Q: How accurate is the information treadmills and step machines provide about calories burned?
A: The listing of calories used during exercise on equipment like treadmills, steppers and ellipticals is calculated based on formulas unique to each equipment manufacturer. The formulas use time and speed, combined with any relevant resistance settings and the personal information you input. Accuracy of the calculations varies, depending on how well the formula was tested on a large number of different people, how well-calibrated the equipment is kept, and the amount and accuracy of the information you provide. The most accurate use of information on calories from these machines is for comparing information from your workouts on the same equipment over time.
According to the American Council on Exercise (ACE), treadmills have been around longer and are more tested than other equipment, and so treadmills may have more reliable formulas than other equipment, such as ellipticals. Accuracy also depends on correct use of the equipment: if you lean on side rails or bars, you allow them to support some of your weight; this burns fewer calories and adds another reason that the calories you see listed may over-estimate what you have actually burned. In addition, different people doing identical exercise burn different amounts of calories.
Heavier people tend to burn more calories than lighter people doing the same activity. People who are less fit or less accustomed to a particular type of equipment burn more calories than people who are more fit and trained on the equipment. Even stride length, amount of lean muscle tissue, individual metabolism and medications can affect calorie-burning. To increase the calories you burn, work toward gradually increasing your speed, resistance/incline or amount of time you spend exercising.
Karen Collins, MS, RDN, CDN is AICR’s Nutrition Advisor, a speaker, writer and consultant who specializes in helping people make sense of nutrition news. You can follow her blog, Smart Bytes® and follow her on Twitter @KarenCollinsRD.