Why and How to Do 30-30 Intervals in Cycling

Cyclists ride in a pace line in a crit-race at very high intensity.

Just recently, former Tour de France and Giro d’Italia champion, Egan Bernal posted a video on Instagram on how he’s performing 30-30 intervals for 10 minutes. 

At it, Bernal is alternating between 30 seconds at high intensity and 30 seconds at low intensity. However, it’s still less discussed at which particular intensity these efforts should be performed. And what these intervals are for? 

We often read that short intervals of alternating intensities improve performance and they’re en vogue nowadays. But we often miss the underlying process that happens and with that in mind, certain caveats of high-intensity intervals are neglected.

What are 30-30 Intervals?

30-30 intervals refer to Tabata-style high-intensity workouts. Their origin goes back to a study done in 1996 by Dr. Tabata where 20 seconds of high intensity was alternated with 10 seconds of rest. 

The result was an increase in maximum aerobic capacity and anaerobic capacity compared to a group that performed steady intervals at 70% of VO2max. 

Even recent research on Tabata training shows increases in aerobic and anaerobic capacity that are comparable to other types of HIIT protocols like 4×4 minutes or 5×5 minutes, for example.

Different Types of Short Intervals

30-30 intervals are just one type of short interval training with a 1:1 work-rest ratio. These intermittent intervals became famous through the studies of French physiologist Dr. Billat, why people also refer to these as Billat’s 30-30 intervals. Variations include the original 20-10 Tabata’s, 30-15, or 40-20, where a 2:1 work-rest ratio is used. 

The Right Intensity for 30-30 Intervals

At very high intensity, there’s no reason to “stay in zone” like at tempo or threshold intensity. However, for 30-30 intervals you want to complete the first surge till the last surge at the highest average power because if you crack at the end you’ll miss the training stimulus.

A good rule of thumb is to perform the 30-second hard part at 130-140% of FTP, while the 30-second recovery is done at 50-55% of FTP. Because we need to work at intensities as close as 95-100% of VO2max to get the desired improvements. Our goal for 30-30 intervals and any other short efforts is to accumulate time over 90% of our max heart rate.

An example session could be 3x8x30-30 with 4-8 minutes of rest between sets. You perform 30 seconds on and 30 seconds off and repeat this rhythm till the 8-minute block is over. 

The Benefits of Short Intervals Like 30-30

The benefits of 30-30 workouts reveal themself over time. Our anaerobic system is immediately able to fire. With a power meter, you see the change in speed immediately. As soon as you accelerate you see the power numbers bumping up. 

In contrast, our maximum aerobic capacity needs some time to ramp up. But our goal during an endurance event is to be able to utilize as much oxygen as possible, hence we need to increase our maximum oxygen uptake or VO2max. To do that we need very high intensity. 

For that reason, we perform 30-30 intervals. It’s an intensity where our aerobic system runs at full speed. And you can see the delay of your aerobic system yourself. As your power numbers are already there, your heart rate needs some 90 seconds or more to increase and so does your oxygen uptake. 

The great thing about these alternating intervals is that during the 30-second rest period, your power numbers drop but your oxygen uptake stays high. 

Therefore, not only does the 30 seconds high-intensity count as interval length but the whole block of 30-30 intervals. As slow as your oxygen uptake increases as slow it decreases as well. During a 3×8 minute block of 30-30s, you get 24 minutes of training effect for just 12 minutes of suffering. Tell me a better deal.

Are Short Intervals the Best Intervals for Cyclists?

However, the elevated oxygen uptake also led to confusion because of a study done by Ronnestad et al. In that study, 30/15 intervals were compared with 4×5 minute HIT intervals, where the 30/15 intervals came out as the winners. 

But, there are two problems with the study. 

The first is that the study compared just the high-intensity part, you have 19.5 minutes total time for the 30/15 intervals and 20 minutes for the 4×5 minute intervals. No surprise that 30/15 came out as the clear winner as subjects were able to produce much higher power for the 30/15 intervals compared to the 5-minute intervals. 

The second problem is that as already addressed during the rest period of short intervals oxygen uptake is still elevated which means the whole block of intermittent exercises needs to be counted. So for 3x13x30/15 intervals, you get 29min15sec of effective training stimulus for VO2max. 

If you compare the total time of 30/15 intervals to a total time of 4×8 minutes HIT intervals, the difference between these two might be minor.

Apart from that, I prefer 30-30 intervals over 30-15 intervals because, with 30 seconds of rest, you might get a better response in lactate clearance capacity as it’s almost impossible to clear any amount of lactate during a 15-second break.

The Frequency of High-Intensity Intervals

As 30-30 intervals are very demanding I recommend only doing two interval sessions per week. Perform these intervals when you’re the freshest which is after rest days. 

How can you schedule these HIT sessions in your seasonal training plan? Looking at the training distribution of gold medal endurance performers we see that the intensity increases when race season approaches. That’s no surprise as we don’t need a lot of high-intensity sessions to see improvements. 

Studies looking at the effects of high-intensity training on well-trained athletes have shown that just six HIT sessions were enough to cause a substantial performance response. 

As fast as these gains come, you get to the point of diminishing returns. Doing HIT intervals all year is an excellent way to get burned out. A good approach is to place 30-30 intervals before race season or your goal event. Thereby, you can include a 4-week block of dedicated HIT and race-specific interval sessions to peak at the right time. 

Because both HIT and race-specific intervals are effective for peaking. And as probably 6 HIT sessions are all you need you can distribute these sessions aligned with race-specific sessions in a 4-week build block.

How long should intervals for cyclists of different levels be? A beginner can start with 3x6x30-30 intervals, while an intermediate rider can do 3x8x30-30s. And a pro might knock out as many as 3x10x30-30 or up to 3x12x30-30 intervals. 

As we discussed some risks, let’s look a bit closer at the caveats.

The Caveats of High-Intensity Intervals

The problem with all high-intensity intervals is the increase in anaerobic capacity and the body’s failure to signal adaptation. While anaerobic capacity is important in cycling, it’s still an aerobic sport. Without a proper aerobic base, we are unable to clear all the lactate and we soon see ourselves dropped in a long event though we smashed all these 30-30 intervals.

It’s a common problem I see among athletes who get way too obsessed with VO2max and HIT workouts while neglecting all the important aerobic work like tempo sessions, threshold intervals, or Zone 2 endurance miles. 

When anaerobic capacity in our fast-twitch fibers increases too high our slow-twitch fibers are unable to clear the lactate or recharge on creatine for repeated sprints. But with sufficient endurance miles, we increase our lactate clearance, and with tempo intervals, our fast-twitch fibers become more aerobically efficient.

In the end, this is what we want: To be as aerobic and enduring as possible. 

Building a solid aerobic base through proper Zone 2 training and sweet spot is the best way for most cyclists for optimal performance. On top of that, fine-tune your VO2max and anaerobic system with a block of 30-30 intervals as they are fun, highly effective, and increase variety in training. 

That way you’re primed for peak performance and arrive at your goal event in the best shape possible.

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