Elliptical machines and trainers are classified as low-impact cardio workouts because you move the platforms on which your feet stand, rather than hitting the surface with your feet. According to USA Today, the number of elliptical trainer machines in use has increased by over 700 percent since 1997. People who are concerned about the effect of impact on their joints are embracing elliptical trainers as a good low-impact alternative to treadmills.

People who have experience with treadmills will take a while to get used to the motion of elliptical trainer machines, but the progression of a workout can be much the same. Elliptical trainers can increase resistance, go faster, and add an incline, so a treadmill workout can easily be adapted to elliptical trainers.

Most elliptical trainer machines also have handlebars that can be moved to work out your upper body as well as your lower body and add to your cardio workout. Another advantage of elliptical trainers is that they can be used to add variety to a low-impact workout. If you get bored with low-impact aerobics or dance, a workout on an elliptical trainer can be just the change of pace you need to get you more engaged with your workout again. If you've put enough mileage on stationary bicycles to cross the country and rowed across virtual oceans on rowing machines, elliptical trainers can give you a good workout and burn calories without the lower-body joint impact that running and jumping can cause.

Popular pieces of health club equipment, elliptical trainer machines are increasingly available and affordable for home use.