Lower limb electrical stimulation alters trunk stability in individuals with spinal cord injury

Abstract
Loss of movement ability below the level of injury is often a consequence of spinal cord injury (SCI). Subsequently, the associated rapid muscle atrophy after the injury may negatively affect overall functional recovery. Previously, our data have shown that a novel form of multi-muscle electrical stimulation (ES) combined with dynamic stand retraining task (SRT) can increase the amplitude of muscle activation in the lower limbs during continuous step training. Our early preliminary data also demonstrated that this dynamic clinical intervention could also potentially improve trunk stability during stepping and standing. The purpose of the present study was to further examine trunk stability in persons with motor-complete SCI during the first minute of a 10-minute stepping bout on a treadmill, using an overhead body-weight support system, before and after the SRT+ES clinical intervention. Sixty sessions of electrical stimulation was applied 4-5 times per week, for 60 minutes each. Symmetrical, biphasic pulses of 300 µs at 35 Hz were delivered to four lower limb muscles over a duty cycle of 11 seconds on and 60 seconds off. During treadmill stepping, trunk stability was measured by examining 2-dimensional spatial and temporal profiles of Center of Mass (CoM), as well as the underlying neuromuscular changes that precipitate the alterations in postural mechanics.Our results demonstrated that the training, which combines the SRT and ES, improves trunk stability by showing a decrease in the anterior-posterior excursions of the CoM. Greater anterior-posterior excursions before the training might be due to a deliberate activation of the trunk muscles during treadmill stepping in order to maintain stability and postural form. However, after the training, it could be argued that the major contribution to the movement is not from the trunk, but the pelvis during treadmill stepping. Furthermore, overall consistency of the CoM excursions across multiple gait cycles improved after the SRT+ES training.

Authors
*K. MOMENI, S. CANTON, A. RAMANUJAM, E. GARBARINI, G. F. FORREST;
Human Performance and Engin. Res., Kessler Fndn., West Orange, NJ
Disclosures
K. Momeni: None. S. Canton: None. A. Ramanujam: None. E. Garbarini: None. G.F. Forrest: None.
LINK: Session 158 – Spinal Cord Injury and Plasticity

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