High-voltage pulsed galvanic stimulation: effects of frequency of current on blood flow in the human calf muscle.

1. Twelve healthy subjects received high-voltage pulsed galvanic stimulation (115-475 V d.c.) delivered in separate treatments of 2, 32 and 128 pulses/s for 10 min at the subject's maximum tolerable voltage while calf muscle blood flow was measured by non-invasive Whitney strain-gauge venous occlusion plethysmography. 2. The high-voltage pulsed galvanic stimulation was administered with negative polarity by an intermittent mode of 30 s on, 30 s off. Measurements of calf muscle blood flow were made during each 30 s period when the stimulus was off. The effect of one 30 s maximum isometric contraction of the calf muscles on blood flow was used as a standard for evaluating the effectiveness of high-voltage pulsed galvanic stimulation on calf muscle blood flow. 3. Significant (paired t-tests; P less than 0.05) increases in calf muscle blood flow over the preceding baseline levels occurred for the isometric contraction (322%) and for frequencies of 2 pulses/s (33.5%) and 128 pulses/s (13.36%), but not for a frequency of 32 pulses at which calf muscle blood flow increased in only six of 12 subjects. The mean increases in calf muscle blood flow at 2 and 128 pulses/s represented 11.63% and 4.0%, respectively, of that resulting from the isometric contraction. 4. A clear positive correlation between voltage level and the magnitude of increase in calf muscle blood flow was demonstrated but differed for each frequency used.(ABSTRACT TRUNCATED AT 250 WORDS)