Using your average heart rate during an exercise session, you can estimate the calories that you expend while working out. Your heart rate is directly related to your calorie expenditure rate. This calculation will be most accurate when your heart rate is between 90 and 150 beats per minute (bpm). The equation used to calculate calories burned also requires weight, gender and duration of the exercise session.
Weigh yourself on a scale. Ensure you measure your weight in pounds.
Wear your heart monitor while you exercise, but wait until your heart rate gets above 90 bpm before recording it. Keep your heart rate between 90 and 150 bpm by slowing down or speeding up as necessary. Complete your exercise session and stop recording your heart rate before it drops below 90 bpm. Your heart monitor should give you your average heart rate for the whole session once it stops recording.
Estimate the calories that you burned during your exercise session. For women, this is given by the equation C = (0.4472 x H – 0.05741 x W + 0.074 x A – 20.4022) x T / 4.184. C is the number of calories that you burned, H is your average heart rate, W is your weight, A is your age and T is the length of your exercise session in minutes. Assume that you’re a 28-year-old female weighing 146 pounds. Your average heart rate during an exercise session that lasted 36 minutes was 138 bpm. You burned C = (0.4472 x 138 – 0.05741 x 146 + 0.074 x 28 – 20.4022) x 36 / 4.184 = 301 calories.
Tips
You can estimate your heart rate without a heart monitor. Place your index finger against the side of your neck to feel the pulse in your carotid artery. Count the number of pulses that you feel in 6 seconds and multiply this value by 10. This will provide an estimate of the number of times your heart is beating in a minute.