Physical activity and sedentary behaviour in a phase III cardiac rehabilitation program: identifying vulnerable subgroups

Abstract Introduction Patients entering a phase III cardiac rehabilitation (CR) program often attend exercise sessions regularly and many meet WHO physical activity (PA) guidelines. However, both PA and sedentary behaviour (SB) are independent cardiovascular risk factors, and meeting PA guidelines does not necessarily protect individuals who accumulate high levels of SB. Additionally, within CR populations, specific subgroups may present less favourable behavioural profiles and require tailored support. Purpose To characterise PA and SB levels in patients entering a phase III CR program and identify subgroups at greater risk for suboptimal activity patterns. Methods In this cross-sectional analysis, patients completed the following baseline assessments: sociodemographic and clinical measures; a symptom-limited ramp cardiopulmonary exercise test; and wore an accelerometer for 7 days. Patients attended supervised 60-min CR exercise sessions, 2-3x/week. Group differences were examined using t-tests or non-parametric alternatives, correlations with pearson coefficient, and multivariable analyses were done with logistic and linear regression models. Results 190 CVD patients were included (62±10 y/o, 17.9% women, 85.8% coronary artery disease, 84.2% completed phase II CR). Patients accumulated on average 45.89±24.81 min/day of moderate-to-vigorous PA (MVPA) and 11.06±1.28 hours/day of SB. Women performed more light PA (LPA), while men accumulated more MVPA (LPA women: 185.7 min/day, IQR = 142.0–210.6 vs men 157.1 min/day, IQR = 128.9–189.6, p=.038; MVPA women 31.1 min/day, IQR=17.9–56.1 vs men 45.1 min/day, IQR = 30.2–61.3, p=.041). Average MVPA was negatively correlated with age (r=–0.19, p=.008) and positively correlated with cardiorespiratory fitness (VO2peak) (r=0.34, p.001). Patients with diabetes accumulated less MVPA (43.7 min/day, IQR = 28.3–61.2 vs 45.9 min/day, IQR=29.9–69.9, p=.011) and patients who completed a phase II CR program had lower SB percentage (76.6%, IQR = 71.1–80.2 vs 78.8%, IQR=74.1–81.9, p=.028). In multivariable models, sex, VO2peak, and accelerometer wear time independently predicted meeting PA guidelines. Men were over 5x more likely to meet PA guidelines than women (OR=5.50, 95% CI 1.7–17.7), and each 1 ml/kg/min increase in VO2peak was associated with 14% higher odds of compliance (OR=1.14, 95% CI 1.01–1.29). Accelerometer wear time was also a significant predictor (p=.004). Completion of phase II CR was the only independent predictor of lower %SB/day, with participants who had completed phase II spending on average 2.9% less of their day in SB (p =.032). Conclusion Although most patients entering phase III CR achieved recommended MVPA levels, SB remained high. Women, individuals with lower VO2peak, those with diabetes, and participants who had not completed Phase II CR showed less favourable activity profiles. These findings highlight the need for tailored strategies within long-term CR to support these vulnerable subgroups.