PP12 Blood flow during alternating and pulsed current electrical stimulation delivered above motor threshold

Abstract

<h3></h3> Electrical muscle stimulation (EMS) has been shown to be a promising method to heal wounds and ulcers by enhancing blood flow in the affected area through increasing transcutaneous partial pressure of oxygen, local tissue oxygen tension and capillary density. Kilohertz-carrier-frequency (kHz) is proposed to improve peripheral vasodilatation and stimulate deeper tissues. The purpose of this study was to compare the effect of alternating current (AC) and pulsed current (PC) on cutaneous blood flow when delivered over muscle belly. Vastus medialis muscle of seven healthy men (23–48 y) was electrically stimulated via surface electrodes by either AC (2.5 kHz, modulated at 75 Hz) or PC (75 Hz) to evoke isometric contractions. Pulse duration (400 μs), on—off ratio (5–15 s) and other stimulation parameters were matched between currents. EMS for each current was delivered at 25% above the motor threshold for 5-min twice separated by 10-min recovery period to allow returning to steady state (vascular re-equilibration). Near-infrared spectroscopy was used to determine skin blood flow through tissue oxygenation. Both currents have shown a significant increase in local haemodynamic and tissue oxygenation changes with a slightly greater rise during AC. It is concluded that AC and PC are both an effective technique to enhance local blood flow, which may accelerate wound-healing processes.