Local and systemic effects of low-power laser on pressure pain threshold in healthy subjects

Abstract

Low-power laser is used as a therapeutic tool for pain control. However, it is still questioned its real effects and the more effective dosimetry for this analgesic effect. Therefore, this study aimed at assessing the local and systemic effects of low-power laser on pressure pain threshold in healthy subjects. One hundred and fifty subjects were randomized into five groups: Control, Placebo Laser, 3 J, 6 J, and 12 Joules. A pressure algometer was used to assess pressure pain threshold in five different periods. In the dominant hand, laser and algometry were performed to determine the local effect, and in the dominant leg, algometry was performed to assess the systemic effect of low-power laser. There was a reduction on local pressure pain threshold in the Group 3 J compared with Control (p=0.0016) and Placebo (p=0.004) groups. No systemic changes on pressure pain threshold were observed. Low-power laser with energy of 3 J decreased pressure pain threshold in healthy subjects, but there was no systemic change.