Exercise boosts your blood pressure and heart rate temporarily and is one of the best ways to promote a healthy heart. But if you experience a drop in your heart rate while exercising, it could be due to a serious underlying cardiovascular problem.
Over time, exercise allows the heart to work more efficiently, which will decrease your resting heart rate, reducing the load on your heart and improving overall cardiovascular health, Amar Shere, MD, cardiologist at Atlantic Health System, tells LIVESTRONG.com.
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"However, a sudden drop in heart rate while exercising could suggest a mild, temporary [issue] or more serious underlying cardiovascular condition, including issues with the electrical conduction system of the heart," he says.
Consult your doctor about any drop in heart rate while exercising.
Tracking Your Heart Rate
Your heart rate, or pulse, is the number of times your heart beats per minute and is a way to tell how hard and effectively your heart is working. When your heart expands and contracts, forcing blood through your veins and arteries, you can feel and count those pulses at places like your wrist or neck to know your heart rate.
You can also wear a heart rate monitor, which most fitness watches have now, to get an idea of your heart rate. While those aren't 100 percent accurate, the technology has improved significantly over the years.
If your resting heart rate is between 60 and 90 beats per minute, it's considered normal. Depending upon your age, the maximum heart rate you should experience during exercise can range from 150 to 200.
If your resting heart rate is slower than 60 beats per minute, that's considered bradycardia, according to the Mayo Clinic. Tachycardia is the opposite — a resting heart rate faster than 100 beats per minute.
If you find that your heart rate isn't dropping during a workout but simply isn't increasing as you'd expect, that's something else. "This is called chronotropic incompetence, which medical providers can test for," Jossef Amirian, MD, a cardiologist with Manhattan Cardiology, tells LIVESTRONG.com.
It's also expected that your heart rate drops after exercise, and the fitter you are, the faster it lowers back to baseline. "A very athletic individual will likely notice that it takes more time for their heart rate to increase as they exercise and that their heart rate drops faster once they finish a workout," Dr. Amirian says.
Symptoms of a Drop in Heart Rate
Wearing a heart rate monitor or fitness tracker is a good way to monitor your heat rate during workouts, but if you experience a sudden drop, you'll likely experience physical symptoms. Dr. Amirian warns that those symptoms might include:
- Dizziness or lightheadedness
- Fainting or loss of consciousness
- Shortness of breath
- Chest discomfort
- Confusion or disorientation
Causes of a Drop in Heart Rate
If you experience a heart rate drop during a workout, there are a few potential causes, and some are more serious than others.
One of the most common causes of a drop in your heart rate while exercising is vasovagal, or neurocardiogenic, syncope, when blood vessels expand and blood pools in the lower parts of your body. This can be precipitated by standing for long periods of time, the Mayo Clinic explains.
"Syncope can also occur during times of strenuous exercise if the person is not adequately hydrated, triggering the vasovagal reflex," Dr. Shere says.
People often faint when they experience vasovagal syncope, which can be dangerous mid-workout.
A heart arrhythmia called bradycardia can cause your heart to beat too slowly. This is usually a result of damage to the heart from a previous heart attack or heart disease, according to American Heart Association.
However, the AHA notes that physically active adults, including athletes, often have a resting heart rate slower than 60 beats per minute. And generally, the more you train, the slower your heart rate will be during exercise.
Stokes-Adams Syndrome and Sick Sinus Syndrome
When there's a sudden drop in cardiac output (often caused by an abnormal heart rhythm) and you faint, that's Stokes-Adams Syndrome, according to the Cleveland Clinic.
Sick sinus syndrome is a relatively uncommon heart rhythm disorder that causes slow heartbeats, pauses or arrhythmias, explains the Mayo Clinic.
The chances of having either of these syndromes increases with age, particularly if you're over 60. The abnormal heart rhythms of both syndromes can be dangerous and cause for visiting a doctor.
Prevention and Treatment
If you feel faint due to a drop in your pulse rate while exercising, the Mayo Clinic recommends that you stop immediately, lie down and lift your legs slightly until you recover, or put your head between your knees.
"Staying hydrated, optimizing electrolyte intake and avoiding too much heat are all important for a healthy heart rate response during physical exercise," Dr. Amirian says.
If your heart rate drop is tied to overheating or dehydration, you should make sure to avoid exercising during the hottest parts of the day, dress appropriately and drink plenty of water (and maybe electrolytes) before, during and after exercise.
If you have bradycardia or vasovagal syncope, you may not need any treatment unless you experience prolonged or repeated attacks, in which case your doctor may give you medication or implant an artificial pacemaker.
"Underlying conditions that may cause bradycardia are not limited to heart issues," Dr. Amirian says. "They include thyroid dysfunction and tick-related illnesses such as Lyme disease. Many times the treatment of the bradycardia will focus on treating the underlying issue causing it."
When to See a Doctor
Both Dr. Shere and Dr. Amirian agree that even one instance of a drop in heart rate warrants visiting a doctor.
"It is always advisable to see your medical provider if you experience a sudden drop in heart rate," Dr. Amirian says. "They may or may not advise testing, however, they will likely obtain a history and do a physical exam to determine if further evaluation is warranted."
Many times a medical provider will work with you to make sure that you're optimizing all the potential ways to prevent a drop in the heart rate in the future.
"For any isolated episode that raises questions or concerns, a healthcare professional should be consulted," Dr. Shere says. "They can decide whether more evaluation is necessary to prevent subsequent events and potentially dangerous complications."
- National Emergency Medicine Association: Heart Rate or Pulse
- Mayo Clinic: Vasovagal Syncope
- American Heart Association: Bradycardia
- American Heart Association: Other Rhythm Disorders
- Comprehensive Cardiovascular Care Group: Neurocardiogenic Syncope
- Cleveland Clinic: Stokes-Adams Syndrome
- Mayo Clinic: Sick Sinus Syndrome