Whilst there are many ways to improve running performance — increasing mileage, tempo running, hill running, strength training, etc — one of the most time efficient and effective ways to gain that extra speed advantage is interval training.
Here there are many effective approaches:
- Short intervals
- Longer Intervals
- Race pace (3k, 5k, 10k, etc)
- Critical velocity
- VO2 max intervals
- Sprint and Speed endurance
One highly effective and research proven method is VO2 max running intervals.
Running at VO2 Max intensity is a crucial training method for endurance runners. Not only will it boost aerobic capacity, but it also improves other key components like your running economy and the velocity at VO2 max.
One of my favourite VO2 max workouts is 30/30 running intervals — essentially this just involves repeatedly running intervals of 30seconds fast and 30seconds easy.
It’s especially useful if your targeting 3k-5ks, but useful for all runners as it provides a potent training stimulus to increase your VO2 max and the velocity at VO2 max.
We can also structure these workouts, so they improve your lactate threshold. And the best part is it’s extremely time efficient.
While I’ve always used these — both as a cycling and running workout — I’ve been using them more frequently during 2020-21 where COVID restrictions have prevented normal track workouts.
Here, they’ve served as an excellent alternative to track interval training. And it’s a great way to prepare for longer VO2max intervals.
Before diving in, here’s what you will find in this article:
- What are 30/30 VO2 max running intervals?
- The proven training benefits
- How to get the most from these
- Some example 30/30 interval workouts
- Alternative sessions (15/15, 30/15, 40/20 and 15/30s)
- Training recommendations
What are 30/30 VO2 max intervals?…
It’s a type of interval training where you alternate between:
- 30 seconds of faster running (at or just above VO2 max pace),
- 30 seconds of easier running at around half of that speed/pace (if you’re new to these intervals), or slightly faster (if you’re a more experienced runner).
We’ll come back to how to the target paces in a second.
The advantage of this approach is that we can train for longer at intensities where oxygen uptake is in the VO2 max zone. Making this an excellent workout for increasing your VO2 max.
A great alternative to a tempo run
So why would you use 30 second intervals as an alternative to a tempo run?
Whilst all runners benefit from tempo runs, they’re more beneficial for longer race distances than shorter distances like 5k.
This shouldn’t be surprising if you consider we run 5k races at close to VO2 max, whereas tempo runs are typically around 85-90% VO2max.
30/30 intervals are run at close to VO2 max, making them more specific to 3k-5k running. And because we run these as a continuous workout (alternating between fast and slow efforts) and at relatively high average intensity, we gain a similar training benefit — in terms of fatigue resistance, muscular endurance and aerobic conditioning.
But we also gain two additional benefits…
First, they help to boost aerobic capacity because we complete a significant portion of the workout at VO2 max intensity. And by increasing the recovery intensity, we increase the aerobic training component.
Second, they help to increase your maximal aerobic speed — something referred to as the velocity at VO2 max (or vVO2max).
Besides, we all benefit from switching up our training from time to time. So whether you’re a 1500m, 5k, or marathon runner, there’s something to gain from these highly efficient interval workouts.
One point to note: if you’re an experienced runner, then you may need to increase the recovery intensity to achieve the same training benefits. To achieve this, we increase the recovery pace/speed so the average workout pace (interval + recovery) falls into the tempo zone.
I’ll explain how to do this in a second.
The science behind 30/30 running intervals
The idea stemmed from research by Veronique Billat.
Veronique is renowned for research into VO2 max training. And specifically, the velocity at VO2max. Indeed, Veronique’s research has really expanded our understanding of how to maximise high intensity running intervals.
Whilst research initially focussed on longer intervals (Billat and Koralsztein, 1996; Billat et al. 1999); Billat found that shorter 30 second VO2 max running intervals were particularly effective for VO2max training (Billat et al. 2000).
This approach is also effective for those with less experience of interval training.
Billat used quite a simple approach — repeated intervals comprising 30seconds of faster running and 30seconds at half that pace.
Here, the faster running was slightly faster than the velocity at VO2max — this would be approximately Mile/1500m pace for a well-trained runner.
While they ran the recovery interval at half that pace.
What Billat found was this allowed athletes to run at near to their VO2max for longer (Billat et al. 2000). And by doing this, you can increase your aerobic conditioning and VO2max.
