title: Use of low-level laser therapy (808 nm) to muscle fatigue resistance: a randomized double-blind crossover trial.
abstract: OBJECTIVE
  The purpose of this study was to investigate whether low-level laser (light) therapy (LLLT) can provide fatigue resistance via maximum repetitions (RM) with an isokinetic dynamometer, and decrease electromyography fatigue index (EFI).
  
  
  BACKGROUND
  LLLT has been used to increase muscle performance when applied before or after intense exercises.
  
  
  METHODS
  This study was a randomized, double-blind, crossover trial with placebo. Seven young men (21±3 years of age) who were clinically healthy, were allocated into two groups: active laser (LLLT) and placebo laser (Placebo). Both groups were assessed at baseline, at one training session, and at the end of this study. Baseline and final assessments recorded the number of RM of knee flexion-extensions using an isokinetic dynamometer at 60 degrees/sec in conjunction with EFI recorded by median frequency. The training sessions consisted of three sets of 20 RM of knee flexion-extensions using an isokinetic dynamometer at 60 degrees/sec plus LLLT (808 nm, 100 mW, 4 J), or placebo, applied to quadriceps femoris muscles between sets, and after the last series of this exercise. After 1 week (washout period), all volunteers were exchanged among groups and then all assessments were repeated.
  
  
  RESULTS
  LLLT group increased RM (52%; p=0.002) with a small EFI for the vastus medialis (p=0.004) and rectus femoris (p=0.004).
  
  
  CONCLUSIONS
  These results suggest an increased muscle fatigue resistance when LLLT is applied during rest intervals, and after the last series of intense exercises.
authors.affiliation: 1 Department of Physical Therapy, Federal University of Rio Grande do Norte (UFRN) , Natal, RN, Brazil .
authors.forename: Wouber Hérickson
authors.initials: WH
authors.lastname: de Brito Vieira
authors.forename: Raphael Machado
authors.initials: RM
authors.lastname: Bezerra
authors.forename: Renata Alencar Saldanha
authors.initials: RA
authors.lastname: Queiroz
authors.forename: Nícia Farias Braga
authors.initials: NF
authors.lastname: Maciel
authors.forename: Nivaldo Antonio
authors.initials: NA
authors.lastname: Parizotto
authors.forename: Cleber
authors.initials: C
authors.lastname: Ferraresi
mesh_terms: D018592:Cross-Over Studies; D004311:Double-Blind Method; D004576:Electromyography; D006801:Humans; D007719:Knee Joint / Q000502:physiology / Q000528:radiation effects; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology / Q000528:radiation effects; D018763:Muscle Fatigue / Q000502:physiology* / Q000528:radiation effects*; D018482:Muscle, Skeletal / Q000502:physiology* / Q000528:radiation effects*; D055815:Young Adult