Abstract
BackgroundRobotic overground gait training devices, such as the Ekso, require users to actively participate in triggering steps through weight-shifting movements. It remains unknown how much the trunk muscles are activated during these movements, and if it is possible to transfer training effects to seated balance control. This study was conducted to compare the activity of postural control muscles of the trunk during overground (Ekso) vs. treadmill-based (Lokomat) robotic gait training, and evaluate changes in seated balance control in people with high-thoracic motor-complete spinal cord injury (SCI).MethodsThree individuals with motor-complete SCI from C7-T4, assumed to have no voluntary motor function below the chest, underwent robotic gait training. The participants were randomly assigned to Ekso-Lokomat-Ekso or Lokomat-Ekso-Lokomat for 10 sessions within each intervention phase for a total of 30 sessions. We evaluated static and dynamic balance control through analysis of center of pressure (COP) movements after each intervention phase. Surface electromyography was used to compare activity of the abdominal and erector spinae muscles during Ekso and Lokomat walking.ResultsWe observed improved postural stability after training with Ekso compared to Lokomat during static balance tasks, indicated by reduced COP root mean square distance and ellipse area. In addition, Ekso training increased total distance of COP movements during a dynamic balance task. The trunk muscles showed increased activation during Ekso overground walking compared to Lokomat walking.ConclusionsOur findings suggest that the Ekso actively recruits trunk muscles through postural control mechanisms, which may lead to improved balance during sitting. Developing effective training strategies to reactivate the trunk muscles is important to facilitate independence during seated balance activity in people with SCI.
Highlights
Robotic overground gait training devices, such as the Ekso, require users to actively participate in triggering steps through weight-shifting movements
If overground roboticassisted gait training (i.e. Ekso) is a successful intervention to engage the trunk muscles compared to a treadmillbased method (i.e. Lokomat), we propose that increased limits of stability (LOS) during dynamic balance control and reduced center of pressure (COP) sway during static balance control will be observed
Gait assessment When participants were able to walk overground with the Ekso in ‘ProStep’ mode at a gait speed of at least 1.0 km/h, which is the minimum speed of the Lokomat, we conducted an assessment of trunk muscle activity comparing each method of robotic-assisted gait
Summary
Robotic overground gait training devices, such as the Ekso, require users to actively participate in triggering steps through weight-shifting movements. Chisholm et al Journal of NeuroEngineering and Rehabilitation (2017) 14:27 from previous studies show that activity in the trunk muscles can be detected by manual palpation [4, 5], and electromyography (EMG) [6] These methods have demonstrated the presence of abdominal muscle activity below the level of injury in individuals with motor-complete SCI [6, 7]. The use of transcranial magnetic stimulation (TMS) has revealed motor-evoked potentials in the abdominal muscles below the level of injury for people classified as motor-complete SCI based on the ISNCSCI examination [7] This implies some preservation of the corticospinal tract to the trunk muscles, raising the possibility for rehabilitation interventions to improve postural control and function in this sub-population
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