Buzz
Most fitness trackers and smartwatches come equipped with optical heart rate sensors, but their accuracy can be inconsistent. A chest strap heart rate monitor provides a more precise reading. Additionally, you can use the chest strap without a fitness watch—simply connect it to your phone. Plus, they are affordable—my personal favorite is just $25.
Why Chest Straps Offer Greater Accuracy Than Watches
Chest strap monitors, particularly the traditional models, detect the electrical signals from your heart. These devices use electrodes that touch your skin, and occasionally, you might need to sweat a little for a strong connection (though I haven't encountered that as a problem during my sessions).
This makes chest straps significantly more precise than optical sensors, which are typically found on the back of smartwatches. Optical sensors use green light to detect your heart rate by measuring the light that bounces off your blood vessels as blood flows through. However, this light-based method isn't as effective when it comes to tattoos and may face challenges with accuracy on darker skin tones. It can also be disrupted by external light sources, which is why they don't perform as well if your watch is worn loosely or is too large. Runners sometimes face an issue called 'cadence lock,' where the rhythm of their footsteps (for instance, 170 steps per minute) leads the watch to mistakenly read their heart rate as matching that cadence. If your app reports a heart rate that mirrors your cadence, it’s likely not reading your actual heart rate at all.
You can avoid all these issues by opting for a chest strap. In my experience with reviewing various devices, even the most accurate smartwatches won’t consistently capture your heart rate with perfect precision. If heart rate tracking is important to you during training, a chest strap is the way to go.
Why the Coospo is My Top Pick
I’ve been using a budget-friendly Coospo heart rate monitor for years. It wasn’t lent to me for a review; I purchased it because I needed an affordable and straightforward way to monitor my heart rate without relying on a watch. (At the time, I was doing a lot of kettlebell exercises, where the kettlebell rests gently on your wrist during overhead movements, making a watch inconvenient.)
I’ve continued using it ever since. It's paired seamlessly with an iPhone, a Peloton, an Apple Watch, a series of Garmins, and likely several other devices I’ve since forgotten. When writing the ‘accuracy’ section in my fitness watch comparisons and reviews, I use the Coospo (whether connected to my phone or a secondary watch) to create a gold-standard heart rate graph, which helps me evaluate how other devices measure up.
The Coospo heart rate monitor I use is an older model than the one linked above (since I've had it for quite a while). It connects via Bluetooth and supports ANT+, powered by a coin cell battery that I typically change once a year. It doesn't store data on the device itself, which isn’t a problem for me, as it transmits the data directly to the paired watch or phone. It’s comfortable, easily adjustable, and the strap is removable for cleaning. Even though there are more expensive options (like the $100 Polar H10, which I've heard is excellent), I can't think of any chest strap feature I could possibly want that I don’t already have.
How to Use a Chest Strap Without a Watch
On my iPhone, I found the easiest method was to download the Polar Beat app (available for free on both iOS and Android), which pairs with my strap over Bluetooth. If you're out for a run or bike ride with your phone, the app also uses your phone’s GPS to track your pace and map your route.
I mainly use mine for indoor cycling and kettlebell exercises (which I record as 'other indoor'). Using a strap without a watch is particularly useful for kettlebell workouts, as the bell can sometimes hit a watch in certain positions. However, if you have a fitness watch and prefer using it, most models can connect to a chest strap directly, giving you the most accurate readings while still allowing you to check the data from your wrist.
