Thursday, June 21, 2012

How Many Calories Do You Burn On the Treadmill? Are You Sure?

Have you ever finished a work-out on the treadmill and felt really great  about the amount of calories burned but somewhere in the back of your mind you did not fully believe the number on the machine? I have. I have also used my GPS running watch to estimate the calories I burned on a run and been skeptical of the large amount expenditure I supposedly put out. I hate to be to bearer of bad news but if like me, you are distrustful of the gym machine’s calorie usage estimate it’s for a good reason. The calories burned on a machine are at best an estimate of the amount of calories an average person with the same weight would burn given your speed, distance, and elevation. The number does not take into account factors such as lean body mass, genetics, and efficiency of exercise that all play are role in one’s total energy expenditure.  In fact, one paper from the American College of Sports Medicine found that calorie counters on one brand of elliptical were about 26% higher than lab based estimates.  
                Calories are a unit of energy that represent the rate at which oxygen is used to breakdown our food products. In order to really measure calories one must measure the amount of oxygen used. The reason heart rate monitors estimate calorie expenditure more accurately than treadmills and other gym machines is because when the body needs more oxygen to fuel its organs the heart begins to beat faster which is detected via a heart rate monitor. The companies that develop heart rate monitors have used research to develop their own formulas that couple heart rate with variables such as age, weight, sex and body composition  to estimate calorie usage. Treadmills and gym machines use formulas as well but factor in less individual variables leaving more room for error. Overall, the number or calories burned reported by the gym machine should be taken with a grain of salt and definitely not a prescription to the amount of food one should eat in a day.
                The good news is that the calorie number on the machines at the gym can provide a means to set goals and measure your effort level. Think about it, if you repeatedly use the same machine at the gym and one day you burn 200 calories and the next day you burned 220 calories you worked harder on day two. Try letting go of calories numbers and focus on improving speed and performance and you begin to naturally burn more calories. If you must have a calorie guide to help plan you meal plan I recommend getting your metabolism tested at our office with our indirect calorimeter , Reevue. For more information visit our website


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