title: Impact of varying pulse frequency and duration on muscle torque production and fatigue.
abstract: Neuromuscular electrical stimulation (NMES) involves the use of electrical current to facilitate contraction of skeletal muscle. However, little is known concerning the effects of varying stimulation parameters on muscle function in humans. The purpose of this study was to determine the extent to which varying pulse duration and frequency altered torque production and fatigability of human skeletal muscle in vivo. Ten subjects underwent NMES-elicited contractions of varying pulse frequencies and durations as well as fatigue tests using stimulation trains of equal total charge, yet differing parametric settings at a constant voltage. Total charge was a strong predictor of torque production, and pulse trains with equal total charge elicited identical torque output. Despite similar torque output, higher- frequency trains caused greater fatigue. These data demonstrate the ability to predictably control torque output by simultaneously controlling pulse frequency and duration and suggest the need to minimize stimulation frequency to control fatigue.
authors.affiliation: Brain Rehabilitation Research Center, North Florida / South Georgia Veterans Health System Department of Physical Therapy, University of Florida, Gainesville, Florida 32610, USA. cgregory@phhp.ufl.edu
authors.forename: Chris M
authors.initials: CM
authors.lastname: Gregory
authors.forename: Warren
authors.initials: W
authors.lastname: Dixon
authors.forename: C Scott
authors.initials: CS
authors.lastname: Bickel
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D004599:Electric Stimulation Therapy / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009135:Muscular Diseases / Q000503:physiopathology / Q000628:therapy; D010146:Pain / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology; D013997:Time Factors; D019415:Torque