Here’s something you already knew: you can put different levels of effort into exercise. And here’s something you instinctively know: those different levels of effort have different effects on your fitness. Working out and tracking your heart rate zones is the best – and, with heart rate monitors appearing on more and more fitness trackers, the easiest – way to make sure you’re putting the right level of effort into a session to achieve the result you’re looking for.
That could mean working hard enough to make high-intensity interval training (HIIT) effective, or it could help new runners follow directions to complete easy, steady, tempo and stride sessions in a training plan.
“If people understood how to use the information that is provided, there is no doubt more people would be using them with all of their training,” says personal trainer and Polar ambassador Harry Thomas. “Every single one of my clients uses heart rate monitors in our sessions and once they’ve experienced the benefits, they wouldn’t go back.”
Using heart rate can also help people give themselves an adequate amount of time to recover after a particularly taxing session. “We know the harder we are training the longer the recovery time,” says Tero Myllymäki, head of physiology research at Firstbeat, a firm that provides heart rate analytics for consumer fitness trackers, professional sports teams and corporate wellness programmes. “Obviously it depends on the training and the person’s fitness level, but typically if you do a hard training session in the high heart rate zones it requires two or three days to recover.”
That’s why heart rate monitoring is one of the most useful features available on fitness trackers – because it can provide an accurate picture of your overall fitness and how challenging individual training sessions actually are.
Planning your training around your heart rate can be an excellent way to ensure you’re working as hard as you intend to each day, or even taking it a bit easier when you’ve planned some active recovery. To do that, however, you need to work out what your heart rate zones are and what each of them means.
How To Calculate Your Heart Rate Zones
There are different methods you can use to work out your training zones, but all of them require your max heart rate so let’s start with that. The simplest method of obtaining your max heart rate is to subtract your age from 220, and you may find your fitness tracker uses this method, but this isn’t especially accurate. In many ways it’s like BMI, a useful measure that’s accurate at a population level, but many individuals will have a higher or lower maximum heart rate for any number of reasons.
“If you’re healthy and able to do exercise safely, without any limiting factors, then it’s good to take your maximal heart rate to understand what your own limits are,” says Myllymäki.
To work out your max heart rate wear a heart rate monitor and push yourself to the limit. Obviously you should be confident this isn’t something that will make you keel over – checking with a doctor first is wise if you’re older. On a treadmill, start with a steady five- to ten-minute warm-up, then run for three minutes at your maximum pace. Then take a three-minute rest and run another three minutes at your max. Use the heart rate peak in the second sprint as your max. Your fitness tracker may allow you to manually set your max heart rate if it’s significantly different to the “220 minus age” formula.
Once you have your max you can work out your heart rate zones as a simple percentage of this – 60-70%, 70-80%, 80-90% and 90-100%.
What Each Heart Rate Zone Means
Broadly speaking, there are four training zones to use based on your heart rate, which break down as below.
The Fat-Burning Zone: 60-70%
Easy training at a conversational pace. Good for building endurance through long workouts. This commonly matches the “easy” designation in running training plans.
The Aerobic Zone: 70-80%
The most effective zone for improving cardiovascular fitness – building your stamina. This is the zone you’ll spend most time in during steady runs and resistance workouts.
The Anaerobic Zone: 80-90%
You’ll be working at a fast pace and breathing hard. This zone improves your anaerobic capacity, increasing your lactate threshold (how long you can sustain this level of effort for). Aim for 80% and above during threshold training, tempo runs and the intervals of HIIT workouts.
Just know that you don’t need to spend much time in this zone to get the performance benefits. “For instance, if you are aiming to develop your speed with hard anaerobic intervals, such as very short speed drills with long recovery periods, you probably won’t spend a lot of time in a high heart rate zone,” explains Myllymäki. “But it will still be a hard training session and good for developing your speed abilities.”
The VO2 Max Zone: 90-100%
Push yourself to the limit, working at sprinting (also known as stride) pace for short periods. If you’re relatively new to exercise, make sure to spend a couple of months training in the lower zones to build a good fitness base before considering pushing above 90%.
Some trackers will also have a fifth zone – 50-60% – which is for warm-ups, active recovery sessions or very easy beginner workouts.
Bear in mind that your heart rate is affected by a range of factors, including dehydration, altitude and even how much you’ve been working out in the days preceding your session. Listen to your body and don’t push yourself too hard if the numbers don’t seem to match up to your effort on a given day.
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What Is The Best Heart Rate Zone For Losing Weight?
As you’ll no doubt have noticed, one of the zones is called the fat-burning zone so you could reasonably expect that one to be the best for losing weight. Of course, it’s more complicated than that but the fat-burning zone has one key advantage – you can do it for ages. “If we look at the relative contribution of different energy systems then the most efficient way to burn fat is to keep the intensity low and to perform the activity for extended periods – two or three hours,” says Myllymäki, although he recognises that dedicating that much time to exercise isn’t realistic for the vast majority of us.
