Sinclair Peter J, Smith Richard M, Davis Glen M
School of Exercise and Sport Science, The University of Sydney, Lidcombe, N.S.W. 1825, Australia.
IEEE Trans Neural Syst Rehabil Eng. 2004 Jun;12(2):303-6. doi: 10.1109/TNSRE.2004.828417.
Neuromuscular electrical stimulation was used to evoke isometric knee extension contractions in seven individuals with spinal cord injury (SCI) and the time for knee extension torque to rise and fall was measured across a range of knee angles. The stimulated muscles took more than twice as long to develop 50% of maximum torque at an angle of 15 degrees, compared to an angle of 90 degrees. This time difference comprised both an increased delay before torque rose above resting levels (31 +/- 3 ms at 90 degrees, 67 +/- 24 ms at 15 degrees), and a prolonged duration over which torque was rising (72 +/- 14 ms at 90 degrees, 140 +/- 62 ms at 15 degrees). There was no change, however, in the time taken for torque to fall after cessation of stimulation at different knee angles (58 +/- 5-ms delay, 60 +/- 11-ms fall time). The difference in torque rise time with joint angle has implications for modeling functional activities that differ greatly in their joint angles. This study provides regression equations whereby activation times for the quadriceps muscles of individuals with SCI can be predicted for specific angles of knee flexion.
对7名脊髓损伤（SCI）患者使用神经肌肉电刺激来诱发膝关节等长伸展收缩，并在一系列膝关节角度下测量膝关节伸展扭矩上升和下降的时间。与90度角相比，在15度角时，受刺激的肌肉产生最大扭矩50%所需的时间延长了一倍多。这种时间差异包括扭矩上升到高于静息水平之前延迟时间的增加（90度时为31±3毫秒，15度时为67±24毫秒），以及扭矩上升的持续时间延长（90度时为72±14毫秒，15度时为140±62毫秒）。然而，在不同膝关节角度下刺激停止后扭矩下降所需的时间没有变化（延迟58±5毫秒，下降时间60±11毫秒）。扭矩上升时间随关节角度的差异对模拟关节角度差异很大的功能活动具有重要意义。本研究提供了回归方程，据此可以预测脊髓损伤患者股四头肌在特定膝关节屈曲角度下的激活时间。
