Many treadmills provide an estimate of the number of calories you burned during your workout based on your weight and the amount of power you produce during your walk or run. Unfortunately, the formulas typically used to estimate calorie burn are based on a standardized resting metabolism of 1 calorie per kilogram of body weight per hour -- which be off by as much as 35 percent. For a more accurate estimate of the number of calories you burn during your treadmill walk, you must start with a more accurate estimate of your own resting metabolism.
Step 1
Estimate your resting metabolism with the Mifflin-St. Jeor predictive equation. For men, the formula is 4.545 * (weight in pounds) + 15.875 * (height in inches) - 5 * (age in years) + 5. For women, the formula is 4.545 * (weight in pounds) + 15.875 * (height in inches) - 5 * (age in years) - 161.
Step 2
Convert your walking speed from miles per hour to meters per minute with the conversion factor 26.8. For example, 3.5 mph is the same as 93.8 meters per minute because 3.5 multiplied by 26.8 equals 93.8.
3.5 * 26.8 = 93.8
Step 3
Multiply your speed in meters per minute by the decimal form of the incline grade during your walk to calculate the horizontal component of your effort. For example, for an 8 percent grade, 0.08 is multiplied by 93.8 meters per minute to equal 7.504.
0.08 * 93.8 = 7.504
Step 4
Multiply grade and speed by 1.8 to calculate the vertical component of your effort. For example, your 0.08 grade times 93.8 meters per minute times 1.8 equals 13.507.
0.08 * 93.8 * 1.8 = 13.507
Step 5
Add the horizontal and vertical components of your effort to the standard resting VO2 of 3.5 mL per kilogram per minute to calculate your total VO2. For example, 7.504 plus 13.507 plus 3.5 equals 24.511.
7.504 + 13.507 + 3.5 = 24.511
Step 6
Divide your VO2 by 3.5 to convert it to METs. For example, 24.511 divided by 3.5 equals about 7 METs.
24.511/3.5 = 7.003
Step 7
Divide your resting metabolism -- estimated in Step 1 -- by 24 to calculate your average hourly resting metabolism. For example, a resting metabolism of 1,320 calories per day is an average of 55 calories per hour because 1,320 divided by 24 equals 55.
1320/24 = 55
Step 8
Multiply your average hourly resting metabolism by the number of METs in your treadmill workout to calculate the number of calories you burned per hour on the treadmill. For example, 7 METs times 55 calories per hour equals 385 calories per hour on the treadmill.
7 * 55 = 385.
Step 9
Subtract the number of calories you would have burned at rest even if you hadn't walked on the treadmill from your hourly calorie burn. For example, 385 calories per hour on the treadmill minus 55 resting metabolism calories per hour equals 330 net calories burned per hour.
385 - 55 = 330
Step 10
Divide the number of minutes in your treadmill workout by 60 to convert your workout time into the decimal form of hours. For example, a 40-minute workout is 0.667 hours because 40 divided by 60 equals 0.667.
40/60 = 0.667
Step 11
Multiply the decimal form of hours by the net number of calories you burned per hour to calculate the total number of extra calories you burned while you were walking on the treadmill. For example, 0.667 hours times 330 equals about 220 calories.
330 * 0.667 = 220
Things You'll Need
- Calculator
- Metabolism calculator, optional
References
- "Journal of Applied Physiology"; Metabolic Equivalent: One Size Does Not Fit All; Nuala M. Byrne, et al.; September 2005
- "Advanced Fitness Assessment and Exercise Prescription"; Vivian H. Heyward; 2010
- Illinois State University Department of Health, Physical Education and Recreation; Metabolic Equations: ACSM Formulas; M.J. Adams
- American College of Sports Medicine: "ACSM's Metabolic Calculations Handbook"; 2006
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