With research linking a higher VO2 max with longevity, there's no shortage of training methods promising to improve your aerobic fitness – and, in turn, your running or cycling performance.
One that's worth knowing about is the Rønnestad method, popularised by Norwegian exercise physiologist Bent Rønnestad, whose research has explored how different interval-training protocols can improve endurance performance and VO2 max.
The good news? The hard efforts last just 30 seconds. The bad news? You're going to be doing quite a lot of them.
What Are Rønnestad Intervals?
Similar to the Norwegian 4x4 method, Rønnestad intervals are designed to accumulate time at a high aerobic intensity. The difference is that rather than relying on longer, sustained efforts, the method breaks the work into much shorter 30-second intervals, separated by just 15 seconds of easier recovery.
The full protocol looks like this:
3 rounds
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- 30 seconds hard
- 15 seconds easy
- Repeat for 13 intervals (9 minutes 45 seconds in total)
- Recover easily for 3 minutes before beginning the next set
That's 39 hard intervals in total, giving you 19 minutes and 30 seconds of high-intensity work.
What Does the Science Say?
A study led by Rønnestad found that trained cyclists completing two short-interval sessions a week for 10 weeks improved their VO2 max by 8.7%, compared with 2.6% in those completing longer intervals.
The short-interval group also saw greater improvements across several measures of cycling performance, suggesting that breaking hard efforts into smaller chunks may allow athletes to accumulate a significant amount of high-intensity work without having to sustain one prolonged effort.
How to Add Rønnestad Intervals to Your Training
You don't need to hammer these intervals every day to see benefits. In the 10-week study, participants completed two interval sessions per week alongside lower-intensity training.
For most recreational runners or cyclists, one or two sessions a week could therefore be incorporated alongside easier aerobic work and recovery days.
And there's no need to jump straight into the full 3 x 13 protocol. If you're new to high-intensity interval training, start with fewer intervals or fewer sets and gradually build your volume as your fitness improves.
Thirty seconds might not sound like much. By interval 39, you may feel differently.
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Kate is a fitness writer for Men’s Health UK where she contributes regular workouts, training tips and nutrition guides. She has a post graduate diploma in Sports Performance Nutrition and before joining Men’s Health she was a nutritionist, fitness writer and personal trainer with over 5k hours coaching on the gym floor. Kate has a keen interest in volunteering for animal shelters and when she isn’t lifting weights in her garden, she can be found walking her rescue dog.
