title: A novel modulation strategy to increase stimulation duration in neuromuscular electrical stimulation.
abstract: BACKGROUND
  Neuromuscular electrical stimulation (NMES) has been shown to be an effective treatment for muscular dysfunction. Yet, a fundamental barrier to NMES treatments is the rapid onset of muscle fatigue. The purpose of this study is to examine the effect of feedback-based frequency modulation on the closed-loop performance of the quadriceps during repeated dynamic contractions.
  
  
  METHODS
  In the first experiment, subjects completed four different frequency modulation NMES protocols utilizing the same amplitude modulation control to compare the successful run times (SRTs). A second experiment was performed to determine the change in muscle response to high- and low-frequency stimulation.
  
  
  RESULTS
  Compared with constant-frequency stimulation, results indicate that using an error-driven strategy to vary the stimulation frequency during amplitude modulation increases the number of successful contractions during non-isometric conditions.
  
  
  CONCLUSIONS
  Simultaneous frequency and amplitude modulation increases the SRT during closed-loop NMES control.
authors: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611-6250, USA.
authors: Ryan J
authors: RJ
authors: Downey
authors: Matthew
authors: M
authors: Bellman
authors: Nitin
authors: N
authors: Sharma
authors: Qiang
authors: Q
authors: Wang
authors: Chris M
authors: CM
authors: Gregory
authors: Warren E
authors: WE
authors: Dixon
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy / Q000379:methods*; D025461:Feedback, Physiological / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D009468:Neuromuscular Diseases / Q000503:physiopathology / Q000628:therapy*; D052097:Quadriceps Muscle / Q000503:physiopathology; D013647:Task Performance and Analysis; D013997:Time Factors