VO2 max is the maximum amount of oxygen your body can use during intense exercise. Decades of research show it's one of the strongest predictors of all-cause mortality — stronger than smoking status, hypertension, or diabetes in some studies. The good news: it's highly trainable, at any age.
A 2018 JAMA study of over 120,000 patients found that the difference in mortality risk between the least fit and the most fit categories was greater than the difference associated with smoking, coronary artery disease, or diabetes. That's a striking finding — and it puts cardiorespiratory fitness in a category of its own.
Why it matters in your 60s, 70s, and beyond
VO2 max naturally declines about 10% per decade after 30. The higher you build it now, the more functional capacity you have later — the difference between hiking with grandkids and struggling with stairs. Doubling your VO2 max roughly halves your all-cause mortality risk.
It's also the aerobic reserve you draw on to recover from illness, surgery, or injury. Older adults with a higher VO2 max recover faster and more completely — the reserve you build in your 40s and 50s is what you spend later.
How to train it
- Zone 2 cardio (conversational pace): 3–4 hours per week — builds the aerobic base
- VO2 max intervals: one session per week of 4 x 4 minutes near max effort, with 4-minute easy recoveries
- Strength training: 2–3 sessions weekly supports the engine that drives output
- Daily steps: the baseline activity everything else builds on
- Progressive overload — same as strength training, but for cardio
The 80/20 rule for cardio
Elite endurance athletes typically do about 80% of their weekly cardio at low intensity (Zone 2) and 20% at high intensity. Most recreational exercisers do the opposite — too much in the middle zone that's too hard to build the aerobic base and too easy to push VO2 max.
Slower most of the time, then genuinely hard once a week, is a more effective template than always going 'medium.'
Measuring progress
Wearables estimate VO2 max reasonably well, and formal testing (a treadmill or bike test with a mask) is widely available if you want a precise number. Track the trend, not the single number — improvement of 10–20% over a year is realistic for most people, and that improvement is the actual longevity lever.
Even simpler: how many flights of stairs can you climb without stopping? How long can you carry heavy groceries? Function tracks fitness more honestly than any dashboard number.