HRM & Exercise Calories Strategy

Bryan190

I finally broke down and bought a heart rate monitor (Polar FT7) because I need to compare exercises to have some confidence in what I record as exercise Calories in my log. Most of the time I use either my bicycle or a treadmill for cardiovascular exercise. I've relied on estimates based upon what my bike computer (a cheapo that “knows” my weight/age/speed/distance/time but nothing else) or treadmill (it “knows” my HR/speed/distance/time but not anything about me) reported or the exercise estimates from the MFP database. Since I only want to record Calories from exercise that I'm willing to eat and still be below my daily Calorie deficit goal I usually reduce the estimated amounts to be about 40 Calories per mile on the bike (a heavy hybrid on rolling hills) and 100 Calories per mile on the treadmill (all uphill, HR control). This estimate strategy has worked for me so far but with colder weather approaching I wanted to have more exercise choices and still be able to have confidence in what I record, hence the HRM purchase to compare exercises.

The HRM obviously can't directly measure Calories but does “know” more than the other estimates I've used so I expect it to be more accurate, but in playing with it a bit it became obvious that simply recording the gross exercise Calories it reports would give me too many Calories to eat in my log. On the treadmill the HRM reported a significantly higher Calorie burn than the treadmill did. The treadmill is I believe, taking out some estimate for non-exercise Calories.

For test period at a sedentary activity level HRM reported an average of 70 bpm for 30 minutes and a total burn of 67 Calories, or 2.23 Cal/min. Since I use a sedentary activity level in MFP to establish my daily Calorie goal, I will now subtract this baseline amount from what the HRM reports for entry into my log. I'll likely remeasure the baseline from time to time and adjust as well. IMO, this would be a nice feature for the HRM to incorporate (not sure if any do) – the ability to subtract a user-entered baseline amount from the workout Calories automatically.