Activating Spinal Circuits to Improve Walking, Balance, Strength, and Reduce Spasticity

During MST participants will perform a series of 6 motor skill exercises designed to challenge balance, lower extremity coordination, agility, and speed. Five of these activities will be performed while standing to promote upright control and one activity will be performed while seated (alternating toe-tapping) to provide opportunity for active recovery. Participants will perform each exercise for one minute each, until 4 cycles of the circuit have been completed (approximately 45 minutes total). Motor training activities will be performed at an intensity of 40-59% of heart rate reserve (HRR). During MST, participants will wear a chest-worn heart rate monitor to ensure that the optimal HRR range is achieved. HRR will be calculated from resting and peak heart rate measures obtained during baseline testing via administration of a graded-exercise test.

TSS will be delivered using a commercially available neuromuscular electrical stimulator. The active electrode will be positioned directly over the spine at the T11/T12 spinous interspace, and the reference electrode will be positioned over the umbilicus. Stimulation intensity will be gradually increased until paresthesia of the lower legs and feet is achieved or to the highest level each participant can tolerate. Stimulation will be delivered for a total duration of 30 min after paresthesia/ maximum tolerability is reached.