The effect of high- and low-frequency H-wave therapy upon skin blood perfusion: evidence of frequency-specific effects

The current study was designed to assess the putative physiological effects of H-wave therapy (HWT, a mode of therapeutic electro-stimulation) on skin blood flow in humans and to determine the relevance of frequency to any su ch effects. Laser Doppler flowmetry was used to record changes in blood per fusion on the dominant forearm of healthy human volunteers (n=36), who were each assigned, under randomized double blind conditions, to one of three e xperimental groups: placebo or HWT at 2 or 60 Hz. HWT stimulation was appli ed for 20 min, during which time concomitant skin temperature was recorded using three surface skin thermistors. Statistical analysis of perfusion mea surement and skin temperature changes pre-, during and for up to 18 min pos t-HWT stimulation showed a highly significant increase in skin blood flow i n the 2 Hz group when compared to placebo and 60 Hz (P less than or equal t o 0.01). This was associated with a significant increase in skin temperatur e during the period of stimulation (P less than or equal to 0.05). No such differences were observed in the 60 Hz group. These results provide evidenc e that low-frequency HWT may produce direct localized effects on cutaneous blood flow, a finding relevant for clinicians working in the field of tissu e repair.