VO₂ Max: Your Oxygen Budget and the True Predictor of Longevity
Originally sent to subscribers on 21 September 2025
What Is VO₂ Max and Why It Matters
This week, a client asked me: “My watch tells me my VO₂ max — what really is this, is it accurate and does it even matter?”. It’s a number on your Apple Watch or Garmin, and it’s not just about fitness; it might be one of the most powerful predictors of how long and how well we live.
VO₂ max is the maximum rate your body can take in, transport, and use oxygen during hard exercise. Think of it as your oxygen budget: the bigger the budget, the more energy you can spend on living—climbing stairs without puffing, recovering faster from illness, protecting your brain and heart for the long haul. People in the highest VO₂ max category have up to a five‑fold lower risk of death compared with those in the lowest category.
When your watch flashes 38 ml/kg/min, 42, 50—it’s not just another metric. It’s a proxy for your healthspan.
DATA
Where insight becomes impact
How Wearables Estimate VO₂ Max
Watches don’t measure VO₂ max directly; they estimate it using algorithms based on heart rate, pace, and weight. They’re not perfect but they’re useful for spotting trends. The gold standard is a lab test with a treadmill or bike and mask—accurate but exhausting. In my clinic, I use the VentriJect Seismofit, a device that measures VO₂ max in three minutes using seismocardiography. It’s quick, accurate, reliable, and comfortable.
DECISIONS
From knowing to doing
Make VO₂ max your new vital sign—your sign of life and long life. Take a deliberate approach to raising it:
Getting started: Commit to the 2‑20: walk for two minutes, then 20 seconds of walking more briskly or sprinting.
Already active: Add one structured interval session weekly. Short bursts of exercising hard enough that you can’t talk in full sentences, repeated with rest in between. Intervals are the magic sauce: nudge your heart rate high enough and keep it there long enough to stimulate change.
Always: Protect your sleep, keep your protein high, and if fatigue lingers, check your iron, especially ferritin. Iron binds to haemoglobin; if iron is low, your haemoglobin can’t carry oxygen, so VO₂ max stalls.
Use wearables for trend tracking but don’t treat estimates as gospel. For precision, come in for a three‑minute test and pair it with iron studies to build a tailored plan.
DIY VO₂ Max Checks
Cooper Test (12 minutes): Run, walk, or jog as far as you can in 12 minutes. Use the Cooper Equation: VO₂ max = (22.351 × distance km) – 11.288.
Rockport Walk Test (1 mile): Walk a mile as briskly as possible, record your time and heart rate at the end, then use the Rockport equation.
Step Test (3 minutes): Step up and down a 12‑inch step at 24 steps/min for 3 minutes, then measure how quickly your heart rate recovers. Faster recovery = higher VO₂ max.
These aren’t perfect but they’re free and repeatable for trend tracking.
Case in point
A 54‑year‑old investor felt “average.” Her watch VO₂ max was 34—fair for her age—but her biological age test said she was running 10 years older. She noticed it too: saying no to hikes and bike rides with her children. When I tested her VO₂ max in clinic with Seismofit, we also checked her iron—her ferritin was low. She wasn’t just under‑trained; she was under‑fuelled at the cellular level.
We built a plan: one interval session a week, daily walks, iron‑rich foods, consistent sleep. Ten weeks later, her VO₂ max climbed to 42 and her biological age dropped by 12 years. The number mattered, but the moment that mattered most was on holiday—climbing hills arm‑in‑arm with her daughter, not trailing behind. That’s the true power of VO₂ max.
DIARY
Last week: Hosted a Million Hour Club masterclass on the gut–brain axis—your microbes help make neurotransmitters like serotonin and dopamine.
This week: At the SIP Family Medical Office Global Health Conference, uniting leaders who understand health and wealth are inseparable. My role: show why protecting your health is the smartest investment strategy.
Next week: Speaking at Pause Live about sleep—tickets available.
DISTINCTION
“Breath is life, but VO₂ max is how much life your breath can give you.”
Wishing you a wonderful week ahead!
Dr Alka