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The textbook definition of a healthy resting heart rate is about 60 to 100 beats per minute. But often, runners and other athletes will see much lower readings—40 bpm, or even 30. “When you’re very well trained, your heart becomes a larger, more efficient pump, and then it doesn’t have to beat as often to have the same cardiac output,” Dr. Allison Zielinski, a cardiologist at Northwestern Medicine and co-director of the sports cardiology program at Northwestern, in Chicago. So what is your heart rate supposed to be?
When you run enough to lower your resting heart rate, that’s likely good news for your health. In one recent meta-analysis, researchers crunched the numbers on 46 studies involving more than 1 million people. The closer their resting heart rates were to 45 beats per minute, the less likely they were to die of any cause, and especially of heart disease.
There’s wide variation within the “healthy range,” for many reasons; your running is only one factor. Some differences are relatively hard-wired. For instance, women’s smaller hearts tend to beat a little faster than men’s overall. And other influences change things day to day, or even minute by minute. “There are a lot of things that can affect your heart rate at any given moment, including stress, illness or fever, temperature, certain medications, stimulants, altitude, body temperature, and hydration levels,” Dr. Zielinski says.
Tracking your resting heart rate over time can help you keep tabs on your health, as well as give you insights into how certain experiences or habits, such as drinking alcohol or having a poor night of sleep, change how hard your heart has to work, says Neely Spence Gracey, an elite runner and coach. She logs hers each morning and has found increases of 10 to 20 beats per minute may mean she’s about to get sick or injured.
You might also notice fluctuations throughout your menstrual cycle. In your luteal phase, between when you ovulate and your period starts, your heart rate may be about 10 beats per minute higher, says Athena Farias, an exercise physiologist and running coach at Get Fit SATX, in San Antonio. Perimenopause—the period before your periods stop completely— can also cause your readings to go a bit haywire, as your hormones shift frequently.
An elevated resting heart rate alone isn’t necessarily cause for medical concern, but it’s worth checking in with your doctor if yours measures 100 or higher (even 90 or higher would be unusual in someone who’s fit, Dr. Zielinski says). This is less true if you’re pregnant, which can cause a higher heart rate.
Sometimes, elevated heart rates can be related to an underlying condition, such as an overactive thyroid or anemia. Many post-COVID patients report a condition called tachycardia, or a spiking heart rate for no reason. And if high numbers go hand in hand with other problems (such as palpitations, dizziness, or lightheadedness) you may have an arrhythmia, a potentially dangerous abnormal heart rhythm.
Apple Watches, along with devices made by companies like Withings and FitBit, even have special apps that can detect signs of a type of arrhythmia called atrial fibrillation. If your watch pings you, or you have concerns for other reasons, your doctor can run tests to check things out, Dr. Zielinski says.
If you’re a regular runner, a low heart rate usually isn’t a problem. That’s a good reason to tell any doctor you see about your running habit (otherwise, they might be more worried about resting heart rates in the 30s and 40s). But if your heart rate drops unexpectedly or you also have symptoms like weakness or dizziness, that’s another good time to check in with your health care team.
Know Your Low
When it comes to resting heart rate, here are the numbers to know.
- Range for a healthy adult: 60 to 100 bpm
- Range for a typical athlete: 40 to 60 bpm
- Average range for women: 78 to 82 bpm
- Average range for men: 70 to 72 bpm
Find Your Max Heart Rate
If you don’t get tested in a lab (something not all runners can do) try one of these formulas to estimate your maximum heart rate.
- Fox formula: 220 – age. It’s simple and relatively accurate, Dr. Zielinski says, especially if you’re around age 40; it slightly underestimates max heart rate for younger people and overestimates it for those who are older.
- Gelish equation: 207 – (0.7 x age)
- Tanaka equation: 208 – (0.7 × age). These are often slightly more accurate, though of course, they involve a bit more math.
Learn Your Lactate Threshold Heart Rate
A lab test is the gold standard for finding your LTHR. But if you don’t have access, or just don’t like needles, there are good ways of estimating it. Try this field test, which Hart uses with her runners:
- Warm up with 10 minutes of easy running
- Run a pace that’s as hard as you can sustain for 30 minutes
- Look at your average heart rate in the final 20 minutes (if you’re using a watch, hit “lap” after 10 minutes in to make it easier)
- Or, note your heart rate once at the 10-minute mark and once at the 30-minute mark, and then average those two numbers
- That number—your average heart rate over the final 20 minutes—is a good estimate of your lactate threshold heart rate, or LTHR.
Things that Affect Your Heart Rate
- Fitness (down)
- Intense workouts (up)
- Heat (up)
- Humidity (up)
- Medications (up or down), including asthma inhalers and antidepressants (up) or heart drugs like beta blockers (down)
- Stress (up)
- Strong emotions, both positive and negative (up)
- Sexual arousal (up)
- Altitude (up)
- Pregnancy (up)
- Caffeine and other stimulants (up)
- Nicotine and cannabis (up)