Heart rate zones and their importance in training

Two days ago

Riding by heart rate zones is the first small step into the world of cycling training. But what do the individual zones mean?

Cycling is rightly considered one of the best sports for weight loss – your heart rate can really soar here. Nowadays, there's a huge variety of cycling computers that offer heart rate monitor strap connectivity. Some people view their heart rate purely as a statistical data point, while for others, it can be a tool for continuous improvement.

In today's article, we won't delve into structured training, but we will introduce the individual heart rate zones and their impact on the body.

Your gateway to heart rate zones

Everyone's heart rate zones are "set up" differently. However, the common denominator is maximum heart rate. This changes with age and is inversely proportional, meaning it decreases as you get older. You can calculate it in several ways, but perhaps the most well-known is this equation: 220 minus your age.

There are also more sophisticated formulas if you're particular about accuracy – but for those, I'll refer you to Google. 🙂 Most modern cycling computers share the feature where you input your maximum heart rate into the device (or app), and they will calculate the individual heart rate zones for you. And then we can go riding!

Zone 1 – Your best friend at the start of the season

If you're not among the small percentage of cyclists who refuse to part with their bike even in winter and prefer to use the colder months for rest (or, like me, for indulging in Christmas cookies 🙂), then your spring strategy will be clear.

Most of us would probably want to hop on our bike and shoot off like a cork from a bottle, but Zone 1 plays a big role when logging those first kilometres.

It's also called active recovery and, in short, it can be said that this zone includes the absolute slowest rides – chatting with friends, "stretching" your legs, or resting between intervals.

Rides in this zone have minimal impact on muscle building. More importantly, however, the body adapts to aerobic metabolism – meaning it uses fats as its primary fuel. See, we're back to Christmas cookies. 🙂 Jokes aside, this adaptation is quite important for later training and rides at higher heart rates.

active recovery
50 – 60 % of maximum heart rate
body's adaptation to aerobic metabolism (fat burning)

Zone 2 – Ideal for long rides

For a "long-distance rider" like myself, this is a favorite. Riding at this intensity can last for hours without accumulating excessive lactate. This is also related to the body's adaptation I mentioned in the previous paragraph – muscles use fats as their primary fuel, not carbohydrates, from which lactate is later produced.

So, if your goal is, for example, to lose weight, you should primarily focus on Zone 1 and 2. At the same time, riding in Zone 2 builds endurance, and a longer ride could be a goal, for instance.

endurance development
60 – 70 % of maximum heart rate
ideal for long rides (fatigue comes later)
ideal for weight loss (fat as primary "fuel" for muscle cells)
increase in the number of mitochondria in cells

Zone 3 – Things are getting serious

Zone 3 is a tempo zone, but it's better known as the "sweet spot." From a training perspective, spending too much time in it won't get you anywhere, and it's better to alternate it with other zones.

Essentially, it's a kind of "no man's land" between the benefits of Zone 2 (fat burning and body adaptation) and Zone 4, or rather 5 (positive impact on musculature and the cardiovascular system – which we'll discuss).

So, is there any point in riding in it at all? That's quite debatable.

Although it improves muscular endurance to some extent, riding in other zones offers far greater benefits from a training perspective. It's not for nothing that the transition between Zone 3 and Zone 4 is called the "gray zone" – it might feel like we're working hard, maintaining a decent pace at a high heart rate, but in reality, the body isn't progressing.

tempo or sweet spot
70 – 80 % of maximum heart rate
every coach's nightmare 🙂

Zone 4 – The body starts to rebel

In Zone 4, we reach an intensity that few people find pleasant. And initially, few can sustain it for more than a few minutes.

Riding in this zone causes lactate to accumulate at a relatively rapid pace and places a significant strain on breathing. However, the very purpose of this is to improve the "transfer" of lactate away from the muscles and its subsequent breakdown.

At the same time, it stimulates muscles to produce mitochondria, strengthens the cardiovascular system, and improves resilience during long rides at moderately high intensity. So, if you want to train for a marathon, you know what awaits you…

anaerobic threshold
80 – 90 % of maximum heart rate

Zone 5 – The toughest part of training?

Zone 5 is also called VO2 max – this refers to the state where the body takes in and utilises oxygen at its maximum rate. More precisely, it's the volume of oxygen in ml that 1 kg of body weight consumes per minute. Spoiler alert: you probably shouldn't try to reach this zone on a full stomach. 🙂

Zone 2 and Zone 5 represent somewhat opposite ends of the spectrum, yet you can benefit the most from both. Here we encounter the concept of polarised training, which simply means alternating between these two zones.

But to avoid straying from the topic, what's the biggest benefit of those few minutes of suffering? First and foremost, as its name suggests, it's about improving oxygen utilisation, as the heart pumps more blood.

Among other benefits, we must certainly include a lower production of toxic metabolic byproducts, which results in a better ability to sustain moderate to high intensity. And last but not least, faster recovery.

VO2 max
90 – 100 % of maximum heart rate

Beyond Zone 5, there's also the fabled Zone 6 – anaerobic capacity. However, I won't delve into that in detail, as few cyclists who are just starting with training will ever reach it.

In short – the body can no longer process oxygen quickly enough, so energy comes from anaerobic metabolism.

We probably won't go into a specific training plan – that would make the article about twice as long. 🙂 But in principle, you should stick to the following:

rides in Z1 at the start of the season
most rides throughout the year in Z1 or Z2
try to avoid the transition between Z3 and Z4 (the gray zone)
include intervals in Z4 and Z5, alternating with Z1 and Z2

…and sooner or later, you'll feel an improvement.

However, it's still true that everyone has different goals in cycling – for some, it's enough to lose weight, others want to feel fit, and for some, participating in a marathon is the motivation. And training should then be adapted accordingly.

Photo source: editorial archive

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