How do fitness trackers measure your heartrate? Perhaps you have ever considered how smartwatches and wrist-based fitness trackers can inform what your heart rate is? I’ve been putting on an Apple Watch for a few months now, and it’s fun to see what my heart rate is during and after workouts.
But it got me thinking about how this technology works, and whether it’s accurate. According to Apple, a technology is used by the Watch called photoplethysmography, or PPG, to measure heart rate. It’s essentially tests how much red or green light it can easily see when looking at your skin on your wrist.
- Let your hands relax down to an extended position and begin your shoulder increases
- Data harvesting
- Take action, every day
- Take the family dog for a walk
- Fitness gives you to essentially”be ready for anything”
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- 7 years back from Connecticut
Blood is red because it demonstrates red light and absorbs green light, so when your heart is better than, there’s more blood circulation in your wrist, and more green light absorption. Between heart beats, there’s less absorption of green light. By blinking its LED lamps hundreds of times per second, Apple Watch can compute the amount of times the center is better than for each minute – your heart rate. You might have even seen this in applications on your phone before.
Using your phone’s camera, the same technology can be employed on-demand. In fact, this technology is old-apparently it was initially found in the past due 1800s quite. At that right time, people would “hold their hand up to a candle in a dark room to start to see the vascular structure and blood circulation”. This technology is also used in hospitals-if you’ve ever seen a finger or ear canal clip that steps pulse and blood oxygen levels, it’s using PPG.
The Apple Watch has two heart rate monitoring modes: when you put the watch into workout mode, it will consistently track your heart rate. All of those other time, the heart rate sensor uses infrared light to measure your heartrate every 10 minutes (unless your arm is moving, rendering it hard to obtain a reliable reading).
You can also check your heartrate anytime from the heartrate glance. As the watch depends on screening the light absorption of your skin layer to infer your heart rate, there are several ways the watch can struggle to get an accurate reading-or any reading at all. Tattoos, for instance, can prevent the heartrate sensor’s light.
There’s certainly a debate about how exactly accurate this technology is even in the perfect circumstances. Users have complained about inaccurate readings during workout routines that involve lots of irregular movements, which is something Apple points out as leading to trouble for the watch’s receptors. How the sensors are worn can also impact the result: putting on the watch too loosely can give inaccurate readings.
Other tests show the heartrate readings to be very accurate (see graph above), but without a study with a huge sample size, we can’t make a call about how accurate the tech is on average. Fitbit doesn’t mention photoplethysmography, but their tech seems to be inline with Apple’s. The Fitbit bands with heartrate tracking built-in (the Charge HR, Surge, and Blaze) uses “optical heart rate sensors that still maintain extended battery life”.
Fitbit brands their heart rate technology as PurePulse-calling it “the only heart rate technology to provide automatic, constant wrist centered tracking for all-day health workout and insights intensity”. The Fitbit trackers have the same struggles as the Apple Watch: you need to wear the band correctly, and tight enough for the lights to be touching your skin, and irregular exercise like boxing can throw off the measurements.