Impact of Exercise Training Response on Quality of Life and Cardiovascular Risk Factor Profiles in People with Coronary Artery Disease: Insights from the HIIT or MISS UK trial

Objective To compare the characteristics of “responders” and “non-responders” to 8-weeks of exercise training to determine differences in key cardiovascular disease outcomes in people with coronary artery disease (CAD). Design Secondary analysis of data from the HIIT or MISS UK trial. Setting Six outpatient National Health Service cardiac rehabilitation centers in the UK. In people with CAD attending cardiac rehabilitation, the HIIT or MISS UK trial reported that short-term, low-volume, high intensity interval training (HIIT) was more effective than moderate intensity steady state (MISS) exercise training for improving peak oxygen uptake (VO2peak). Participants 382 participants with CAD (mean age: 58.8 ± 9.6 years; mean BMI: 29.0 ± 4.3 kg∙m−2). Main Outcome Measures We identified “responders” and “non-responders” based on a meaningful change in peak oxygen uptake, using two established methods. Key clinical, quality of life, and cardiopulmonary exercise test (CPET)-derived outcomes were compared between groups. Results Responders were more likely to be younger (P<0.05), and demonstrate greater improvement in CPET-related outcomes e.g. oxygen uptake efficiency slope (OUES), ventilatory efficiency (VE/VCO2 slope), and peak power output (all comparisons, P<0.001). Responders were more likely to observe improvements in quality of life (EQ-5D-5L; mean Δ 13.6 v mean Δ 9.4; P=0.045), and HDL-cholesterol (mean Δ 0.09 mmol.L−1 v mean Δ 0.04 mmol.L−1; P=0.004), compared to non-responders. Conclusions In people with CAD attending cardiac rehabilitation, “responders” to exercise training were more likely to be younger, and demonstrate greater improvements in health-related QoL and HDL-cholesterol.