1. THE GEM | The one workout that raises VO2 max
You want to know how to improve your VO2 max. The short answer is intervals, and one in particular.
First, what the number means. VO2 max is the most oxygen your body can use per minute when you push hard. Think of it as the size of your engine. A bigger engine means more energy for hard efforts and easier daily life.
It matters more than most fitness numbers. VO2 max is one of the tightest links we have to living longer and staying well. And the good news: it is trainable at almost any age.
Here is the gem for this week: add one interval session. The most-tested version is the Norwegian 4x4. You go hard for 4 minutes, recover easy for 3 minutes, and repeat that four times.
That is the whole workout. It is free, it takes about half an hour, and it does more for your VO2 max than the same time spent jogging easy.
2. The Evidence | What the studies show about VO2 max
The core story rests on large cohorts and several meta-analyses, so we grade it Strong.
What the research found, by the numbers
The least fit adults had about 5 times the risk of dying early versus the fittest, with no upper limit to the benefit (Mandsager 2018, a cohort of 122,007 people).
Each small step up in fitness cut early-death risk about 13% (Kodama 2009, a meta-analysis of 33 studies).
Hard intervals beat steady cardio for raising VO2 max by about 1.2 mL/kg/min for the same effort (Milanović 2015, 28 controlled trials).
The 4x4 raised VO2 max about 7% in 8 weeks (Helgerud 2007, a trial of 40 men).
It still works past 60: intervals raised VO2 max across 87 trials in older adults (Men 2025).
How it works, in plain English
When you go hard for a few minutes, your heart fills and pumps near its limit. Train that often enough and the heart pumps more blood per beat. In the 4x4 trial, that stroke volume rose about 10% (Helgerud 2007).
Inside the muscle, training builds more mitochondria and capillaries, the parts that use oxygen. A 2024 review found this machinery keeps growing across the lifespan (Mølmen 2024).
Cardiorespiratory fitness is inversely associated with long-term mortality with no observed upper limit of benefit.
What we don't know yet
The 4x4 is the protocol everyone cites, but the famous "7% in 8 weeks" comes from one trial of 40 fit men (Helgerud 2007). So we grade that single number Moderate, even though larger reviews back the broader pattern that intervals beat easy cardio. A few sports scientists argue the 4x4 hype runs ahead of the proof. The pattern is solid; the exact percentage for you will vary.
One more honest note: the VO2 max on your watch is an estimate, not a lab value. Use it to track your own trend over weeks. Skip the friend comparison.
3. How to do it: the 4x4 interval protocol
Safety first. Hard intervals are safe for most people, but they are a real load on the heart. If you have heart disease, chest symptoms, or you are over 50 and new to intense exercise, check with your doctor before you start.
The protocol has five parts.
1. Warm up easy for 5 to 10 minutes. Get the blood moving and the heart rate climbing. (The original trial did not report its exact warm-up length, so use what feels right.)
2. Go hard for 4 minutes. Aim for an effort where you cannot hold a full sentence. If you track heart rate, that is about 90 to 95% of your max.
3. Recover easy for 3 minutes. Slow right down. You want to be ready to go hard again.
4. Repeat the hard and easy cycle four times. That is the "4x4." The intervals run about 28 minutes, plus your warm-up and cool-down.
5. Do it about three times a week. Keep your other cardio days easy. In the trial, three sessions a week for 8 weeks raised VO2 max about 7% (Helgerud 2007).
No running? No problem. The same structure works on a bike, a rower, or brisk uphill walking. You are chasing the effort, not the sport. This is the route for stiff knees, extra weight, or busy weeks.
At minimum: even one hard interval session a week beats none. Stack it onto a day you already train, so it joins a habit instead of fighting for a new slot.
4. The Transformation | What to expect in week 1, week 3, and month 3
This is a build measured in weeks, not days. Here is the honest arc.
Week 1: you learn the effort
The first 4-minute push feels hard. That is the point.
You figure out your pacing, so you finish the fourth interval, not just the first.
