title: Interaction of poststroke voluntary effort and functional neuromuscular electrical stimulation.
abstract: Functional electrical stimulation (FES) may be able to augment functional arm and hand movement after stroke. Poststroke neuroprostheses that incorporate voluntary effort and FES to produce the desired movement must consider how forces generated by voluntary effort and FES combine, even in the same muscle, in order to provide an appropriate level of stimulation to elicit the desired assistive force. The goal of this study was to determine whether the force produced by voluntary effort and FES add together independently of effort or whether the increment in force depends on the level of voluntary effort. Isometric force matching tasks were performed under different combinations of voluntary effort and FES. Participants reached a steady level of force, and while attempting to maintain a constant effort level, FES was applied to augment the force. Results indicate that the increment in force produced by FES decreases as the level of initial voluntary effort increases. Potential mechanisms causing the change in force output are proposed, but the relative contribution of each mechanism is unknown.
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, 2071 Martin Luther King Jr. Dr, Cleveland, OH 44106, USA. nhm6@cwru.edu
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Makowski
authors.forename: Jayme
authors.initials: J
authors.lastname: Knutson
authors.forename: John
authors.initials: J
authors.lastname: Chae
authors.forename: Patrick
authors.initials: P
authors.lastname: Crago
mesh_terms: D000328:Adult; D000368:Aged; D001132:Arm / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation