Everything we wear is becoming smarter. Smartwatches are slowly replacing analog watches (aka dumb watches) and smart glasses allow us to see more than what’s around us.
People now prefer wearing a smartwatch over a dumb watch because of its usefulness in tracking health. Many smartwatches offer heart rate tracking features and there are also chest straps that can monitor your heart. Many people track their heart rate data to estimate their energy expenditure, which is very helpful for body composition.
But how accurate is the data your device is giving you and which ones are better for monitoring your heart – smartwatches or chest straps? Here we compare few types of chest straps and smartwatches.
Both, smartwatches and chest straps, do the same thing but in hugely different ways.
Before smartwatches, only way to monitor heart rate was a chest strap. Electrodes embedded on these chest straps press against the skin and uses electrocardiography to get the heart’s electrical activity. Chest straps are very accurate. Some brands like Polar claim their straps can measure heart rate to a granular degree of accuracy. A 2017 study published in the Journal of Medicine and Science in Sport and Exercise showed that Polar H7 chest strap was 99.6% accurate when tested against an ECG.
Many people find chest straps to be uncomfortable. On the other hand, constant exposure to sweat can cause them to corrode, which means interference with the electrodes and delivering inaccurate readings. To pick up electrical impulses coming from your heart, the pads on the chest straps need a bit of moisture, so they may need a few minutes once you get sweating to give you an accurate reading, reports Colin Levitch in CyclingNews.
Smartwatches and fitness trackers use a method called photoplethysmography (PPG) to measure heart rate. PPG is a technical term for shining light into the skin and measuring the amount of light that is scattered by blood flow. When you’re wearing your smartwatch or fitness tracker, the heart rate sensors at the bottom of the dial press up against the skin and tracks heart rate. This is very comfortable for the user but there are drawbacks.
Wrist-based heart rate trackers need to be worn accurately (tight, above the knuckle on your wrist) to get a precise heart rate. Also, skin tone, hair, moles, etc. can affect accuracy. A 2019 study, published in the Journal of Sports Science, found that the point-to-point accuracy in these wearables can vary from +/- 1% to error rates as high as +/-13.5%. Types of LEDs and algorithms also can affect the accuracy of these wearables.
When it comes to point-to-point accuracy, chest straps are more accurate than optical heart rate sensors. Chest straps are proved to be the most accurate of the heartrate-measuring devices, with a 99.6% accuracy. The wrist-worn devices, however, are far less accurate. If you want real-time heart rate monitoring and don’t care about point-to-point accuracy, then a smartwatch should be good enough for you.