Why a Chest Strap Is the Best Way to Track Your Heart Rate During a Workout
Almost every fitness tracker and smartwatch has an optical heart rate sensor, but it’s not always completely accurate. Not only can you improve your measurement accuracy by wearing a chest heart rate monitor, but you can also use the chest strap without a fitness watch—just connect it to your phone. Chest straps don’t cost much either; my favorite is only 25 bucks.
Why Chest Straps Are More Accurate Than Watches
Chest monitors (traditional ones, anyway) measure the electrical activity of your heart. They use electrodes that make contact with your skin, and sometimes you may need to wait until you sweat a little before they get a good connection (though I haven’t found this to be an issue in my workouts).
This makes them much more accurate than the optical sensors you’ll see on the back of smartwatches. Optical sensors use (usually) green light and measure heart rate by detecting the light that reflects off blood vessels as blood pulsates through them. Relying on light means tattoos don’t always work as well, and accuracy can be an issue on darker skin tones. They can also be confused by external light, so they won’t be as accurate if your watch is worn loosely or is too large . Runners sometimes experience “cadence lock,” where your cadence (say, 170 steps per minute) tricks the clock into thinking your heart is beating at that rate. If your app reports a heart rate that matches your step rate, there’s a good chance it didn’t measure your heart rate at all.
You can get around all of these problems by wearing a chest strap. As I’ve found in my device reviews, even the most accurate watches don’t always accurately record your heart rate 100% of the time. If you’re really concerned about your heart rate during workouts, just invest in a chest strap.
Why Coospo is my favorite
I’ve been wearing a cheap Coospo heart rate monitor for years. I didn’t borrow it for review, I just bought it because I wanted a cheap and easy way to track my heart rate without a watch. (I’ve trained with kettlebells many times, and during overhead exercises, the kettlebell rests softly on the wrist, where the watch gets in the way.
I have continued to use it since then. It has been successfully paired with iPhone, Peloton, Apple Watch, Garmins series, and probably a bunch of others I’m forgetting about. When I write the “accuracy” section of my fitness watch comparisons and reviews , I use the Coospo (either paired with my phone or a third watch) to get the gold standard heart rate graph and see how the tested devices perform.
My Coospo heart rate monitor is a slightly older version of the one above (since I’ve had it for a long time). It uses Bluetooth and also supports ANT+ and is powered by a coin cell battery that I have to replace about once a year. It has no storage space on the device, which I don’t need since it transfers data directly to the connected watch or phone. It is convenient and easy to adjust. The device is removable and I can wash the strap. And while there are more expensive straps out there (like the $100 Polar H10 , which I’ve heard is great), I can’t think of a single sternum strap feature that I’m interested in that I don’t already have.
How to use a chest strap without a watch
On my iPhone, I found the easiest way was to download the Polar Beat app (free for iOS and Android ), which connects to my band via Bluetooth. If you’re going for a run or bike ride with your phone, it can also use your phone’s GPS to track your pace and record where you went on a map.
However, I usually use mine for indoor cycling and kettlebell training (which I write down as “other indoor”). Using a strap without a watch is especially useful with weights, as in some positions the bell would otherwise hit the watch. But if you have a fitness watch and enjoy using it, most models will allow you to connect the watch directly to your chest strap. This way you can get the most accurate readings and check the numbers from your wrist.