Heart-Rate Changes in Exercise

Q I’m a 44-year-old male who started running this past year and managed to lose over 19kg. I wear a heart-rate monitor and recently noticed that my heart rate doesn’t drop during exercise. I don’t feel like I am working at all until my heart rate exceeds 160, which is well above my target zone of 148 max. Is exceeding 148 preventing my heart from getting stronger? – JOHN


A Target heart rates based on the formula “220-age = maximum heart rate” are not truly data based and probably not accurate for many people. Nonetheless, the formula has been the basis of many training programs and recommendations. There are many variations for max heart-rate calculations, but no single formula that is accurate and precise for all people across all ages. Maximum heart rate can be individually determined by doing a graded maximal stress test, but that is generally not necessary or recommended for healthy people. That said, heart rate can be a useful individual target for gauging workout intensity and progress.

When you first started running, a target heart rate goal of 148 probably worked well for you, but like building your biceps doing push-ups, your heart muscle got stronger as you increased your mileage and pace. Training also lowered your resting heart rate so your reserve has been improved. The difference now between your resting heart-rate and your workout heart-rate is larger and your heart chamber is likely bigger, so you move more blood with each heart contraction enabling you to do more work.

Another strategy for gauging training intensity is to use your “perceived exertion.” When you feel like you are working hard, you are probably doing enough to improve your conditioning. After you have trained for a time, you can fall into a training rhythm that adequately stresses your cardiovascular system based on how you feel. I know that many people that I have run with over the years were not taxed by my pace, but slowed for me to be nice, and social. I can also remember the day when I could no longer keep up with my daughter and she “volunteered” to slow down for me. Humbling times that come with aging.

It is also important to remember that exercise for overall fitness and weight loss do not depend on hitting the top end of your target heart rate. Weight loss may be better accomplished at 50 per cent maximum heart-rate over a longer duration of activity. For most of us, this is a pace at which we can easily converse while exercising. – BILL


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