Exclusion of influence of physical activity on ambulatory blood pressure.

Objective: The basal blood pressure (BP) is more intimately related to hypertension severity than casual BP. BP values obtained by ambulatory blood pressure monitoring (ABPM) tend to be influenced by patients' physical activity because values are not always obtained with the patient at rest. The purpose of this study was to estimate the influence of physical activity on BP and determine daytime BP adjusted for activity as measured by ABPM.

Methods: This study targeted three clinically different groups: healthy medical students (HS, n = 40), patients with hypertension (HT, n = 20), and patients with diabetes mellitus (DM, n = 7). The subjects' BP, heart rate (HR), and physical activity level were measured by a noninvasive portable multi-biomedical recorder. To identify the influence of physical activity on BP in the three study groups, a least squares regression analysis of the relation between BP and ACT (an index of activity with acceleration) was performed for each group.

Results: ACT had a positive influence on systolic BP (SBP) in the HS, HT, and DM groups (R2 = 0.319, 0.576, 0.697, respectively). SBP adjusted for ACT (walking level) by means of the regression model with dummy variable was 0-24 mmHg lower than the value of SBP measured by ABPM, and daytime SBP (walking level) was overestimated by approximately 10 mmHg in comparison to the value of SBP at rest (ACT = 0).

Conclusion: Physical activity had a positive effect on SBP. The results showed that physical activity (walking-level) had a positive effect on SBP of about 10 mmHg.