You just spent an hour on the elliptical with your heart pounding and your body sweating up a storm. A quick glance at the machine’s display shows you burned an impressive 600 calories. “Wow, I deserve a post-workout donut,” you think to yourself. Unfortunately, your assessment could be wrong.
According to experts, while exercise equipment measurements of heart rate, distance and pace are usually pretty accurate, calorie counts can be off by as much as 30 percent—on the high side. That means if you rely on the machine’s calculations of your calories burned, you may think you’ve worked off 30 percent more than you actually have.
There are many reasons for these inaccuracies. These three are most common:
- The manufacturer’s algorithm.
Manufacturers use different algorithms in the calorie burn calculations. If your health stats vary from the average the manufacturer used, the calorie count is not going to be accurate for you. Some machines compensate for this—at least to some degree—by allowing you to enter your weight and age. Few, however, allow you to specify your gender and fitness level—two factors which also significantly affect caloric expenditure.
- Wear and tear on the equipment.
The older the machine you’re using, the more likely it is to be inaccurate. Treadmill belts stretch and slip as they age, reducing resistance. Elliptical, stair climber and rowing machines also have parts that can break down. And if you’re using the equipment at a gym—especially one that gets heavy use—even machines that look new may have resistance issues that contribute to calorie expenditure miscalculations.
- Operator error.
Maybe you’re a perfectly average human, of average weight, height and fitness. Your stats could be exactly those used in the manufacturer’s algorithm and you could still get an inaccurate calorie calculation if you’re not practicing proper form. This includes leaning on the handrails while using the treadmill, elliptical or stair climber. In essence, you’re reducing the amount of bodyweight you’re moving, so you’re burning fewer calories than the machine says you are.
If you must know how many calories you are burning with each workout—perhaps to stay motivated or because you want a better estimate of calories in versus calories out for weight loss—you may want to invest in a wearable monitor. Those that directly measure heart rate (though a strap around your chest) and have settings for gender, age, height, weight and fitness level are going to be best.