Effect of graded electrical stimulation on blood flow to healthy muscle.

The purpose of this study was to determine whether 2,500-Hz sine-wave electrical stimulation modulated at 50 bursts per second producing graded muscular responses affects blood flow. Healthy volunteer subjects were assigned randomly to an Experimental group (n = 14) that received bursts of electrical stimulation to the gastrocnemius muscle or to a Control group (n = 14) that received no treatment. Using a Doppler device, pulsatility index (PI) values were determined for multivariate statistical analysis. Electrical stimulation graded to simulate isometric torques equivalent to 10% and then 30% of the subjects' isometric maximum voluntary contraction resulted in respective mean increases in PI values of 20.5% and 19.6% over prestimulation PI values. We found no significant difference in PI values between the two levels of torque. No significant change in PI values was found among the Control group subjects. Our results indicate that electrical stimulation, as used in this study, can alter the blood flow to the muscle being stimulated.