The importance of daily physical activity for improved exercise tolerance in heart failure patients with limited access to centre-based cardiac rehabilitation

Abstract

Background: Supervised cardiac rehabilitation provided at dedicated centres ameliorates exercise intolerance in patients with chronic heart failure.

Objective: To correlate the amount of physical activity outside the hospital with improved exercise tolerance in patients with limited access to centre-based programs.

Methods: Forty patients (median age 69 years) with stable heart failure due to systolic left ventricular dysfunction participated in cardiac rehabilitation once per week for five months. Using a validated single-axial accelerometer, the number of steps and physical activity-related energy expenditures on nonrehabilitation days were determined.

Results: Median (interquartile range) peak oxygen consumption was increased from 14.4 mL/kg/min (range 12.9 mL/kg/min to 17.8 mL/kg/min) to 16.4 mL/kg/min (range 13.9 mL/kg/min to 19.1 mL/kg/min); P<0.0001, in association with a decreased slope of the minute ventilation to carbon dioxide production plot (34.2 [range 31.3 to 38.1] versus 32.7 [range 30.3 to 36.5]; P<0.0001). Changes in peak oxygen consumption were correlated with the daily number of steps (P<0.01) and physical activity-related energy expenditures (P<0.05). Furthermore, these changes were significantly correlated with total exercise time per day and time spent for light (≤3 metabolic equivalents) exercise, but not with time spent for moderate/vigorous (>3 metabolic equivalents) exercise.

Conclusions: The number of steps and energy expenditures outside the hospital were correlated with improved exercise capacity. An accelerometer may be useful for guiding home-based cardiac rehabilitation.

Keywords: Accelerometer; Cardiac rehabilitation; Heart failure.

Figure 1)

Correlation between the daily number of steps and % changes in peak oxygen consumption (%ΔPVO₂)

Figure 2)

Correlations between daily physical activity-related energy expenditures (PAEE) and % changes in peak oxygen consumption (% ΔPVO₂). PAEE are reported as absolute values in kcal/day (A) and as body weight (BW)-adjusted values in kcal/kg/day (B)

Figure 3)

Per cent changes in peak oxygen consumption (%ΔPVO₂) are plotted against the total daily exercise time (A), the time spent for light exercise (B) and the time spent for moderate to vigorous exercise (C). n.s Not statistically significant

Figure 4)

Per cent changes in minute ventilation/carbon dioxide production slope (%ΔVE/VCO₂) are plotted against the daily number of steps (A) and body weight (BW)-adjusted physical activity-related energy expenditures (PAEE) (B). n.s Not statistically significant