# Calculation of Oxygen Uptake during Ambulatory Cardiac Rehabilitation

## TL;DR

This study shows that accurate estimates of oxygen uptake in cardiac patients during rehabilitation can be made using specific equations.

## Contribution

The study validates the FRIEND equation and a simplified method for estimating peak oxygen uptake in cardiac rehabilitation.

## Key findings

- The FRIEND equation and a combination of rules of thumb showed strong agreement with measured VO2 values.
- The ACSM equation performed less reliably compared to the other methods.
- These methods are effective for estimating VO2 both at the start and end of rehabilitation.

## Abstract

Background: Cardiopulmonary exercise testing is not used routinely. The goal of this study was to determine whether accurate estimates of VO2 values can be made at the beginning and at the end of a rehabilitation program. Methods: A total of 91 cardiac rehabilitation patients were included. Each participant had to complete cardiopulmonary exercise testing at the beginning and at the end of a rehabilitation program. Measured VO2 values were compared with estimates based on three different equations. Results: Analyses of the means of the differences in the peak values showed very good agreement between the results obtained with the FRIEND equation or those obtained with a combination of rules of thumb and the results of the measurements. This agreement was confirmed with the ICCs and with the standard errors of the measurements. The ACSM equation performed worse. The same tendency was seen when considering the VO2 values at percentage-derived work rates. Conclusions: The FRIEND equation and the more easily applicable combination of rules of thumb are suitable for estimating the peak VO2 and the VO2 at a percentage-derived work rate in cardiac patients both at the beginning and at the end of a cardiac rehabilitation program.