title: Effects of electrical stimulation pattern on quadriceps isometric force and fatigue in individuals with spinal cord injury.
abstract: BACKGROUND
  Variable frequency trains (VFT) or train combinations have been suggested as useful strategies to offset the rapid fatigue induced by constant frequency trains (CFT) during electrical stimulation. However, most studies have been of short duration with limited functional application in those with spinal cord injury (SCI). We therefore tested force and fatigue in response to VFT, CFT, and combined patterns in strength training-like conditions (6-s contractions).
  
  
  METHODS
  Ten SCI individuals underwent either CFT or VFT patterns until target torque was no longer produced and then switched immediately to the other pattern.
  
  
  RESULTS
  Target torque was reached more times when VFT was used first (VFT: 6.7 ± 0.8 vs. CFT: 3.5 ± 0.2 contractions, P < 0.05) and when it was followed by the CFT pattern (VFT-CFT: 10.3 ± 1.2 vs.
  6.9 ± 1.2 contractions, P < 0.05).
  
  
  CONCLUSIONS
  These findings suggest that for the same initial forces the VFT pattern is less fatiguing than CFT and that when combining train types, VFT should be used first.
authors.affiliation: INSERM - U1093 Cognition, Action, et Plasticité Sensorimotrice, Université de Bourgogne, Dijon, France.|Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, and Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Gaelle
authors.initials: G
authors.lastname: Deley
authors.affiliation: INSERM - U1093 Cognition, Action, et Plasticité Sensorimotrice, Université de Bourgogne, Dijon, France.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Denuziller
authors.affiliation: INSERM - U1093 Cognition, Action, et Plasticité Sensorimotrice, Université de Bourgogne, Dijon, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Babault
authors.affiliation: Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, and Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: John Andrew
authors.initials: JA
authors.lastname: Taylor
mesh_terms: D000328:Adult; D004558:Electric Stimulation / Q000379:methods; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000175:diagnosis* / Q000503:physiopathology* / Q000628:therapy; D019415:Torque; D016896:Treatment Outcome
keywords: FES; constant frequency trains; functional electrical stimulation; muscle fatigue; variable frequency trains