Department of Exercise and Medical Physiology, Verve Research, Oulu, Finland; Division of Cardiology, Department of Internal Medicine, University of Oulu, Oulu, Finland.
Altered frequency of slow (0.04-0.15Hz) arterial pressure and R-R interval oscillations has been observed in various diseases but the mechanisms for this frequency shift are unclear. The median (Med) frequencies of slow R-R interval and blood pressure (BP) oscillations were recorded in 11 healthy subjects with paced breathing (0.25Hz) during muscle metaboreflex and baroreflex mediated sympathetic stimuli: 1) handgrip exercise (HG) followed by post-exercise circulatory occlusion (PECO), 2) handgrip exercise during ischemia by circulatory occlusion (IHG) and 3) passive head-up tilt (TILT). Med(BP) shifted to the higher frequency during HG, PECO and IHG (from 0.070+/-0.009Hz to 0.088+/-0.013, 0.085+/-0.015 and 0.099+/-0.013Hz, respectively, p