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 (VO2 peak).

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.