Step count, estimated kcal consumed, support for a wide variety of sports, wrist notifications and app store. Having an Apple Watch on your wrist means having a history of daily physical activity and a small smartphone, which can be independent if it is also a version with LTE/4G connection.

Like the vast majority of “smart” watches on the market, the Apple Watch incorporates a heart rate sensor. The more recent it is, the more precise it is. In fact, since the Series 6 and SE, the Apple Watch has been one of the most accurate heart rate smartwatches on the market, which is no small feat.

Although it is accurate and registers well in many physical activities, a chest heart rate sensor is even more reliable and the faithful companion of athletes who want to precisely control their effort during training.

How the chest heart rate sensor works

Using a chest heart rate sensor in the form of a strap has long been the default option, before the integration of optical wrist sensors in wearables such as the Apple Watch, Galaxy Watch or devices entirely sports-oriented ones like those from Garmin.

These devices have two components: a monitor or transmitter (worn on the chest strap) and a receiver (either the smartwatch or other compatible products). When a heartbeat is detected, a radio signal is sent which the receiver picks up to display the heart rate at that time. Most use Bluetooth or ANT technologies to operate, which rely on low-power radio links. There is also the older Polar 5.1 kHz transmission technology, which even works underwater.

Apple Watches and similar wrist-worn devices have built-in optical sensors. These are characterized by measuring the heart rate using a beam of LED light which penetrates through the skin and is scattered through the blood vessels. The most modern models can even measure oxygen saturation in the blood.

Why use a chest heart rate sensor?

The Apple Watch’s optical sensor was found to have a high reliability percentage, similar to that of the flagship chest sensor: the Polar H10. However, depending on your physical activity, you may find it more difficult to measure your pulse. Weightlifting is an often under-reported workout. In addition, sweat and a poor fit of the device can cause reading errors because it moves from the wrist and has problems for a correct measurement.

On the side of chest heart rate sensors, several studies, such as a 2017 report from the American Medical Association Cardiology, confirmed that a good band is able to achieve 99% similarity in readings with an EKG. However, they also have their buts. For some people they can be uncomfortable, they have a limited battery (they usually work with button batteries and their autonomy is about a year, but it depends on the use) and the constant contact with sweat can end up wreak havoc and deteriorate, provide bad readings.

How to Connect an External Heart Rate Sensor to Apple Watch

watchOS, the operating system for Apple Watches, offers native support for chest heart rate sensors. This must be compatible with Bluetooth technology and 4.0 or LE, otherwise the watch will not detect it and pairing will not be possible.

We connect the chest heart rate belt and make sure it is visible to other devices. Many models must be worn and next to the skin to “wake up”. Let’s move on to the Apple Watch’s Bluetooth settings. A section called Health devices will appear and in which we will find the heart rate chest straps with Bluetooth.

There may be connection errors. The most common reason for it not being detected by the Apple Watch is that it has previously been synchronized with another device, mainly the iPhone. It’s a good idea to remove it from your smartphone’s Bluetooth settings before trying to use it with Apple Watch.

Apple Watch compatible chest heart rate sensors

CooSpo H808S

We start with one of the best value for money chest heart rate sensors, the CooSpo H808S ($31.29). This bracelet is compatible with Bluetooth 4.0 and ANT+ to connect to a wide variety of GPS devices from Garmin, Polar, Suunto or smartwatches such as the Apple Watch. Can be used with many apps (Apple Training, Nike Running, Adidas Runtastic/Running, Strava, etc.). It is sweat and water resistant (IP67) and works with a button battery (replaceable CR2032) and its autonomy is approximately 300 hours. It has an LED indicator to check its status and beeps when it starts or stops working.

