In the last few years, heart-rate tracking has rapidly evolved with more accurate sensors and algorithms, new methods of detection and even locations to wear devices. If you don’t want to wear a traditional chest strap, now your watch or even earphones can track the rise and fall of your heartbeat. Whether you want to do some basic tracking or use heart-rate-zone training—now an option with most run and fitness apps and watches—your pulse gives a key metric for measuring the intensity of exercise, your physiological progress and recovery as well as the quality of sleep. Here are the basics on different methods…
Quite frankly, this option isn’t particularly comfortable for most, but it does have certain advantages. Chest-based heart-rate monitors work by detecting and transmitting the electric charge the heart emits when it contracts, and your beats are shown on your watch or a compatible app. In dry, cold conditions, they can take some time to “warm up” and reliably detect. If you also swim and want to record heart rate, your best bet is a run- and swim-enabled chest strap with data storage such as the Garmin HRM-Swim ($100), Suunto Smart Sensor ($85) or new Polar H10 ($90), since you don’t have to carry or wear anything beyond the strap. Data storage is important as radio signals such as Bluetooth don’t transmit well in water. The new Polar is the most comfortable chest strap we have ever worn; the pod is slightly curved up at the electrodes with less pressure on the edges, it has non-slip dots along the strap and a flat, plastic snap closure instead of a metal one.
Many, if not most, GPS running watches now offer wrist-based optical heart-rate sensing. It is continually improving and is very close to the accuracy standard set by chest straps. This single-device solution has a distinct advantage of comfort and convenience. LED lights shine through your skin, and the reflected light captured by the sensor detects fluctuations in blood flow. These can be inaccurate with variations in blood flow to the extremities, which can be affected by cold temperatures, vigorous motions or even gripping weights or handlebars. Skin pigmentation can also impact the light shining through skin. To provide better reliability, brands are going beyond the usual two or three lights to as many as six (Polar M430, $300, and Android Wear M600, $330) and mixing green and orange LEDs (Suunto Spartan Wrist HR, starting at $499). In some cases, such as with Garmin Elevate (starting at $130) and Fitbit PurePulse ($150 or more), sensing is continuous to help inform your overall status and not just workouts. Accuracy is also very dependent on fit; a good seal prevents air and light that can interfere with sensing from sneaking in or confusion between blood flow and cadence. Also fitness bands can transmit to apps (and some watches) to add the benefits of heart-rate training to devices you already have.
With the miniaturization of components and longer battery life, heart-rate sensing earbuds have emerged in the last year, starting with Bragi Dash ($336), which even included a 4GB music player in the earbud. In-ear optical heart-rate sensing is ideal for those who run with a phone or work out in the gym with music and prefer to hear stats and info. About the size of standard earbuds, they include a tiny heart-rate sensor in at least one earbud. As the head has good blood flow, it is an ideal place for sensing, but fit is critical for a reliable reading. The completely wire-free Jabra Elite Sport ($250) will not even let you see heart-rate data in its app until it determines you have a good fit. Going beyond heart rate, some of these earbuds add sensors such as accelerometers to count gym reps, barometric altimeters and even speech recognition. The new LifeBeam Vi ($249) provides great music quality and a beginner-focused heart-rate-based training program powered by artificial intelligence with on-the-run speech recognition. Simpler, the Bose SoundSport Pulse ($200) just gives you great sound and heart rate. These generally can’t simultaneously transmit data to a GPS watch, so plan on using a phone app.