Heart rate zones – what are they and how will they get you fitter?

Most people want to get fit faster and training using heart rate zones is one such method that can get you there – but how does it work, and how do you get started?

Heart rate measurements can be a fantastic training aid, and this guide will show you how working out in a particular heart rate ‘zone’ will not only get you fitter but – crucially – require less effort on your part. Or, to look at it another way, you’ll reap greater rewards for the amount of effort you put in – so what’s not to like?

But first off…

What are heart rate zones?

A ‘heart rate zone’ is essentially a range within which your heart’s beats per minute sit. So you might train in a zone where you’re working at 70% of your top effort level, known as your ‘maximum heart rate’.

The point here is that while the zones are set ranges, they shift to fit the individual based on maximum and resting heart rates. These zones change depending on your age and fitness level. So no matter who you are, heart rate zone training will still work for you individually.

The heart rate zone in which you train will determine the effects of this training on your body. This is important since it enables you to achieve specific fitness goals, from burning more fat to building muscle. To find the right zone to achieve your aim, you first need to work out your maximum heart rate (HRmax) and resting heart rate (HRrest).

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How do I calculate my maximum heart rate and resting heart rate?

A common formula for calculating these variables is that your maximum heart rate should be roughly 220 beats per minute minus your age. So if you’re 30, your heart rate max will be around 190bpm.

To work out the zone in which you should be training, you first need to determine your resting heart rate. Do this by lying down for 20 minutes and taking a reading of your heart rate – lots of fitness trackers and wearables will do this for you as you sleep overnight. Some also offer max heart rate tests and will use both these variables to let you know your heart rate zones without any user maths.

But if you do want to do it manually, here’s an example:

If your HRmax is 185 and HRrest is 65, then the following is how you calculate a 70% zone commonly targeted for fat burn.

  • Subtract your HRrest from HRmax to get your  heart rate reserve: 185 (HRmax) – 65 (HRrest) = 120
  • Calculate the percentage you’re aiming for based on your heart rate reserve: 70% of 120 = 84
  • Now add HRrest to this calculated percentage: 84 + 65 = 149
  • So for this example, if you wanted to work in the 70% heart rate zone you’ll be aiming for 149bpm.

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Running

How do heart rate zones work?

There are four heart rate zones that you usually work in to improve health.

Energy efficient or recovery zone: 60-70%

Starting at the bottom is the energy efficient or recovery zone. In this zone, where you can get plenty of oxygen into your blood, your body learns to better utilise that oxygen, pump blood efficiently and utilise fat for energy. For that reason, this is a great zone to aim to burn fat while re-energising your muscles with glycogen. 

Aerobic zone: 70 – 80%

The next zone up is the aerobic zone, at 70% to 80% of your HRmax, where your body works to boost cardiovascular fitness. In this zone your body’s ability to carry oxygen to muscles and remove carbon dioxide is being enhanced. As a result, this is a great way to increase overall muscle strength. A nice long run at a decent pace should put you in this zone.

Related: What is HIIT?

Anaerobic zone: 80 – 90%

The third of the four zones is the anaerobic zone at 80% to 90% of your HRmax. This is where your body is burning glycogen and producing the by-product of lactic acid at such a rate that it can’t remove it from the muscles fast enough – this is known as your lactate threshold. By training in this zone, which you’ll really feel, you can improve your lactate efficiency to help remove it at higher quantities in the future. Activities that will put you in this zone include sprinting and high-power cycling.

VO2 Max: 90 – 100%

The final zone is the red line zone or VO2 max, at 90% to 100% of your heart rate max. This is specifically for increasing speed since it helps your fast twitch muscle fibres. This is a zone when your muscles are in oxygen debt, and is for the very fit – even then such training should only be maintained for short bursts, such as for intense sprints.

Related: What is VO2 Max?

How do I measure heart rate zones?

Nowadays, the simplest way to measure a heart rate zone is using a wearable that tracks and provides feedback on your heart rate. Any running watch worth its salt will have this functionality. In the case of GPS watches and activity trackers, most have screens that offer a display that shows the zone you’re in – many are even colour-coded to provide at-a-glance information that’s ideal for training.

Devices vary between those with optical heart rate sensors built in and those that work alongside chest straps. In general, the latter are considered to be more accurate and will alert you to a zone change more quickly and efficiently than a wrist-worn heart rate monitor. This is due to much higher sampling rates compared to wrist-worn optical HRMs.

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Headphones with heart rate monitoring built in are also a decent option, such as the Jabra Elite Sport. The skin in the ear is very thin and headphones are less prone to moving around, as a result it’s a more accurate way  to optically measure your heart rate. Such devices will usually come with an app that will feedback your zone using audio, doing away with the distraction of having to look at a screen – which is just what you’ll want if you’re training in higher heart rate zones and want to avoid potential mishaps.