If you practice a cardio-intensive sport, like running or cycling, you may have run across something called zone training. Here, the word zone refers to your heart rate. When you keep your heart rate in an easy zone—at, say, 50 percent of your HR maximum—different metabolic processes take place than when you push yourself and your heart to work harder.
The idea is that to improve your performance, you need to spend more time in your lower HR zones. This builds in recovery time and greater tolerance for cardiac stress. In the month that I wore Polar’s new running watch, the Polar Pacer Pro, I practiced zone training involuntarily. Despite keeping my runs at a grimly slow and unsatisfying pace and keeping my heart rate under 140, the Polar Pacer Pro simply found my workouts unacceptable.
Every day, I logged into the Polar Flow app and Polar’s software sternly informed me that not only was I overreaching, injury was likely on the way. There did not seem to be a way to tell the app that I have a resting HR of about 60 (this is good) and I’ve been running this way for over 20 years. Polar's software is probably its standout feature, but as with the last Polar watch I reviewed, it might be trying to do a little too much.
The Pacer Pro is just one of the latest of a crop of sports watches determined to horn in on the success of the Garmin Forerunner series. What features attract both new and experienced runners? Well, like the Coros Pace 2 (8/10, WIRED Recommends), they generally hover around the $200 price point, have satellite capabilities, are lightweight, and offer data that is both easy to understand and actionable.
Polar's $200 Pacer is probably the most comparable to its competitors, the Pace 2 and the Garmin Forerunner 55 ($200). The version I tried is the Pacer Pro, which unlike the Pacer, has a barometer to measure altitude changes and little upgrades like an aluminum bezel. To be honest, it looks a ton like both the Pace 2 and Polar's previous watch, the Vantage M ($399). It weighs 41 grams, which is about 11 grams more than the Pace 2, and it has a bright, crisp memory-in-pixel (MIP) display.