Effects of rhythmic muscle compression on arterial blood pressure at rest and during dynamic exercise in humans

This study was designed to examine the hypothesis that a rhythmic mechanica l compression of muscles would affect systemic blood pressure regulation at rest and during dynamic exercise in humans. We measured the changes in mea n arterial pressure (MAP) occurring (a) at rest with pulsed (350 ms pulses at 50 pulses min(-1)) or static compression (50 and 100 mmHg) of leg muscle s with or without upper thigh occlusion, and (b) during 12-min supine bicyc le exercise (75 W, 50 r.p.m.) with or without pulsed compression (50, 100, 150 mmHg) of the legs in synchrony with the thigh extensor muscle contracti on. At rest with thigh occlusion, MAP increased by 4-8 mmHg during static l eg compression, and by 5-9 mmHg during pulsed leg compression. This suggest s that at rest pulsed leg compression elicits a reflex pressor response of similar magnitude to that evoked by static compression. During dynamic exer cise without leg compression, MAP (having risen initially) gradually declin ed, but imposition of graded pulsed leg compression prevented this decline, the MAP values being significantly higher than those recorded without puls ed leg compression by 7-10 mmHg. These results suggest that the rhythmic in crease in intramuscular pressure that occurs during dynamic exercise evokes a pressor response in humans.