Physical activity and heart rate variability in older adults: the Cardiovascular Health Study

Abstract

Background: Cardiac mortality and electrophysiological dysfunction both increase with age. Heart rate variability (HRV) provides indices of autonomic function and electrophysiology that are associated with cardiac risk. How habitual physical activity among older adults prospectively relates to HRV, including nonlinear indices of erratic sinus patterns, is not established. We hypothesized that increasing the levels of both total leisure-time activity and walking would be prospectively associated with more favorable time-domain, frequency-domain, and nonlinear HRV measures in older adults.

Methods and results: We evaluated serial longitudinal measures of both physical activity and 24-hour Holter HRV over 5 years among 985 older US adults in the community-based Cardiovascular Health Study. After multivariable adjustment, greater total leisure-time activity, walking distance, and walking pace were each prospectively associated with specific, more favorable HRV indices, including higher 24-hour standard deviation of all normal-to-normal intervals (Ptrend=0.009, 0.02, 0.06, respectively) and ultralow-frequency power (Ptrend=0.02, 0.008, 0.16, respectively). Greater walking pace was also associated with a higher short-term fractal scaling exponent (Ptrend=0.003) and lower Poincaré ratio (Ptrend=0.02), markers of less erratic sinus patterns.

Conclusions: Greater total leisure-time activity, and walking alone, as well, were prospectively associated with more favorable and specific indices of autonomic function in older adults, including several suggestive of more normal circadian fluctuations and less erratic sinoatrial firing. Our results suggest potential mechanisms that might contribute to lower cardiovascular mortality with habitual physical activity later in life.

Keywords: electrophysiology; epidemiology; exercise; heart rate; motor activity.

Figure 1

Timeline of assessment of PA and HRV in the Cardiovascular Health Study. *Including swimming, hiking, aerobics, tennis, jogging, racquetball, walking, gardening, mowing, raking, golfing, bicycling or exercise cycle, dancing, and calisthenics. **Both distance and pace of walking were assessed.

Figure 2

Longitudinal associations of leisure-time activity and walking distance with specific HRV indices at 1994–95, assessed using 24-hour Holter, among 985 older US adults. Dots and vertical lines represent the adjusted mean differences and the respective SD 95% between participants in a given quintile; quintile of walking distance (images in the left) or leirure-time activity (images in the right). Adjusted for age (years), sex (male, female), race (white, nonwhite), enrollment center (4 sites), education ($25,000), smoking (never, former, current), alcohol (<1 drink/week, 1–2 drinks/week, 3–7 drinks/week, 8–14 drinks/week, >14 drinks/week), and consumption of fish (<1 serving/month, 1–3 servings/month, 1–2 servings/week, 3–4 servings/week, 5+ servings/week), dietary fiber (quintiles, g/day), and total calories (quintiles, kcal/day).

Figure 3

Longitudinal associations of leisure-time activity and walking distance with specific HRV indices at 1994–95, assessed using 24-hour Holter, among 985 older US adults. Solid lines represent restricted cubic splines (smoothed fits); dashed lines represent 95% confidence intervals. Adjusted for age (years), sex (male, female), race (white, nonwhite), enrollment center (4 sites), education ($25,000), smoking (never, former, current), alcohol (<1 drink/week, 1–2 drinks/week, 3–7 drinks/week, 8–14 drinks/week, >14 drinks/week), and consumption of fish (<1 serving/month, 1–3 servings/month, 1–2 servings/week, 3–4 servings/week, 5+ servings/week), dietary fiber (quintiles, g/day), and total calories (quintiles, kcal/day). P nonlinearity for leisure-time activity: SDNN= 0.30; ULF= 0.67; DFA1=0.96) and walking distance P nonlinearity: SDNN= 0.66; ULF= 0.86; DFA1=0.97.