title: Effects of low-level laser therapy (LLLT) in the development of exercise-induced skeletal muscle fatigue and changes in biochemical markers related to postexercise recovery.
abstract: METHODS
  Randomized crossover double-blinded placebo-controlled trial.
  
  
  OBJECTIVE
  To investigate if low-level laser therapy (LLLT) can affect biceps muscle performance, fatigue development, and biochemical markers of postexercise recovery.
  
  
  BACKGROUND
  Cell and animal studies have suggested that LLLT can reduce oxidative stress and inflammatory responses in muscle tissue. But it remains uncertain whether these findings can translate into humans in sport and exercise situations.
  
  
  METHODS
  Nine healthy male volleyball players participated in the study. They received either active LLLT (cluster probe with 5 laser diodes; lambda = 810 nm; 200 mW power output; 30 seconds of irradiation, applied in 2 locations over the biceps of the nondominant arm; 60 J of total energy) or placebo LLLT using an identical cluster probe. The intervention or placebo were applied 3 minutes before the performance of exercise. All subjects performed voluntary elbow flexion repetitions with a workload of 75% of their maximal voluntary contraction force until exhaustion.
  
  
  RESULTS
  Active LLLT increased the number of repetitions by 14.5% (mean +/- SD, 39.6 +/- 4.3 versus 34.6 +/- 5.6; P = .037) and the elapsed time before exhaustion by 8.0% (P = .034), when compared to the placebo treatment. The biochemical markers also indicated that recovery may be positively affected by LLLT, as indicated by postexercise blood lactate levels (P<.01), creatine kinase activity (P = .017), and C-reactive protein levels (P = .047), showing a faster recovery with LLLT application prior to the exercise.
  
  
  CONCLUSIONS
  We conclude that pre-exercise irradiation of the biceps with an LLLT dose of 6 J per application location, applied in 2 locations, increased endurance for repeated elbow flexion against resistance and decreased postexercise levels of blood lactate, creatine kinase, and C-reactiveprotein.
  
  
  METHODS
  Performance enhancement, level 1b.
authors.affiliation: Center for Research and Innovation in Laser, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil. ernesto.leal.junior@gmail.com
authors.forename: Ernesto Cesar Pinto
authors.initials: EC
authors.lastname: Leal Junior
authors.forename: Rodrigo Alvaro Brandão
authors.initials: RA
authors.lastname: Lopes-Martins
authors.forename: Lucio
authors.initials: L
authors.lastname: Frigo
authors.forename: Thiago
authors.initials: T
authors.lastname: De Marchi
authors.forename: Rafael Paolo
authors.initials: RP
authors.lastname: Rossi
authors.forename: Vanessa
authors.initials: V
authors.lastname: de Godoi
authors.forename: Shaiane Silva
authors.initials: SS
authors.lastname: Tomazoni
authors.forename: Daniela Perin
authors.initials: DP
authors.lastname: Silva
authors.forename: Maira
authors.initials: M
authors.lastname: Basso
authors.forename: Pedro Lotti
authors.initials: PL
authors.lastname: Filho
authors.forename: Francisco
authors.initials: F
authors.lastname: de Valls Corsetti
authors.forename: Vegard V
authors.initials: VV
authors.lastname: Iversen
authors.forename: Jan Magnus
authors.initials: JM
authors.lastname: Bjordal
mesh_terms: D000293:Adolescent; D001132:Arm; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D003402:Creatine Kinase / Q000097:blood; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D028022:Low-Level Light Therapy; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000528:radiation effects*; D005082:Physical Exertion; D020127:Recovery of Function; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019344:Lactic Acid; D002097:C-Reactive Protein; D003402:Creatine Kinase