title: Effects of low-level laser therapy on biceps braquialis muscle fatigue in young women.
abstract: OBJECTIVE
  This study aims to investigate the effects of low-level laser therapy (LLLT) on biceps brachi muscular fatigue in 20 young females.
  
  
  BACKGROUND
  Exhausting physical activity leads to muscular fatigue, which could decrease muscular strength, and may cause impairment in motor control and muscle pain. Several biochemical and biophysical resources have been studied in an attempt to accelerate the recovery of muscle fatigue. Among these, LLLT is emphasized.
  
  
  METHODS
  Twenty subjects were randomized in one laser group and one placebo group in two sessions of a crossover design experimental procedure; the second session taking place within 7 days of the first. In the first session, subjects underwent a collection of surface electromyographic (SEMG) data of the biceps brachii muscle, followed by active or placebo LLLT at the same muscle, followed then by another EMG sample of biceps brachii. Blood samples were collected five times during the experimental procedure. Second session procedures were identical to the first, with exception of LLLT, which was the opposite of the first session. The fatigue protocol consisted of 60 sec of elbow flexion-extension movement performed with 75% of one maximum repetition. Blood lactate, EMG fatigue, and the number of elbow flexion-extension repetitions during the fatigue protocol were used to evaluate the effects of laser therapy (808 nm wavelength, 100 mW output power, power density of 35.7 W/cm(2), 70 sec each point and 7 J/point on eight points).
  
  
  RESULTS
  No statistical differences were found for eletromyographic fatigue and blood lactate values between groups. Mean numbers of elbow flexion-extension repetitions were 22.6 ± 7.58 after placebo, and 25.1 ± 9.89 after active LLLT group, but these differences were not statistically significant (p=0.342).
  
  
  CONCLUSIONS
  LLLT had limited effects on delaying muscle fatigue in a young female sample, although a tendency was observed in the active laser group toward showing lower electromyography fatigue of biceps brachii muscle. No intergroup differences were found in the number of muscle contractions and lactate concentration.
authors: 1 Department of Biosciences, Federal University of São Paulo , Campus Baixada Santista, Santos, SP, Brazil .
authors: Renan Hideki
authors: RH
authors: Higashi
authors: Renata Luri
authors: RL
authors: Toma
authors: Helga Tatiana
authors: HT
authors: Tucci
authors: Cristiane Rodrigues
authors: CR
authors: Pedroni
authors: Pryscilla Dieguez
authors: PD
authors: Ferreira
authors: Gabriel
authors: G
authors: Baldini
authors: Mariana Chaves
authors: MC
authors: Aveiro
authors: Audrey
authors: A
authors: Borghi-Silva
authors: Anamaria Siriani
authors: AS
authors: de Oliveira
authors: Ana Claudia Muniz
authors: AC
authors: Renno
mesh_terms: D018592:Cross-Over Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D028022:Low-Level Light Therapy; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000528:radiation effects*; D055815:Young Adult
chemical_list: D019344:Lactic Acid