Abstract
[Purpose] The purpose of this study was to clarify the effect of therapeutic ultrasound on pain threshold. [Subjects] The subjects were 10 healthy males. [Methods] All participated in three trials: ultrasound (US) without powered ultrasound (placebo), and rest (control). US was applied at 3 MHz, 1.0 W/cm2, and a duty cycle of 100%, for 10 minutes. The outcome measures were the pin-pricking pain threshold (PPPT), the pressure pain threshold (PPT), the visual analog scale (VAS) of PPPT and PPT measurements, and skin surface temperature (SST). Measurements were taken 10 minutes before trials, just before and after trials, 10 minutes after trials, and 20 minutes after trials. [Results] After the US trial, PPPT, PPT, and SST increased significantly more than after the placebo and control trials at 20 minute after the trials. There were no significant differences in VAS. [Conclusion] The results suggest that US has a sustained effect on the pain threshold.
