What are heart rate zones and how can you incorporate them into your exercise routine?

If you spend a lot of time browsing fitness content online, you may have come across the concept of heart rate zones. Heart rate zone training has become more popular in recent years, in part due to the rise of wearable technology that, among other features, allows people to easily monitor their heart rate.

Heart rate zones reflect different levels of intensity during aerobic exercise. They are often based on a percentage of your maximum heart rate, which is the highest number of beats your heart can achieve per minute.

But what are the different heart rate zones and how can you use these zones to optimize your training?

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The three-zone model

Although there are several models used to describe heart rate zones, the most common model in the scientific literature is the three-zone model, where the zones can be classified as follows:

• zone 1: 55%82% of maximum heart rate

• zone 2: 82%87% of maximum heart rate

• zone 3: 87%97% of maximum heart rate.

If you are not sure what your maximum heart rate is, you can calculate it using this equation: 208 (0.7 age in years). For example, I am 32 years old. 208 (0.7 x 32) = 185.6, so my predicted maximum heart rate is about 186 beats per minute.

There are also other models used to describe heart rate zones, such as the five-zone model (as the name suggests, this one has five different zones). These models describe much of the same thing and can mostly be used interchangeably.

What do the different zones involve?

All three zones are based around a person’s lactate threshold, which describes the point at which exercise intensity changes from predominantly aerobic to predominantly anaerobic.

Aerobic exercise uses oxygen to help our muscles continue, ensuring that we can go on for long periods of time without tiring. Anaerobic exercise, however, uses stored energy to fuel exercise. Anaerobic exercise also accumulates metabolic byproducts (such as lactate) that increase fatigue, meaning we can only produce energy anaerobically for a short time.

On average, your lactate threshold is usually around 85% of your maximum heart rate, although this varies from person to person and can be higher in athletes.

In the three-zone model, each zone loosely describes one of three types of training.

Zone 1 it represents high-volume, low-intensity exercise, usually performed for long periods and at an easy pace, well below the lactate threshold. Examples include jogging or cycling at a gentle pace.

Zone 2 is threshold training, also known as tempo training, a moderate intensity training method performed for moderate durations, at (or around) lactate threshold. This could be running, rowing or cycling at a speed where it is difficult to speak complete sentences.

Zone 3 mainly describes high-intensity interval training methods, which are performed for shorter durations and at intensities above the lactate threshold. For example, any circuit-style workout that has you exercising hard for 30 seconds and then resting for 30 seconds would be zone 3.

Achieving a balance

To maximize endurance performance, you need to strike a balance between training enough to cause positive changes, while avoiding overtraining, injury, and burnout.

Although zone 3 is believed to produce the greatest improvements in maximal oxygen uptake, one of the best predictors of endurance performance and overall health, it is also the most fatiguing. This means you can only do so much of it before it becomes too much.

Training in different heart rate zones improves slightly different physiological qualities, so by spending time in each zone, you ensure a variety of performance and health benefits.

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So how much time should you spend in each area?

Most elite endurance athletes, including runners, rowers and even cross-country skiers, tend to spend the majority of their training (about 80%) in zone 1, with the remainder split between zones 2 and 3.

Because elite endurance athletes train so much, most of it needs to be in zone 1, otherwise they risk injury and burnout. For example, some runners accumulate more than 250 kilometers per week, which would be impossible to recover if everything was done in zone 2 or 3.

Of course, most people are not professional athletes. The World Health Organization recommends that adults get 150,300 minutes of moderate-intensity exercise per week, or 75,150 minutes of vigorous exercise per week.

If you look at this in the context of heart rate zones, you might think of training in zone 1 as moderate intensity and zones 2 and 3 as vigorous. You can then use your heart rate zones to make sure you’re exercising to meet these guidelines.

What if I don’t have a heart rate monitor?

If you don’t have access to a heart rate monitor, that doesn’t mean you can’t use heart rate zones to guide your training.

The three heart rate zones discussed in this article can also be prescribed based on feel using a simple 10-point scale, where 0 indicates no effort and 10 indicates the maximum amount of effort you can produce.

With this system, zone 1 ranks as a 4 or less out of 10, zone 2 as a 4.5 to 6.5 out of 10, and zone 3 as a 7 or more out of 10.

Heart rate zones aren’t a perfect measure of exercise intensity, but they can be a useful tool. And if you don’t want to worry about heart rate zones, that’s fine too. The most important thing is to simply move.