The thermal and nonthermal effects of high and low doses of pulsed short wave therapy (PSWT)

The study aimed to investigate the thermal and non-thermal effects of pulsed short wave therapy (PSWT) using high and low dose of PSWT together with placebo and control conditions in healthy subjects.

A single-blind, crossover design was employed with 31 subjects who all participated in three conditions: High PSWT (PD 200 μsec, PRR 800 Hz, MP 24 W, 10 minutes), Low PSWT (PD 100 μsec, PRR 200 Hz, MP 3 W, 10 minutes), and Placebo PSWT (PD 20 μsec, PRR 50 Hz, MP 0.05 W, 10 minutes). Fourteen subjects additionally participated in a Control condition (no treatment, 10 minutes). Measurements of skin temperature, blood flow, heart rate, and core temperature were taken before, during, and after the application of PSWT. Data were analyzed using a repeated measures analysis of variance (ANOVA) model with a Bonferroni post-hoc comparison.

A significant increase in blood volume and skin temperature with both the high- and low-dose applications during the treatment period was demonstrated. There were significant differences between time periods and between treated and untreated limbs compared with the control condition. The blood flow changes during the low-dose application were not significantly different from placebo. Some subjects were unable to detect significant changes in skin temperature.

Significant physiological changes associated with the application of PSWT have been demonstrated, challenging the notion of a lack of effect of this therapy. The study also demonstrated a measurable increase in skin temperature, which was not associated with thermal sensory perception; thus, skin sensation may not be clinically reliable for detecting real changes in temperature. Subjects with a wide age range of ages were deliberately recruited; however, these results may not extrapolate to a patient population who could react differently to the same intervention. Further studies in the clinical environment are therefore needed.