title: Electrically Elicited Muscle Torque: Comparison Between 2500-Hz Burst-Modulated Alternating Current and Monophasic Pulsed Current.
abstract: METHODS
  Single-blind, block-randomization crossover design.
  
  
  OBJECTIVE
  To compare the knee extensor muscle torque production elicited with 2500-Hz burst-modulated alternating current (BMAC) and with a monophasic pulsed current (MPC) at the maximum tolerated stimulation intensity.
  
  
  BACKGROUND
  Neuromuscular electrical stimulation (NMES) is often used for strengthening the quadriceps following knee surgery. Strength gains are dependent on muscle torque production, which is primarily limited by discomfort. Burst-modulated alternating current stimulation is a clinically popular waveform for NMES. Prior research has established that MPC with a relatively long pulse duration is effective for high muscle torque production.
  
  
  METHODS
  Participants in this study were 20 adults with no history of knee injury. A crossover design was used to randomize the order in which each participant's dominant or nondominant lower extremity received NMES and the waveform (MPC or BMAC) this limb received. Stimulation intensity was incrementally increased until participants reached their maximum tolerance. The torque produced was converted to a percentage of each participant's maximum volitional isometric contraction of the respective limb.
  
  
  RESULTS
  A general linear model for a 2-treatment, 2-period crossover design was utilized to analyze the results. The mean ± SD electrically induced percent maximum volitional isometric contraction at maximal participant tolerance was 49.5% ± 19.6% for MPC and 29.8% ± 12.4% for BMAC. This difference was statistically significant (P = .002) after accounting for treatment order and limb, which had no effect on torque production.
  
  
  CONCLUSIONS
  Neuromuscular stimulation using MPC may be more efficacious than using BMAC to achieve a high torque output in patients with quadriceps weakness.
authors.forename: Wayne
authors.initials: W
authors.lastname: Scott
authors.forename: Cheryl
authors.initials: C
authors.lastname: Adams
authors.forename: Shantelle
authors.initials: S
authors.lastname: Cyr
authors.forename: Brianna
authors.initials: B
authors.lastname: Hanscom
authors.forename: Kevin
authors.initials: K
authors.lastname: Hill
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lawson
authors.forename: Colin
authors.initials: C
authors.lastname: Ziegenbein
mesh_terms: D018592:Cross-Over Studies; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007717:Knee / Q000502:physiology*; D008297:Male; D052097:Quadriceps Muscle / Q000502:physiology*; D016037:Single-Blind Method; D019415:Torque; D055815:Young Adult
keywords: NMES; current; electrical stimulation; pulse duration