Monitor your heartbeat, safeguard your health

A heart rate monitor is a practical and convenient tool for tracking and monitoring heart activity. The heart rate data it gathers can be utilized in creating and running fitness training programs, boosting health, and, in certain cases, aiding medical diagnosis. Although a heart rate monitor can never replace regular health examinations, especially when the body is showing abnormal signs, it empowers people to take an active role in managing and maintaining their own health.

Let’s take a closer look at heart rate monitors, especially the technology, applications, and development of optical heart rate monitors.

What is a heart rate monitor?

A heart rate monitor is a type of device for detecting and measuring heart rate or pulse rate. Thanks to technological advances in recent years, these devices are small enough to be worn. Many of them employ highly accurate sensors.

Heart rate monitoring has won over consumers as a function of wearable devices such as smartwatches and fitness trackers. These devices can connect wirelessly to smartphones and computers, giving users convenient access to their heart rate and other health information during exercise. In addition, they can monitor daytime stress and activity levels and track nighttime sleep quality. They can even monitor vital signs at home, which is particularly beneficial for patients with certain conditions that can flare up without notice. Convenience and round-the-clock operation are key to the popularity of heart rate monitors.

How do heart rate monitors work?

Essentially, heart rate refers to the number of heartbeats per minute and pulse rate refers to the number of times per minute that arteries dilate in response to the beating of the heart. Heart rate and pulse rate typically do not differ, or deviate only slightly, from each other. Hence heart rate detection and pulse rate detection provide two different methods for tracking heart activity. Heart rate monitors typically use one of two types of sensors to facilitate pulse rate and heart rate monitoring. They are:

• Electrical (electrocardiography): Each heartbeat generates a slight current. Heart rate monitors that detect electrical signals can track these currents.
• Optical (optical electrocardiography): These devices use infrared light to observe arterial dilation as the heart pumps blood. These devices can monitor your pulse frequency, and some may even be able to estimate blood oxygen saturation.

It is important to note that certain health conditions, medications and environments can make it difficult to detect the pulse in your arm and interfere with the operation of some heart rate monitors.
 

What are the most common types of heart rate monitors, and how accurate are they?

Today’s heart monitors can be categorized according to their operational principles and modes of use. Some devices may be worn like smart watches on the wrist or forearm; others are worn as rings on the finger; and others have their sensors mounted on a chest strap. Depending on the model, some devices may feature either a wired or wireless connection to the device itself, which is clipped on clothing or placed in a pocket, and many new devices connect wirelessly to a cellphone or another device.

• Chest-strap devices
  These devices use electronic detection to track heart rate. They detect the heart’s electrical activity through a strap that crosses over the chest. These devices are the most accurate, especially when used correctly, as they directly measure heart rate, not pulse rate. Consequently, they deliver unsurpassed accuracy for fitness tracking, whether you are at rest, running, riding a bike, or using various types of exercise equipment.
• Wearable devices worn on the wrist or forearm
  There are two main arteries in the forearm and wrist: the radial artery, which flows toward the thumb, and the ulnar artery, which flows toward the little finger and the ring finger. Both of these arteries deliver large volumes of blood to the skin on the surface of the wrist and forearm. Hence wearable devices worn on the wrist or forearm are equipped with light-emitting diodes (LEDs) and sensors that adhere to the skin and use LED light to detect minute dilations in blood vessels beneath the skin’s surface. These devices are typically highly accurate when you are at rest or walking. Many of these devices are also highly accurate when you’re walking or riding a bike.
• Smart rings
  Worn as accessories on a finger, these devices use optical detection to track the heart rate and other vital signs of their wearer. Though these devices are relatively new to the market, early research shows that they are highly accurate when at rest. Their accuracy during exercise and other activities is still unproven.
• Pulse oximeters
  Typically clipped on a finger, these devices also use optical detection methods. They may track both pulse rate and blood oxygen levels. In healthcare settings, they are fixed in place by adhesives or attached to fingers to help healthcare providers conduct certain types of tests. Outside healthcare settings, pulse oximeters are not suitable for use during exercise.
• Smartphones
  Various smartphone apps across different platforms are capable of detecting pulse rate. Some use optical detection. When you point finger at the camera lens, the flash on the camera will illuminate subcutaneous blood vessels and thus detect the pulse. Other apps use the camera itself, which is pointed toward your face and detects your pulse rate based on changes in your skin that are visible but imperceptible to the naked eye. Smartphone apps that have you touch the camera lens for detection are typically more accurate than those that use the camera to scan your face. However, since cellphones and their cameras were not primarily designed for this purpose, they are understandably prone to error.

The risks of using heart rate monitors are very low. In most cases, the worst case scenario is that you might develop an allergy to the composite band or the device itself. However, the safety of use of these devices does not mean that they can replace medical devices that have received official approval.
 

What are optical heart rate monitors?

As the name suggests, optical heart rate monitoring uses an optical sensor to measure the human heart (pulse) rate. This method is commonly employed in various wearable devices such as fitness trackers and smartwatches, as well as in some medical instruments.

The operating principle behind an optical heart rate monitor uses light to detect and measure minute changes in blood flow within the capillary bed in the epidermis (the outermost layer of the three skin layers) as blood flows through the wrist. An optical heart rate monitor measures the pulse wave, which reflects changes in vessel volume as the heart pumps blood. The pulse wave is measured as changes in volume detected by optical sensors and light-emitting diodes. The sensor block uses an optical filter specially optimized by pulse wave detection, which efficiently reduces interference from infrared light and other sources of ambient light. Hence high-quality pulse signals can be collected even outdoors. This data is stored in the watch and can be used in analyzing daily heart rate or activity records.

Notable for their non-invasive nature, optical heart rate monitors facilitate continuous heart rate monitoring throughout activities such as exercise, sleep, and daily life. A popular function of wearable technology, their ability to provide users with valuable health and fitness information secures their important place in the smart health ecosystem.

Optical heart rate monitors empower individuals to monitor their own cardiac and overall health for the early detection of health problems, and provide valuable information for healthcare providers. As technology continues to advance, the relationship between heart rate monitors and smart health will undoubtedly strengthen further. A healthier and more informed way of living is just a heartbeat away.