An evaluation of the role of the exercise training dose for changes in exercise capacity following a standard cardiac rehabilitation program.

BACKGROUND

To retrospectively characterize and compare the dose of exercise training (ET) within a large cohort of patients demonstrating different levels of improvement in exercise capacity following a cardiac rehabilitation (CR) program.

METHODS

A total of 2310 patients who completed a 12-week, center-based, guidelines-informed CR program between January 2018 and December 2019 were included in the analysis. Peak metabolic equivalents (MET) were determined pre- and post-CR during which total duration (ET time) and intensity [percent of heart rate peak (%HR)] of supervised ET were also obtained. Training responsiveness was quantified on the basis of changes in MET from pre- to post-CR. A cluster analysis was performed to identity clusters demonstrating discrete levels of responsiveness (i.e., negative, low, moderate, high, and very-high). These were compared for several baseline and ET-derived variables which were also included in a multivariable linear regression model.

RESULTS

At pre-CR, baseline MET was progressively lower with greater training responsiveness (F = 44.2, P < 0.01, η = 0.71). Likewise, average training duration (F = 10.7 P < 0.01, η = 0.02) and %HR (F = 25.1 P < 0.01, η = 0.042) quantified during onsite ET sessions were progressively greater with greater training responsiveness. The multivariable linear regression model confirmed that baseline MET, training duration and intensity during ET, BMI, and age (P < 0.001) were significant predictors of MET post-CR.

CONCLUSIONS

Along with baseline MET, delta BMI, and age, the dose of ET (i.e., training duration and intensity) predicts MET at the conclusion of CR. A re-evaluation of current approaches for exercise intensity prescription is recommended to extend the benefits of completing CR to all patients.