1.Treadmill

   The top-ranked home aerobic equipment for years running is available with a wide array of features, from varying incline to feedback on time, distance, and calories burned.

Look for a wide, long, stable belt that can accommodate your stride and weight; emergency shutoff; and slow-start speeds; as well as quality in the drive train, belt, and deck. Cushioning features can help lessen the impact on feet and knees.

2.Stationary cycle

  With a small learning curve, stationary cycles are easy to use, and low impact. Available in upright or recumbent styles, some cycles come with movable handles to work your upper body as you go, and you should make sure the one you buy has a comfortable, adjustable seat, interchangeable seat posts, and adjustable handles and toe straps. Less costly trainers allow you to convert your outdoor bicycle for indoor use.

3.Step machines

  Whether stair-climbing or pedal-pushed, these can provide a good workout, though with a larger learning curve than treadmills and cycles.

Machines with independent steps require more coordination. Look for steps parallels to the floor at all times, and a stable railing to grasp.

4.Elliptical trainers

  The hot new category of machines—a cross between stair-climbing, cross-country skiing, and jogging, extremely low impact injuries, and cardiovascular effectiveness.