Fitness tracker, heart rate monitor, or smartwatch?

By Stephen Fellner, Lune Smartwatch Inventor & Founder

The fitness market is flooded with fitness trackers and heart rate monitors, but there are increasing doubts as to their accuracy. We’ve often wondered, can a smartwatch perform these functions more accurately?

A wrist-worn pulse monitor, such as the FitBit, Apple Watch or Nike+ Fuelband typically monitor your pulse by shining light through your skin, and look for changes in skin colour due to variations in oxygen levels carried by your blood, using optical sensors, which can give an indication of your heart rate.

This monitoring system isn’t foolproof though, due to three key issues:

  1. The oxygen levels of the blood in your wrist do not reflect your actual heart rate accurately (whereas the small blood vessels at the tip of your finger do).
  2. As your muscles contract during exercise, they also influence the amount of blood being picked up by external sensors and this can produce false readings.
  3. External light such as sunlight or street lights are also picked up by optical sensors and this can give false readings. For example, there may be a cyclic variation if external light picked up as you move your hands back and forth during a run is mistaken for your heart rate.

We don’t believe anyone has succeeded in creating an accurate wrist-worn heart rate monitor yet. You can read more here and here.

An accurate heart rate monitor will measure the electrical activity of your heart (EKG), and can send your heart rate wirelessly to your smartwatch. There are some great heart rate monitors on the market including Zephyr’s HxM Smart, Polar’s H7 device and Wahoo’s Tickr.

Heart rate monitoring is important to ensure your heart rate remains within acceptable limits during your workout. Unreliable monitors have the potential to be harmful for people with certain health conditions.

At Lune, we believe that an accurate heart rate monitor, connected to your smartwatch, and supported by your smartwatch’s inbuilt motion and altitude tracking is the best way to support your fitness goals.

Young woman checking smart watch in the street before a run


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