Elliptical machines, also called cross-trainer exercise machines, are cardio machines designed to provide an aerobic workout with little to no impact. The movement required to operate the machine is a cross between walking and running, without the joint stress that running imparts. Elliptical machines will often have a display that shows distance traveled, or revolutions or strides performed during a workout. If your machine does not display distance traveled, there are ways to figure out how many miles you've gone by plugging the strides made into some basic math formulas.
Check the display of your NordicTrack elliptical machine. Most should display the miles traveled, or have the option to change the display to show distance traveled. Many will scroll through different functions if you press "Display," "Mode," or "Distance." If the machine's display does not offer to track distance traveled, then it should show revolutions performed.
Some machines have adjustable stride lengths. With others, you will have to measure the stride length. Measure from the farthest-back position of the pedal to the farthest-forward position of the pedal in inches. Convert that measurement into feet and divide by 5,280. That is the number of feet in one mile. The resulting number is the number of strides you must take to travel the equivalent of one mile.
Measure the radius of the wheel. If it is enclosed, measure from the center to just inside the outer edge of the plastic cover. Multiply the radius times two to determine the diameter. The next step is to determine the circumference of the wheel. The easiest way to do that is to multiply the diameter times pi, which is 3.141592. Say your radius is 10. That means the diameter is 20, and the circumference is 62.83184. Convert the circumference measurement, which is in inches, into feet (divide by 12). The circumference is 5.23598. This number is the distance traveled per revolution. Figure out the number of revolutions it takes to travel one mile by dividing the number of feet in one mile into the number of feet traveled per revolution. 5,280 divided by 5.23598 is 1008.4. Therefore it takes approximately 1008 revolutions to travel one mile on this elliptical exercise machine.
Not all machines are calibrated properly and so the distance traveled display may not always be correct. Generally, the higher the quality of the machine, the more accurate its readout will be, but do not assume it is correct. The best way to figure out distance traveled is to measure either the stride length or the wheel circumference.