Ground Truths • 14084 implied HN points • 23 Feb 26
- Cardiorespiratory fitness (CRF) and VO2max are not the same: CRF is estimated in METs from real-world or treadmill tests, while true VO2max requires a lab gas-exchange test and smartwatch VO2 estimates are indirect and often inaccurate.
- Nearly all the evidence linking fitness to lower all-cause and cardiovascular mortality is based on CRF/METs, with about a 14–15% reduction in mortality risk per 1-MET improvement, not on wearable or routinely measured VO2max.
- For most people, don’t obsess over smartwatch VO2 numbers; prioritize increasing real-world activity, improving METs and muscle strength, and reserve lab VO2max testing for elite athletes or specific clinical cases, since AI and apps can amplify misleading wearable data.