Equipment Estimated Calories versus Actual Calories Burned: How to calculate calories burned during exercise
October 15, 2012 | Comments: 2 Comments
Categories: Science, Uncategorized
This is a topic I talk about all of the time. How many calories did I actually burn during that workout? It is an excellent question with a particularly convoluted answer. Calorie expenditure is related to age, weight, heart rate during exercise and sex. In general, male-bodied people burn more calories for similar effort than female-bodied people and heavier people burn more calories for similar effort as lighter people.
The Journal of Sports Sciences provides a calorie expenditure formula for male and female.
Males use this formula:
Calories Burned = [(Age x 0.2017) – (Weight x 0.09036) + (Heart Rate x 0.6309) — 55.0969] x Time / 4.184.
Females use this formula:
Calories Burned = [(Age x 0.074) – (Weight x 0.05741) + (Heart Rate x 0.4472) — 20.4022] x Time / 4.184.
I am a 41 year old female who weighs 115 pounds. My average heart rate over this 70 minute period was 143bpm**, so my calculations look like this:
Calories Burned = [(Age{41} x 0.074) — (Weight{115} x 0.05741) + (Heart Rate{143}x 0.4472) — 20.4022] x Time{70} / 4.184.
41 x 0.074 = 3.034
115 x .05741 = 6.60215
143 x 0.4472 = 63.9496
(3.034) – (6.60215) + (63.9496) – (20.4022) x 70min = 669 cal burned
4.184
So I did not quite burn 706 calories. The treadmill had some help with these calculations because I did check in with it and take my heart rate several times. If I hadn’t, the number would be even more off. In fact, I’ve had these numbers be as much as 30% too high! In general, when you haven’t programmed the equipment with your specifics and it’s not keeping track of your heart rate, the number of calories burned will be over-estimated. Now you know.
**How I determined my average heart rate: My heart rate monitor isn’t working so I took my heart rate on the treadmill at intervals throughout the session, which comprised 10 minutes of warm up, 30 minutes of 1 minute sprints followed by 1 minute of active recovery, and finished with 30 minutes of active recovery at approximately 60% of my maximum heart rate, for a total of 70 minutes.
125bpm x 40min = 5000 (warm up and recovery)
163bpm x 20min = 3260 (beginning on intervals)
173bpm x 10min = 1730 (end of intervals)
(5000+3260+1730)/70min total = average 143bpm
I wish more people knew this! So many people are relying on the faulty readers on overused, and well loved gym equipment and assume it’s correct.
Great post!!
Thank you very much! I do try 🙂