CooSpo Heart Rate Monitor Bluetooth Band Monitor Sports Heart Rate Sensor Ant+ for Garmin Wahoo Suunto Polar UA Run -SW-RD…

Athletic A5

We continue with another chest heart rate sensor that stands out for its value for money, the Atletica A5 (39.90 euros). With a maximum deviation of one beat per minute (depending on the brand), it is compatible with ANT+, Bluetooth 5.0 and 5.3kHz for use with a wide variety of devices. The band is made of 27% spandex and 47% spandex for comfortable wear without skin irritation. Works with apps like Runtastic Pro, Runkeeper, Strava, Apple Training, Map my Fitness, etc.

Athletic A5 | Heart Rate Monitor | The only chest strap that connects to all three standards 5.3 kHz, Bluetooth and Ant+ | Compatible with Apple Samsung Huawei Xiaomi Garmin

Wahoo TICKR X

With a more striking design, the Wahoo TICKR X (78.31 euros) has LED lights on the top that allow us to easily check our heart rate. It has 50 hours of internal memory with which to capture heart rate data in cardiovascular and strength training machines for later downloading and analysis. It is Bluetooth and ANT+ compatible. It can be simultaneously connected to three Bluetooth devices and apps to create a dynamic workout experience. It is also able to synchronize running dynamics such as cadence, ground contact and vertical oscillation.

Wahoo TICKR X Heart Rate Monitor with Memory

Polar H10

The ultimate chest heart rate sensor. A safe bet if you want reliability and good quality. The Polar H10 (79 euros) records heartbeats with good precision and reliability. It allows simultaneous connections, has Bluetooth, ANT+ and 5kHz connectivity, standalone recording, upgradable software, washable elastic band and is suitable for swimming. Their bands are available in different colors. Its rechargeable battery lasts 400 hours.

Polar H10 heart rate sensor, ANT+, Bluetooth, waterproof ECG with internal memory, compatible with fitness apps, bike computers and smartwatches

Garmin HRM-Pro

Garmin is another of the brands to take into account in the devices for the practice of sport. The Garmin HRM-Pro (98.98 euros) is a chest heart rate sensor which is one of the most complete. It is able to collect data on running dynamics to help with fitness (vertical oscillation, ground contact time, stride length and vertical ratio, among others). You can store this data during swimming and other activities while the watch is out of range. Its user-replaceable battery lasts up to a year. It is compatible with ANT+ and Bluetooth 5.0.

Garmin HRM-Pro, premium heart rate monitor, ANT+ and Bluetooth

optical sensors

We’re making a small split and including optical sensors that aren’t placed on the chest, but on the arm, for users who feel discomfort with previous sensor bands and are also looking for accurate metrics in their workouts.

Polar Verity Sense

For those who can’t stand chest straps and want Polar technology, the Polar Verity Sense ($83.30) can be placed on the arm, in swim goggles, or firmly against the skin under tight clothing. It is Bluetooth and ANT+ compatible, allowing two simultaneous Bluetooth connections. It also allows the recording of training sessions to transfer the data to the mobile later. It is waterproof (50 meters), its battery is rechargeable and the firmware is upgradeable.

Polar Verity Sense – Optical HR Sensor Armband, ANT+ Bluetooth Dual, Sports HR Sensor with One Button, Compatible with Peloton, Endomondo, Zwift and more, M-XXL, Black/Grey

CooSpo HW807

We finish with the CooSpo HW807 (55.99 euros), another arm heart rate sensor with which it is not necessary to connect it to a watch for it to work: the heart rate data is stored in the wristband and can be synced with the Hearttool app after exercise. Compatible with a wide variety of applications, it has five “intelligent” LEDs that change color depending on the heart rate training zone in which we are and in real time. It also has a heart rate alert that will vibrate if we exceed the value we have set through the app. It is Bluetooth and ANT+ compatible, it is sweat resistant (IP67) and has a battery life of up to 20 hours of continuous use.

CooSpo Heart Rate Bluetooth 4.0 Ant+ Optical Arm Pulse Sensor for Wahoo Garmin Zwift Strava Rouvy Trainerroad

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