What is a healthy resting heart rate? Experts explain why it matters.

While some measures of physical fitness such as athletic ability and one's strength or stamina may be difficult to ascertain right away, others are more obvious. One's resting heart rate, for instance, is easy to check and says a lot about a person's wellbeing. "Your heart rate is one of the first signs that gives your doctor insight into your overall health," says Doris Chan, DO, a cardiologist at NYU Langone Hospital in Brooklyn. "It guides us in the right direction when, and if, further testing is necessary."

Despite the importance of resting heart rates, some people don't understand what they mean or why they fluctuate. Knowing yours can be a helpful way to identify potential health problems and gauge how healthy your heart really is.

What is a resting heart rate?

One's resting heart rate, or pulse, is simply the number of times the heart beats per minute while in a rested state. It's a measurement that should be taken in the absence of a stressful or exciting event and at least an hour after exercise. The American Heart Association says its best to check one's resting heart rate first thing in the morning and while still in bed to get the most accurate reading.

Elevated heart rates can be an indication of "stress, anxiety, dehydration, health conditions or physical excursion," says Barbara Olendzki, RD, MPH, LDN, associate professor of population & quantitative health sciences at UMass Chan Medical School, though she says "its normal to have a heart rate increase from exercise."

Other conditions can affect one's blood volume and heart rate. For example, any loss of blood "will result in a loss of blood pressure and will cause the heart rate to increase for a time to compensate," explains Viet Le, PA-C, associate professor of preventive cardiology and physician associate at Intermountain Health. Caffeine consumption, illness, medications, and electrolyte abnormalities may also temporarily impact one's resting heart rate.

What is a healthy resting heart rate?

A commonly accepted range for a healthy resting heart rate is between 60 and 100 beats per minute, "though some argue that the resting heart rate lower limit be shifted down to 50 beats per minute," says Chan. That's because generally, the lower one's pulse is ? to a point anyway, the more efficient their heart is thought to be working. Indeed, athletes frequently aim to get their heart rates down with some high endurance athletes striving to reach a resting heart rate in the 40s.

Still, it's important to note that there are numerous exceptions to the 60-100 beats-per-minute rule and a "normal" pulse varies from person to person. As noted before, numerous external factors can temporarily affect one's resting heart rate, but some outside influences may affect one's heart rate for much longer. For example, an overactive thyroid, anemia, rare adrenal tumors, unhealthy organs, pregnancy, abnormal heart rhythms and one's age can affect resting heart rate for extended periods of time. "We expect a slightly higher heart rate in children," Le explains. Babies 12 to 24 months, for instance, "have a resting heart rate in the low 100s to mid 110s," he says, and teens commonly "have resting heart rates in the 60-90 range."

How to check your heart rate

Checking one's heart rate is simple. Per the Mayo Clinic, simply place your index and third fingers on your neck, to the side of your windpipe, then count the number of beats from the first time you feel your pulse, continuing for 15 seconds. Multiply that number by four to calculate your beats per minute. To check your pulse at your wrist, place two fingers between the bone and the tendon over your radial artery, which is located on the thumb side of your wrist, then count the number of beats the same way.

What is an unsafe resting heart rate?

A resting heart rate below 60 is called bradycardia or slow heart rate, and one over 100 is called tachycardia, or fast heart rate. Staying too low or too high for extended periods of time without a known cause is worth looking into. "One should seek out professional attention if high heart rates are prolonged and persistent as it may cause symptoms of palpitations, skipped beats, shortness of breath, fainting or lightheadedness, excessive fatigue, or chest tightness or pressure," advises Le.

A consultation can also help identify or rule out pre-existing conditions or other external factors that may be affecting one's pulse and lead to helpful recommendations for improving heart health. "It's important for you to learn your own body and how it responds," says Olendzki, "so ask your doctor what a healthy heart rate means for you."

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This article originally appeared on USA TODAY: What is a healthy resting heart rate?