Learning how to operate in different heart rate zones is the key to elevating your performance, maximizing output, and generally preventing you from running out of breath on those hard workouts. Here’s everything you need to know.

We get it. You might just enjoy a casual gym session. Or an easy paced jog during which you’re more focused on your podcast than breaking records. So why, you ask, do you need to know about heart rate zones?

Learning about how your heart powers your performance isn’t just for those who live for the thrill of a new PB. No, by taking a scientific approach to your workouts, you can not only fast-track improvements, but also stave off worrying health conditions in later life.

So, instead of looking at heart rate zone training as homework, look at it as a tool to safeguard your sporting ability and long term wellness.

Now that’s something to get excited about.

What do we mean by ‘heart rate zone’ and how does it relate to exercise?

GCSE science not your thing? Don’t worry. ‘Heart rate zone’ just means the number of  heartbeats per minute (BPM) we experience during exercises of different intensities. We write them as a percentage of your maximum heart rate (MHR), which is the highest number of beats per minute your heart can reach during exercise.

A healthy resting heart tends to be between 60 and 100 beats per minute, although the super fit among us may have lower rates.

Make sense?

As for how it applies to your actual workouts, Joanna Dase, fitness coach at female-focused trainers Curves explains:

“When we exercise, our heart rate increases to pump more blood around the body in order to deliver more oxygen to the muscles. The muscles then convert this oxygen into energy,” she says. “As our heart rate rises, the respiratory system also ramps up, increasing the breathing rate to supply more oxygen, and expel waste carbon dioxide.”

There are five main heart rate zones, as follows:

Zone 1 (Active Recovery): 50-59 percent of MHR. “This is the moderate-intensity zone, used for warm-ups and cool-downs,” says Dase.

Zone 2 (Fat Burning): 60-69 percent of MHR. “Stepping it up for steady-state exercises. You should be able to carry on a conversation at this intensity,” Dase explains.

Zone 3 (Aerobic): 70-79 percent of MHR. “Welcome to the moderate to high-intensity zone, used for improving cardiovascular fitness and burning calories,” says Dase.

Zone 4 (Anaerobic Threshold): 80-89 percent of MHR. “This is the high intensity zone that is good for building power,” says Dase.

Zone 5 (Maximum Effort): 90-100 percent of MHR. “This is used for the peak phase of interval training or short bursts of exercise,” Dase explains.

How can heart rate zone training benefit me?

These days we tend to focus more on trying to control our heart rate through breathing exercises as a tool for coping with daily stresses.

But, as we’ve seen, a faster heart rate can be beneficial in certain situations. Without our ability to operate at high heart rate zones, the Olympics would be pretty tepid, and your own training plan would be pretty static.

“A high heart rate isn't necessarily bad, it depends on the context and duration,” says Farren Morgan, founder of the Tactical Athlete. “A high heart rate is normal during intense workouts because it tells us that the heart and muscles are being challenged and tested in the way they should be,” he says.

What’s more, short periods of high heart rates can improve cardiovascular fitness and endurance.

In fact, a study published in the International Journal of Exercise Science found that training close to the metabolic threshold – i.e. our maximum limit for converting oxygen into energy – actually increased oxygen uptake in triathletes. Meanwhile, another study found that high intensity interval training, or HIIT, improved cardiorespiratory fitness not just in healthy adolescents, but in overweight ones too.

In other words, pushing yourself beyond your comfort zone really is the best way to break through your fitness barriers.

Isn’t a high heart rate dangerous?

Not every workout needs to leave you red faced and in a sweaty pile. In other words, you shouldn’t aim to be working in zones 4 and 5 all the time.

According to Morgan, having a consistently high heart rate – especially at a resting state – can signal potential health issues including: stress, dehydration, overtraining, or underlying health conditions like cardiac arrhythmias or heart disease. Yikes.

Worried your resting heart rate is too high? Dase suggests you seek medical attention. Pointing to research in The Journal of Hypertension, she explains that a high heart rate and sustained hypertension activate the sympathetic nervous system, responsible for our ‘flight or fight’ responses.

“This increases our heart rate and constricts blood vessels, leading to higher blood pressure,” she says. “Both conditions can strain the cardiovascular system, leading to an increased risk of heart disease, stroke and other complications.”

“As well as this, having an excessively high heart rate during exercise (above 85-90 percent of maximum heart rate) for lengthy periods can lead to overtraining and injury,” Dase warns. “A nice rule of thumb is that if you do a high intensity workout, make your next workout a recovery session.”

“It's vital to differentiate between a healthy elevated heart rate due to exercise and an unhealthy one due to medical issues,” Morgan adds. This is where purposeful observation and well considered training plans come in. “Managing heart rate through monitored training ensures that we maximize performance without overtraining and putting extensive strain on our bodies.”

How can we control our heart rate zone?

So, while training in different heart rate zones can be useful, it’s important that we approach this kind of work with intention.

Gymbox PT Laura Martin recommends using a fitness watch, but warns that their readings can be a little delayed, as they’re located on the risk, not closer to your heart. “Opting for a heart rate monitor that can be placed around the chest can be more precise,” she says.

If you want to get more technical, Dase recommends former Olympic coach Edmund Burke’s book ‘Precision Heart Rate Training’.

“The first thing Burke says you should do when using a heart rate monitor is to determine your MHR,” Dase explains.

Burke’s formula to estimate MHR is the number 220 minus your age. This means that the mean MHR for a 40-year-old would be 220-40, or 180 beats per minute.

“Once you’ve calculated MHR, choose your target zone,” says Dase. This depends on your fitness goals. Weight loss might favor the fat burning Zone 2, while building endurance might target the anaerobic threshold Zone 4.

The research paper ‘Exercise and Mobile Application’ suggests lightly warming up to gradually elevate your heart rate into your target zone, then maintaining your zone for the duration of your workout. Stay in your zone by adjusting the intensity, speed, incline and resistance of your workout.

“Running, cycling and swimming are great for all zones and are easy to adjust the intensity of,” says Dase.

Don’t forget to cool down at the end, returning your heart rate to its resting rate. “I like to use the eight second breathing method,” says Martin. “Take a three second inhale, hold for two seconds, then exhale for three.”

Try upping it to ten minutes of deep breathing if you can: one study found that a single 10-minute session of slow breathing caused a temporary fall in both blood pressure and heart rate.

What workouts can we do to maximize heart rate zones?

To help you put theory into practice, Morgan has put together three running workouts, each designed to get you moving in a different heart rate zone, ensuring that you experience a range of intensities, maximizing cardiovascular benefits.

Using the zone guide at the start of this article, choose one of more of the workouts below according to your fitness goals, working it into your training plan at least once per week, upping the intensity as needed.

Interval Runs

• Warm-up: 5-10 minutes in Zone 1.
• Work Phase: 3 minutes in Zone 4, followed by 2 minutes in Zone 2. Repeat 5-8 times.
• Cool-down: 5 minutes in Zone 1.

Tactical Circuit

• Warm-up: 5 minutes of light jogging.

• Circuit: 1 minute of push-ups (Zone 3), 1 minute of sprinting (Zone 4), 1 minute of burpees (Zone 4), 2 minutes of walking (Zone 2). Repeat 4 times.

• Cool-down: 5 minutes of stretching.

Hill Sprints

• Warm-up: 5-10 minutes of jogging.
• Work Phase: 30 seconds sprint uphill (Zone 5), walk back down (Zone 2). Repeat 10 times.
• Cool-down: 5-10 minutes of light jogging.

Words: Tom Ward