Implications of Cardio-Respiratory Fitness on the Performance of Exercise Tests

In 2016, the American Heart Association (AHA) produced a position paper on cardiorespiratory fitness (CRF) which defined CRF as the most important cardiac risk factor in the assessment of prognosis in a wide variety of clinical states [1]. The aim of the paper was to improve patient management and to encourage life-style based strategies designed to improve cardiovascular risk. The authors showed that:

• Cardiorespiratory fitness was a stronger predictor of patient survival than other clinical and exercise test variables in both men and women.

• Non-exercise cardiac risk factors clustered in unfit people.

• People unable to exercise to five METs were at the highest risk of premature mortality. (1 MET = 3.5ml/kg/minute of oxygen intake).

• Improvement in CRF from the least fit to intermediate CRF reduced the mortality risk more than an increase in CRF from the intermediate CRF group to the high CFR group.

• They showed that adding a measure of CRF to baseline risk factors better predicted mortality in a wide variety of subjects with various clinical presentations.

• That adding measures of CRF to prediction models, particularly those based on the Framingham Risk Score, improved estimations of risk of cardiovascular disease.

• That CRF can be reasonably well predicted from a standardised questionnaire.

In this Brief Communication, we expand on how CRF can be assessed and reported in exercise testing.