Indeed, several studies have since shown that this approach can increase your VO2 max (Thevenet et al. 2007; Abderrahmane et al. 2013). And this holds true, even amongst athletes with already high VO2max scores (~60ml/kg/min).
The researchers also found the 30/30 intervals significantly increased the velocity at VO2 max (Thevenet et al. 2007) — a key component of endurance running performance.
How to run a 30/30 VO2 Max Workout
First, start with a good warm up.
I normally start with a good 10-15 minute warm up, including easy running along with 4-5 x 20second accelerations, where I build the pace to around 1500m/mile pace.
Including some dynamic mobility exercises (lunges, squats, drills, etc…) during the warmup, is also a good idea.
Second, complete the VO2 max intervals as either:
- One continuous workout e.g. 20 x 30 secs fast, 30secs easy — this is by far the toughest option and only recommended for advanced runners.
- Or break them up into 2 smaller sets, e.g. 2 x (10 x 30 secs fast, 30secs easy), with 3-5minutes recovery between sets.
- You can even break these up it into multiple sets, e.g. 4 x (5 x 30 secs fast, 30secs easy), with 3-4minutes between sets. This is the best option if you’re completely new to these. It’s also useful if you’re looking to push the intensity on the intervals. And this can also be a good option for younger athletes.
Third, cool down with some easy running and congratulate yourself on completing a great workout.
How fast should you run these?
As I mentioned earlier, most runners should run the 30second intervals at around Mile/1500m pace, although this depends on your fitness level — start slower if you’re new to these.
One key factor is how fast your 1500m/Mile time is?
- If your 1500m/mile time is 8minutes, or longer, then you should aim for slightly faster than this.
- Whereas if your 1500m/mile time is around 4-5minutes, then that would be a good target pace.
For most runners, this approach works best when using an intensity that you could hold for around 4-5minutes whilst racing.
Whilst VO2max normally occurs at around 8-9minute race pace, by using 4-5minute race pace we’re using the upper limits of VO2max training. This works better with these short intervals. It also places greater emphasis on the velocity at VO2max.
What about the recoveries?…
During the research, the recovery interval was at about half the speed of the faster interval.
So, if your Mile pace was 3:30min/km you would multiply the interval pace by 2 to find your recovery pace — in this example that would be 7:00min/km.
This gives an average pace (interval + recovery) that’s equivalent to a top end aerobic run. However, the average intensity (in terms of oxygen uptake) is far higher, because you won’t fully recover during the 30second recovery.
As I mentioned earlier, if you want to use these to replace a tempo run, then you need to increase the intensity of the recovery interval.
However (and this is important), don’t follow this approach if you’re new to this type of training. First, start with the easier approach to recoveries — we’ll look at that in a second.
My experience is that these work well for advanced runners when you work at a slightly higher recovery intensity — for me that’s around 70-80% of maximum aerobic speed.
Adjust the recovery pace if you have a high VO2max
The truth is: the fitter you are, the more quickly you will recover. Meaning you can run the recovery at faster speeds, or you can increase the pace of the faster intervals.
This means that fitter runners should increase the relative exercise intensity of the recovery, otherwise you’ll get less training benefit. For example, you could run the recovery at 60% of your interval pace rather than 50%. Or another way to view that is to run the recovery at a moderate rather than easy pace.
The key point is: as your fitness improves, progress your recoveries and your intervals.
The real advantage from increasing the recovery intensity is you can achieve more total training volume at a high VO2max.
The crucial factor is:
- The recovery must not be too easy, because oxygen uptake will decrease too much during the recovery.
- But it must be easy enough to allow you to sustain a high intensity during the work interval.
As you can appreciate, this can be a challenging balancing act. But once you’ve done these a few times, you’ll find it easier to judge the interval and recovery intensities. And find an approach that works best for you.
How I run 30/30 intervals…
Recently I’ve been running the intervals at around my mile pace (sometimes just slightly above this), but to increase the aerobic training benefit I only slow the recovery interval to around 70-80% of the maximal aerobic speed.
This means I maintain a much greater average intensity (faster average running speed) and crucially I accrue more total time at VO2max intensity.
For example, I run the intervals at around 2:50/km, and the recovery intervals at around 4:10-4:20/km. This keeps the average pace around 3:30-3:35/km.
