Total body work, sans impact.

Ever since their introduction on the fitness scene several years ago, elliptical exercise machines have become increasingly popular and sophisticated. By some estimates, up to six million people now use elliptical machines in their homes. The machines provide a low impact, upper and lower body workout that is challenging enough for serious athletes but safe enough for beginners.

It's well documented that in order to maintain healthy bone density, it's necessary to engage in weight bearing activities such as running, racquetball, aerobics, and other forms of exercise where you remain on your feet. But a low impact crosstraining tool like an elliptical machine can allow you to work out on additional days without overusing recovering bone structures, tendons, and muscles--or aggravating old injuries, most commonly to the knees, ankles, hips, and back. Additionally, pregnant women, people with arthritis, and those who are recovering from a sports injury or accident often require a regular low impact exercise routine.

With an elliptical machine, you stand with your feet on small, movable pedals. You are therefore bearing your own weight, which is good for bone density, but the oval movement you create by stepping up and down on the pedals is smooth. Although the lower body movement is similar to running, there is none of the impact force that occurs on the road or treadmill, reducing the stress on your joints.

Some people compare elliptical exercise equipment to pedaling a bicycle while standing up. It also may be thought of as a hybrid between stair climbing and cross country skiing. But while a stair stepper comes to a halt before reversing direction between up and down strokes, an elliptical machine provides continuous flow. By using different inclines and stepping speeds, you can vary the amount of flexion at the ankles and knees, which can further reduce the amount of repetitive overuse on your lower body.

By selecting a model with handles and arms, you can achieve a fairly high quality full body workout. Your leg muscles, buttocks, back, and abdomen do the pedaling work, while you sculpt your biceps, triceps, and several other upper body muscles with a fluid arm swinging motion. This will also increase your calorie burn and the cardiovascular benefits of your time on the machine. (If your machine does not have a handlebar attachment, you can swing your arms while wearing small wrist weights to enhance the upper body workout.) Most elliptical machines also have a setting to reverse the direction of motion, allowing you to pedal backwards and work additional muscles. By adjusting the resistance and incline, you can discover a variety of different workouts targeting different muscle groups. Increased resistance on hip flexion, for example, will provide you with greater strength and range of motion for your runs on the roads.

Depending on your goals, elliptical trainers may not be adequate substitutes for all other upper body strength training, but they can certainly serve to enhance your regimen. And as noted above, the cardiovascular benefits of adding upper body resistance while working the lower muscle groups in an impact-free running motion are certainly worthwhile.

(Parts of this article were adapted from "Elliptical Exercise Machines Provide Low Impact, Total Body Workouts While Improving Cardiovascular Health," by C.J. Gustafson, a freelance writer for www.elliptical-machines-n-trainers.com, which provides consumer information on elliptical crosstrainers.)