title: Comparison between the effects of 4 different electrical stimulation current waveforms on isometric knee extension torque and perceived discomfort in healthy women.
abstract: BACKGROUND
  We studied the effects of different neuromuscular electrical stimulation (NMES) currents, 2 kHz-frequency alternating currents (KACs, Russian and Aussie) and 2 pulsed currents (PCs), on isometric knee extension torque and discomfort level, both in isolation and combined, with maximum voluntary contraction (MVC).
  
  
  METHODS
  Twenty-one women (age 21.6 ± 2.5 years) were studied. We evaluated torque evoked by NMES or NMES combined with maximum voluntary contraction of the quadriceps muscle of healthy women. Discomfort level was measured using a visual analog pain scale.
  
  
  RESULTS
  Despite comparable levels of discomfort, evoked torque was lower for Russian current compared with the other modalities (Russian 50.8%, Aussie 71.7%, PC500 76.9%, and PC200 70.1%; P < 0.001). There was no advantage in combining NMES with MVC compared with isolated NMES.
  
  
  CONCLUSIONS
  The Aussie and PC approaches proved superior to Russian current for inducing isometric knee extension torque. This information is important in guiding decision making with regard to NMES protocols for muscle strengthening.
authors.affiliation: Department of Physical Therapy, Federal University of São Carlos, São Paulo, Brazil.
authors.forename: Lucas Ogura
authors.initials: LO
authors.lastname: Dantas
authors.forename: Amilton
authors.initials: A
authors.lastname: Vieira
authors.forename: Aristides Leite
authors.initials: AL
authors.lastname: Siqueira
authors.forename: Tania Fatima
authors.initials: TF
authors.lastname: Salvini
authors.forename: João Luiz Quagliotti
authors.initials: JL
authors.lastname: Durigan
mesh_terms: D000704:Analysis of Variance; D001703:Biophysics; D004558:Electric Stimulation; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007717:Knee / Q000294:innervation; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D019415:Torque; D055815:Young Adult
keywords: NMES; alternating current; discomfort; electrophysiology; pulsed current; torque