Reference Standards for Cardiorespiratory Fitness Measured With Cardiopulmonary Exercise Testing: Data From the Fitness Registry and the Importance of Exercise National Database

Abstract

Objective: To develop standards for cardiorespiratory fitness by establishing reference values derived from cardiopulmonary exercise testing (CPX) in the United States.

Patients and methods: Eight laboratories in the US experienced in CPX administration with established quality control procedures contributed data from January 1, 2014, through February 1, 2015, from 7783 maximal (respiratory exchange ratio, ≥ 1.0) treadmill tests from men and women (aged 20-79 years) without cardiovascular disease (CVD) to the Fitness Registry and the Importance of Exercise: A National Data Base (FRIEND). Percentiles of maximal oxygen consumption (VO 2max) for men and women were determined for each decade from 20 years of age through 79 years of age. Comparisons of VO 2max were made to reference data established with CPX data from Norway and to US reference data established without CPX measurements.

Results: There were significant differences between sex and age groups for VO 2max. In FRIEND, the 50th percentile VO 2max of men and women aged 20 to 29 years decreased from 48.0 and 37.6 mLO2 · kg(-1) · min(-1) to 24.4 and 18.3 mLO2 · kg(-1) · min(-1) for ages 70 to 79 years, respectively. The rate of decline in this cohort during a 5-decade period was approximately 10% per decade.

Conclusion: These are the first cardiorespiratory fitness reference data using measures obtained from CPX in the United States. FRIEND can be used to provide a more accurate interpretation of measured VO 2max from maximal exercise tests for the US population compared with previous standards on the basis of workload-derived estimations.

FIGURE 1

Boxplot of measured maximal oxygen update (V̇_O2max) in the Fitness Registry and the Importance of Exercise National Database obtained from men performing treadmill exercise tests during a 6-decade period. Error bars indicate SD.

FIGURE 2

Boxplot of measured maximal oxygen update (V̇_O2max) in the Fitness Registry and the Importance of Exercise National Database obtained from women performing treadmill exercise tests during a 6-decade period.