Pros & Cons
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- Accurate.
- Soft and flexible.
- Easily adjustable.
- Compatible with both fitness devices and smartphones.
- Good price.
- Machine washable strap.
- Uses Bluetooth.
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- Slightly bulky sensor.
- Only works with a few mobile apps.
Tech lovers have been wooed by optical heart rate monitors recently, especially the unconventional ones that read heart rate through the arm or ear. While a few of the best heart rate monitors (HRMs) certainly do break the mold, the most accurate ones for sports and fitness are still chest straps that use an electrical rather than optical signal. Polar's $79.95 H7 Heart Rate Sensor is by far one of the best, especially if you use other Polar devices, although it does work with several fitness apps independently. It's our Editors' Choice among chest strap HRMs.
Price and Comparisons
At $79.95, the H7 costs a little more than Garmin's Soft Strap Premium Heart Rate Sensor ($69.99). Among chest straps, they're both on the higher end, but still reasonable. For example, Garmin has another HRM called the Garmin Heart Rate Monitor that costs only $49.99, but it uses more plastic in its design and is not as comfortable as the Soft Strap.
Other standalone heart rate monitors cost about the same, even when they are worn on the arm and use optical technology (chest straps, instead, use an electrical pulse). The Mio Link is my favorite among them because it adds color-coded indicator lights that match up different heart rate zones, just as you might see in a good runner's watch. The Scosche Rhythm+ is a similar armband, but it doesn't deliver any useful information via lights the way the Mio Link does.
Some of the less conventional HRMs cost more but they typically do double duty. The JBL UA Sport Wireless Heart Rate is a good example. It's a neckband-style pair of earphones, with HRM thrown in as a feature. The same can be said for the equally priced Samsung Gear IconX earphones, which have even more fitness tracking capabilities and are completely. Because of the high price, neither is an impulse buy, unless you were already in the market for both sports headphones and a heart rate sensor.
Women might consider buying a sports bra that doubles as a HRM. A few manufacturers have experimented with weaving heart rate sensors directly into the garment itself. Several brands have tried and failed, but the Sensoria Fitness Sports Bra isn't a bad price, considering a good sports bra is already so expensive.
There are smart clothes for men, too, that incorporate HRM, like the Ralph Lauren PoloTech Shirt. In general, smart clothes are still in the earliest stages of consumer readiness, so if you're getting into this market, prepare for a lot of experimentation and troubleshooting.
Design and Fit
Good chest straps generally have flexible electrodes along the inside that look like a thin strip of rubbery plastic. There are two snaps on the front where you connect the heart rate sensor, so it sits at or just below your sternum.
The H7's sensor is an average size, but a little larger than the one on Garmin's Soft Strap and its HRM-Run ($99.99). Because Garmin makes a thinner sensor (the company calls it a "module"), those devices are a little less visible under clothing. They're also about 0.2 to 0.4 ounces lighter than Polar's device, which weighs in at 2.0 ounces (sensor and strap together). Less than a half ounce is an imperceptible different when worn, however.
When you buy an H7, you choose a blue, pink, or black strap, and either size XS-S or M-XXL. Extra straps without the sensor sell for $19.95 and come in two additional colors: white and orange.
The closure is a coated metal hook that slides into a sturdy nylon loop sewn to the strap. A soft tag flops over it, between you and the hook, to protect your skin from the clasp. A single sliding adjuster lets you tighten and loosen the strap for a snug fit.
Pop off the sensor, and you can wash the strap either in the washing machine with like colors or by hand with a mild detergent. It's not advisable to submerge the sensor, but it should survive a sweaty workout with no problem.
You can swim while wearing the Polar H7, but from underwater, it only works with devices that support 5kHz transmission. The Garmin Soft Strap, while waterproof, does not read heart rate accurately underwater. There is another, more expensive Garmin HRM that does, however, the HRM-Tri ($129.99).
Compatibility and Battery
The Polar H7 uses Bluetooth instead of the more traditional ANT+ to connect to devices. That means more versatility. You can connect it to both Polar devices and smartphone apps. Check the list of phones that work with the H7 to make sure yours is included.
Often with HRMs that only use ANT+, you need a runner's watch or another compatible fitness device that is the intermediary between the HRM and the app. So the HRM collects heart rate data, sends it to the device, and the device then connects to your smartphone, where it can share that data with other fitness apps. The H7, however, can do both. The list of apps that work with the H7 independent of a device, according to Polar's website, isn't terribly long: Polar Beat, Runtastic, Endomondo, Cardio Mapper, and iSmooth Run. Still, I like that the strap works without an expensive watch.
Of course, with a Polar device, you'll get a whole lot more out of heart rate training. A few of the supported Polar devices include the underrated Polar A360, the M600, M400, M200, V800, Loop 2, and several others.
When it comes to larger fitness equipment, such as treadmills, ellipticals, and stationary bikes, you'll have to check the machines you use to make sure the H7 is supported. In my experience, there's usually a logo of the preferred HRM company right on the machine's console, and it tends to be either Polar or Garmin.
The battery powering the Polar H7 is a standard coin cell (CR2025), the same kind used in many watches. They're easy to find in many drugstores and online. Expect to get at least four years of use before you have to replace the battery.
Accuracy, Chest Strap vs. Band
I've been wearing the Polar H7 here and there for about a year. I've worn it while riding a compatible stationary bike, and while running and walking on a compatible treadmill. It has come with me to a barre fitness class and to the weight room.
When I held the handlebar sensors on the treadmill and walked (those handlebar sensors tend to be less accurate at higher levels of intensity), the readings nearly matched those coming from the H7. Another low-intensity test I did was to compare the H7 readings to those coming from the Runtastic Heart Rate iPhone app. Again, I saw nearly identical results.
At higher intensities, the Polar H7 was found to correlate with EKG readings 99 percent of the time, according to Forbes. While I don't have an EKG reader for comparison, I can say with certainty that there is less lag time between any chest strap heart rate monitor, the Polar H7 included, and an optical wrist one. When I do an intense activity that gets my heart rate up, and then I stop abruptly, I see my heart rate drop first on the chest strap's readout (whether the connected device is a watch or an app) before I see the drop on the optical sensor. The difference is a few seconds at most.
While chest straps are, overall, more accurate than armband HRMs, the main complaint against them is that they are uncomfortable and cause chafing when used for an extended period, like during an ultra-marathon or triathalon. If comfort is a concern, there are certainly other options, such as the Mio Link, or any other band worn on the arm. You can also use any of the best fitness trackers or running watches that include a built-in optical HRM. But bands are less accurate than chest straps.
That said, unless you are an elite athlete doing very specific training, precision isn't all that important. If you're exercising with heart rate information for health benefits, the delay of one to two seconds in the reading isn't going to make a difference. Moreover, for this kind of training heart rate zones are more important than a precise number of beats per minute, and those zones often span about 35bpm.
The last point I want to make about accuracy between chest straps and arm bands at large is that it's easier to wear an arm band incorrectly and get an inaccurate reading for that reason. Optical arm bands work better if you slide them up your forearm a bit during activity and secure them tightly so they don't move. Chest straps don't have those problems.
Conclusions
Polar users in need of an accurate HRM can't go wrong with the H7, but it's also good for anyone looking to add heart rate data to their run-tracking using one of the five supported apps. And if it works with your home or gym fitness equipment, all the better. The price is right, too. The Polar H7 is one of the most versatile and accurate HRMs available, and a PCMag Editors' Choice.