Developing a Coaching System for Functional Electrical Stimulation Rowing for Individuals with Spinal Cord Injury
Pirashanth Theventhiran (1,2), Gongkai Ye (1,2), Thomas Nguyen (1,2), Kei Masani (1,2).
1: Rehabilitation Engineering Laboratory, Toronto Rehabilitation Institute -University Health Network, Toronto, Ontario
2: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario.
Background: Spinal cord injury (SCI) can drastically impact an individual’s quality of life due to paralysis and inactivity. This leads to a higher risk of cardiovascular disease and decreases in muscle mass and bone density. Functional electrical stimulation (FES) induces artificial muscle contractions using an electric current, which is currently used for rehabilitation. Integrating FES with the rowing exercise can help restore voluntary function in their legs, and counteract the comorbidities of SCI. Many closed loop feedback systems have been developed to administer FES to the legs automatically, but SCI individuals prefer to use a manual button, which gives them the most control over when and how long the stimulation is administered. However, it requires over thirteen sessions for new rowers to learn the proper timing and coordination.
Objective: We aimed to develop a coaching system to instruct new SCI rowers on the optimal timing to administer FES to their legs.
Methods: We modified a rowing ergometer instrumented with back and leg support for SCI individuals, and sensors for data collection. Able-bodied rowers performed rowing exercise at a constant rate of 30 strokes/min for 2 minutes. Kinetic data such as the handle and feet forces, as well as leg muscle activation data using electromyograms were collected during the rowing exercise. We detected the timing of leg muscle activation in relation to the force exertions at the hands and legs.
Results: Sequential muscle activation patterns were observed: the leg forces initiated the drive phase of a rowing stroke followed by the arm forces. Furthermore, vastus lateralis (thigh muscle) activation for leg extension occurred around 0.4 seconds before seat position movement. This leg extension caused the seat to move backwards and this timing difference was consistent across various cadences.
Conclusions: Based on the timing of the thigh muscle activation, we found that FES should be administered at 0.4 seconds before the seat position peak. The coaching system will take into account the position of the seat, instruct SCI rowers on the appropriate timing of administering FES using a manual button, and provide real time feedback on their performance. In the future, the coaching system will be validated and attuned after testing in a few individuals with spinal cord injury.