Can You Rely On Your Wristband Heart Rate Monitor?

2015 is the year of fitness wearables. However, activity trackers no longer are just tracking steps and sleep. The latest wearables are monitoring your heart rate too, but how accurate are they?

October 19, 2015
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2015 is the year of fitness wearables. Seriously, I literally have gibr activity trackers myself. But, activity trackers no longer are just tracking steps and sleep. The latest wearables are monitoring your heart rate too, but how accurate are they?

Heart rate monitors have been around for a long time. Industry leaders, like Polar and Garmin, have become just as important to runners as a good pair of running shoes. However, more and more people are wanting the same valuable information too – whether they are an avid runner or not.

Since heart rate monitors have always required the user wear a matching chest strap to pick up the heart rate, it’s no wonder these new wristband heart rate monitors have gained so much popularity. No more sweaty, stinky chest straps. The question is, “How accurate are these new wristband heart rate monitors?”

Since this was a question I was getting a lot at the gym, I decided to do my own research so I could give an intelligent answer.

How It Works

My first mission was to figure out how in the world these things worked. What I discovered is most of them use what they call an optical heart-rate monitor, which uses light to measure the pulse. Since blood absorbs more light, the fluctuations in light levels can be translated into a heart rate.

Chest strap monitors use a totally different method though. Instead of using light to measure blood flow, it measures the heart’s electrical activity similar to an EKG (electrocardiogram). An electrical signal is transmitted through the heart as it beats, which can be detected through the skin. The chest strap is the transmitter, which picks up the signal and sends the information to your receiving device.

So, after I fully understood how both of these heart rate monitors worked, it was time to compare the two. I found many unbiased studies and tests on various wristband wearables against the traditional chest strap devices like the Polar H7. Many of them also used an EKG to set an accurate baseline.

Each tester checked their heart rate during all stages of activity. Multiple devices were tested at rest as well as during intense activity. Testers also used varied placements and wristband pressure to check inconsistencies. Since a wristband wearable relies on light, testers discovered placement was key to accuracy.

Wristband wearable’s must be carefully placed and secured to the skin with no space between the back of the watch and your wrist. This means the band must be pretty tight. One of the testers actually said the watch left an indention in her skin after testing the device with the correct placement. However, when the watch is secure, most of the wristband devices were within 10-15% of the accurate reading. In every study I found, the chest strap was nearly dead on in comparison to the EKG.

Pros and Cons

The most obvious pro to wristband wearable’s is the pure convenience. The monitor is already built in the back of the watch so you no longer have go to the locker room to clip on your chest strap. The con, however, is there a many variables to getting an accurate reading. This means there is a lot more room for error. And, some devices proved to not be very accurate even if it the device was secure.

Another interesting variable I found was skin perfusion. The Apple Watch, for instance, explains that skin perfusion (how much blood flows through your skin) varies from person to person and can be affected by the environment. I could really see this being an issue for people who run in cold climates. If you exercise in the cold, your skin perfusion in the wrist may be too low for the heart rate monitor to get a reading.

Some devices, like Apple watch, also admit that irregular motion can also decrease accuracy. Another words, you may get an accurate reading while jogging, but you may not get as accurate of a reading while taking a kickboxing class or playing a sport.

Lastly, another factor, which may prevent accuracy, are tattoos. Depending on ink, color and saturation, some tattoos may block the sensor’s light resulting in an unreliable reading.

Besides the different variables which can affect accuracy, you should also know you still have to open the appropriate app, or press the appropriate buttons, to choose your activity and start your training session the same way you would a traditional heart rate monitor watch with the chest strap. It’s not a huge deal, but a step you still need to take either way.

Fit or Flop

When it comes to choosing the right heart rate monitor, the question you have to ask yourself is “What is more important? Accuracy or convenience?” If you don’t mind sacrificing 10-15% accuracy, a wristband wearable may be perfect for you. However, if you need to have accurate numbers to stay in your desired training zone and accurately track calories burned, the chest strap is the more reliable device.

If you have been one of the millions who have been drooling over the Apple watch, but you don’t want to sacrifice accuracy, don’t fret. I have good news for you too. You can still use a chest strap with the Apple watch and enjoy all the other Apple features as well. While it may cost more than twice as much as the Polar M400, Polar’s new smartwatch (which I have and love by the way!), you can have the best of both worlds.

Are wristband wearable’s a Fit or Flop? I’m ready to give you my final answer. Wristband wearables can be a total fit for the right person, but they aren’t for everyone. If you decide you want to go the wristband route, I just highly recommend you do thorough research when shopping. as I quickly found not all wristband wearable are created equal. Finally, I would also recommend checking your device against a chest strap to make sure your wearable is giving you the most accurate information possible.

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