Heart Rate Monitors

Heart rate monitors measure how fast your heart is pumping in beats per minute (bpm). They’re usually small and wearable as a watch, an arm band or a ring, allowing you to track your heart rate all day or even at night. While they’re often reliable and convenient, they’re no substitute for check-ups and tests from a healthcare provider. Instead, they offer more information that you can share with your provider.

A heart rate monitor can help you:

• Exercise at a safe intensity that won’t strain your heart
• Reach target heart rate zones to get the most out of your workout
• Track heart rate data during the day and/or at night while you sleep

Most heart rate monitors give you numbers in the moment, plus save data for you to review later — like your average heart rate during a workout or overnight. All this information can help you take an active role in managing your health. It’s also useful if you have a heart condition that your provider wants to keep a close eye on.

Heart rate monitors are generally very safe and don’t pose risks to your health. But it’s possible that getting so much data may stress you out. If you find yourself constantly checking the numbers or worrying about your heart rate, tell your provider. They may suggest wearing it only at certain times, like when exercising.

How do heart rate monitors work?

Heart rate monitors detect either your heart rate or your pulse rate. Your heart rate is the number of times your heart squeezes per minute to push out blood. Your pulse rate is the number of times your arteries widen and narrow in response to your heart’s activity. Usually, these numbers are the same or very close. That’s why devices that technically measure your pulse still report that data as “heart rate.” Some monitors can even detect abnormal rhythms.

Any heart rate monitor you use will be equipped with one of these technologies:

• Electrocardiography (EKG/ECG): This means electrodes in the monitor detect your heart’s electrical signals. With EKG technology, you’re directly measuring your heart rate.
• Photoplethysmography (PPG): This means the device sends tiny beams of light into your skin and uses sensors to detect changes in blood volume. That’s why you might see green lights shining on the back of your watch. PPG measures your pulse.

Monitors that use EKG technology are the gold standard in terms of accuracy. But as technology improves, many that use PPG are also highly accurate.

How do I use my heart rate monitor?

How you use it depends on the type you have. Here are some common ones:

• Smartwatch: For many, a watch is the most convenient way to track heart rate. You fit it around your wrist so it’s snug but not too tight. Certain watches use EKG technology, while others use PPG.
• Chest strap: This type of monitor uses EKG technology to measure your heart rate. You wrap a stretchy strap around your chest. It has sensors that pick up your heart’s electrical signals. You can sync the strap with a watch to easily view your data.
• Arm band: This is a stretchy band that you wrap around your bicep or forearm. For some people, it’s more comfortable than a chest strap or even a watch. Most arm bands use PPG technology.
• Smart ring: This is a newer type that uses PPG to track your heart rate and other vital signs. You wear it on your finger as you would a regular ring.
• Pulse oximeter: Unlike watches, chest straps and rings, a pulse ox isn’t wearable. But you can easily clip it onto your finger to check your heart rate (via detection of your pulse) and blood oxygen levels.
• Smartphone app: Instead of buying something new, you may be able to download a heart rate monitor app to your phone. These apps usually use PPG. You press a finger over the phone’s camera, which emits light to detect blood flow.

Be sure to read the instruction manual before you start using it — or even before you buy it. Each one works a little differently. Many monitors have websites with user forums, where you can ask questions and learn from others.

Make a note of key points like:

• When to charge it: Some watches or other devices last for days without needing a recharge. Others you must charge every day. It also depends on how often you use it in certain modes, like GPS.
• How wet it can get: Some monitors you can wear while swimming. Others can get a little wet, like if you get caught in the rain, but shouldn’t be submerged.
• How to clean it: Devices that track your heart rate are often sensitive to soap or cleaning supplies. Even certain sanitizing wipes might keep the screen or sensors from working properly. Follow cleaning instructions to avoid damage.
• Where to access your data: Some devices require you to download an app or computer software. You’ll sync your monitor in order to view all of your data. You may need to upgrade the app or software over time as newer versions become available.
• Which features are included: You might start off just wanting to track your heart rate. But many devices track other things, too, like your heart rhythm, VO2 max and sleep. Learning what’s available can help you make the best use of the technology.

Are heart rate monitors accurate?

Heart rate monitors that use EKG technology are the most accurate. Those that use PPG — especially the latest models — are often highly accurate. But it depends on the exact one you’re using.

Researchers are constantly testing heart rate monitors to learn more about their accuracy. Getting the right reading is important for anyone, but especially for those who have heart disease or conditions that require close monitoring.

Monitors that underestimate heart rate can be dangerous because they give you a false sense of security — you think your heart rate is lower than it actually is, and you may push yourself harder during a workout.

In general, heart rate monitors that use PPG (detecting your pulse) may be less accurate if:

• You have certain heart conditions: AFib, heart failure and some other conditions can cause weak heartbeats that aren’t detectable as a pulse. This means your heart rate may be higher than a monitor that measures pulse is showing you.
• You have arm tattoos: PPG sensors don’t work as well when the light travels through ink on your skin. This can lead to inaccurate readings.
• Your skin is darker: Darker skin contains more melanin. This natural substance tends to absorb more of the light from PPG devices, which may affect readings.
• You’re moving your arms a lot: PPG monitors don’t always capture the correct heart rate when you’re swinging your arms— like if you’re lifting weights or using an elliptical with moving handlebars. The movements may throw off the sensors.
• Your heart rate gets high: Some research shows that as the intensity of your workout goes up, the accuracy of PPG watches goes down. This may be due to a mix of things like arm motion and reduced contact between the device and your skin.

When should I call my doctor?

Check with a healthcare provider before choosing a heart rate monitor. They’ll help you find one that meets your health needs.

You should also call your provider if:

• Your heart rate is fast (over 100 bpm) at rest.
• Your heart rate is slow (below 60 bpm), and this isn’t typical for you.
• You’re more aware of your heartbeat, or it feels like your heart is pounding, skipping beats or flip-flopping in your chest.
• Your watch tells you that you’re in atrial fibrillation (a rhythm that some monitors can detect), which may need medical treatment.