How to calculate the recovery pace as a percentage of maximal aerobic speed (MAS):
If you’re not sure how to calculate the recovery pace, you can use the following to calculate 50-80% of Maximal Aerobic Speed (MAS)
- 50% of MAS — multiply your interval pace by 2
- 55% of MAS — multiply your interval pace by 1.9
- 60% of MAS — multiply your interval pace by 1.8
- 65% of MAS — multiply your interval pace by 1.7
- 70% of MAS — multiply your interval pace by 1.6
- 75% of MAS — multiply your interval pace by 1.5
- 80% of MAS — multiply your interval pace by 1.4
For example: interval pace (MAS) is 3:20/km and you want to run the recovery pace at 75% of MAS.
First, convert the interval pace to seconds, e.g. 3:20/km = 200sec/km
Second, multiply the time in seconds by 1.5 e.g. 200s x 1.5 = 300s
Third, convert back to minutes — 300s/km = 5:00/km
Recovery pace = 5:00/km
Controlling the running pace
One problem here is that it’s really difficult to control the pace using your GPS watch. The intervals are just too short to make this an effective option. And you don’t want to be spending the entire time looking at your watch!
To get the most from these it requires an awareness of pacing, or (more importantly) an awareness of effort.
Here, it’s really important not to push the intervals too hard at the start.
By allowing yourself some time to settle in to a rhythm — by backing off slightly over the first few intervals — you’ll get more of a feel for what intensity you can sustain throughout the workout and be able to maintain a higher average intensity (pace) across all the intervals.
One key point is to make sure there’s an obvious difference between the pace of the work intervals and the recovery intervals. We don’t want to fall into the trap of focussing just on the average pace of the workout.
One approach that can work well is to pay attention to your heart rate at the end of each interval. I find these work best when my heart rate only decreases by around 4-6bpm during the recovery.
That said, don’t get too hung up on pace or heart rates. The main thing to focus on is finding an effort level that you can sustain across all of the planned intervals. Here, it’s easier to start slightly below that intensity because you can always pick up the intensity as the workout progresses. However, if you push too hard at the start the workout then your effort level will drop over the second half.
In the image below you can see one of my recent 30/30 VO2max interval workouts. Here the average heart rate was 166bpm (pretty close to threshold) for the entire workout.
However, when I broke that down further, the highest 10 minute average was over 171bpm (94% of HRMax). Making this a great workout for targeting VO2max and lactate threshold training.
The average pace was also close to threshold pace.
Here, I needed to maintain around 70-80% of MAS during the recovery to sustain the high average intensity. And by doing this, heart rate only decreased by around 4-6bpm during the recovery.
The other point to note is that heart rate continued to rise until the last 8-10 intervals where it leveled off. So allow time for your heart rate to level off during the workout.
How to progress 30/30 intervals:
First, as I mentioned earlier, you can make these easier by running these as multiple sets e.g. 4 x (5 x 30 secs at mile pace, 30 secs recovery at half that pace) with 3-4mins recovery between sets.
This is a great approach if you’ve not run these before.
You can then progress this to longer sets e.g. 2 x (10 x 30 secs at mile pace, 30 secs recovery at half that pace) and 4-5mins recovery between sets.
And then to one continuous workout e.g. 20-25 x 30 secs at mile pace, 30 secs recovery at half that pace.
Beyond that, you can increase the work to rest ratio to increase the average intensity of the workout and increase the aerobic component.
For example, you can progress from 30s fast/30s easy to…
- 30s fast/20s easy*
- 30s fast/15s easy*
- 40s fast/20s easy*
- 60s fast/30s easy*
*These can be run as one set or split into sets.
One point to note is that whilst these increase the average workout intensity, they will cause a slight decrease in the interval intensity — you just can not maintain the same work rate off such a quick recovery.
Another point is…
These workouts can be really challenging
The 30/15 and 40/20 workouts are exceptionally tough, especially if you complete them as one continuous workout.
In the example below, I ran 25 x 40/20s.
Here, the average heart rates were:
- The average for the entire 25mins was 170bpm (94% of HRMax)
- Peak 20min heart rate was 172bpm (95% HRmax)
- Peak 12mins was 174bpm (96% HRMax)
- And peak heart rate was 177bpm (98%)
The average pace was also right in the top end of the tempo zone.
Whilst I use the 40/20s, I find these physically and mentally quite exhausting — the session above required several days recovery.
Here it’s really important that you don’t overuse these.
