Do we need to rethink the determination of exercise-related energy expenditure in cardiac telerehabilitation interventions?

The American College of Sports Medicine determined the energy consumption of daily activities and sports. Cardiac telerehabilitation (CTR) requires knowing how much energy people consume in daily life outside of cardiac rehabilitation activities. Therefore, we have investigated if the estimated values are valid in CTR. Data from two studies were incorporated. The first study measured ventilatory threshold (VT)1, VT2, and peak exercise on cardiopulmonary exercise testing (CPET) collected from 272 cardiac (risk) patients and compared them to the estimated oxygen consumption (VO₂) at low-to-moderate-intense exercise (3-6 metabolic equivalents [METs]). Next, a patient-tailored application was developed to support CTR using these estimated values, and the intervention (the second study) was conducted with 24 coronary artery disease patients using this application during a CTR intervention. In the first study, VO₂ at VT1, VT2 and peak exercise corresponded to 3.2 [2.8, 3.8], 4.3 [3.8, 5.3], and 5.4 [4.5, 6.2] METs, which are significantly different from the estimated VO₂ at low-to-moderate-intense exercise, especially lower in older, obese, female, and post-myocardial infarction/heart failure patients. These VO₂ varied considerably between patients. The telerehabilitation study did not show significant progress in peak VO₂, but using the application's estimated target, 97.2% of the patients achieved their weekly target, which is a significant overestimate. The estimated and observed exercise-related energy expenditures by CPET were significantly different, resulting in an overestimation of the exercise done by the patients at home. The results can have a significant impact on the quantification of exercise dose during (tele)rehabilitation programs.