When you exercise, your heart rate goes up. It seems like a pretty straightforward concept, but why does it matter? Also, why does almost every smartwatch have a heart rate reader built-in?
Checking your heart rate during a workout might seem enlightening, but do you really know what that number means? Some fitness apps tell you what a heart rate zone means, maybe they assign a color, but do you really understand what your heart rate should be during a workout?
What Is Your Max Heart Rate?
Perhaps you know that (220 – your age) is the calculation for maximum heart rate. Very good. But that number seems to be more subjective than scientists realized. It turns out that heart rate is a very individualized thing. It can tell you more than how hard your workout is. Stimulants like caffeine can affect heart rate, as can changes in diet and blood pressure.
That’s because heart rate is a pretty good gauge of the cardiovascular system overall. When your heart rate increases, blood is moving faster around the body. However, that’s not the only way your body gets better at delivering blood. Stroke volume, which means the amount of blood your heart pushes out per beat, is another important measure of how fit you are.
What Does Your Heart Rate Tell You?
So, what can you learn from your heart rate? Quite a bit, actually, as long as you know what to look for. If you’re curious, start by taking your resting heart rate. Try to do it in the morning when you wake up, or sometime during the day when you’re completely calm. Turn on your heart rate monitor, lie down, and close your eyes. After about 5 minutes stop your heart rate monitor and look at your average heart rate.
If your resting heart rate is between 40 – 60 beats per minute, you’re in good shape. The closer you are to 40, the better shape you’re in.
Let’s assume your resting heart rate was 50. Now we’ll calculate something called heart rate reserve. Take your max heart rate (220 – age). Let’s say you’re 40. That’s 180.
Now, subtract 180 – 50 to get 130. That number is called your heart rate reserve. You can use that to calculate roughly how hard your workout should be.
We do this by picking an intensity. At TS, the average intensity of your workout might be 80%. To figure out where your heart rate should be, we take your heart rate reserve (130) and multiply by .8 (80%). That gives us 104. Now, we add your resting heart rate (50) and get 154.
Therefore, if your average heart rate for a workout at TS was 154 beats, you were working at roughly 80% of your potential. Try this out to see if you get a better sense of what your heart rate is telling you. How do you feel when you’re at a certain number of beats per minute? How about when you’re above or below that?