Beta blockers are medications used for treating high blood pressure, chest pain, congestive heart failure, irregular heartbeat and glaucoma. They work by blocking the effects of the hormone epinephrine, also known as adrenaline, on your body. During exercise, these drugs can also have several effects on the body, including an inability to reach your target heart rate, an improvement or reduction in your exercise tolerance, and a decrease in your blood pressure.
Heart Rate
Beta blockers slow down your heart rate both at rest and during exercise. This means that your heart is able to fill with more blood between each heartbeat, thus increasing the amount of blood and oxygen supplied to your tissues. Having a lower than normal heart rate may affect your ability to reach your target heart rate during exercise, which is the heart rate range at which you gain the maximal health benefits. MayoClinic.com recommends lowering your target heart rate by the amount that your resting heart rate has been lowered by the beta blocker. For example, if your resting heart rate has decreased from 70 to 50, work at a heart rate 20 beats per minute lower than what you used to do.
Exercise Tolerance
Your exercise tolerance may increase or decrease depending on the type of medical condition for which you take the beta blocker for. Exercise tolerance improves in patients suffering from chest pain, and tends to worsen in patients with left ventricular dysfunction, or impaired function of the left ventricle of the heart. Decreased exercise tolerance can manifest as fatigue, shortness of breath, weakness and inability to complete exercise routines.
Blood Pressure
Beta blockers can cause an unsafe drop in blood pressure, making you feel lightheaded, dizzy, nauseous, tired or unable to concentrate. This may be more likely to occur if you are dehydrated while exercising. You can lower your risk of hypotension by avoiding foods and drinks that tend to cause dehydration, such as salty foods, alcohol and caffeinated drinks, as well as drinking plenty of water throughout the day. Aim to drink at least eight 8-oz. glasses of water a day to stay hydrated.
Warning
Talk to your doctor before starting an exercise program if you are taking a beta blocker. The most common side effects of beta blockers are fatigue, weakness, drowsiness, dizziness, and dry mouth, skin and eyes. Less common side effects include slow heart rate, difficulty sleeping, vivid dreams, wheezing, shortness of breath, difficulty breathing, and swelling of the feet and hands. Rare side effects include diarrhea, constipation, vomiting, abdominal cramps, skin rash, joint pain, sore throat, memory loss, depression, hallucinations, confusion and impotence. Notify your doctor if you experience these unwanted effects, but do not discontinue your medication unless instructed by your doctor.
References
- Texas Heart Institute: Beta Blockers
- Mayo Clinic: High Blood Pressure (Hypertension): Beta Blockers: How Do They Affect Exercise?
- "Journal of Professional Exercise Physiology"; Cardiac Drugs -- Lecture II: Drugs Used to Treat Angina; Larry Birnbaum; October 2006
- Mayo Clinic: Low Blood Pressure (Hypotension)
