Abstract
BACKGROUND: Few studies have considered the relationship between risk factors, physical activity and sedentary behaviour in people with heart disease. Here we examine the independent relationship of device-measured physical activity and sedentary behaviour on risk factors, quality-of-life and exercise capacity over 12-months in cardiac rehabilitation attendees. METHODS: Hospital-based phase II cardiac rehabilitation participants with coronary heart disease were assessed at the start and end of cardiac rehabilitation (6-weeks), 6 and 12-months. Physical activity (moderate-to-vigorous (MVPA), light-intensity (LIPA); min/day) and sedentary behaviour (min/day, bouts, breaks) were measured using an ActiGraph accelerometer. Risk factors included waist circumference, body mass index, systolic blood pressure (SBP), fasting blood lipid and glucose levels, anxiety and depression. Quality-of-life and exercise capacity were also collected. Associations were assessed with Generalized Estimating Equation modeling. RESULTS: Sixty-seven participants were included (mean age = 64 (SD 9) years; 81% male). An association was found between higher MVPA and lower high density lipoprotein (p ≤ 0.001). No significant (p ≤ 0.001) associations were found between sedentary behaviour variables and other outcomes. At p < 0.05 several associations were significant. Increased MVPA and LIPA were associated with decreased total cholesterol. Higher MVPA was associated with decreased SBP, whereas higher LIPA was associated with decreased waist circumference and body mass index. Higher sedentary behaviour bouts and breaks were associated with increased total cholesterol, anxiety and depression, and decreased SBP over time. CONCLUSIONS: Any intensity of physical activity was associated with decreased total cholesterol. Increased LIPA was associated with improved measures of adiposity, while breaking up sedentary behaviour and increasing MVPA may decrease SBP over time. Further investigation of MVPA, LIPA and the distribution of sedentary behaviour is indicated in cardiac rehabilitation attendees to explore their relationship with risk factors. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12615000995572, http://www.ANZCTR.org.au/ACTRN12615000995572.aspx . Registered 22 September 2015.