Pro Teams Are Doing Zone 2 Intervals. Should You? (#297)

Zone 2 intervals are trending across pro pelotons and training apps, but are they actually superior to steady endurance riding, or just a complicated solution to a simple problem? Coach Adam Pulford breaks down the science, shares real athlete data, and gives you an honest answer on whether structured Zone 2 intervals are worth your time.

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RESOURCES

• Cycling’s Latest Trend: Structured Zone 2 Intervals
• Zone 2 Training to Improve Aerobic Endurance and Fat Burning - CTS

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HOST
Adam Pulford has been a CTS Coach for nearly two decades and holds a B.S. in Exercise Physiology. He's participated in and coached hundreds of athletes for endurance events all around the world.

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Transcript

Zone 2 Intervals Question

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Are zone two intervals actually better than just riding steady in your endurance training zone? Pro teams are using them, training apps are pushing them, but are we just overcomplicating something that was never complicated to begin with? I'm Adam Pulford, head cycling coach at CTS. I hold a degree in exercise physiology and have spent the past 20 years coaching full-time at CTS, helping junior riders, amateurs, and professional athletes perform at their best. Let's unpack whether structured zone two intervals actually create bigger aerobic gains, or if steady zone two riding still wins. Let's revisit why you do any kind of intervals in the first place. There's three reasons in my experience why you'd do intervals of any kind, and this is using all intensities. First one is you do more work and less time. Second one, train specific energy systems. And third, train the specificity of the race or a course demand. So does zone two intervals make sense based on the three scenarios above? Let's take more work and less time first. Maybe, but sometimes no. Does it train an energy system? Yes. But zone two intervals versus steady riding in zone two, they still train the same energy system. So not needed, in my opinion. How about specificity? I mean, you do need aerobic development for all races and events, so sure, but steady non-interval training does this too. So the next question is are zone two intervals superior to zone two steady? But when you start reading this Bella News article, you may start thinking otherwise. Oftentimes, an unstructured zone 2 ride will basically be the same as a structured zone 2 ride when it comes to the total TSS, kilojoul, and other metrics when riding outside. Here's an example from one of my pro riders who just got on a new team this year, and they wanted him to do three by 30 FatMax intervals with easy endurance in between. Fatmax is basically just the upper end of zone two or right around 65 to 75% of FTP. And easy endurance is going to be more like 55 to 60% of FTP. So again, these differences aren't much. And it's aerobic. In the first image, you see that Fatmax ride that I'm talking about. Total time was four hours, four minutes, and 30 seconds. The average heart rate was 130 beats per minute. The average power was 183 watts. The normalized power was 197. The work in kilojoules was 2,690, and the TSS was 170. In image two, you see the endurance ride for four hours. Again, the total time was four hours and five minutes. Average heart rate was 125 beats per minute. The average power was 185 watts. The normalized power was 197. Shocking. The work in kilojoules was 2737, and the TSS was 160. Now, this athlete did spend more time in zone at the upper end of zone 2 range, which is considered to be fat max or the point at which you're utilizing the most fat as a fuel source, according to his team director. But without actually confirming that in a lab test, you don't actually know. Each training ride was basically the same FTP and same percentage of low end and high end of zone two. The first ride was structured, the second wasn't, and pretty much the same TSS and normalized power. Now, sometimes for my time crunched folk in particular, steady zone two rides may be higher average power overall. In fact, I leverage indoor riding for my athletes in this way. For many people living in cities or hilly areas where you don't get 15, 20, 60, 90 minute stretches of time of uninterrupted time by traffic lights, stop signs, traffic, or steep descents, I have them ride for 60, 90, or 120 minutes straight with no brake. And they often achieve their peak aerobic power production inside simply by riding steady. Finally, when I've got someone who can ride for four to six hours for an endurance ride, I just tell them to ride in zone two power, make sure it feels like a three to five out of ten rate of perceived effort most of the time, and then check in on the normalized power every 30, 45 minutes, make sure that you're at the mid to upper end of zone two. Pretty simple if you want to use the numbers to guide you, and way more