Effect of low-level laser (Ga-Al-As 655 nm) on skeletal muscle fatigue induced by electrical stimulation in rats

• Published in: Journal of applied physiology (1985) Vol. 101; no. 1; pp. 283 - 288
• Main Authors: Lopes-Martins, Rodrigo Alvaro B, Marcos, Rodrigo Labat, Leonardo, Patricia Sardinha, Prianti, Antonio Carlos, Jr, Muscara, Marcelo Nicolas, Aimbire, Flavio, Frigo, Lucio, Iversen, Vegard V, Bjordal, Jan Magnus
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.07.2006; American Physiological Society
• Subjects: Animals; Biological and medical sciences; Creatine Kinase - blood; Dose-Response Relationship, Radiation; Electric Stimulation; Fatigue; Fundamental and applied biological sciences. Psychology; Hypoxia - physiopathology; Hypoxia - prevention & control; Lasers; Low-Level Light Therapy; Male; Muscle Contraction - physiology; Muscle Contraction - radiation effects; Muscle Fatigue - physiology; Muscle Fatigue - radiation effects; Muscle, Skeletal - enzymology; Muscle, Skeletal - innervation; Muscle, Skeletal - physiopathology; Muscle, Skeletal - radiation effects; Musculoskeletal system; Rats; Rats, Wistar; Rodents; Studies; Therapy; electrical stimulation; Vertebrata; Mammalia; Rat; Electrical stimulus; Rodentia; Fatigue; rats; Striated muscle; skeletal muscle; laser therapy
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01318.2005

1 Department of Pharmacology, Laboratory of Biochemical Pharmacology of Free Radicals, Institute of Biomedical Sciences, University of São Paulo, São Paulo; 2 Laboratory of Animal Experiments, IP&D UNIVAP, São José dos Campos; 3 Centro de Ciências Biológicas e Saúde, Universidade Cruzeiro do Sul, São Paulo, Brazil; 4 Department of Physiology, University of Bergen, Bergen; and 5 Section of Physiotherapy Science, Institute of Public Health and Primary Health Care, University of Bergen, Bergen, Norway Submitted 14 October 2005 ; accepted in final form 27 February 2006 We investigated whether low-level laser therapy (LLLT) can reduce muscular fatigue during tetanic contractions in rats. Thirty-two male Wistar rats were divided into four groups receiving either one of three different LLLT doses (0.5, 1.0, and 2.5 J/cm 2 ) or a no-treatment control group. Electrical stimulation was used to induce six tetanic muscle contractions in the tibial anterior muscle. Contractions were stopped when the muscle force fell to 50% of the initial value for each contraction (T50%). There was no significant difference between the 2.5 J/cm 2 laser-irradiated group and the control group in mean T50% values. Laser-irradiated groups (0.5 and 1.0 J/cm 2 ) had significantly longer T50% values than the control group. The relative peak force for the sixth contraction in the laser-irradiated groups were significantly higher at 92.2% (SD 12.6) for 0.5 J/cm 2 , 83.2% (SD 20.5) for 1.0 J/cm 2 , and 82.9% (SD 18.3) for 2.5 J/cm 2 than for the control group [50% (SD 15)]. Laser groups receiving 0.5 and 1.0 J/cm 2 showed significant increases in mean performed work compared with both the control group and their first contraction values. Muscle damage was indirectly measured by creatine kinase levels in plasma. A distinct dose-response pattern was found in which 1.0 and 2.5 J/cm 2 LLLT groups had significantly lower creatine kinase levels than the 0.5 J/cm 2 LLLT group and the control group. We conclude that LLLT doses of 0.5 and 1.0 J/cm 2 can prevent development of muscular fatigue in rats during repeated tetanic contractions. laser therapy; skeletal muscle; electrical stimulation; rats; fatigue Address for reprint requests and other correspondence: R. A. B. Lopes-Martins, Laboratory of Pharmacology and Phototherapy of Inflammation, Dept. of Pharmacology, Inst. of Biomedical Sciences, Univ. of São Paulo, Av. Prof. Lineu Prestes, 1524, Butantan, São Paulo, SP, Brazil 05508-900 (e-mail: rmartins{at}icb.usp.br )