Q: I was curious if there are any known reasons to avoid strenuous exercising that creates a ‘maximum-heart rate’ scenario? When I ride my bicycle on steep hills or mountains, I can easily max out my HR but it doesn’t seem to be a problem. I’m curious to hear your take on it.

A: Many things in medicine are black and white, but certain  principles are somewhere in the spectrum of grey. When it comes to exceeding your maximum heart rate, we are talking about a very grey topic.

Maximum Heart Rate = 220 – Your Age

In general, you can’t burn out your heart from exercise if your heart is otherwise healthy. Your skeletal muscles will fatigue far before any chance of your heart fatiguing. Your body is built so that any blood pumped from your heart goes back to it before it reaches any other part of your body. It is also unlikely that frequently exceeding your maximum heart rate will cause long-term damage. In fact, the opposite is most likely true. Your heart muscles will become stronger, you will pump out more blood with each beat and your blood will become more efficient in carrying oxygen and nutrients to your skeletal muscles. As these adaptation occur, your heart rate will likely drop with continued training.

But you don’t need to exercise that hard.

Keep in mind that exercising to such an intense point in which you exceed your maximum heart rate can put you at risk for other problems including hypoglycemia (low blood sugar), or musculoskeletal injury. You will be better off starting a workout program and gradually increasing your intensity as you get in better shape. The best rule is based on the Borg Exertion Scale, which states that you should exercise in the range of 13-17 on a scale of 1-20. In addition, you must listen to your body. If you have chest pain, shortness or breath, lightheadedness, dizziness, nausea, vomiting or severe musculoskeletal pain, you should slow down your intensity or stop!

As far as continually exceeding your maximum heart rate — I would advise slowing down your intensity for a few workout, and then gradually increasing your intensity to the level that is currently causing you to exceed your maximum heart rate. If your rate is still too fast, the safest bet is to run it by your doctor. An inability for your heart to safely monitor its rate may be a cause for concern — at least a cause for evaluation.

If you do have known heart disease or an enlarged heart, you are at risk for further heart damage, no doubt about it. In this case, you should follow your doctor’s specific exercise recommendations.