It's a number that pops up on our Apple Watches and Garmins and it's not just about fitness - it might be one of the most powerful predictors of how long and how well we live. I like to break it down simply: V = volume, O2 = oxygen, Max = maximal. It’s the maximum rate your body can take in, transport, and use oxygen during hard exercise.
This week, a client asked me: “My watch tells me my VO2max - what really is this, is it accurate and does it even matter?” Great question! It's a number that pops up on our Apple Watches and Garmins and it's not just about fitness - it might be one of the most powerful predictors of how long and how well we live. Let's dive in...
Where insight becomes impact
What I’ve been looking at this week…
What exactly is VO2max? I like to break it down simply: V = volume, O2 = oxygen, Max = maximal. It’s the maximum rate your body can take in, transport, and use oxygen during hard exercise. Think of VO2max as your oxygen budget. The bigger the budget, the more energy you can spend on living- not just exercising, but climbing the stairs without puffing, recovering faster from illness, and protecting your brain and heart for the long haul. And here’s the data point that made me sit up: people in the highest VO2max category have up to a 5-fold lower risk of death compared with those in the lowest category. That’s not a supplement. That’s not a pill. That’s simply your body’s ability to use oxygen efficiently. So when your watch flashes a number- 38 ml/kg/min, 42, 50 - it’s not just another metric. It’s a proxy for your healthspan.
Track it to hack it.
What I’ve been monitoring this week…
Here’s where it gets interesting. Watches don’t measure VO2max directly - they estimate it. They use algorithms based on your heart rate, pace, and weight. Are they perfect? No. Are they useful? Yes - especially for spotting trends over time. The traditional “gold standard” is a lab test: treadmill or bike, mask on, pushing until you hit your ceiling. Accurate, yes - but can be exhausting and inconvenient. In my clinic, I use the VentriJect Seismofit- my "platinum standard." It's a device that uses seismocardiography to measure VO2max in literally 3 minutes. It’s quick, accurate, reliable, convenient and far more comfortable than the lab mask protocol.
From knowing to doing.
What this means for YOU…
Make VO2max your new vital sign. Your sign of life and your sign of a long life. Take a more deliberate approach to raising your VO2max. Here’s how:
If you’re just getting started: commit to the 2-20: walk for 2 minutes, then 20 seconds of walking even more briskly or sprinting.
If you’re 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. These “intervals” are the magic sauce. What matters is nudging your heart rate high enough and keeping it there long enough to stimulate change.
Always: protect your sleep, keep your protein high, and if fatigue lingers - and here's the differentiator - check your iron (especially ferritin).
Why iron? Because iron binds to haemoglobin, the protein in red blood cells that physically carries oxygen. If your iron is low, your haemoglobin can’t carry as much oxygen. And if you can’t carry it, you can’t deliver it, no matter how big your lungs or how strong your heart or how hard you train your VO₂ max will stall.
And remember: if you have a wearable, use it for trend tracking, but don’t treat estimates as gospel. If you want precision, you're welcome to come into clinic for a 3-minute, in-house test. It’s fast, accurate, comfortable, and avoids lab exhaustion or mask protocols. We can pair the results with your bloodwork, like iron studies, and then build a plan around your training, recovery, and nutrition.
DIY VO2max Checks (at home) No wearable? Not ready for a clinic test yet? Here are three simple ways to ballpark your VO₂ max at home: 1️⃣ The Cooper Test (12 minutes) Run, walk, or jog as far as you can in 12 minutes. Use the Cooper Equation to estimate VO2max. VO2 max = (22.351 x distance in km) - 11.288 2️⃣ The Rockport Walk Test (1 mile) Walk a mile as briskly as possible, record your time, and measure your heart rate at the end. Enter both into this Rockport equation for an estimate. VO2 max = 132.853 - (0.0769 x your weight in pounds) - (0.3877 x your age) + (6.315 if you are male or 0 if you are female) - (3.2649 x your walking time) - (0.1565 x your heart rate at the end of the test) 3️⃣ The 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, simple, and repeatable. Use them to track trends. If you want precision, that’s where clinic testing comes in — I use VentriJect Seismofit to give you the real number without the bike-and-mask drama.
💼 Case in point: One of my clients, a 54-year-old investor, felt “average.” Her watch VO₂ max was 34 - technically 'fair' for her age, but her biological age test told another story: she was running 10 years older than her calendar age. She noticed it too, saying no to hikes with friends and no to bike rides with her children and feeling her world shrink. When I tested her VO2max in clinic with Seismofit, we also checked her iron. Her ferritin was low, meaning her haemoglobin couldn’t carry enough oxygen. 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, and consistent sleep. 10 weeks later, her VO₂ max had climbed to 42, excellent. And her biological age? Younger 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 VO2max: not medals, but moments.
🎯 If you'd like to make decisions with precision based on your personal data and using devices that are specific for you, then book a private consultation and let's start to decode your health.
Where you’ll find me…
Last week: I hosted a Million Hour Club masterclass on the gut–brain axis. Did you know your microbes are involved in making neurotransmitters like serotonin and dopamine? Those "butterflies in your stomach" that signal how you feel and how you focus.
This week: I’m at the SIP Family Medical Office Global Health Conference, an event that unites leaders who understand that health and wealth are inseparable. Here, conversations about financial legacy sit right alongside conversations about biological longevity. My role? To show why protecting your health is the smartest investment strategy of all.
Next week: I'll be speaking at Pause Live about all things sleep. Tickets here - be great to see you!
A thought to pause on…
“Breath is life, but VO2max is how much life your breath can give you.” Wishing you a wonderful week ahead! Dr Alka
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