Muscle fatigue during spinal stimulation and resistive ankle exoskeleton use in children with cerebral palsy

Evaluating fatigue during rehabilitation can help prevent overexertion to improve motor learning. The purpose of this study was to quantify how walking with transcutaneous spinal cord stimulation (tSCS) impacts muscle fatigue during treadmill training with and without a resistive ankle exoskeleton (Exo) in children with cerebral palsy (CP). Nine children with CP (4-14 years old) participated in four walking conditions: (1) No Device, (2) tSCS only, (3) Exo only, and (4) tSCS+Exo. Plantarflexor maximum voluntary contraction (MVC) was performed before and after each condition. Soleus amplitude root mean square (RMS) and median frequency (MDF) from electromyography recordings were used as biomarkers for fatigue. Participants only showed signs of soleus fatigue in the first five minutes of the Exo only condition with increased RMS (p < 0.001) and decreased MDF (p < 0.001). After ten minutes of walking, there was a slight decrease in MDF in the No Device and tSCS only conditions (p = 0.002), but no change in RMS. There were no significant differences in changes in MVC force, RMS, or MDF between conditions. Walking with tSCS may reduce the impact of the Exo on soleus fatigue for children with CP.