FRIEND Registry
About this reference
The FRIEND Registry is a national database of cardiopulmonary exercise test (CPET) results collected from multiple clinical exercise physiology laboratories across the United States. It provides age- and sex-specific reference values for cardiorespiratory fitness, measured as VO2 max, based on maximal treadmill testing with direct gas exchange analysis. The registry was established to address the lack of standardised normative data from a large, diverse US population.
Known limitations
- Primarily reflects clinical populations referred for exercise testing, not a general population sample
- US-based sample — may not generalise to all populations
- Treadmill protocol only — values may differ from cycle ergometer testing