So if you use 30/15s or 40/20s, then only fit them in at key points during your training schedule. And only if you’re physically conditioned for training at this intensity — if in doubt, always seek guidance first.
Another option is to try 15/15 intervals. These follow the same approach as the 30/30s, just with shorter intervals and recoveries.
The shorter intervals allow greater work, whilst the 15 second recovery is barely enough to allow any reduction in heart rate.
In terms of effort, they’re comparable to the 40/20s, so again only use these with caution.
My preference is the 30/30 intervals as they allow you to maintain a higher interval intensity, whilst still maintaining a good average intensity. They’re also more manageable, both physically and mentally. I can use these and be fully recovered within 2 days, whereas the 40/20s often require longer.
Switching the emphasis to interval intensity
Another option is to reduce the work to rest ratio. This allows you to increase the interval intensity. Because the recovery interval is longer, there will be a slight reduction in the average workout intensity.
Whilst this approach might not appeal to endurance purists, this really can be an excellent alternative — not everything is about average workout intensity after all.
And even though the average intensity may be slightly lower, it’s still a good workout. As an example, in recent workout involving 20 mins of 15/30s my average heart rate was 90% of HRMax with a 12minute peak of 92% of HRMax. Whilst that was slightly lower than with the 30/30s, the advantage here is the work interval pace/intensity is much higher.
They’re also a great introduction to the 30/30 sessions, and I find they work well within the early phases of training.
- 25-30 x 15s fast/30s recovery
- 20 x 20s fast/40s recovery
- 15 x 30s fast/60s recovery
As with the 30/30s, we can complete these as one continuous set, or split into two, or more, smaller sets.
Training recommendations for 30/30 running intervals:
If you are new to this type of training…
First, only do these sessions if you have developed a good level of base fitness, are free of injury, illness, and are physically fit with no serious underlying medical conditions. And have some experience of interval training.
3-4 sets* of 4-5 x 30secs fast/30secs easy.
2 sets* x 10 x 15 secs fast/30secs easy.
*Separate each set with 3-4minutes of easy jogging.
Intervals: Aim for a pace you could sustain for around 4-5minutes in a one-off effort. Slightly quicker if using the 15/30s.
Recoveries: Half that pace — or walk if needed.
The most important point is that the recovery should be easy enough to allow you to maintain the interval intensity.
Increase the number of reps in a set e.g. progress 4 x 5 x 30/30 to 3 x 7 x 30/30.
Intermediates — those with interval training experience…
2 sets of 10 x 30/30, with 3-4minutes recovery between sets.
1 set of 20 x 15/30.
Intervals: Again we’re looking for a pace you could sustain for around 4-5minutes in a one-off effort. Slightly quicker if using the shorter efforts.
Recoveries: 50-60% of interval pace.
Progress the recovery interval pace e.g. 50% MAS to 60% MAS.
2 sets of 10-12 x 30-30, with 3-4minutes recovery between sets — use this approach if the focus is on interval intensity
1 x 20-25 x 30/30
Intervals: 4minute race pace — can use a slightly faster pace if using multiple sets.
Recoveries: 65-75% of MAS
Increase recovery pace from e.g. 65 to 70, and then to 75% MAS.
Increase the work to rest ratio e.g. from 30/30s to 40/20s — although be careful not to overuse these!
To sum this up:
- 30/30 running intervals are an excellent alternative to the traditional tempo run. Combining the benefits of VO2 max interval training, whilst maintaining an average pace that’s comparable with tempo running.
- They’re proven to benefit VO2max and the velocity at VO2max — even amongst well-trained runners.
- These work well when running the intervals at mile pace, with the recoveries run at half that pace. If you have a higher fitness level, then you may find you’re able to run the recoveries at a slightly faster pace. This will push up the average intensity and increase the aerobic emphasis.
- We can complete these as one continuous workout, or break them into two, or more, smaller sets.
- To make them more challenging, you can increase the speed of the recoveries. You can also increase the work to rest ratio. By doing this, you increase the average workout intensity.
- Another option is to increase the interval intensity. To achieve this, we reduce the work to rest ratio. This allows you to maintain a greater work rate during the intervals. But the tradeoff is that it reduces the average workout intensity.
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- Recovery Intervals: A Key Part of VO2 Max Training
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- Optimising Recovery Between Intervals: Why Your VO2 Max Matters
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