title: Low-level laser therapy reduces the fatigue index in the ankle plantar flexors of healthy subjects.
abstract: Low-level laser therapy (LLLT) has been suggested as a resource capable of increasing resistance to fatigue and enhancing muscle performance through its metabolic and photochemical effects. This study evaluated the immediate effects of the application of LLLT on neuromuscular performance of the plantar ankle flexors in healthy subjects through a fatigue-induced protocol. This is a randomized controlled clinical trial, attended by 60 young and physically active volunteers of both genders. The subjects were randomly assigned into three groups, control, placebo, and laser, and underwent a preliminary evaluation of the isokinetic performance of plantar flexors and electromyographic activity of the soleus muscle to ensure homogeneity between groups. After the application of the respective intervention protocols, participants were induced to fatigue by performing 100 isokinetic concentric contractions of ankle plantar flexors at a speed of 90°/s. The dynamometric fatigue index (DFI) and median frequency were recorded during the fatigue protocol for comparison between groups. The group receiving the laser application showed significantly lower dynamometric fatigue index (p = 0.036) when compared to control and placebo groups. In relation to the median frequency during the fatigue test, there was a decrease in all groups, however with no differences between them. We suggest that LLLT being applied prior to exercise can reduce the fatigue index in the ankle plantar flexors of healthy subjects.
authors.affiliation: Neuromuscular Performance Analysis Laboratory (LAPERN) - Department of Physiotherapy, Federal University of Rio Grande do Norte (UFRN), Natal, RN, Brazil.
authors.forename: Clécio Gabriel
authors.initials: CG
authors.lastname: de Souza
authors.affiliation: Neuromuscular Performance Analysis Laboratory (LAPERN) - Department of Physiotherapy, Federal University of Rio Grande do Norte (UFRN), Natal, RN, Brazil.
authors.forename: Daniel Tezoni
authors.initials: DT
authors.lastname: Borges
authors.affiliation: Neuromuscular Performance Analysis Laboratory (LAPERN) - Department of Physiotherapy, Federal University of Rio Grande do Norte (UFRN), Natal, RN, Brazil.
authors.forename: Liane
authors.initials: L
authors.lastname: de Brito Macedo
authors.affiliation: Neuromuscular Performance Analysis Laboratory (LAPERN) - Department of Physiotherapy, Federal University of Rio Grande do Norte (UFRN), Natal, RN, Brazil. brasileiro@ufrnet.br.|Departamento de Fisioterapia, Universidade Federal do Rio Grande do Norte, Av. Senador Salgado Filho, 3000, Campus Universitário, Lagoa Nova, Natal, RN, CEP 59.078-970, Brazil. brasileiro@ufrnet.br.
authors.forename: Jamilson Simões
authors.initials: JS
authors.lastname: Brasileiro
mesh_terms: D000328:Adult; D000842:Ankle / Q000528:radiation effects*; D015444:Exercise / Q000502:physiology; D005260:Female; D005528:Foot / Q000528:radiation effects; D064368:Healthy Volunteers; D006801:Humans; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D018763:Muscle Fatigue / Q000528:radiation effects*; D018482:Muscle, Skeletal / Q000528:radiation effects*; D055815:Young Adult
keywords: Electromyography; Muscle fatigue; Muscle strength dynamometer