What Your Heart Rate May Be Telling You


Your heart rate during exercise, as well as at rest, can tell you a lot about how fit you are-and perhaps even some other things about your health. Here’s what to know about your heart rate.

What should your resting heart rate be?

Resting heart rate, or pulse rate, refers to the number of times your heart beats per minute when you are at rest. Though a normal range is 50 to 100, most people’s hearts beat 60 to 80 times a minute at rest. Above 100 is considered a rapid pulse, called tachycardia; an unusually slow resting heart rate is called bradycardia.

Resting heart rate varies from person to person and even over the course of the day, due to a variety of factors, including genetics. Your heart rate is faster when you get excited, anxious, or angry; it also increases if you are in pain or have a fever. And it rises temporarily if you smoke or drink a lot of alcohol or coffee. In contrast, your heart rate slows during most stages of sleep and tends to be lower if you are very fit. Certain medical conditions, such as thyroid disease, and some medications can affect resting heart rate.

What should your heart rate be during exercise?

To benefit most from aerobic exercise, you should work out hard enough to raise your heart rate to its training zone (target heart rate) for at least 20 minutes on most days. This enhances your aerobic capacity- that is, the ability of your cardiovascular system to deliver oxygen to the body’s cells during exercise.

The conventional way to compute your target heart rate is to subtract your age from 220-that’s your maximum heart rate (MHR)-and then calculate 60 and 80 percent of that number. For example, if you are 50, your maximum heart rate is 220 minus 50, or 170. Then multiply 170 by 0.6 (for the low end) and by 0.8 (for the high end), which gives a range of 102 to 136. Your heart rate should fall between these two numbers while you exercise. If you have been sedentary, start with 50 to 60 percent of your maximum rate. Trained athletes may aim as high as 90 percent.

This MHR formula has been criticized in recent years, however. One complaint is that it was developed using data mostly from young and middle-aged men, and that it produces targets that are too low for older women, in particular. Thus, some newer formulas differentiate between the sexes. These include ones from researchers at the Mayo Clinic, which say that women over 40 should multiply their age by 67 percent (that is, by 0.67) and subtract the result from 200 to get their MHR, while men should multiply their age by 93 percent (0.93) and subtract the result from 216. Another alternative MHR formula, called the Tanaka formula, aims to be more accurate for older people:

You subtract 70 percent of your age from 208. Still, for most people, these and other alternative formulas produce only slightly different numbers from the conventional one, and the simple method is still considered adequate. A more accurate target heart rate can be determined by an exercise stress test, which your doctor may recommend if you are first starting an exercise program.

How do you measure your heart rate during exercise?

Hold a finger gently over the carotid artery in your neck or the radial artery on the underside of your wrist (on the thumb side); count the beats for 15 seconds and multiply that number by 4 to get the beats per minute. Don’t stop exercising while you do this, since your pulse will drop right away. Some gym machines measure your pulse and calculate your target heart rate (after you enter your age). Or you can use a heart rate monitor, widely available today as “wearables” that include chest straps and wristband devices.

Once you learn how it feels to work out at your target heart rate, you should be able to estimate the intensity of your workout just by focusing on how you feel-by paying attention to how hard you are breathing, how much you are sweating, and how hard your heart is pumping. This is called the “rate of perceived exertion.” Or you can use the simple “talk test”: If you can engage in conversation of short sentences, your exercise intensity is about right.

How long should it take to reach your target heart rate?

That largely depends on how conditioned you are. If you are in poor shape, your heart rate will go up quickly with exercise; if you are in good shape, it will take longer. If your heart rate is naturally low, you may have to overwork to get into the standard target zone; if your heart rate is high to start, you may get into the zone too easily. A more complicated formula for determining target heart rate takes into account your resting heart rate and changes in your aerobic fitness level as you improve with training, and it usually yields a higher range.

How quickly should your heart rate drop after exercise?

The length of time it takes for heart rate to return to normal is a good measure of fitness. The more fit you are, the faster the recovery. This “recovery heart rate” is measured as part of an exercise stress test.

Does exercising regularly lower resting heart rate?

It may reduce it somewhat over time. Aerobic exercise (such as jogging and cycling) remodels the heart muscle and strengthens it so it pumps more blood with each contraction. Not every exerciser experiences this reduction in heart rate, however, and it may take years of exercise for it to occur. But low resting heart rate is often associated with high cardiovascular fitness, and lowering the rate over the course of an aerobic fitness program may be a sign that you are achieving a training effect. Studies have shown that people who work out regularly have resting heart rates about 10 beats per minute slower, on average, than sedentary people, and well-trained athletes generally have heart rates 15 to 20 beats lower than average. Even if you don’t experience a drop in resting heart rate over time, exercise reduces blood pressure and has other cardiovascular benefits.

How risky is a high resting heart rate?

In general, a slower resting heart rate may be better than a faster one. A number of studies have linked faster resting heart rates with increased risk of heart disease and premature death from all causes, independent of fitness level and other known cardiovascular risk factors such as high blood pressure, high cholesterol, and being overweight. In fact, some research suggests that resting heart rate may be an even better predictor of premature death than blood cholesterol and blood pressure.

For instance, a 2017 systematic review and meta-analysis in Nutrition, Metabolism & Cardiovascular Diseases linked a higher resting heart rate to increased risk of cardiovascular disease and various cardiovascular events (including strokes, sudden cardiac death, and heart failure). “As resting heart rate is an easily measured risk factor, and can be modified by lifestyle changes and medical treatment, the present findings suggest lowering resting heart rate may be a potential target to reduce risk of cardiovascular disease and premature mortality,” the paper concluded. But keep in mind, there is no consensus of what an optimal heart rate might be and where increased health risks may begin.

Bottom line: Your resting heart rate can serve as one more piece of information your doctor can use in evaluating your cardiovascular risk and how to best manage your overall health.