All the same, if you’ve decided you need to lose some weight there’s a good chance you’re lacking fitness too. In that case Myllymäki recommends sticking to a lower intensity for whatever amount of time you have available, gradually building the aerobic base and toleration to exercise.
Once you’ve developed your capacity, however, it can be beneficial to step up the intensity. “After a while, if you have an hour or half an hour, work in a higher heart rate zones because the overall cost of activity in terms of calories is greater with higher-intensity exercise,” says Myllymäki. “Also, by doing more intensive sessions you will burn more calories during the recovery – it activates the metabolism outside the training and is more effective in improving your fitness, which is a very important factor for overall health.”
Heart Rate Training
Thomas recommends trying these four different styles of training, and using heart rate zones to make sure you’re exercising at the right intensity for each.
- High-intensity interval training (HIIT)
- High-intensity steady state (HISS)
- Low-intensity interval training (LIIT)
- Low-intensity steady state (LISS)
To help you do just that, here’s more information from Thomas on each training style and a suggested workout you can do to try it out.
High-Intensity Interval Training (HIIT)
Training at high intensity means around 85-100% of your maximum heart rate. This can be very uncomfortable and hard – some people even find it virtually impossible to push themselves that much. If you are doing a HIIT class for over 45 minutes, chances are that you will not be going at your maximum throughout because it would be very difficult to sustain.
The key word here is “interval”, which refers to your heart rate and not the rest between exercises. Your heart must spike up to around 85-100% for a short period of time, but then return to a lower state, and this pattern should then be repeated for the remainder of the session. People often assume that having a 30-second rest between exercise and getting hot and sweaty is HIIT, but what you will see using a heart rate monitor is that your heart rate stays high and does not have enough time to lower before the rest time is up. You should work on 1:4, 1:5 or even a 1:6 work-to-rest ratio when performing real HIIT.
The Workout: Assault Bike Intervals
Rounds 4-6 Work 10sec Rest 60sec
If you are short of time and are looking to burn calories, add this to your workouts.
High-Intensity Steady State (HISS)
HISS training is the most demanding of these four training styles, because you are working hard to sustain maximum effort as long as you can. HISS is often mistaken for HIIT, but there is a difference between the two. For it to be HIIT we need enough time for our heart rate to recover. If you are training at a high intensity and there is not enough recovery time between sets, what you are doing is more like HISS training.
HISS is super-hard, and while it’s great to go all out in some workouts, this is certainly not the only type of training you should be doing. Be warned that injuries can sneak up on you if you don’t adjust the intensities in your training programmes.
The Workout: Tabata rowing
Rounds 5 Work 20sec Rest 10sec
We are often told that Tabata is HIIT but 10 seconds is not enough time for the heart rate to change, so you will be in the red zone for the entire time.
Low-Intensity Interval Training (LIIT)
This would be a normal weights session for the average gym-goer. With each set you do, your heart rate will elevate, but because the demand is not too high your body will recover quicker. Over the years I have realised that most people rest far too much between exercises and that is why they do not achieve the results that they want. This is where a heart rate monitor comes in handy.
Weight training will see the heart rate rise slightly and then drop again between exercises. The key is to make sure that you go again when your body is recovered, and this is where the grey zone (50-60% of your max heart rate) is a great thing to focus on. As soon as your heart rate reaches the grey zone, it’s time to go again. Sometimes I will not focus on a set amount of time to rest, but pay attention to my heart rate instead.
Do the two exercises as a superset, only resting after the second move.
1A Dumbbell bench press Sets 3 Reps 10 Rest 0sec
1B Dumbbell bent-over row Sets 3 Reps 10 Rest 60sec
Low-Intensity Steady State (LISS)
LISS is usually associated with endurance sports, but it can be done with weight training as well. Beginners, long-distance athletes and anyone training for their health should be spending a lot more time doing this type.
With LISS you focus on sustaining your heart rate in a lower zone for a longer period of time. Your aerobic endurance will improve very quickly after a few weeks of this. It puts less stress on the nervous system and your body will become more efficient at metabolising fat.
Do this circuit three times. The weights should not be heavy and you should focus on form. Other examples of LISS would be running, cycling and swimming.
1 Side lunge Work 45sec Rest 15sec
2 Press-up Work 45sec Rest 15sec
3 Single-leg Romanian deadlift Work 45sec each side Rest 15sec
4 ViPR chops Work 45sec Rest 15sec
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Nick Harris-Fry is a journalist who has been covering health and fitness since 2015. Nick is an avid runner, covering 70-110km a week, which gives him ample opportunity to test a wide range of running shoes and running gear. He is also the chief tester for fitness trackers and running watches, treadmills and exercise bikes, and workout headphones.