he elliptical trainer at your fitness club is worth a try. These exercise machines give you a vigorous, low-impact, cardiovascular workout. Best of all, you work all the major muscle groups in your legs and buttocks in the process. Also, you can adjust the difficulty of the workout and select forward or backward movement to emphasize different muscle groups in the legs. Elliptical trainers look like a cross between a StairMaster and a Nordic Track. When using the contraption, your feet move both up and down and back and forth in a long circular pattern known as an ellipse. The workout compares to a moderate jog, without the pounding that can leave runners' knees aching. Before you try the machine, have a staff member show you how to use it properly. Start your workouts slowly, and gradually increase to a more strenuous workout. Also, if you like the machine so well that you're considering buying one for home, be cautious. Home models aren't nearly as sturdy as the one at your health club. © Your HealthStyle, 1999.