Exercise Machines and Calories

The treadmill display says you just burned 300 calories. How are these figures determined and what do they mean?

A calorie is actually a measure of heat, given off when energy is produced in our bodies. Calories burned during exercise is a measure of the total amount of energy used during a workout. This can be important, since increased energy usage through exercise helps reduce body fat.

To calculate the calories burned during exercise you must multiply the intensity level of the exercise by your body weight (in kilograms). This gives you the amount of calories burned in an hour. A unit of measurement called a MET is used to rate the intensity of an exercise. 1 MET is equal to the amount of energy expended at rest.

For example: the intensity of walking 3 mph is about 3.3 METS. At this speed, a person who weighs 132 lbs. (60 kg) will burn about 200 calories per hour (60 x 3.3=198).

The computer controls in higher-quality exercise equipment can make this calculation easily. Based on your workload, they calculate exercise intensity and calories burned according to established formulae.

The readings you get from your equipment are only accurate for you if you were able to input your body weight. If the machine does not allow this, then the "calories per hour" or "calories used" displays are only approximations. The machines have built-in standard weights (usually 174 lbs.) that they use when there is no specific user weight.