Correlation between spectral measures of systolic blood pressure variability and heart rate variability during paced breathing, standing and exercise

To provide insight on the somewhat controversial issue of the physiological correlates of spectral indexes of systolic pressure variability (SPV) we assessed the relations between them and those of heart rate variability (HRV) in 20 subjects during two sympathetic maneuvers, standing (S) and exercise (E). We also evaluated the percentage of statistical differences among 50-s epochs (PSDE) of the spectral measures dynamics obtained in 5-min steady-state conditions. From time-frequency spectra, high-frequency power of RR intervals (HF RR ), low-to-high-frequency ratio (LF RR /HF RR ), low-frequency of systolic pressure (LF SP ), high-frequency of systolic pressure (HF SP ), high-frequency of respiration (HF Re ) and HF SP -HF Re time-frequency coherence were computed. LF SP -lnHF RR , LF SP -RR and LF SP -LF RR /HF RR correlations were -0.73±0.09, -0.77±0.06, and 0.66±0.13 respectively. During E, HF RR decreased, HF SP increased (p