Most cyclists interested in improving their performance have probably heard that you should spend the majority of your time riding at an effort that allows you to chat with your buddies. This intensity, known as Zone 2 training, provides a variety of payoffs in terms of fitness and performance.

Also referred to as the ‘aerobic zone’, ‘conversational pace’ or ‘all-day pace’ (although those titles are sometimes misleading), this effort can get confusing to master. To help you conquer it, we explain what Zone 2 training actually means, why it matters, how it can help your performance, and how to do it for maximum gains.

The benefits of Zone 2 training

Considered the leading global expert on all things Zone 2, Iñigo San Millán – a professor at the University of Colorado School of Medicine, and former advisor to UAE Team Emirates – has spent three decades studying the effects of training in this aerobic zone. The ex-pro cyclist has worked with the current crop of the world’s best, but he also applies his knowledge to people suffering from medical conditions such as diabetes, where this kind of training can have real health benefits.

In the past, San Millán was on Tadej Pogačar’s coaching team. “Let’s be clear,” he said. “A normal person would be in Zone 5 trying to keep up with Pogačar in his Zone 2.”

That’s just the beginning of the nuance around this aerobic zone. To explain the context, let’s briefly dig into the science side, which explains why it’s so important.

San Millán’s original interest in Zone 2 came when he realised that optimal cellular mitochondrial function is key for both health and performance. (Mitochondria are the powerhouses of our cells.) While you can’t see your mitochondria doing their thing when you exercise, you can feel how well your muscles clear lactate that’s produced by more intense exercise. “When you don’t clear lactate correctly, it builds up in the blood, and that’s a sign that your mitochondria aren’t keeping up very well,” says San Millán.

In Zone 2, your body produces lactate, but it’s also able to clear it quickly. Millán noticed that when athletes trained for extended periods in Zone 2, the benefits spilled over into more intense exercise. When they had to sprint or do a burst of hard riding, for example, their muscles cleared the lactate more efficiently. Essentially, training at a lower intensity allowed them to perform better at higher intensities.

The same effect applies to recreational cyclists: training in the zone where the body burns fat rather than glycogen improves both performance and health outcomes, thanks to how it improves mitochondrial function.

What makes Zone 2 training particularly interesting is that it’s one of the few training stimuli that’s as good for health and longevity as it is for performance. San Millán’s research has found that many clinical populations – those with certain cancers, type 2 diabetes, and other metabolic diseases – have significant mitochondrial dysfunction. While exercise alone isn’t a cure-all, San Millán found that adding a protocol of Zone 2-based exercise led to significant health improvements for those populations. 

And at the same time, it makes you get up hills faster.

Misconceptions about Zone 2 

Because it’s become so popular, there are many misconceptions around Zone 2 training. For starters, there’s the question of ‘What is Zone 2?’ Most people will say it’s all-day pace, conversational pace, or they refer to it as LSD (long, slow distance). 

But often, the pace you’re riding at in Zone 2 is a bit harder than you may think. “You should be able to hold a conversation,” says San Millán. “But it shouldn’t be easy to do so. If it’s easy to chat, that’s more Zone 1 recovery versus Zone 2.”

Popular health and wellness bloggers who have honed in on Zone 2 will talk about walking as a great way to get some Zone 2 exercise. That may work for someone who doesn’t exercise regularly; but if you’re training a few times a week, you’ll need to make that walk pretty brisk in order to move from Zone 1 to Zone 2.

“Zone 2 is different for everyone. The most important thing is to pay attention to your own effort to make sure you’re hitting the right intensity.”

In other words: Zone 2 is different for everyone. The most important thing is to pay attention to your own effort to make sure you’re hitting the right intensity.

San Millán is also quick to point out that while Zone 2 is the training foundation for cyclists, you do still need to do intervals and harder efforts if you want to make real gains in your performance. After all, if you never go hard, why bother improving that mitochondrial function that allows you to push the intensity in the first place?

Zone 2 is efficient at burning fat, but once you get above that zone you start burning glucose. That’s something you need to train your body for, rather than getting to race day and hoping that you’ll magically be really good at going hard after training solely in Zone 2.

How to find your Zone 2 pace

The ultimate test for finding your Zone 2 pace is a lactate test, because Zone 2 is where your body is clearing the lactate you produce during exercise, not letting it accumulate. In an ideal world, San Millán would send you to a lab for lactate testing; but you can also base your Zone 2 pace on your FTP (functional threshold power) or your heart rate. 

Still, you need to match the numbers to the correct feeling. As mentioned, your Zone 2 pace should be sustainable for a few hours and you should be able to hold a conversation, although it shouldn’t be easy to do so.

Kristen Legan, gravel cycling coach and former winner of the 560km Unbound XL race in the US, knows a thing or two about spending a lot of time in Zone 2. When you’re training for races like the XL, most of your time is spent in the aerobic zone; though as with racers like Pogačar, she does need to spend some time going as fast as possible.

She says that even if you’re not riding for six hours, it should feel like you could if you wanted to. “Zone 2 is the pace that you can sustain for a really long time – as long as you’re eating and drinking,” she says. 

A pace you can sustain for a long time sounds like the ride should be easy, but again, that’s a misconception. “Zone 1 is a recovery or easy ride,” says Legan. “In a Zone 1 ride you’re in your easy gears, you’re really relaxed, and the goal is just getting your body moving. It’s not about pressure on the pedals. Zone 2 is a bit harder than that.”

How to stay in Zone 2 on rides

“You can use your heart rate monitor or power meter if you’re not comfortable with relying on perceived exertion,” says Legan. “But I think just trying to keep that conversational pace is the best way to ensure you stay in the zone.”

In that sense, Zone 2 can take some practice to perfect, since it runs the fine line between going too easy and going too hard. “It takes practice,” says Legan. “But the more you do it, the easier it will become to just fall into Zone 2 rather than staying in the easier Zone 1 or ratcheting up to Zone 3 or higher. I think a lot of us hate that feeling of having to shift down… We want to be pushing all the time; to feel like we’re <itals>doing something. There’s definitely some mental practice involved, to be okay with not trying to speed up a hill.”

Don’t forget: outside influences can also impact your Zone 2 pace. According to San Millán, heat or altitude can cause a 10% decrease in the power you’re able to hold while staying within your Zone 2 heart rate, because the environment is also taxing your body.

The right amount of time to spend in Zone 2

“Ideally, someone would be training three to four days a week in Zone 2,” says San Millán. “These sessions don’t need to be as long as you might think. People always assume Zone 2 rides need to be three or more hours in order to ‘count’, but even 90 minutes in Zone 2 will show good results.”

Legan’s recommendation is that most cyclists should spend about 80% of their time in Zone 2, and 20% doing intervals and recovery from said intervals. “Whether you’re a road racer, gravel racer or mountain biker, that breakdown works – you just do different intervals in the other 20% of your time. But the biggest physiological boost comes from that 80% in Zone 2,” she says.

When to expect results from Zone 2 training

Like most things, training in Zone 2 takes time before you see major benefits. “You’ll start feeling stronger after a couple of months if you’re training in Zone 2 consistently,” San Millán says. “But the real improvements come after a year of keeping your Zone 2 training consistent, with some intervals and high-intensity work thrown in.

“I compare Zone 2 to planting a vineyard,” he continues. “In the first season of planting, you’re not going to have any harvest, even if you do all the right preparation. You’ll see some vines, you’ll see that it’s coming, but you won’t have grapes yet. But the second year… that’s when you have that first harvest.”

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