Objectively measured physical activity relates to night-time blood pressure in older adults: cross-sectional analysis in the HEIJO-KYO cohort.

Abstract

Prognostically, night-time blood pressure (BP) is more important than other BP parameters. Previous physiological studies suggested physical exercise continuously decreases subsequent BP levels, although the association between daytime physical activity and night-time BP has not been evaluated in large populations. This cross-sectional study of 1111 older adults (mean age, 71.8 years) measured physical activity using actigraphy and ambulatory BP parameters. The mean night-time SBP and DBP were 115.9 mmHg (SD, 16.2) and 67 mmHg (8.6), respectively, and the mean average daytime physical activity was 299.2 counts/min (104.3). A multivariable linear regression analysis, adjusted for potential confounders, suggested greater average daytime physical activity was significantly associated with lower night-time SBP (regression coefficient per 100 counts/min increment, -1.18; 95% CI -2.10 to -0.26), and DBP (-0.69; 95% CI -1.17 to -0.17). Significant associations between time above activity thresholds and night-time SBP were consistently observed (≥500 counts/min: regression coefficient per log min increment, -1.61, 95% CI -3.14 to -0.08; ≥1000 counts/min: -1.00, 95% CI -1.97 to -0.03; ≥1500 counts/min: -1.13, 95% CI -2.11 to -0.14). A subgroup analysis without antihypertensive medications (n = 619) strongly associated time above activity thresholds with night-time SBP (≥500 counts/min: -2.94; 95% CI -5.20 to -0.68). These results were consistent in the analysis using dipping as a dependent variable. Objectively measured daytime physical activity was significantly and inversely associated with night-time BP in older adults. Further longitudinal studies would ascertain effects of physical activity on night-time BP.