Updated FRIEND CPET standards
About this reference
The updated FRIEND analysis contains 22,379 cardiopulmonary exercise tests performed from 1968 through March 2021: 16,278 treadmill and 6,101 cycle-ergometer tests. It publishes sex- and decade-specific percentiles of directly measured peak oxygen uptake separately by exercise mode and by peak respiratory exchange ratio criterion. FitnessNorms uses the treadmill standards for tests with peak RER at least 1.10, as implemented in study coauthor James E. Peterman's FRIENDanalysis package. The exact size of that stricter displayed subset is not stated in the public implementation, so 22,379 is the parent-study n and must not be read as the n behind every displayed cell.
Known limitations
- The registry is a retrospective collection from participating exercise laboratories, not a probability sample of the US population
- Tests span 1968-2021 and 34 laboratories, with variation in equipment, treadmill protocols, stopping decisions, and VO2peak averaging methods
- The paper's 22,379 total includes treadmill and cycle tests; 16,278 is the treadmill parent cohort, not the exact n of the stricter peak-RER-at-least-1.10 table used by FitnessNorms
- The source reports VO2peak, which should not be assumed to be a plateau-confirmed physiological VO2max for every participant
- Treadmill and cycle-ergometer standards are separate and are not interchangeable
- Apparently healthy registry eligibility does not make these values clinical cutoffs, treatment targets, or a guarantee of health