Blood pressure morning surge, exercise blood pressure response and autonomic nervous system

We investigated blood pressure (BP) response to exercise with respect to BP morning surge (MS), and the association between MS, exercise treadmill test (ETT) and heart rate variability (HRV) indices.

Eighty-four healthy subjects without hypertension were enrolled. Ambulatory BP monitoring and 24-hour Holter recordings were obtained for sleep-trough MS and HRV indices: low-frequency (LF) component, high-frequency (HF) component and LF/HF ratio. ETT was performed, and BPs were obtained at rest, end of each stage, and recovery. Third-minute heart rate recovery (HRR) and BP recovery ratio (BPRR) were calculated.

When analysed in quartiles of MS, systolic BP at low workloads was higher in the highest than in the lowest quartile, although maximum BPs at maximum exercise were not significantly different. BPRR was highest in the highest quartile in contrast to HRR, which was lowest in the highest quartile. LF/HF was highest during both at daytime and night-time in the highest quartile. BPRR and LF/HF were positively, and HRR was inversely associated with MS.

Subjects with a high MS have higher BP at low workloads, at which most daily activities are performed, and impairment in some indices, which indirectly reflect the autonomic nervous system.