If you have been training for a while and feel like your easy pace has stopped improving, VO2 max is probably part of the conversation. It is one of those numbers that gets thrown around a lot but rarely explained well. Here is what it actually means and, more importantly, what you can do about it.
What VO2 Max Actually Means
VO2 max is the maximum amount of oxygen your body can use during intense exercise. The "V" stands for volume, "O2" is oxygen, and "max" is exactly what it sounds like. It is measured in millilitres of oxygen per kilogram of body weight per minute (mL/kg/min).
Think of it as the size of your aerobic engine. A higher VO2 max means your body can deliver more oxygen to working muscles, which means you can sustain a faster pace before things start falling apart. Elite marathon runners typically test in the 70 to 85 mL/kg/min range. Recreational runners are more often in the 40 to 55 range. That gap is partly genetics and partly training.
The reason it matters to everyday runners is simple: it sets a ceiling. You can run closer to your VO2 max or further from it depending on other factors like running cadence and running form, but you cannot sustainably run faster than your aerobic system allows. Raise the ceiling and everything beneath it gets easier.
Why It Is Not the Only Thing That Matters
VO2 max gets a lot of attention, but it only tells part of the story. Two runners with identical VO2 max scores can have very different race times, because what also matters is running economy (how efficiently you use oxygen at a given pace) and your lactate threshold (the intensity at which fatigue accumulates faster than your body can clear it).
This is worth saying upfront because VO2 max improvement should sit alongside other aspects of your training, not replace them. If you have not put in consistent easy mileage, building your aerobic base will move your performance more than any amount of high-intensity work.
That said, if you do have a solid base and want to push your aerobic ceiling higher, targeted training genuinely works.
The Training Methods That Actually Improve VO2 Max
Interval Training
This is the most direct way to stimulate VO2 max adaptations. The goal is to spend time running at or near your VO2 max effort, roughly 95 to 100 percent of your maximum heart rate. This is a pace where you can hold a conversation for about two words before needing to breathe.
Classic VO2 max intervals look like this: 4 to 6 repetitions of 3 to 5 minutes at hard but controlled effort, with equal or slightly longer recovery between reps. A session might be 5 x 4 minutes at your 3km to 5km race effort with 3 minutes of easy jogging recovery. Interval training like this is hard on the body, so most runners do one session per week, sometimes two if total training volume supports it.
Tempo Running and Threshold Work
Tempo runs will not push you all the way to VO2 max, but they build the lactate threshold that lets you race closer to it for longer. A threshold pace feels comfortably hard, roughly a pace you could hold for about an hour in a race. Tempo running done consistently across months produces real aerobic gains that complement direct VO2 max work.
Zone 2 Running
Easy running does not feel like it should matter for VO2 max, but it does. The mitochondria adaptations that happen during Zone 2 training are the foundation everything else builds on. Runners who neglect easy mileage and try to solve fitness problems with more intervals usually plateau or get injured. The ratio most coaches recommend is 80 percent easy, 20 percent harder work.
Hill Running
Running uphill forces your cardiovascular system to work harder at lower speeds, which makes it useful for getting close to VO2 max effort without the impact of flat-out sprinting. Short hill repeats (30 to 90 seconds) at maximum effort are particularly effective. Hill training builds leg strength at the same time, which is a useful side effect.
How Long Does It Take?
VO2 max responds relatively quickly to training in the early stages. New runners often see significant improvements in the first year. For experienced runners, gains slow down, and the improvement from a targeted training block is more like 3 to 5 percent over several months. That is still meaningful. It is the difference between a 4:30 marathon and a 4:18.
Genetics plays a role in where your ceiling sits, but most recreational runners are nowhere near their genetic potential. Consistency, structured training, and adequate recovery matter far more than worrying about limits.
Gear That Supports This Kind of Training
You do not need much, but a few things make hard training sessions easier to execute well.
A GPS running watch helps you pace intervals accurately, which matters more than most runners realise. Going out too hard in the first rep costs you quality in the later ones.
Good running shoes with cushioning suited to the surface make a difference on recovery days, when your legs need to absorb mileage without accumulating extra fatigue. A shoe rotation with a daily trainer and a faster shoe for intervals is a setup that works well.
If you are doing outdoor intervals, sunglasses help more than most runners expect. Squinting changes your head position, and over a 20-minute interval session in bright conditions, that adds up. Re. running sunglasses are built specifically for running, with a no-bounce fit that stays put through hard efforts. The Adaptor lens is a good choice for early morning or mixed-light sessions as it adjusts to changing light automatically. If you are running in full sun, the Purity lens with polarisation keeps glare down. You can compare both on the lens guide.
Strength training two days a week also supports VO2 max work by reducing injury risk and improving running economy. Single-leg exercises, hip work, and a bit of plyometrics cover most of what runners need.
Realistic Expectations
VO2 max is a long game. One interval session will not move the needle. A consistent block of 8 to 12 weeks with one or two quality sessions per week, supported by easy mileage and recovery, will. Then you maintain and build again.
It is worth testing your current fitness before you start, even roughly. A 5km time trial gives you a good proxy. Run one, record the time, train for 10 to 12 weeks, run another. The gap tells you far more than any watch estimate.
The Takeaway
VO2 max is worth understanding and worth training, but it fits into a bigger picture. Most runners who want to get faster benefit most from more consistent easy mileage, one quality session per week, and time. If that foundation is already in place, adding targeted VO2 max intervals is a logical next step.
If you are building toward a spring race, the taper guide covers how to structure your final weeks, and the race fuelling guide is worth reading before race day. For a breakdown of how to build a complete training week, the fartlek training guide pairs well with structured interval work.
Browse Re. running sunglasses at all running sunglasses, or use Find Your Pair if you are not sure which lens suits your training conditions.
Tim Golubev
Founder, Re. (Re Your Run)
Tim built Re. after years of running in sunglasses that bounced, fogged, and ended up on his forehead. After discovering the UV damage that builds up without eye protection (even on cloudy days) and hearing the same frustrations from hundreds of other runners, he decided it was a problem worth fixing properly. With a background in Product across multiple industries, he approached it like any product problem: figure out what's broken, then build something that actually fixes it. He runs daily, co-founded Rose Bay Run Club, and Re. is his attempt to make one less thing that gets in the way of a good run.
