OMY! Sports News

Why do heart rate monitors may lie to you? How to measure HR accurately?

Useful Tech
Your heart rate accurately determines your body’s capabilities. Depending on how you feel, climatic conditions, altitude and other external factors, your heart rate is a direct indication of what you are capable of today. Running pace is a derivative of heart rate. The better you know how to manage your heart rate and feel your body, the potentially higher your pace.
That’s why it’s important to measure your heart rate accurately. Especially when starting running.

Heart rate measurement technology.

There are many heart rate sensors and they all measure heart rate in one of 2 ways:
  • optical method
  • electrical method
Optical (photoplethysmography): these devices use infrared light to see the expansion of the arteries as the heart pumps blood through them. These devices monitor heart rate, and some can also assess the level of oxygen in the blood.
These wearable devices have light-emitting diodes (LEDs) and sensors that rest against the skin in that area. The sensor uses LED light to detect tiny expansions of blood vessels beneath the surface of the skin.
The electrical (electrocardiography) method detects a small electrical current which your heart generates with each beat.

Optical sensors on the wrist.

A sports watch with a built-in optical sensor measures heart rate through the expansion of the radial artery, which goes to the thumb. These are one of two arteries that provide blood flow to the skin on the surface of the wrist and forearm. But the problem is that the expansions are so microscopic that the optical sensors measure and show you incomprehensible data. After all, the wrist is far away from the heart and its beats, well picked up in the chest area, may be elusive in the extremities.
Nevertheless, optical heart rate sensors are quite popular and are now on almost every brand of sports watches and wearable devices, from Apple and Android watches to Whoop and others.

Forearm optical sensors.

If you want to make your heart rate monitor a fashionable and stand out accessory, consider forearm sensors. These sensors are made by Polar, Garmin, Coros, Wahoo, and others. They count the heart rate on the larger ulnar artery that goes to the pinky and ring finger. This gives more reliable data than a wrist sensor, but intense running also degrades the quality of the data.

Accuracy of optical sensors in different modes of use.

Typically, optical sensors are very accurate when you are resting, walking or jogging. Many of these devices are also accurate if you ride bike. But a fast running mode can cause your watch to show cadence data rather than heart rate data. When you’re actively running and moving your hands, the watch’s sensor moves away from your skin and starts responding to the sweeps of your arm. These movements are actually cadence, not the heart rate at all.

Chest heart rate monitors.

The most reliable way to measure your heart rate remains a chest heart rate monitor. Because chest monitors use the electrical impulse of the heart, they are the most accurate. This is because they directly measure your heart rate movements rather than your pulse rate, giving them greater accuracy whether you are resting, running, cycling or using various exercise machines.
The best known manufacturers of such heart rate monitors remain Polar, who were the first in the world to patent the technology to measure heart rate in this way and offered the first chest sensors on the market. Other well-known manufacturers are also Garmin, Wahoo and others.
Choose the one that suits your needs. Ask your questions in the OMY! Sports app chat and stay well informed about your real HR while training.