The resting heart rate of most normal, healthy adults is 60 to 100 beats per minute. Your heart rate should increase as your body's demand for oxygen rises during exercise -- but not everyone's heart responds the same. Various factors can result in an abnormally slow pulse in some people. A low heart rate can be caused by certain medications or may simply indicate a strong heart muscle that doesn't need to contract as frequently. Unfortunately, it can also signal a health condition. Until a doctor has determined the cause, a low pulse during exercise should be taken seriously.
A slow heart rate is known as bradycardia. While some people with bradycardia may have no symptoms at all, it may cause insufficient blood flow to vital tissues and organs in others. Bradycardia can result from disease of the sinoatrial node, atrioventricular node or the conduction tissues. It is normal for the heart rate to slow somewhat as people grow older, due to normal, age-related degeneration. However, if degeneration or disease slows the heart rate so much that vital organs are adversely affected, a medical pacemaker may need to be implanted in order to maintain a healthy heart rhythm.
A class of drugs known as beta blockers can slow the heart during exercise. Beta blockers reduce the heart rate and are often prescribed to people with high blood pressure, cardiac arrhythmias or who have experienced a heart attack. If you are on beta blockers, it may be impossible to reach your target heart rate during exercise; however, this doesn't mean you aren't reaping the fitness benefits. If you're taking beta blockers, simply reduce your target heart rate by the number of beats per minute the medication has decreased your resting heart rate.
A slow heart rate during exercise can also simply indicate superior heart health. It isn't unusual for endurance athletes like marathon runners and distance cyclists to have very low resting and exercise heart rates. This is simply due to an incredibly strong heart that has been rigorously conditioned.
Follow your doctor's advice if you experience a slow heart rate during exercise. Keep your heart in optimal health by not smoking, eating a healthy diet and getting plenty of exercise. Stop immediately if you begin to feel faintness or shortness of breath during a workout.
- Practical ECG for Exercise Science and Sports Medicine; Greg Whyte & Sanjay Sharma
- MayoClinic.com: Beta blockers: How do they affect exercise?
- DrWeil.com: Abnormal Heart Rhythm (Bradycardia)
- NEMA.org: What you should know about your Heart Rate or Pulse
- Heart Health Your Questions Answered; Deborah Ascheim & Robert Ascheim
- Heart 411: The Only Guide to Heart Health You'll Ever Need; Marc Gillinov, M.D. & Steven Nissen, M.D.
Jessica Bell has been working in the health and fitness industry since 2002. She has served as a personal trainer and group fitness instructor. Bell holds an M.A. in communications and a B.A. in English.