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

Magnus Bjordal. Effect of low-level laser (Ga-A1-As 655 nm) on skeletal muscle fatigue induced by electrical stimulation in rats. J Appl Physiol 101: 283–288, 2006. First published April 20, 2006; doi:10.1152/japplphysiol.01318.2005.—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 stim-ulation 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