Development of Global Reference Standards for Directly Measured Cardiorespiratory Fitness: A Report From the Fitness Registry and Importance of Exercise National Database (FRIEND)

Abstract

Objective: To begin the process of developing global reference standards for adults from directly measured cardiorespiratory fitness (CRF).

Methods: Percentiles of maximal oxygen consumption (VO₂max) for men and women were determined for each decade from 20 through 79 years of age using International data from the Fitness Registry and Importance of Exercise: A National Database (FRIEND-I) along with previously published data from seven studies. FRIEND-I data from January 1, 2014, through January 1, 2019, included 11,678 maximal treadmill tests from three countries, whereas the previously published reports included 32,329 maximal treadmill tests from six countries.

Results: FRIEND-I data revealed significant differences between sex and age groups for VO₂max (P<0.01). For the 20- to 29-years of age group, the 50^th percentile VO₂max in men and women were 49.5 mLO₂⋅kg^-1⋅min^-1 and 40.6 mLO₂⋅kg^-1⋅min^-1, respectively. VO₂max declined an average of 9% per decade with the 50^th percentile for the 70- to 79-years of age group having a VO₂max of 30.8 mLO₂⋅kg^-1⋅min^-1 in men and 25.0 mLO₂⋅kg^-1⋅min^-1 in women. These results were similar in magnitude and direction to the previously published literature. Within both the FRIEND-I and previously published data there were CRF differences between countries.

Conclusion: This report begins to establish global reference standards for CRF. Continued development of FRIEND-I will increase global representation providing an improved ability to identify and stratify CRF risk categories.