Revisiting Exercise Calories

James_1954

A few years ago, I used my nice new heart rate monitor to measure the calories I was using for some of my typical cardio activities: 30 minutes on the elliptical, 45 minutes of spin class, 21-mile training ride outdoors, etc. After I'd done that a few times and averaged the results, I pretty much put the HRM away ... didn't seem to need it, so why bother? Recently, I put it back into use, and discovered that it now reports fewer calories used for the same activities. Both subjectively and from whatever objective measures I can come up with (distance, time, size of sweat puddle, etc.), I'm working just as hard. But average and peak heart rates are lower, and its claims of calories burned are lower, too.

I'm thinking that, as my heart-and-lungs conditioning has improved, it might be reasonable that I'm doing less work per mile or per minute or whatever. It could be that I've become more efficient. Alternatively, I wonder if this is simply an aging effect (I'm 61); it could be that an older heart just goes slower, and the heart rate is the only physical measurable that the HRM can use to estimate calories used.

In any case, if you're using "old" HRM data to quantify your exercise calories, it might be a good idea to remeasure every now and again.