Wrist Heart Rate vs Chest Strap: Which Is Better For Running?

Heart rate has become one of the standard pieces of information runners see on their watches. Start a run with most modern running watches or smartwatches and you can monitor your heart rate alongside your pace, distance and time without wearing any additional equipment.

You may also have seen runners wearing a heart rate monitor around their chest and wondered why they bother when their watch already measures the same thing. Chest straps measure heart rate differently and can generally provide more consistent information during exercise, particularly when your effort is changing quickly.

That does not mean every runner needs one. For many runners, especially beginners and those primarily interested in monitoring their general effort, wrist heart rate is likely to provide all the information they need.

How Does Wrist Heart Rate Work?

Most running watches and smartwatches measure heart rate using an optical sensor on the back of the watch. Small lights shine into the skin and the sensor detects changes in blood volume as your heart beats.

This technology is known as photoplethysmography, or PPG, although you certainly do not need to remember the name to use it. The important thing is that your watch is using an optical signal at your wrist to estimate your heart rate.

Modern optical heart rate sensors can work very well during running. Research into wearable heart rate technology has found that wrist devices can provide useful heart rate measurements, although accuracy varies between devices, people, activities and exercise conditions.

They also have one enormous advantage over a chest strap: convenience. If you are already wearing your running watch, you do not have to remember, fit or maintain another piece of equipment before heading out for a run.

Read more about running metrics here.

How Does A Heart Rate Chest Strap Work?

A traditional heart rate chest strap works differently. It sits against the skin around your chest and uses electrodes to detect the electrical signals associated with your heartbeat.

The sensor then sends your heart rate to a compatible running watch, phone or other device. Current heart rate straps commonly use Bluetooth, ANT+ or both, although the connection options vary between models.

Because a chest strap measures an electrical signal close to the heart, it remains a very dependable way of measuring heart rate during exercise. Chest straps are also commonly used as reference devices when researchers test the accuracy of wrist based heart rate monitors.

Is A Chest Strap More Accurate Than Wrist Heart Rate?

If accurate heart rate measurement during exercise is particularly important to you, a good chest strap is generally the better option. That does not mean the difference will be significant on every run, however, and modern wrist sensors can perform extremely well.

Research comparing consumer wrist devices with ECG and chest strap measurements has found that wrist based heart rate can be accurate during activities including running. Wider reviews of wearable technology also show that heart rate is one of the measurements that modern consumer wearables tend to perform relatively well.

The difficulty is that wrist sensor accuracy is not completely consistent. Movement, watch position, individual physiology, temperature and the type of exercise can all affect the optical signal.

This distinction matters because it is easy to exaggerate the shortcomings of wrist heart rate. On a steady easy run, a good running watch may give you readings that are perfectly adequate for your training.

The potential advantage of a chest strap becomes greater when your heart rate is changing quickly or when you are basing important training decisions on relatively small differences in the number being displayed.

Why Can Wrist Heart Rate Readings Be Wrong?

Optical heart rate measurement depends on the sensor maintaining good contact with your skin and obtaining a clean optical signal. Anything that interferes with that signal can potentially affect the reading.

Watch fit is one of the simplest factors. If your watch is loose enough to move as your arms swing, the sensor may struggle to maintain a consistent reading. Manufacturers generally recommend wearing the watch snugly above the wrist bone during exercise, while still keeping it comfortable.

Cold conditions can also make wrist measurement more difficult because blood flow near the skin can be reduced. Garmin, for example, recommends warming up before exercising in cold conditions to help improve blood flow to the wrist.

Movement and wrist position can affect optical measurement as well. Individual factors, including tattoos in the area beneath the sensor, may also interfere with some optical sensors.

None of these factors means you should assume that every unusual heart rate reading is wrong. They simply help explain why wrist readings occasionally behave in ways that do not match how hard you feel you are running.

What Is Cadence Lock?

One problem that can occur with optical heart rate measurement during running is known as cadence lock. This is when the sensor appears to track the repetitive movement associated with your running cadence rather than your actual heartbeat.

Your displayed heart rate may suddenly sit close to your cadence and remain there even though the number does not make sense for the effort you are producing. Garmin specifically identifies cadence lock as a potential limitation of optical heart rate measurement and says excessive movement from a loose watch can contribute to it.

Ensuring your watch fits securely can reduce the risk. If you repeatedly experience unreliable wrist readings and heart rate is important to your training, using a chest strap is one way of obtaining a more dependable signal.

Read more about running cadence here.

When Is A Chest Strap Useful For Running?

A chest strap becomes more worthwhile when you are deliberately using heart rate to control or analyse your training rather than simply glancing at the number after a run. If you regularly try to stay within particular heart rate zones, more consistent readings can make those zones easier to use.

It can be particularly useful during sessions in which your intensity changes repeatedly. Intervals, hills and threshold workouts place different demands on a heart rate monitor from a long run completed at a broadly steady effort.

