I went to the YMCA recently to work out on the treadmill. It was 20 degrees outside so there was no way I was going to run in that. I think everyone else in town had the same idea because every machine was occupied. Finally, one treadmill became available so I hopped on. I set my weight, age and time so I could see the calorie burn. After all, the machines do give an accurate calorie count, right? I hate to exercise beside my husband because he burns about 800 calories in our workout time and I burn 350-400. Why is that? We are both working at a very intense level. It is because he weighs so much more than I do, taller than I am, and has much more muscle mass, so he burns more calories. But the machine does not take into account anything but his weight so perhaps he is not expending as many calories as the exercise machine displays or maybe he is expending more.
In reality most exercise machines probably do not give us an accurate count of the calories we are burning. I tell my clients to use it as estimation not as 100 percent accurate. Each manufacturer uses their own patented algorithms that take into account the workload and duration of the exercise. The higher end the machine the more likely it is to use a validated formula.
According to the article “Are the calorie counts on exercise machines accurate?” by Valentour, M.S., EMT-B, an American Heart Association Training Center Coordinator and a media spokesperson for The American Council On Exercise (ACE), elliptical machines usually use a formula for walking but may be set up on a formula for biking. This discrepancy often throws off the measurements from one elliptical to another. Treadmills have been around longer and therefore these algorithms have been validated on more subjects, so they are more likely to be accurate. Ellipticals tend to err on the high side and can be as much as 20-30 percent off.
According to Valentour aside from workload and duration, there are other variables that affect the caloric expenditure that are not accounted for in some algorithms. For example, body size will make a difference. A larger person will burn more calories per minute on a given exercise at the same intensity because they have a bigger mass to move (like my husband). Body fat percentage and fitness level can also make a difference. A person with a greater percentage of lean muscle mass will burn more calories at a given intensity. Fitness level is a factor as beginners are less efficient and therefore will burn more calories doing the same exercise than someone who does it regularly. Other factors such as the type of exercise and if the user holds the handrails of a machine affects the caloric expenditure as well.
The bottom line is that unfortunately readings are not totally accurate but they do give a reasonable estimate that you can use approximate your calorie burn. My advice is to err on the low side of what the machine says you burned and you will always be safe. My motto is to overestimate the calories you eat and underestimate the calories you burn. That’s a safe plan.
See you in the gym.
Linda Stollings is a personal fitness trainer in Bristol, Tenn. Email her at email@example.com.