First off let’s answer question, do cardio machines overestimate the amount of calories you burn while exercising? Simply put, yes. By 2011 enough research has been done to reliably prove that almost all cardio machines overestimate caloric burn. The better question to ask would be, by how much and why?
The biggest reason why manufactures develop and sell machines that they know don’t accurately estimate calories is because, it gives the exerciser a bigger sense of accomplishment when they finish working out. Long term, manufactures are hoping that this intrinsic gratification is paired together with their brand of cardio equipment.
In the defense of the manufactures there are reasons for overestimation that are beyond there control. To accurately measure caloric burn you need a VO2 analyzer, the user’s height, weight, age, sex, and % body fat. Obviously, mass producing machines that could accommodate all of the features would highly expensive. Another valid reason for the inaccuracies is wear and tear, over time the internal resistance of the machines change creating skewed caloric values.
Mostly all cardio machines overestimate calories, buy by how much? The University of California at San Francisco’s Human Performance Center conducted a study to answer this question. They found stationary bikes to be the most accurate at an overestimation of 7%, stair climbers at 12%, treadmills by 13%, and ellipticals overestimated calories a staggering 42%. Researchers proposed a reason for the high overestimation by ellipticals could be due to the fact that isn’t a natural motion and therefore exerciser’s had many different techniques for using the machine which made it hard to develop a standard formula for calories burned.
Knowing why and by how much cardio machines are inaccurate by, allows their users different ways of finding the most accurate estimation of caloric burn. One suggested way is when entering your weight into a machine to use a figure that is 10% lower than your actual body weight. Another way is to invest in a mid-range heart rate monitor where you can input your height, weight, age, and allow the monitor to calculate the amount of calories burned using your instantaneous heart rate.