title: Effects of low-level laser therapy applied before or after plyometric exercise on muscle damage markers: randomized, double-blind, placebo-controlled trial.
abstract: Promising effects of phototherapy on markers of exercise-induced muscle damage has been already demonstrated in constant load or isokinetic protocols. However, its effects on more functional situations, such as plyometric exercises, and when is the best moment to apply this treatment (pre- or post-exercise) remain unclear. Therefore, the purpose of this study was to investigate the effect of low-level laser therapy (LLLT) before or after plyometric exercise on quadriceps muscle damage markers. A randomized, double-blinded, placebo-controlled trial was conducted with 24 healthy men, 12 at pre-exercise treatment group and 12 at post-exercise treatment group. Placebo and LLLT (810 nm, 200 mW per diode, 6 J per diode, 240 J per leg) were randomly applied on right/left knee extensor muscles of each volunteer before/after a plyometric exercise protocol. Muscular echo intensity (ultrasonography images), soreness (visual analogue scale - VAS), and strength impairment (maximal voluntary contraction - MVC) were assessed at baseline, 24, 48, and 72 h post-exercise. Legs treated with LLLT before or after exercise presented significantly smaller increments of echo intensity (values up to 1 %) compared to placebo treatments (increased up to ∼7 %). No significant treatment effect was found for VAS and MVC, although a trend toward better results on LLLT legs have been found for VAS (mean values up to 30 % lesser than placebo leg). In conclusion, LLLT applied before or after plyometric exercise reduces the muscle echo intensity response and possibly attenuates the muscle soreness. However, these positive results were not observed on strength impairment.
authors.affiliation: Physiotherapy Department, Universidade Federal de Ciências da Saúde de Porto Alegre, Rua Sarmento Leite, 245, Porto Alegre, RS, 90050-170, Brasil.
authors.forename: Carolina Gassen
authors.initials: CG
authors.lastname: Fritsch
authors.affiliation: Physiotherapy Department, Universidade Federal de Ciências da Saúde de Porto Alegre, Rua Sarmento Leite, 245, Porto Alegre, RS, 90050-170, Brasil.
authors.forename: Maurício Pinto
authors.initials: MP
authors.lastname: Dornelles
authors.affiliation: Physiotherapy Department, Universidade Federal de Ciências da Saúde de Porto Alegre, Rua Sarmento Leite, 245, Porto Alegre, RS, 90050-170, Brasil.
authors.forename: Lucas
authors.initials: L
authors.lastname: Severo-Silveira
authors.affiliation: Physiotherapy Department, Universidade Federal de Ciências da Saúde de Porto Alegre, Rua Sarmento Leite, 245, Porto Alegre, RS, 90050-170, Brasil.
authors.forename: Vanessa Bernardes
authors.initials: VB
authors.lastname: Marques
authors.affiliation: Physiotherapy Department, Universidade Federal de Ciências da Saúde de Porto Alegre, Rua Sarmento Leite, 245, Porto Alegre, RS, 90050-170, Brasil.
authors.forename: Isabele de Albuquerque
authors.initials: IA
authors.lastname: Rosso
authors.affiliation: Physiotherapy Department, Universidade Federal de Ciências da Saúde de Porto Alegre, Rua Sarmento Leite, 245, Porto Alegre, RS, 90050-170, Brasil. bmbaroni@yahoo.com.br.
authors.forename: Bruno Manfredini
authors.initials: BM
authors.lastname: Baroni
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D006801:Humans; D007866:Leg; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D018763:Muscle Fatigue / Q000528:radiation effects*; D059385:Plyometric Exercise / Q000009:adverse effects*; D052097:Quadriceps Muscle / Q000528:radiation effects*; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: Exercise recovery; Muscle damage; Phototherapy; Quadriceps muscle