NEUROMUSCULAR PROPAGATION AFTER FATIGUING CONTRACTIONS OF THE PARALYZED SOLEUS MUSCLE IN HUMANS

We analyzed the M wave and torque after repetitive activation and reco very of the human soleus muscle in individuals with spinal cord injury . Fifteen individuals with complete paralysis had the tibial nerve act ivated for 330 ms every second with a 20-Hz train. The M wave and torq ue were analyzed before fatigue. immediately after fatigue, and during recovery. The torque and three M-wave measurements (amplitude, durati on, median frequency) changed significantly after fatigue in the chron ic group, but the M-wave area was not changed. The M wave was complete ly recovered after 5 min of rest, even though the torque remained depr essed during recovery. The M-wave changes appeared to contribute minim ally to the reduced torque in individuals with chronic paralysis. The disassociation in the M-wave-torque relationship during fatigue and re covery suggests, that electrical stimulation under electromyography co ntrol is not an ideal method to optimize torque in paralyzed muscle. ( C) 1998 John Wiley & Sons, Inc.