Elliptical trainers can provide much the same aerobic and cardiovascular benefits as treadmills, and burn as many calories. Elliptical trainers are also lower-impact than treadmills, and many people prefer them for that reason.

Elliptical machines don't directly train your body for any specific sport, although the motion can be similar to cross-country skiing. If you're training to run a road race, you'll want to train on a treadmill when you can't be outdoors. If you're training for a triathlon, elliptical trainers will help your endurance and cardiovascular fitness, but you'll need to use a stationary bike to get in shape for the cycling portion. If you're going Mountain climbing, stair climbers can help build the leg and glute muscles you need more specifically than elliptical trainers will.

A particularly nice thing about elliptical machines is the reversible motion that helps work your lower body in a unique way. You won't go as fast, and thus it will be less of a cardio workout, but using elliptical trainers in reverse is a great way to exercise your quads and other lower body muscles.

Elliptical machines have become extremely popular in the last few years precisely because they do things differently. And studies continue to show that you can burn just as many calories on elliptical trainers as you can on treadmills. For lower impact, involvement of the upper body, variability and the ability to work different muscles, elliptical trainers are hard to beat.

A personal trainer at the gym can help you explore the options for working out on elliptical trainers, and manufacturers often provide extensive workout guides and suggestions if you are considering buying an elliptical trainer machine of your own.