The Impact of Obesity on Cardiorespiratory Fitness and Weight Changes in a Cardiac Rehabilitation Program

The global burden of obesity is increasing at an alarming rate worldwide.Approximately 2 billion people are overweight, and one third of them are obese; in the United States alone, over 200 million adults (72%) are overweight or obese, with the anticipated rate even higher in 2030.1,2 Obesity may adversely affect the cardiorespiratory fitness (CRF) of patients with cardiac disease and thus limit their ability to engage in and benefit from cardiac rehabilitation (CR) programs.3,4 Our objective was to test the effect of obesity on the improvement in CRF (i.e., change in metabolic equivalents, MET). METHODSWe utilized data from an established retrospective cohort of 312 consecutive patients who underwent CR at the University of California, San Diego, between January 1, 2018 and March 15, 2019 (IRB #190538).5,6 Patients completed either standard (~36 hr) or intensive CR (~72 hr).Eleven participants lacked data on the change in MET (primary outcome), thus the final cohort consisted of 301 patients.Charts were manually reviewed to collect baseline characteristics including demographics, body mass index, reason for CR, type of CR (standard/intensive), duration of CR (d), CR adherence (% completion of all sessions), smoking and alcohol status, and select co-morbidities that could affect exercise (asthma, chronic obstructive pulmonary disease, and obstructive sleep apnea [OSA]).Cardiorespiratory fitness was assessed by MET using a treadmill exercise test before and after CR.This testing was performed according to the standard Bruce protocol, which