Interleaved Neuromuscular Electrical Stimulation After Spinal Cord Injury

IntroductionNeuromuscular electrical stimulation (NMES) over a muscle belly (mNMES) recruits superficial motor units (MUs) preferentially, whereas NMES over a nerve trunk (nNMES) recruits MUs evenly throughout the muscle. We performed tests to determine whether interleaving pulses between the mNMES and nNMES sites (iNMES) reduces the fatigability of contractions for people experiencing paralysis because of chronic spinal cord injury.MethodsPlantar flexion torque and soleus electromyography (M-waves) were recorded from 8 participants. A fatigue protocol (75 contractions; 2 s on/2 s off for 5min) was delivered by iNMES. The results were compared with previously published data collected with mNMES and nNMES in the same 8 participants.ResultsTorque declined approximate to 40% more during mNMES than during nNMES or iNMES. M-waves declined during mNMES but not during nNMES or iNMES.DiscussionTo reduce fatigability of electrically evoked contractions of paralyzed plantar flexors, iNMES is equivalent to nNMES, and both are superior to mNMES. Muscle Nerve56: 989-993, 2017