Movement-provoked muscle torque and EMG activity in longstanding motor complete spinal cord injured individuals

Muscle resistance was evaluated by measurement of movement-provoked torque performed during simultaneous thigh muscle EMG recordings in individuals with a motor complete spinal cord injury (SCI). Fifteen men with a motor complete (ASIA grade A or B) cervical injury participated in the study. The activity started at an average of 0.11 seconds after the start of the provoking movement as evidenced by EMG recordings. However, no activity at all was found before the end of the movement provocation for 0.3 seconds in >60% of the test situations, whereas muscle torque was recorded in all cases. Significantly higher resistive muscle torque (p = 0.049) was provoked during extension movement compared with that of flexion. On the contrary, the maximum muscle activity was significantly higher (p = 0.009) during flexion movement compared with that during extension, with no differences between muscle groups. The resistive muscle torque seems to measure the passive viscoelastic component rather then the active spastic component of the movement-provoked muscle resistance in our group of motor complete SCI individuals.