title: Strength training prior to muscle injury potentiates low-level laser therapy (LLLT)-induced muscle regeneration.
abstract: We evaluated whether strength training (ST) performed prior to skeletal muscle cryolesion would act as a preconditioning, improving skeletal muscle regeneration and responsiveness to low-level laser therapy (LLLT). Wistar rats were randomly assigned into non-exercised (NE), NE plus muscle lesion (NE + LE), NE + LE plus LLLT (NE + LE + LLLT), strength training (ST), ST + LE, and ST + LE + LLLT. The animals performed 10 weeks of ST (climbing ladder; 3× week; 80% overload). Forty-eight hours after the last ST session, tibialis anterior (TA) cryolesion was induced and LLLT (InGaAlP, 660 nm, 0.035 W, 4.9 J/cm2/point, 3 points, spot light 0.028 cm2, 14 J/cm2) initiated and conducted daily for 14 consecutive days. The difference between intergroups was assessed using Student's t test and intragroups by two-way analysis of variance. Cryolesion induced massive muscle degeneration associated with inflammatory infiltrate. Prior ST improved skeletal regeneration 14-days after cryolesion and potentiated the regenerative response to LLLT. Cryolesion induced increased TNF-α levels in both NE + LE and ST + LE groups. Both isolated ST and LLLT reduced TNF-α to control group levels; however, prior ST potentiated LLLT response. Both isolated ST and LLLT increased IL-10 levels with no additional effect. In contrast, increased TA IL-6 levels were restricted to ST and ST + LE + LLLT groups. TA myogenin mRNA levels were not changed by neither prior ST or ST + LLLT. Both prior ST and LLLT therapies increased MyoD mRNA levels and, interestingly, combined therapies potentiated this response. Myf5 mRNA levels were increased only in ST groups. Taken together, our data provides evidences for prior ST potentiating LLLT efficacy in promoting skeletal muscle regeneration.
authors.affiliation: Programa Multicêntrico de Pós-Graduação em Ciências Fisiológicas-SBFis/UNESP, Araçatuba, Brazil. samuelrodrigues@foa.unesp.br.|Laboratory of Endocrine Physiology and Aging-Department of Basic Sciences, Araçatuba, São Paulo, Brazil. samuelrodrigues@foa.unesp.br.
authors.forename: Samuel Rodrigues Lourenço
authors.initials: SR
authors.lastname: Morais
authors.affiliation: São Paulo State University (UNESP), School of Dentistry, Araçatuba, São Paulo, Brazil.
authors.forename: Alexandre Ginei
authors.initials: AG
authors.lastname: Goya
authors.affiliation: School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Úrsula
authors.initials: Ú
authors.lastname: Urias
authors.affiliation: School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Paulo Roberto
authors.initials: PR
authors.lastname: Jannig
authors.affiliation: School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Aline Villa Nova
authors.initials: AV
authors.lastname: Bacurau
authors.affiliation: Programa Multicêntrico de Pós-Graduação em Ciências Fisiológicas-SBFis/UNESP, Araçatuba, Brazil.|Laboratory of Endocrine Physiology and Aging-Department of Basic Sciences, Araçatuba, São Paulo, Brazil.
authors.forename: Wagner Garcez
authors.initials: WG
authors.lastname: Mello
authors.affiliation: Group of Research and Study on Laser in Dentistry (GEPLO), Division of Periodontics, Department of Surgery and Integrated Clinic, São Paulo State University (UNESP), School of Dentistry, Araçatuba, São Paulo, Brazil.
authors.forename: Paula Lazilha
authors.initials: PL
authors.lastname: Faleiros
authors.affiliation: São Paulo State University (UNESP), School of Dentistry, Araçatuba, São Paulo, Brazil.
authors.forename: Sandra Helena Penha
authors.initials: SH
authors.lastname: Oliveira
authors.affiliation: Group of Research and Study on Laser in Dentistry (GEPLO), Division of Periodontics, Department of Surgery and Integrated Clinic, São Paulo State University (UNESP), School of Dentistry, Araçatuba, São Paulo, Brazil.
authors.forename: Valdir Gouveia
authors.initials: VG
authors.lastname: Garcia
authors.affiliation: São Paulo State University (UNESP), School of Dentistry, Araçatuba, São Paulo, Brazil.
authors.forename: Edilson
authors.initials: E
authors.lastname: Ervolino
authors.affiliation: School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil.|Experimental Physiopathology-Medical School, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Patricia Chakur
authors.initials: PC
authors.lastname: Brum
authors.affiliation: Programa Multicêntrico de Pós-Graduação em Ciências Fisiológicas-SBFis/UNESP, Araçatuba, Brazil.|Laboratory of Endocrine Physiology and Aging-Department of Basic Sciences, Araçatuba, São Paulo, Brazil.|São Paulo State University (UNESP), School of Dentistry, Araçatuba, São Paulo, Brazil.
authors.forename: Rita Cássia Menegati
authors.initials: RC
authors.lastname: Dornelles
mesh_terms: D000818:Animals; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D028022:Low-Level Light Therapy; D008297:Male; D008954:Models, Biological; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects*; D010805:Physical Conditioning, Animal; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017208:Rats, Wistar; D012038:Regeneration / Q000528:radiation effects*; D014945:Wound Healing / Q000528:radiation effects
chemical_list: D016207:Cytokines; D009124:Muscle Proteins; D012333:RNA, Messenger
keywords: Low-level laser therapy; Myf5; MyoD; Myogenin; Skeletal muscle regeneration; Strength training