How Welltory tracks heartbeat

Only a few thousand people use Bluetooth heart rate monitors with Welltory. The other 98% use their smartphone cameras to take measurements.

We use a method called photoplethysmography (PPG). That’s when you use light-based technology to sense the rate of blood flow, which is controlled by the heart.

When your heart beats, blood flows in and out of the capillaries in your finger. These changes in blood volumes make the tissue in your finger change color.

During a measurement, the flash illuminates the tissue in your finger, the camera takes a video of the changes in blood volumes, and the result is a short clip of your heartbeat.

PPG has been used by healthcare professionals to track the heartbeat since 1972, and has been proven to be just as effective as ECG machines. It’s the technology behind pulse oximeters and is used in many wristbands and fitness trackers to track heart rate.

Can I use a fitness band that tracks my pulse for measurements?

Not unless it’s a professional heart rate monitor. While wristbands like Withings, MiFit, Xiaomi and Fitbit can track heart rate, the measurement accuracy of these devices isn’t good enough to track heart rate variability yet.

Once pulse trackers are accurate enough, we’ll gladly let you use them for measurements.

How do I know the camera is accurate then?

Like ECG machines, the Polar chest strap uses electrodermal activity to register electrical signals that control the expansion and contraction of heart chambers. The data showed that Welltory measurements are just as accurate as the ones taken with the ECG-accurate chest strap. Camera measurements have also been validated by another team of researchers here.

What devices could be used besides the camera?

For the first couple of decades, HRV measurements had to be done with clunky, expensive ECG machines. Luckily, there are plenty of heart rate monitors on the market now — ECG-accurate chest straps were invented by Polar back in 1977.

Here’s a list of devices we support for measurements:

  • Polar H7
  • Polar H10
  • 4iiii Innovations V100
  • Zephyr HxM Smart Heart Rate Monitor
  • Suunto Smart Belt
  • Sigma Sports R1 BLUE Comfortex
  • Armour39 Module & Chest
  • Jarv Bluetooth Wireless Heart Rate Monitor and Sensor
  • Wahoo TICKR X

Always, always stick to our measurement rules.

Heart rate variability is a very sensitive method, and everything affects your numbers: breathing, movement, lighting, and how you hold your finger during a measurement. Our guidelines will help you take accurate readings every time.

04 Dec. 2019
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05 Dec. 2019
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