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 peak ) were determined pre- and post-CR during which total duration (ET time) and intensity [percent of heart rate peak (%HR peak )] of supervised ET were also obtained. Training responsiveness was quantified on the basis of changes in MET peak 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 peak was progressively lower with greater training responsiveness (F (4,2305) = 44.2, P < 0.01, η 2 p = 0.71). Likewise, average training duration (F (4,2305) = 10.7 P < 0.01, η 2 p = 0.02) and %HR peak (F (4,2305) = 25.1 P < 0.01, η 2 p = 0.042) quantified during onsite ET sessions were progressively greater with greater training responsiveness. The multivariable linear regression model confirmed that baseline MET peak , training duration and intensity during ET, BMI, and age (P < 0.001) were significant predictors of MET peak post-CR.
Conclusions: Along with baseline MET peak , delta BMI, and age, the dose of ET (i.e., training duration and intensity) predicts MET peak 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.
Competing Interests: Declaration of Competing Interest The authors report no relationships that could be construed as a conflict of interest.
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