# Utility of Field Tests for Predicting Cardiorespiratory Fitness and Prescribing Exercise Intensity in Cardiac Rehabilitation Programs: A Randomized Crossover Trial

## TL;DR

This study finds that field tests are not accurate enough to replace CPET for predicting cardiorespiratory fitness or prescribing exercise intensity in cardiac rehab.

## Contribution

The study provides empirical evidence on the limitations of field tests for exercise prescription in cardiac rehabilitation.

## Key findings

- Field tests showed variable accuracy for predicting V̇O2peak, with none meeting predefined agreement criteria.
- Regression models can estimate VT1, but HR agreement levels suggest CPET is still necessary for accurate exercise intensity prescription.

## Abstract

The aims of this study are the following: To examine whether field tests predict cardiorespiratory fitness in people with coronary heart disease (CHD) and to determine if heart rate (HR) agreement between the first ventilatory threshold (VT1) and field tests is sufficient for prescribing exercise intensity. Participants randomly completed field tests and a cardiopulmonary exercise test (CPET). Linear regression models were developed to predict VT1. Agreement between predicted and measured peak oxygen consumption (V̇O2peak) as well as field test terminal HR and HR at VT1 (VT1HR) was assessed using Pearson correlations, Bland–Altman analyses, mean absolute percentage error (MAPE), Lin’s concordance correlation coefficient (CCC), and standard error of estimate (SEE). Agreement between predicted and measured V̇O2peak was modest (Pearson’s r = 0.27–0.77; Lin’s CCC = 0.132–0.735; MAPE = 16.1–30.1%; SEE = 4.7–6.8 mL·kg−1·min−1). Agreement between field test terminal HR and VT1HR was moderate (Pearson’s r = 0.50–0.67; Lin’s CCC = 0.36–0.68; MAPE = 8.9–13.7%; SEE = 11.9–18.7 bpm; Bland–Altman 95%LOA = −3.5 to 13.7 bpm). Field tests demonstrated variable accuracy for predicting V̇O2peak, with none meeting predefined agreement criteria. Regression models indicate field tests can estimate VT1; however, levels of HR agreement indicate CPET is necessary for prescribing exercise intensity.