SHOULD YOU USE A HEART RATE MONITOR?
These days there’s a profusion of technology available that tracks your health, from counting steps to counting calories to letting you know how well you slept. But the most valuable fitness device is a heart monitor, which tells you how many times a minute your heart beats. I have a Fitbit Charge 2 wristband that continually monitors my heart rate. Most of the time I don’t much care what it reads, but when I jog I refer to it all the time to make sure I’m exercising at the right intensity. Using it, I learn when I need to pick up the pace or slow it down. Guessing what my right intensity should be without the monitor doesn’t work—I’m usually way off. If you participate in endurance activities such as running, biking, hiking or even fast walking you too would probably get use out of a heart rate monitor.
Heart Rate Terms Defined
Here’s an excerpt from the December 2014 Harvard Heart Letter How to choose and use a heart rate monitor:
- Resting heart rate: This is your heart rate when you’re most relaxed. Using your heart rate monitor, measure it either right after you wake up in the morning or during the day when you’re relaxing. For men, resting heart rates are usually between 60 to 80 beats per minute (bpm); for women, they’re 70 to 90 bpm.
Target (or training) heart rate: This range is 65% to 80% of your maximum heart rate. “To get the most health benefit from your exercise, try to stay in your target heart rate range for at least 20 minutes during an exercise session,” says Dr. Aaron L. Baggish, associate director of the Cardiovascular Performance Program at Harvard-affiliated Massachusetts General Hospital. When you start out, aim for the lower end of the zone. As you become more fit, your target heart rate should increase- Maximum heart rate: This is an estimate of the highest heart rate a person could reach while exercising very strenuously. The formula for calculating maximum heart rate is 220 minus your age, but it varies as much as 25 bpm from person to person. If you’re healthy, there’s no risk in going above your expected maximum heart rate for short periods of time.
Types of Monitors
There are two main types of monitors, and each uses a different kind of sensor technology. Here’s an excerpt from the October 2018 Harvard University article Rating heart monitors:
Chest-strap monitors. An elastic band fits snugly around your chest with an attached transmitter pad fixed in place above your heart. The transmitter uses sensors to detect the electrical activity of your heart, and that information is relayed to display as beats per minute on a wristwatch or cell phone app. (The strap needs to maintain contact with the skin on your chest, as electrodes in the pad use moisture or sweat to pick up the heart’s electrical signal.)
Activity trackers. Activity trackers that you wear on your wrist have photoplethysmography sensors that use light to measure your pulse. They work like this: Small LEDs on their undersides shine light onto the skin of your wrist. The light refracts off the blood flowing beneath the skin, and another sensor in the tracker translates that information to a pulse reading.
Some monitors have small display screens, but others need to be connected to a sports watch or smartphone. Basic models show just your heart rate, while more advanced ones let you program desired levels and sound an alarm if your heart rate goes too high or too low.
I’ll talk about activity trackers in more depth in a future post. But for now, here are excerpts on a review of just the heart-rate measurement for various top selling wrist-worn fitness trackers and smartwatches from the Caitlin McGarry article in the October 11, 2018 Tom’s Guide Heart Rate Monitor Reviews:
What Was Tested
“We put several of the top-selling wrist-worn fitness trackers and smartwatches from Apple, Fitbit, Garmin and Samsung to the test against a Polar H10 chest strap to see to see how they stack up to the gold standard in consumer-grade heart-rate accuracy.”
The Apple Watch Series 3 and Series 4, as well as the Samsung Galaxy Watch, were the most accurate in measuring heart rate, each with a variance of under 1% from the chest strap readings. The Garmin watches had a 1% to 2% variance. [My Fitbit Charge 2 had a 4% variance vs. the chest strap. I can live with that since it cost me $100 compared to the Apple Watch Series 4, which is $400.]
Heart-rate sensors’ accuracy depends on a variety of factors. “We know from our studies that the accuracy of any one of those devices can vary substantially based on the fit,” said Dr. Gregory Marcus, director of clinical research for the University of California, San Francisco’s Division of Cardiology. “Sometimes to get the most accurate measurements, it needs to be quite tight — to the point where it can be uncomfortable. Other things that can affect readings include the skin tone of the wearer, as well as the ambient temperature.
There are pros and cons to both the chest strap and trackers. I prefer a wrist-worn tracker to a chest strap because I find chest straps to be uncomfortable and awkward to wear. But fitness trackers and smartwatches have to fit just so to take accurate readings.