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What is an unsafe resting heart rate?

A person’s resting heart rate is the number of times their heart beats per minute when they are relaxed and not engaged in physical activity. For most healthy adults, a normal resting heart rate ranges from 60 to 100 beats per minute (bpm). However, a resting heart rate that is consistently above or below that normal range may be a sign of an underlying health issue that requires medical attention.

What is considered a dangerously high resting heart rate?

Doctors consider a resting heart rate of more than 100 bpm to be tachycardia, which means a dangerously high heart rate. More specifically:

  • A resting heart rate between 100-120 bpm is classified as inappropriate sinus tachycardia.
  • A resting heart rate between 120-140 bpm is worrisome and requires investigation.
  • A resting heart rate consistently over 140 bpm is considered very serious and potentially life-threatening if left untreated.

Some of the common causes of an overly high resting heart rate include:

  • Hyperthyroidism (overactive thyroid)
  • Anemia
  • Fever
  • Dehydration
  • Heart conditions like atrial fibrillation
  • Lung diseases
  • Anxiety disorders
  • Drinking too much caffeine or energy drinks
  • Taking certain medications or stimulants

In most cases, a high resting heart rate by itself may not cause any noticeable symptoms. But over time, it can place extra strain on the heart and lead to complications like heart disease and heart failure. That’s why it’s important to investigate unexplained tachycardia with a doctor.

What is considered a dangerously low resting heart rate?

On the other end of the spectrum, doctors consider a resting heart rate below 60 bpm to be bradycardia, or a dangerously low heart rate. More specifically:

  • A resting heart rate between 50-60 bpm is considered mild bradycardia.
  • A resting heart rate between 40-50 bpm is classified as moderate bradycardia.
  • A resting heart rate below 40 bpm is severe bradycardia and requires prompt medical attention.

Some potential causes of an abnormally low resting heart rate include:

  • Hypothyroidism (underactive thyroid)
  • Heart conditions like heart block
  • Sleep apnea
  • problems with the sinus node, the heart’s natural pacemaker
  • Very high fitness levels from intense athletic training
  • Side effect of medications like beta blockers or calcium channel blockers
  • Electrolyte imbalances

Mild forms of bradycardia may not have any symptoms. But more severely low heart rates can lead to fatigue, fainting, dizziness, confusion, and shortness of breath. Severe or persistent bradycardia requires prompt medical care to identify the underlying cause.

What is a normal resting heart rate by age?

A normal resting heart rate can vary somewhat based on a person’s age. Here are the typical normal ranges:

  • Newborns 0-3 months: 70-190 bpm
  • Infants 3-6 months: 80-160 bpm
  • Babies 6-12 months: 80-130 bpm
  • Toddlers 1-2 years: 75-115 bpm
  • Preschoolers 3-4 years: 65-110 bpm
  • Kids 5-11 years: 65-95 bpm
  • Youths 12-15 years: 60-90 bpm
  • Teens 16-19 years: 60-80 bpm
  • Adults: 60-100 bpm
  • Seniors over 65 years: 50-80 bpm
  • Highly trained athletes: 40-60 bpm

Keep in mind that normal ranges are just broad general guidelines and your personal normal may differ. The most important thing is to be aware of your own resting heart rate baseline. If you notice any unexplained changes or your heart rate falls outside the normal range for your age, discuss it with your doctor.

How to measure resting heart rate

To measure your resting heart rate at home:

  1. Sit or lie down comfortably and relax for 5 minutes before taking the measurement.
  2. Use your fingers to feel your pulse point on your wrist or side of your neck and count the beats for 60 seconds.
  3. Use a timer for accuracy. You can also use heart rate monitors or fitness trackers.
  4. Measure first thing in the morning before getting out of bed for the most accurate resting rate.
  5. Repeat over multiple days and average the measurements. This helps account for natural fluctuations.

Try to measure your resting heart rate at the same time of day under similar conditions for consistency.

What’s a normal resting heart rate for athletes?

For athletes and others who engage in intense regular exercise training, a resting heart rate below 60 bpm is common and not necessarily a concern. Endurance athletes often have very low resting heart rates thanks to their efficient hearts and high aerobic fitness. For example, a marathon runner may have a resting heart rate in the 40-50 bpm range.

However, athletes should still monitor their resting heart rate and watch for any unexplained jumps. For instance, if a marathon runner’s resting heart rate increases to 70 bpm for no clear reason, it should be evaluated by a sports medicine physician.

Can medication affect resting heart rate?

Yes, many common medications can directly raise or lower heart rate. Some examples include:

  • Beta blockers and calcium channel blockers (decrease heart rate)
  • Atropine, isoproterenol, epinephrine (increase heart rate)
  • Thyroid medications when doses are too high (increase heart rate)
  • Diuretics like furosemide (can increase resting heart rate)
  • Blood pressure medications like hydralazine (can cause increased heart rate)
  • Decongestants and diet pills (can raise resting heart rate)

If you are taking any medications, talk to your doctor about whether they may be impacting your heart rate. Don’t stop taking any prescribed medications without your doctor’s guidance.

Can lifestyle factors affect resting heart rate?

Yes, certain lifestyle factors and behaviors have been shown to raise resting heart rate, including:

  • Caffeine consumption
  • Alcohol abuse
  • Tobacco smoking
  • Lack of exercise
  • Being overweight or obese
  • Chronic stress
  • Dehydration
  • Electrolyte imbalances

Making healthy lifestyle changes like quitting smoking, reducing caffeine, staying hydrated, and exercising regularly can potentially lower an elevated resting heart rate.

When to see a doctor about your resting heart rate

Consult your physician if you have any of the following:

  • Resting heart rate consistently over 100 bpm or under 50 bpm
  • New unexplained change in resting heart rate
  • Noticeable pounding, racing, or irregular heart beats
  • Dizziness, shortness of breath, chest pain, fainting
  • Fatigue, confusion, electrolyte imbalances

Diagnostic tests for abnormal heart rates may include an EKG, Zio patch heart monitor, blood tests, stress test, and cardiac imaging. Underlying heart rhythm conditions like atrial fibrillation often require treatment with medications or procedures.

Tips for improving an abnormal resting heart rate

Some ways to help normalize an unhealthy resting heart rate include:

  • Follow doctor’s treatment recommendations for any underlying conditions
  • Cut back on stimulants like caffeine, energy drinks, tobacco
  • Stay well hydrated and ensure proper electrolyte balance
  • Reduce stress through techniques like meditation, yoga
  • Take medications as prescribed to control heart rate
  • Exercise regularly as able to build cardiovascular fitness

Talk to your doctor before making any major lifestyle changes. With proper treatment and monitoring, it’s often possible to regain a healthy normal resting heart rate.

The takeaway on resting heart rate

Your resting heart rate offers valuable insight into your overall heart health. A normal resting heart rate for healthy adults ranges from 60-100 bpm. It’s important to be aware of your normal baseline resting rate. Consult a doctor if your resting heart rate is consistently over 100 bpm or under 50 bpm, as this may signal an underlying medical condition requiring treatment.