title: Effect of low-level laser therapy on muscle adaptation to knee extensor eccentric training.
abstract: OBJECTIVE
  Eccentric training has been popularized for physical conditioning and prevention/rehabilitation of musculoskeletal disorders, especially due to the expressive responses in terms of muscular strength gain. In view of evidence that low-level laser therapy (LLLT) is able to increase exercise performance and accelerate post-exercise recovery, the aim of this study was to verify the effect of LLLT on hypertrophy and strengthening of knee extensor muscles submitted to eccentric training.
  
  
  METHODS
  Thirty healthy male subjects were randomized into three groups: Control Group (CG), Training Group (TG) and Training + LLLT Group (TLG). CG received no intervention, while TG and TLG were engaged on an 8-week knee extensor isokinetic eccentric training program. Only subjects from TLG were treated with LLLT (wavelength = 810 nm; power output = 200 mW; total dosage = 240 J) before each training session. Knee extensor muscle thickness and peak torque were assessed through ultrasonography and isokinetic dynamometry, respectively.
  
  
  RESULTS
  CG presented no changes in any variable throughout the study, while eccentric training led to significant increases in muscle thickness and peak torque in TG and TLG. Subjects from TLG reached significantly higher percent changes compared to subjects from TG for sum of muscles' thicknesses (15.4 vs. 9.4%), isometric peak torque (20.5 vs. 13.7%), and eccentric peak torque (32.2 vs. 20.0%).
  
  
  CONCLUSIONS
  LLLT applied before eccentric training sessions seems to improve the hypertrophic response and muscular strength gain in healthy subjects.
authors.affiliation: Universidade Federal de Ciências da Saúde de Porto Alegre, Sarmento Leite St., 245, Porto Alegre, RS, 90050-170, Brazil, bmbaroni@yahoo.com.br.
authors.forename: Bruno Manfredini
authors.initials: BM
authors.lastname: Baroni
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Rodrigues
authors.forename: Bruno Bolla
authors.initials: BB
authors.lastname: Freire
authors.forename: Rodrigo de Azevedo
authors.initials: Rde A
authors.lastname: Franke
authors.forename: Jeam Marcel
authors.initials: JM
authors.lastname: Geremia
authors.forename: Marco Aurélio
authors.initials: MA
authors.lastname: Vaz
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D006801:Humans; D007717:Knee / Q000502:physiology; D028022:Low-Level Light Therapy; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology*; D063806:Myalgia / Q000517:prevention & control*; D055070:Resistance Training; D019415:Torque