It is common to use heart rate during exercise to tell if you are getting a “good workout”. Measuring heart rate on exercise machines or with monitors has become easier. But how important is it to monitor your heart rate? What does it mean? I addressed this in a previous blog and will sum it up quickly here in addition to how medications affect heart rate.
Measuring heart rate is not a direct measure of exercise quality. It can give us a clue as to how hard the heart is working, but it is not the big picture of how the heart gets stronger with exercise.
Why?
- The cardiovascular system is made up of the heart muscle (a pump) and all of the blood vessels that deliver oxygen and remove waste when we move.
- What makes the the heart stronger is not it is not the amount of times
your heart pumps in a minute, it is the strength of the heart beat. When we exercise, more blood is sent into the heart and that makes it beat stronger. This is what strengthens the pump, not the heart rate. - Cardio exercise (more than strength training) triggers the heart to beat faster AND stronger. Over time, the stronger beat strengthens the pump.
- When we drink coffee, the heart beats faster but the system is not challenged to get stronger. When we exercise, the increase in blood flow through the whole system, the increased oxygen used by the system and the challenge of the system to remove waste products effectively is what makes the system stronger.
- So the heart getting stronger is only one part of cardiovascular exercise training. With cardio training, new blood vessels grow to bring more blood to working muscles, and the working muscles get more efficient at using the oxygen brought by the blood and removing waste produced when we exercise.
Another issue with using heart rate is that way we predict what your heart rate is based upon age and has a +/- 15 beat error to it! That means if you are striving for a heart rate of 130 based upon the equation – your actual target heart rate could be anywhere from 115-145 – that is a HUGE difference.
Other factors affect heart rate such as air temperature, body position, stress, and body size. These all need to be taken into consideration when using heart rate as a guide. The work of the heart can be increased at rest and thus exercise can be more intense than usual as these conditions change.
Medications can affect heart rate by increasing it or decreasing it. It is important to know how your medications affect your heart rate. The most common type of medication that affects heart rate is beta blockers.
Beta blockers are designed to lower heart rate to decrease the work of the heart with daily life. They are prescribed for many heart conditions, including heart failure and arrhythmia as well as for blood pressure. Common names include:
- Acebutolol – Sectral
- Atenolol – Tenormin
- Betaxolol – Kerlone
- Bisoprolol – Zebeta, also sold as Ziac
- Carteolol – Cartrol
- Carvedilol – Coreg
- Labetalol – Normodyne, also sold as Trandate
- Metoprolol – Lopressor, also sold as Toprol
If you are on a beta blocker, the recommended heart rate for exercise is generally 20-30 beats per minute above resting. For example, if your resting grate is 60 BPM, your target range for exercise would be 80-90bpm. If you are pushing to get your heart rate up on these medications to get a “better workout”, you are straining your heart. Talk to your doctor about any specific recommendations for you.
So what to do?
Your shortness of breath level is a direct measure of how hard your cardiovascular system is working. Exercising at a breathing level that is moderate (a light challenge) to somewhat heavy (a good challenge) is a good general guide. In research studies, this subjective rating matches true heart rate range very well. If you are pushing to an uncomfortable breathing level, you are probably pushing too hard for safely improving general fitness and weight loss. On the left is the scale used for this guide. A general guideline is to stay between 3-4 on this scale.
Please post any questions on this topic. It can be an area of much confusion. Confusion leads to lower motivation to exercise. So if you are not sure, just ask.
Keep Moving, Be Well,
Janet
Janet Huehls, MA, RCEP, CHWC
Please share these posts with anyone you know interested in losing weight with or without weight loss surgery. Click here to learn more about the UMass Memorial Weight Center
These weekly blogs are general guidelines. These guidelines apply to patients who are cleared by a physician for the type of exercise described. Please contact your physician with any concerns or questions. Always report any symptoms associated with exercise, such as pain, irregular heartbeats, and dizziness or fainting, to your physician.
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