95% of your running and cycling performance is determined by these 2 things. Here is what they are.

What determines endurance performance? A 2026 Sports Medicine study analysing 888 runners and cyclists found that VO₂ max and exercise economy account for approximately 95% of performance differences between athletes. In this article, Emma O'Toole explains what these findings mean, why exercise economy matters, and how strength training can improve running and cycling performance.

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TRAINING BREAKDOWN

"Similar endurance performances can be achieved with very different physiological profiles!"

By Emma O'Toole

Hi there!

What do you think determines your running and cycling performance?

Is it your VO₂ max? Your lactate threshold? Your weekly mileage or training hours? Your ability to sustain a hard effort for a long time?

All of those things matter, but a study published in Sports Medicine this year looked at 888 runners and cyclists from recreational to world class level, including both men and women.

The study has given us one of the clearest answers yet on what determines your endurance performance and how much each factor contributes.

I found this really interesting and I think you will too, so let's get into it!

The researchers tested 495 runners and 393 cyclists across a wide range of performance levels. Worth knowing that the study had a larger proportion of male participants than female, particularly in the cycling group, so the findings should be interpreted with that in mind.

In the study, they measured three key things.

1. VO₂ max: The maximum amount of oxygen your body can use during exercise. Think of it as the size of your engine.

2. Exercise economy: How efficiently your body moves at a given speed or power output. Think of it as how well your engine runs.

3. Fractional utilisation: The percentage of VO₂ max used at lactate threshold (or lactate turnpoint). Think of it a bit like how fast you can go before you start to struggle.

They then looked at how much each of these factors contributed to performance between runners and cyclists, and here’s what they found.

VO₂ max is still king! It was the single biggest determinant of endurance performance for both runners and cyclists, accounting for between 65 and 76% of the differences.

Exercise economy was the second most important factor, contributing between 20 and 24% of performance differences.

Fractional utilisation, despite being something many coaches and athletes talk about a great deal, contributed only between 4 and 11% of performance differences across this mixed population.

In other words, VO₂ max and exercise economy together accounted for around 95% of the variation in performance between runners and cyclists.

Now, before you jump to look at the VO₂ max score on your smartwatch, I want to put this in context! The VO₂ max score on your watch is a benchmark, the most accurate way to get your score is to go to a lab for testing (as they do in the study), and this isn’t something practical for most of us. VO₂ is also influenced by genetics and by your cumulative training history. It is trainable and should be part of a periodised running and cycling training plan, but as you’re about to read it’s not the only quality you should be training. At the end of the day, what matters most is the time you stop the clock at or the distance you cover, not the number your watch gives you for your VO₂ max.

I've talked before about how we can either push our fitness up from the bottom, or pull it up from the top (read that here). An endurance athlete who tries to pull their fitness up from the top, by doing lots of VO₂ max work, will be doing so off an unstable, small base. The endurance athlete who never touches VO₂ max work, things like 30/30 intervals or 6 x 4 minute efforts at VO₂ max, will be trying to build fitness on top of a wide but short pyramid.

Think of it like this: your aerobic system supports your anaerobic system, and to maximise your fitness we want different training stimuli in your week, not just one or the other.

Before we come onto the other important factor in endurance performance, I want to highlight something else that is really important and very reassuring.

Similar endurance performances can be achieved with very different physiological profiles!

If we could accurately predict who wins a race just by measuring VO₂ max, it wouldn’t be much fun, would it?! The study highlighted two runners who achieved the same speed at their lactate turnpoint despite very different physiological profiles. One had a significantly higher VO₂ max but worse economy and a lower fractional utilisation. The other compensated with superior economy and a higher fractional utilisation despite a lower

VO₂ max. Basically they had the same result on paper, with a very different physiological make-up.

The same finding has been seen in world-class runners. Frank Shorter and Steve Prefontaine achieved similar personal best performances at 5km (13:26.6 vs13:21.9 min) and 10km (27:45.9 vs 27:43.6 min) despite a large VO₂ max difference with Prefontaine’s VO₂ max sitting just over 13 points higher than Shorter.

What this tells us is that you do not need the perfect physiology to perform well. Some runners and cyclists will excel through a very high VO₂ max, whilst for others, endurance economy will be their greatest strength. Understanding your own training profile and applying that knowledge into your training is far more useful than comparing yourself to anyone else.

Now, exercise economy, this is what I really want to dig into.

Exercise economy is how efficiently you move. A runner with good economy uses less oxygen to cover the same distance at the same pace as a runner with poor economy. A cyclist with good economy produces the same power output at a lower oxygen cost. Economy matters because it determines how much of your engine you actually need to use to sustain a given effort.

So how do you improve it?

For runners, the study highlighted that strength training and plyometric training are among the most effective strategies for improving running economy, both when fresh and when fatigued. That second part matters a lot! The ability to maintain good economy when you are tired, late in a race or at the end of a long run, is something strength and plyometric work specifically develops.

For cyclists, it is slightly different. Studies point to heavy strength training and some studies have looked at plyometrics, though the evidence for cyclists is less extensive than for runners.

I see this week in and week out with the runners and cyclists that I coach and it’s why periodised strength training alongside consistent endurance work makes such a meaningful difference to performance.

The study also noted that for both runners and cyclists, high training volumes over multiple years are associated with improvements in exercise economy. Consistency is not just about getting fitter, it’s about developing the skill of running and cycling too!

There are three things I’d like you to take from today’s blog:

1. VO₂ max matters enormously, which means that the quality and consistency of your endurance training matters.

Volume, intensity distribution, and showing up week after week are not just good training habits, they are the primary driver of your performance. Including some higher intensity work in your training, VO₂ max intervals, threshold efforts, and quality sessions done consistently in a periodised approach across your training year, is how you develop your performance over time.

2. Exercise economy is a meaningful and trainable contributor to performance, and strength training is one of the most evidence supported ways to improve it. 

If you are not doing structured strength work alongside your running or cycling, you are leaving a meaningful performance gain on the table. 2x sessions a week, roughly 30 to 45 minutes, built around the demands of your sport, and done throughout the year (not just in the off-season!) is what you need to improve your exercise economy.

3. Your physiological profile is your own.

You do not need the highest VO₂ max to perform well. Understanding what your limiters are and working specifically to address them, whether that is aerobic capacity, economy, or the ability to sustain a high fraction of your VO₂ max, is far more valuable than comparing yourself to anyone else.

If you want to carry on this conversation further with advice on applying this to your own training, plus get started with structured strength training that supports your running or cycling, come and join the free community. There are over 850 runners and cyclists over 30 in there and you can grab a free strength workout for runners or cyclists when you join.

You can click here to join.

I hope today’s blog post has given you something to think about with your training!

Happy running and riding!

Emma x

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