Experienced runners who analyse their training in considerable detail may therefore get more benefit from a chest strap. Some straps can provide additional data when used with compatible running watches, although the available features depend on the particular watch and sensor combination.

Do Beginners Need A Heart Rate Chest Strap?

For most beginners, no. A chest strap should not be regarded as another piece of essential equipment that you have to buy before you can start running properly.

If you already own a running watch with wrist based heart rate, start by using that. It can give you useful information about how your body responds to different runs and help you understand the relationship between pace, effort and heart rate.

There is also a danger in becoming too focused on numbers when you are starting out. Building your running gradually, developing consistency and learning what different levels of effort feel like are much more important than worrying about a difference of a few beats per minute.

If you later decide to train more extensively using heart rate zones, or discover that the readings from your watch are frequently unreliable, you can consider adding a chest strap then.

Do You Need A Chest Strap For Heart Rate Zone Training?

You can certainly start heart rate training using the sensor in your watch. For steady easy runs and longer controlled sessions, a good wrist sensor may provide all the information you need.

A chest strap becomes more useful if you want greater confidence in the heart rate figure you are seeing during the run. This can be particularly helpful when you are trying to keep your effort below or above a particular heart rate threshold.

There is another issue to remember, however. Having an extremely accurate heart rate reading does not necessarily mean the heart rate zones programmed into your watch are accurate for you.

Zones are sometimes calculated using estimates of maximum heart rate or other generic formulas. There is little advantage in measuring your heart rate with exceptional precision if you are comparing it with training zones that do not properly reflect your own physiology.

Read more about heart rate zone training here.

What About Easy Runs?

Easy running is where many runners have the least reason to buy a chest strap. If your watch gives reasonably stable heart rate readings and those readings broadly correspond with how the run feels, wrist heart rate will usually provide enough information to monitor your overall effort.

You should also pay attention to how you feel rather than becoming completely dependent on the watch. If you are running comfortably and can speak in sentences, one brief unusual heart rate reading does not necessarily mean you need to change your pace immediately.

Heart rate can be a useful additional guide to intensity, but it is still only one part of the picture. Pace, breathing, perceived effort, terrain, temperature, fatigue and how you feel on the day all contribute to how hard a run actually is.

Read more about easy runs here.

What About Interval Training?

Intervals highlight one of the reasons some runners prefer chest straps. Your effort may rise and fall repeatedly, and the heart rate monitor needs to track those changes as they happen.

Optical wrist sensors can sometimes respond less consistently when exercise intensity changes rapidly. Electrical chest straps are generally better suited to providing dependable beat by beat information as your heart rate changes.

There is an important qualification, however. Your actual heart rate does not instantly leap to the appropriate level when you start running faster, so heart rate is not always the best way to control very short intervals.

Pace, time and perceived effort may be more useful during short repetitions, while heart rate can provide additional information when you analyse the overall session.

Read more about interval training here.

Is A Chest Strap Uncomfortable?

Some runners simply do not like wearing chest straps. They need to sit firmly against the skin and, while many people stop noticing them once they start running, others find having a strap around their chest uncomfortable.

A properly adjusted strap should be secure without restricting your breathing. With traditional electrode based straps, moistening the electrode areas before training can help establish good contact with the skin, and manufacturers such as Polar recommend doing this before use.

Chest straps also need a little more care than the sensor built into your watch. The strap will need cleaning, batteries or charging will eventually need attention depending on the model, and textile straps can wear out over time.

For a runner who is perfectly happy with their wrist heart rate readings, that additional equipment and maintenance may simply not be worthwhile.

Can You Connect A Chest Strap To Any Running Watch?

Not every chest strap will connect to every running watch. Different sensors and watches can support Bluetooth, ANT+ or other connection methods, so compatibility should be checked before buying.

Many modern heart rate straps support Bluetooth and some also support ANT+, making them compatible with a wide range of running watches, smartphones and training apps. You do not necessarily have to buy a heart rate strap made by the same manufacturer as your watch.

What matters is that the watch and sensor support a compatible connection method. If you are considering a particular strap, check the specifications for both devices rather than assuming that they will work together.

Final Thoughts On Wrist Heart Rate Vs Chest Strap

So what wins in the wrist strap vs chest strap debate? A heart rate chest strap remains the better choice when dependable heart rate measurement during exercise is particularly important, but that does not make wrist based heart rate inadequate. Modern running watches can provide very useful readings and, during straightforward steady running, that may be everything you need.

Beginners certainly do not need to add a chest strap to their list of essential running equipment. Start with your watch, learn what different levels of effort feel like and use heart rate as another source of information rather than allowing one number to dictate every run.

If you eventually start training extensively by heart rate, take a greater interest in analysing your data or find that your watch repeatedly struggles to provide sensible readings, a chest strap can become a worthwhile addition. Until then, there is a good chance that the heart rate monitor already sitting on your wrist will do the job perfectly well.