Low-level laser therapy enhances muscular performance as measured by isokinetic dynamometry in humans

Abstract

Skeletal muscle fatigue is a novel research area in laser therapy, there being few studies carried out. Though low-level laser therapy (LLLT) applied prior to exercise has showed positive results in delaying skeletal muscle fatigue, no studies could be found that measured muscle performance and fatigue by means of isokinetic dynamometry. This clinical trial aims at assessing the effects of LLLT (655 nm, 50 mW and 12 J total energy delivered) on anterior tibialis muscle performance and fatigue by means of isokinetic dynamometry (30 concentric-mode repetitions at 240º.sec-1 angular speed) in 14 healthy male subjects. Results show that, when volunteers had been treated with LLLT prior to exercise, torque peak values (30.91±5.86 N.m) were significantly higher than those of three previous measurements with no LLLT (24.92±7.45 N.m, p<0.001; 26.83±7.74 N.m, p<0.01; and 26.00±7.88 N.m, p<0.001). However, no decrease in fatigue indexes could be found. It may thus be said that LLLT increased skeletal muscle torque in irradiated muscles, but had no effect on muscle fatigue.