Zone 2 training: Magical formula or waste of time?

It probably hasn’t escaped your notice that zone 2 training is everywhere at the moment. It’s a hugely popular training method advocated by many across the internet and social channels by those who think that it’s more important than any other training you can do.

One of the big appeals is that it’s pretty straightforward to understand and claims to reap fitness benefits through a relatively easy training program. But is it all it’s cracked up to be?

Si Richardson recently chatted with Olav Aleksander Bu. He’s a renowned Norwegian training coach who has worked with the former Ironman World Champion Gustav Iden and Olympic triathlon champion Kristian Blummenfelt. Between them, they have redefined what was considered humanly possible through their performances in their given fields.

Olav is at the cutting edge of human performance so knows a thing or two about performance training theories and methods. And he has some fascinating opinions on zone 2 training and its effectiveness on our bodies.

Before we find out a little more about him and his reservations let’s first have a little recap of what zone 2 is all about.

Read more: What are power and heart rate zones and what do they mean for cyclists?

What is zone 2 training and what are the reported benefits?

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Zone 2 training shouldn’t feel hard but it shouldn’t be too easy either and you should be slightly out of breath

Training zones correspond to different levels of intensity, for example recovery, endurance or sprint zones. They can be calculated using your FTP or maximum heart rate.

Most training models have between three and seven different training zones but they all tend to have the same zone 2 which is sometimes referred to as the endurance zone.

Zone 2 is a level of relatively low-level exertion that you can hold for a long time that’s around 60% to 70% of your maximum heart rate. It shouldn’t feel hard but equally shouldn’t be too easy, and you should be slightly out of breath while doing it. It’s all about building an aerobic base, which is required to perform at higher intensities too.

Read more: How effective is lower intensity training: Riding at zone 2 for six weeks

In theory, it’s the optimal exercise intensity to stimulate the body’s mitochondria. This stimulation leads to improving the efficiency and volume of mitochondria. The reason mitochondria are so important is because they are essentially the powerhouse of your cells – they’re responsible for turning the food you eat into energy.

So the more mitochondria you have, the better they function and the fitter, faster and healthier you become.

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Mitochondria are the cells in your body that turn the food you eat into energy. Zone 2 training helps increase the volume and efficiency of mitochondria in your body

Does zone 2 training actually work?

During Si’s chat, he puts the above theory of zone 2 training to Olav to find out his take on it. He finds out that while Olav doesn’t disagree with the principle he does think the approach to it needs to be more nuanced.

“For most people, whatever training you do, as long as you do it consistently over time that is normally what will contribute most to an increase in performance,” Olav says. “And most often when people go out and they want to exercise, people are super motivated, they go too hard and they burn themselves.

“This is also why it’s maybe easier to say ‘Hey, Zone 2 training seems to work’ because it’s something that often promotes better consistency in the training, without it actually being the holy grail to become fitter.”

From previous conversations with Dr Iñigo San Millán, a specialist in physiology and metabolism in health and disease at the University of Colorado, Si’s understanding of Zone 2 is that the main dictator of performance is mainly on a cellular level. Olav thinks there are other more central systems involved too.

“All training you do will have an impact on all systems in your body,” he explains. “For the sake of the debate, to make it more clear... it really doesn’t matter whether it [improvement] comes from the mitochondria or not. What really matters is the ability to do something consistently and sustainably in a workout but also over a long time… not a couple of weeks or months but year after year. Then it's more about using the tools that we have available and looking at power, duration and robustness.”

Olav agrees that Zone 2 can work and will help in improving fitness and performance but it comes with the caveat that it can only get you so far before you start to stagnate and improvement drops off. For that reason, you shouldn’t only rely on Zone 2. He suggests that you also need to pay attention to high-intensity and low-intensity training to see progression benefits. As he puts it: “Variety in your training is still the king in order to reap maximum reward."

It’s a fascinating conversation in which they also talk about the type of training you should focus on when you're time stretched – how do you balance low, high, and zone 2 during a week and where and how you should focus your efforts. As well as revealing some interesting takes on training schedules by having harder and easier days during a week of training as well as the importance of recovery and training smarter.

The video features the full, uncut interview so check it out if you want to learn more about Olav’s theories and expert opinion.

For more fitness articles head over to the dedicated cycling fitness section on the GCN website.

Simon Richardson

GCN Presenter

Former pro road and mountain biker racer

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