What Should My Heart Rate Be During Exercise?

What Should My Heart Rate Be During Exercise?

Optimize your exercise to stay healthy and burn the most fat.

You may have been told you should be exercising moderately for 150 minutes per week or vigorously for 75 minutes per week, but you probably haven’t been told how to exercise. What does “moderate” and “vigorous” mean? The answer lies in your heart rate. We sat down with James A.M. Smith, DO, a cardiologist with Wesley Medical Center in Wichita, Kansas, to demystify heart rate and exercise.  

Max and target heart rates
To get a handle on heart rate, the first thing you’ll need to do is some simple math. Take your age and subtract it from 220. That’s an estimation of your maximum heart rate. There are other ways to find this number, but this method is the easiest. According to the calculation, a 50-year-old, for example, would have a maximum heart rate of about 170.

Your target heart rate during exercise is a percentage of your maximum heart rate. Dr. Smith recommends a target heart rate of about 75 percent. For a 50-year-old person, that would be about 130 beats per minute. No need to take your pulse, says Smith; just go by how you’re feeling. “You should be breathing heavily and have a light sweat going,” he explains.

Why 75 percent?
A heart rate of about 75 percent of your maximum heart rate is a good target, says Smith, because that pace will help you to burn fat. “Above or below, you’re burning carbohydrates,” he says.

The body has three main sources of energy: carbohydrates, fat and protein. “Carbohydrates are basically the first to burn,” says Smith. At about 75 percent of your maximum heart rate, the ratio of fat to carbs burned is highest. Fat burning drops off the closer you get to your max heart rate.  

Exercise recommendations
According to the Physical Activity Guidelines set forth by the US government, everyone should aim for 150 minutes per week of moderate cardiovascular exercise. Smith says the bare minimum is 30 minutes three times per week. “The heart is a muscle and we’re trying to condition that muscle to improve blood flow to the brain and the skeletal muscles,” says Smith.

The recommended 150 minutes of exercise can be reduced with interval training. Interval training—often called high intensity interval training (HIIT)—means increasing your pace and heart rate for a brief period, then dialing the energy back down for an active rest. For example, if you’re on an elliptical trainer, go all out for 15 or 30 seconds every quarter mile. Then reduce your speed until the next quarter mile.

“You’re creating hypermetabolic conditions,” says Smith. “You’re breathing fast, your heart is beating fast and the body is clearing waste products fast.” A 2015 meta-analysis of 50 studies found that HIIT can improve metabolic health, especially in people with or at risk of diabetes. “For people who don’t have an hour to work out, you can accomplish a lot through interval training,” Smith said.  

If high intensity sounds intimidating, don’t discount something as simple as walking. A brisk stroll can help you lose weight, decrease your risk of heart disease and diabetes, slow mental decline, stave off stress and help you sleep more soundly. Start with a 15-minute walk and then track your steps every day so you can set goals to increase. An app like Sharecare (available on iOS and Android) has a built-in steps tracker. Just keep your phone on you and get moving, keeping your optimal heart rate in mind.

Medically reviewed in November 2019.

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