The effect of high- and low-frequency transcutaneous electrical nerve stimulation upon cutaneous blood flow and skin temperature in healthy subjects

The reported non-analgesic effects of transcutaneous electrical nerve stimu lation (TENS) include alterations to the local circulation; however, resear ch in this area has produced equivocal findings. In the present study, the effect of low- (4 Hz) and high-frequency (110 Hz) TENS on forearm skin bloo d perfusion was assessed using laser Doppler flowmetry. The effect on skin temperature was also assessed using a skin thermistor. Thirty healthy human volunteers were recruited and randomly assigned to a control or one of the two treatment groups. TENS was applied to the skin overlying the median ne rve under double-blind conditions for 15 min. Blood flow and skin temperatu re readings were recorded pre-TENS, during TENS application and continued f or 15 min post-TENS application. Analysis of results showed significant inc reases in blood perfusion during the treatment period in the low-frequency group when compared to the other two groups (P = 0.0106; ANOVA). No signifi cant changes in skin temperature were observed. The results of this study d emonstrate that low-frequency TENS produces a local increase in cutaneous b lood flow.