Effects of gallium arsenide laser irradiation overdose on the quadriceps of rats

Objective. To obtain information on the effects of laser irradiation in order to determine maximum free of deleterious effects dose on muscle tissue. Materials and methods. Twenty male Sprague Dawley rats were studied randomly divided into four groups A, B, C and D. All groups were irradiated with a Laser, using a Gallium Arsenide diode machine. Irradiation was applied in the same point once a day for 10 consecutive days. Groups: A: 15 minutes a day, with a total dose of 24.3 Joules, B: 30 minutes, 48.6 Joules, 45 minutes, 72.9 Joules C: D: 60 minutes, 97.2 joules. Samples from quadriceps were taken for optical and electron microscopy. Results. No alterations were exposed under optical microscopy in any of the groups studied. The electron micrographies showed ultrastructural alterations only in D Group. Conclusions. The difference between the therapeutic dose and the doses that produce ultrastructural alterations in muscle tissue is so great that it make of laser an efficient and safe element to be used in physical therapy.