Lopes-Martins Rodrigo Alvaro B, Marcos Rodrigo Labat, Leonardo Patrícia Sardinha, Prianti Antônio Carlos, Muscará Marcelo Nicolas, Aimbire Flavio, Frigo Lúcio, Iversen Vegard V, Bjordal Jan Magnus
Department of Pharmacology, Laboratory of Biochemical Pharmacology of Free Radicals, Institute of Biomedical Sciences, University of São Paulo, Brazil.
J Appl Physiol (1985). 2006 Jul;101(1):283-8. doi: 10.1152/japplphysiol.01318.2005. Epub 2006 Apr 20.
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/cm2) 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/cm2 laser-irradiated group and the control group in mean T50% values. Laser-irradiated groups (0.5 and 1.0 J/cm2) 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/cm2, 83.2% (SD 20.5) for 1.0 J/cm2, and 82.9% (SD 18.3) for 2.5 J/cm2 than for the control group [50% (SD 15)]. Laser groups receiving 0.5 and 1.0 J/cm2 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/cm2 LLLT groups had significantly lower creatine kinase levels than the 0.5 J/cm2 LLLT group and the control group. We conclude that LLLT doses of 0.5 and 1.0 J/cm2 can prevent development of muscular fatigue in rats during repeated tetanic contractions.
我们研究了低强度激光疗法（LLLT）是否能减轻大鼠强直性收缩期间的肌肉疲劳。32只雄性Wistar大鼠被分为四组，分别接受三种不同剂量的LLLT（0.5、1.0和2.5 J/cm²）中的一种，或作为不治疗的对照组。采用电刺激诱导胫骨前肌进行六次强直性肌肉收缩。当每次收缩的肌肉力量降至初始值的50%（T50%）时，收缩停止。2.5 J/cm²激光照射组和对照组的平均T50%值无显著差异。激光照射组（0.5和1.0 J/cm²）的T50%值显著长于对照组。激光照射组第六次收缩的相对峰值力显著高于对照组，0.5 J/cm²组为92.2%（标准差12.6），1.0 J/cm²组为83.2%（标准差20.5），2.5 J/cm²组为82.9%（标准差18.3），而对照组为50%（标准差15）。接受0.5和1.0 J/cm²的激光组与对照组及其第一次收缩值相比，平均做功显著增加。通过血浆中的肌酸激酶水平间接测量肌肉损伤。发现了一种明显的剂量反应模式，即1.0和2.5 J/cm²的LLLT组的肌酸激酶水平显著低于0.5 J/cm²的LLLT组和对照组。我们得出结论，0.5和1.0 J/cm²的LLLT剂量可以预防大鼠在重复强直性收缩期间肌肉疲劳的发展。
