title: Effects of pre-irradiation of low-level laser therapy with different doses and wavelengths in skeletal muscle performance, fatigue, and skeletal muscle damage induced by tetanic contractions in rats.
abstract: This study aimed to evaluate the effects of low-level laser therapy (LLLT) immediately before tetanic contractions in skeletal muscle fatigue development and possible tissue damage. Male Wistar rats were divided into two control groups and nine active LLLT groups receiving one of three different laser doses (1, 3, and 10 J) with three different wavelengths (660, 830, and 905 nm) before six tetanic contractions induced by electrical stimulation. Skeletal muscle fatigue development was defined by the percentage (%) of the initial force of each contraction and time until 50 % decay of initial force, while total work was calculated for all six contractions combined. Blood and muscle samples were taken immediately after the sixth contraction. Several LLLT doses showed some positive effects on peak force and time to decay for one or more contractions, but in terms of total work, only 3 J/660 nm and 1 J/905 nm wavelengths prevented significantly (p < 0.05) the development of skeletal muscle fatigue. All doses with wavelengths of 905 nm but only the dose of 1 J with 660 nm wavelength decreased creatine kinase (CK) activity (p < 0.05). Qualitative assessment of morphology revealed lesser tissue damage in most LLLT-treated groups, with doses of 1-3 J/660 nm and 1, 3, and 10 J/905 nm providing the best results. Optimal doses of LLLT significantly delayed the development skeletal muscle performance and protected skeletal muscle tissue against damage. Our findings also demonstrate that optimal doses are partly wavelength specific and, consequently, must be differentiated to obtain optimal effects on development of skeletal muscle fatigue and tissue preservation. Our findings also lead us to think that the combined use of wavelengths at the same time can represent a therapeutic advantage in clinical settings.
authors.affiliation: Postgraduate Program in Rehabilitation Sciences, Universidade Nove de Julho (UNINOVE), Rua Vergueiro, 235, 01504-001, São Paulo, SP, Brazil.
authors.forename: Larissa Aline
authors.initials: LA
authors.lastname: Santos
authors.forename: Rodrigo Labat
authors.initials: RL
authors.lastname: Marcos
authors.forename: Shaiane Silva
authors.initials: SS
authors.lastname: Tomazoni
authors.forename: Adriane Aver
authors.initials: AA
authors.lastname: Vanin
authors.forename: Fernanda Colella
authors.initials: FC
authors.lastname: Antonialli
authors.forename: Vanessa dos Santos
authors.initials: Vdos S
authors.lastname: Grandinetti
authors.forename: Gianna Móes
authors.initials: GM
authors.lastname: Albuquerque-Pontes
authors.forename: Paulo Roberto Vicente
authors.initials: PR
authors.lastname: de Paiva
authors.forename: Rodrigo Álvaro Brandão
authors.initials: RÁ
authors.lastname: Lopes-Martins
authors.forename: Paulo de Tarso Camillo
authors.initials: Pde T
authors.lastname: de Carvalho
authors.forename: Jan Magnus
authors.initials: JM
authors.lastname: Bjordal
authors.forename: Ernesto Cesar Pinto
authors.initials: EC
authors.lastname: Leal-Junior
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000528:radiation effects; D003402:Creatine Kinase / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D009119:Muscle Contraction / Q000528:radiation effects*; D018763:Muscle Fatigue / Q000528:radiation effects*; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology / Q000528:radiation effects*; D017208:Rats, Wistar; D013746:Tetany / Q000503:physiopathology* / Q000628:therapy*
chemical_list: D003402:Creatine Kinase