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For many of us, our workout partner has become a gadget, not a person. Be it a Fitbit, Apple Watch, a screen at the gym or an app on our smart phone, we’re often wearing a device that reports our sleep patterns, heart rate and overall activity.

But what does all of this information really tell us? Is a heart rate of 150 a good thing? Are my 10,000 steps worth bragging to my friends about?

It’s less about the numbers and more about the behaviors and motivation the numbers help create.

“The Fitbits are a great motivational tool to use for encouragement for exercise—being able to track steps and how much activity you are taking part in,” says Asher Shafton, MD, a cardiologist at the Heart Institute of Colorado. Whether it is heart rate, step-tracking, sleep-tracking or stand-up reminders, these tools are about driving decisions, not about amassing data.

Heart rate monitors in particular are touted as a great way to measure the intensity of your workout. Your heart rate can tell you what intensity your workout was and if it really looked like the hardcore workout montage you just starred in in your mind.

 

What's in a Heart Rate?

With heart rate monitors on workout machines, watches and smartphones, we’re paying more attention to our tickers than ever, but do we know what we’re looking at? And how should that guide our workout? Dr. Shafton breaks it down:

• Resting heart rate: 60-80 beats per minute

• Maximum target heart rate: Take 220 – your age. For a 40-year-old, maximum would be 180.

• Moderate intensity: 50-69 percent of your maximum heart rate. 90 to 124 beats per minute for a 40-year-old.

• High intensity: 70-90 percent of maximum heart rate. 125 to 162 beats per minute for a 40-year-old.

So should you now make sure to faithfully log 20 minutes of high-intensity workouts three times a week? Is that the perfect workout to help the weight fall off your body and make your heart beat with the strength of 10 bass drums?

Research and Dr. Shafton suggest that meticulously tracking your heart rate during exercise will not reap outsized benefits. And while heart rate monitors may be a useful way to evaluate how hard you’re exercising, Dr. Shafton is quick to point out that it is no substitute for simply listening to your body the old-fashioned way.

“If you can carry on a conversation during a workout, your heart rate is probably at a good pace,” says Dr. Shafton. “If you are feeling light-headed and can’t carry on a conversation, then you should pay attention to your heart rate because you may be pushing yourself too hard. Listening to your body and knowing how you feel is key.”

Dr. Shafton says you should aim for 45 minutes of moderate-intensity exercise a day and research shows that moderate-intensity exercise can reduce risk for heart attack, stroke and blood clots. As for your device, Dr. Shafton says it’s doing its best work by motivating you to move in the first place. So whether you’re walking 200 steps or 20,000, or if your heart rate is 130 or 170, if that little screen is making you dig a little deeper and break a sweat, then it’s doing its job.

 

To Burn or Afterburn?

A relatively new buzzword in fitness is “afterburn,” the idea that a high-intensity interval workout can help burn calories at a higher rate even after you stop working out than a more evenly-paced workout. The scientific name for this process is excess post-exercise oxygen consumption (EPOC), and some proponents claim it boosts your body’s ability to burn calories for up to 24 hours after your workout.

So we can burn calories while we work out and while we work a barstool over a couple drinks later in the night? Let’s do it!

As reality would have it, the benefits are probably not that profound. While some research has shown a nice post-workout boost to a high-intensity workout, a more comprehensive review of research on EPOC found that the vast majority of calories are burned during the workout for both high- and moderate-intensity workouts.

If you find it motivating to track your heart rate during a workout or want a more time-efficient workout then you might try pushing into the high-intensity percentile. Just don’t expect it to turn your body into a 24-hour calorie burning furnace. And above all, listen to your body.

 

Note: Heart rate monitors are NOT intended to serve in diagnosing your health. If you suspect you have a heart condition, consult your doctor.