Calculating Calories Burned During Workouts
“How many calories do you think I burned during my workout today?”
That’s a question I get just about every day. After all, most people work out so they can burn calories. They want to track the calories they burn throughout the day and compare them with the calories they consume so they can create a caloric deficit, thus leading to weight loss. I can only estimate based on what I’ve been able track with my own workouts and calculations. There are several factors such as age, weight, heart rate, and intensity of the workout.
One way that people can calculate calories burned is by wearing a heart rate monitor. This can be either a sports watch, a chest strap with wrist monitor, or there’s even a chest strap that sends data to your smart phone via Blue Tooth technology. However, these may not be accurate.
One problem with the sports watch is that the back of the watch or back of the transmitting device must remain in constant contact with the skin on your wrist or your chest. If it’s not making contact, it doesn’t calculate. I’ve found that when I sweat or do certain exercises, that contact is broken and my watch is no longer monitoring my heart rate, thus missing calories burned. I’ve often found that “calories burned” number on my watch to be quite a bit less than what I manually calculate following a workout.
I need to also point out that the readouts of calories burned that you see on treadmills, elliptical machines and other cardio equipment are just general estimates. Most are not sophisticated enough to factor in your age, height, weight, body fat percentage, etc… So, don’t rely on these numbers if you are trying accurately calculate how many calories you burn. Some overestimate calories burned by as much as 40%!!!
One of the more standard and most accurate ways to calculate the equation is to use the calorie expenditure formula below . It comes from the Journal of Sports Sciences and provides a formula for each gender.
Men use the following formula:
Calories Burned = [(Age x 0.2017) — (Weight x 0.09036) + (Heart Rate x 0.6309) — 55.0969] x Time / 4.184.
Women use the following formula:
Calories Burned = [(Age x 0.074) — (Weight x 0.05741) + (Heart Rate x 0.4472) — 20.4022] x Time / 4.184.
For example, here’s my formula based on a 49 year old male weighing 155 for a workout where my heart rate averages about 148 bpm throughout a 60-minute boot camp workout.
[(49 x 0.2017) — (155 x 0.09036) + (148 x 0.6309) – 55.0969] x 60/4.184 =
[9.8833 — 14.0058 + 93.3792 – 55.0969] x 14.3403 = 489.47 calories (or 15 kcal/min)
I hope you find this formula helpful. As always, check with your physician, nutritionist, or a certified personal trainer if you have any questions or desire more accurate testing and results.
To your health!