Your easy days feel easy by comparison.
Weeks 2 to 3: it starts to click
The hard intervals feel a touch smoother at the same pace.
Your easy pace creeps faster for the same effort.
Recovery between intervals comes quicker.
Months 1 to 3: the engine grows
By 8 weeks, VO2 max can rise about 7% in trained adults (Helgerud 2007).
The heart pumps more blood per beat, so hard efforts feel easier.
It is not just for the young. Across 87 trials in older adults, intervals still raised VO2 max (Men 2025), and in the best-quality older-adult trials they beat steady cardio (Oliveira 2024).
Don't fear the age curve
VO2 max does drift down with age. But a big share of that drop is a training problem, not just biology. Sedentary adults lose roughly 10% per decade after 30. Trained adults lose about half that (Rogers 1990). The lever stays in your hands.
What you're really buying
A bigger engine for the rest of your life. More energy on the hard days, and a real edge on living longer and well. Most people never train the top end. You can.
5. Common VO2 max mistakes
Mistake 1: Training too easy. This is the big one. If you run a few times a week and your number is stuck, the missing piece is usually intensity. Intervals beat steady cardio for the same time (Milanović 2015).
Mistake 2: Intervals that are too short. A few 20-second sprints feel hard, but to beat a steady jog the hard pieces need to be long, around 4 minutes (Wen 2019).
Mistake 3: Trusting the watch number as exact. Wearable VO2 max is an estimate. Watch your own trend over weeks, and ignore the friend comparison.
Mistake 4: Expecting a supplement to do the work. Beetroot helps a hard effort feel a little easier, but it barely moves the VO2 max number itself (Tian 2025). Training moves it.
Mistake 5: Going hard every day. Intensity needs easy days around it. Three hard sessions a week, with easy or rest days between, is plenty.
6. Worth paying for: gear and supplements, the honest ranking
For most readers: nothing. The 4x4 is free and needs no gear. Skip this section.
If you want a little more, here is the honest order.
A heart-rate chest strap, about $80 to $90. A strap reads your heart rate more accurately than a wrist sensor during hard efforts. It helps you hit the right zone on intervals. Useful, not required. You can train by breath alone.
A lab VO2 max test, often $100 to $250. If the watch estimate bugs you, a metabolic test gives a real number. It is a nice one-time check. You do not need it monthly.
Beetroot or nitrate, food first. Beetroot makes your muscles use oxygen a bit more efficiently, which can make a hard effort feel easier (Wylie 2013). But it barely raises the VO2 max number (Tian 2025). Get it from food first: arugula, beets, leafy greens.
What to skip
If you just want a higher number, skip all of it and do the workout. No strap, no test, no juice will raise your VO2 max the way the intervals will.
7. VO2 max FAQ
Does Zone 2 cardio improve VO2 max?
It helps, but it is the weaker lever for the top number. Easy Zone 2 work builds your aerobic base and is great for health. To raise the VO2 max ceiling for the same time spent, you need hard intervals (Milanović 2015). The best plan uses both: mostly easy, with one or two hard sessions a week.
How long does it take to improve VO2 max?
In the landmark trial, about 7% in 8 weeks with three 4x4 sessions a week (Helgerud 2007). Most people feel the early change, easier breathing on hard efforts, within a few weeks.
How can I improve VO2 max without running?
Use the same 4x4 structure on a bike, a rower, or a steep walk. The effort is what counts, not the sport. This is the joint-friendly route for many readers over 40.
Is my Garmin or Apple Watch VO2 max accurate?
Treat it as an estimate. It is good for watching your own trend over time, not for an exact lab-grade score or a comparison with someone else.
Can strength training raise my VO2 max?
Not much. Lifting builds muscle, but cardio is what raises VO2 max. Across 38 trials, aerobic training beat resistance training for VO2 max by about 1.8 mL/kg/min (An 2024). Do both, for different jobs.
Does VO2 max still improve after 50 or 60?
