Association Between Home-Based Exercise Modality and Improvements in Exercise Capacity During Outpatient Cardiac Rehabilitation　― A Retrospective Observational Study ―

Background: Peak oxygen uptake (V̇O 2 ) is a clinically meaningful indicator of functional capacity and prognosis during cardiac rehabilitation (CR). Although home-based exercise is essential in outpatient CR, the impact of different exercise modalities on exercise capacity remains unclear. Methods and Results: This retrospective observational study included 69 patients who underwent outpatient CR and completed cardiopulmonary exercise testing at baseline and follow up. Home-based exercises were classified as ergometer based or walking based. Exercise self-efficacy was assessed as a behavioral factor. When the peak V̇O 2 was analyzed as a continuous outcome via analysis of covariance, ergometer-based home exercises were independently associated with a higher post-intervention peak V̇O 2 after adjustment for baseline peak V̇O 2 , age, and sex. This association was attenuated after additional adjustment for changes in exercise self-efficacy. The proportion of patients with ≥6% improvement in peak V̇O 2 was non-significantly higher in the ergometer-based exercise group. Conclusions: In an outpatient CR setting, ergometer-based home exercises were associated with modestly greater improvement in exercise capacity, assessed as peak V̇O 2 , particularly as a continuous outcome. Although self-efficacy was not an independent predictor, its association with this relationship highlights the potential importance of behavioral engagement in the relationship between prescribed exercises and physiological improvements. The principles underlying ergometer-based exercise – such as structured intensity prescription and objective feedback – may be applicable to broader home-based exercise programs, including walking-based interventions.