle, and demonstrate the use of SMP to estimate the timing of knee extensor muscle stiffness during gait.
表面肌电图（SEMG）可以准确记录步态过程中的肌肉电活动，但目前还没有非侵入性估计肌肉力量的方法。为了更好地了解肌肉的力学行为，我们结合 SEMG 评估了表面肌肉压力（SMP）。通过肢体上的压力传感器记录等长收缩和步态过程中前大腿径向压力的变化。在单个受试者进行的单膝伸展等长收缩期间，SMP 波形与 SEMG 高度相关（r=0.97），并且 SEMG 起始时间比 SMP 提前 35-40ms。在 0.4、0.8、1.1、1.4 和 2.2m/s 的速度下，同时从 10 名健康受试者的股四头肌记录 SMP 和 SEMG 信号。两种方式的肌肉活动起始和停止时间均为客观确定，结果显示高度的组内相关性。SMP 波形在步与步之间非常一致，而 SEMG 波形变化很大。SEMG 波形通常很短暂，而 SMP 波形往往呈双相，并且在所有速度下都比 SEMG 延长约 40%的步态周期。这些结果与肌肉的力学模型一致，并证明了使用 SMP 来估计步态中膝关节伸肌刚度的时间。