Yes. A 2025 review of 87 trials in older adults found intervals still raised VO2 max (Men 2025). The muscle keeps adapting across life (Mølmen 2024).
Does beetroot juice raise VO2 max?
Barely. It can make a hard effort feel easier by improving oxygen economy, but the effect on the VO2 max number is very small (Tian 2025). It can help on a race day. The intervals are what raise your score.
How often should I do 4x4 intervals?
About three times a week, with easy or rest days in between (Helgerud 2007). More is not better here. The hard days work because the easy days let you recover.
Why 4 minutes and not 30-second sprints?
Short, all-out sprints help versus doing nothing, but to beat a steady jog the hard pieces need to be long, around 4 minutes or more (Wen 2019). That length lets your heart reach near its limit.
Is high-intensity training safe for me?
For most healthy adults, yes. If you have heart disease, chest pain, or you are over 50 and new to hard exercise, talk to your doctor before starting. This is not medical advice.
8. Further Reading on Increasing VO2 Max
Book: Peter Attia, Outlive (2023). A clear case for why VO2 max and aerobic fitness sit near the top of the longevity list.
Primary study: Mandsager and colleagues 2018, JAMA Network Open. Cardiorespiratory fitness and long-term mortality.
Podcast: Peter Attia, The Drive. Several episodes go deep on VO2 max, Zone 2, and interval training.
Related gem: 10 High Impact Longevity Protocols — The 10 behaviors with the strongest human evidence to increase longevity, zero cost to implement, start today.
9. The Shift
Most people let their engine shrink one quiet decade at a time. You get to push back, in 30 minutes a week, with a workout that costs nothing. The number on the watch is just the scoreboard. The work is the point.
10. Get the free guide: the 10 longevity protocols, ranked by the evidence
This gap is the why. Here are the ten habits that close it, ranked.
The 10 High-Impact Longevity Protocols is our free guide to the behaviors with the strongest human evidence for a longer, healthier life. Ranked, so you know what to do first.
The 10 behaviors with the best evidence, scored and ranked
The benefit, the effect size, and the "start here" move for each one
A one-page ranking table, with every claim tied to a named study
About Distilled Gems
Distilled Gems turns peer-reviewed science into one weekly gem: one small change you can actually make this week. The journals do the proving. We do the translating.
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Citations
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[^4]: Kyu HH, et al. (GBD 2017 DALYs and HALE Collaborators). Global, regional, and national DALYs and HALE for 195 countries, 1990–2017. Lancet. 2018;392:1859-1922. Study type: systematic analysis (Global Burden of Disease).
[^5]: Yang Y, et al. Compression of morbidity by interventions that steepen the survival curve. Nature Communications. 2025. Study type: mathematical theory plus model-organism data. DOI to be confirmed from the journal before publishing.
[^6]: Garmany A, Terzic A. Healthspan-lifespan gap differs in magnitude and disease contribution across world regions. Communications Medicine. 2025;5(1):381. Study type: cross-sectional analysis with projections.
[^7]: Permanyer I, et al. Healthy lifespan inequality: morbidity compression from a global perspective. European Journal of Epidemiology. 2023;38:511-521. Study type: global demographic analysis.
[^8]: Roebuck G, Lotfaliany M, Agustini B, et al. The effect of depressive symptoms on disability-free survival in healthy older adults. Acta Psychiatrica Scandinavica. 2022;147(1):92-104. Study type: prospective cohort (n=19,110).
[^9]: Scott AJ, Ellison M, Sinclair DA. The economic value of targeting aging. Nature Aging. 2021;1:616-623. Study type: health-economics modeling.
[^10]: Crimmins EM. Lifespan and healthspan: past, present, and promise. The Gerontologist. 2015;55(6):901-911. Study type: narrative review.Each citation ends with a plain-English study type so you can judge how the evidence was generated.Each citation ends with a plain-English study type so you can judge how the evidence was generated. Each citation ends with a plain-English study type so you can judge how the evidence was generated.
Last updated: July 5th, 2026.