effective, in my opinion. So why do zone two intervals at all then? Here are the main reasons, in my opinion, why you do zone two intervals. Number one, entertainment. If you're indoor and you're raw dogging it inside with no virtual platform to ride on and you wanted something to help pass the time, sure, five by ten minutes with two minute easy in between, Simbaut Juncle. Outdoor. If you live in a place that's super flat, like Oklahoma here in the States or the Flanders region of Belgium, maybe you're doing a four-hour ride as 30 minutes at zone two with two to three minute easy in between. Totally fried it. If your brain needs it, give it. It'll break up the day for you and you'll have something to focus on. But it simply is a matter of your brain needing it more than your legs. Yeah, and fat max training. Let's talk about that a little bit more. I kind of mentioned this already, but if your goal is to improve your metabolism to rely upon burning fat as a fuel more effectively, riding at or around your FatMAX is beneficial. And doing some intervals here can be good. However, like I said, it's best to have a lab test to confirm this. Usually this correlates to the intensity of 65 to 75% of your functional threshold power. However, if you're a time-crunched athlete, sprinter, or huge anaerobic rider, do you really need this for performance? Not as much because your sport doesn't depend on this for a performance determinant. And you're likely getting enough of your FatMax training on zone two endurance rides anyway by not thinking too much about it. So that's my take on the whole FatMax chapter of life. Let's talk about mechanical versus aerobic work. This is an interesting one because I think of mechanical work as external stress measured by your power meter in the form of kilojoules or KJ. Aerobic work can best be thought of as an internal stress shown by your average heart rate. Now, both aspects are considered work, but when you separate them, like I just did, as external and internal, it can be really helpful to think about where the strain is hitting harder. For example, your peripheral system, i.e., your legs as a cyclist. If it can't handle something like one hour steady zone two riding from a mechanical standpoint, meaning your legs are giving out before your heart, then maybe break up your one hour of zone two riding into that five by ten at upper zone two with two minutes easy in between. For pros, it's a little different. They're already pretty good at both aerobic and mechanical work. Some domestics' jobs are to push as much steady power as they can all day in the wind to protect their teammates so that they can go for the win with fresh legs at the right time. Being very targeted with their upper endurance effort for specific workouts is sometimes needed. This Velo News article, which I already mentioned before, goes on and does a pretty good job of explaining that some teams do this, but also not all the teams do it. So I'd check this one out if you're curious about Team Uno X's approach versus team Visma. But just as a reminder, these are professional riders with all the time in the world to train, recover, and have superior genetics. And they have teams with big budgets to do lab tests or lactate draws in the middle of some big Spanish hill climb in the middle of nowhere. Things that amateurs should consider before mirroring what the pros do for zone two training. So there's a final reason to do zone two intervals. If you're super type A. If you just love seeing training files organized in a chronological way, have at it. That's fine as long as you get your prescribed work done. The biggest mistake here is if you're doing shorter endurance rides like 60 to 90 minutes and doing something like six by 10 minutes at zone two with three to five minute recovery, and you think you are doing something more effective than just riding steady within zone two, you have it wrong. If you're wanting something very specific from your training, such as controlled lactate responses or training specifically at higher rate of fat oxidation without using more glycogen than needed, yeah, then maybe zone two intervals are helpful. However, for most amateur athletes, master elites, weekend warriors, these things are overly specific and not as effective at pedaling steady for one, two, three, four, whatever hours straight. If you're riding outside, you'll have some descending and features that will give you a bit of a break and allow the heart rate to come down and mentally lighten things up. If inside, riding on a virtual platform will do the same and will give you a similar training effect, if not better, than results from a structured zone to workout, because you'll get all the physical benefits in and not have to think so much about it. That's it for today. Hope you liked it. If you want to build a bigger aerobic engine, don't overthink it. Ride steady, accumulate work, stay consistent. And if you want help structuring your training the right way for your physiology, that's what we do here at CTS. Links below.