Elliptical trainers are a low impact form of exercise and you get all the benefits of a stepper and a treadmill combined. Ellipticals or cross trainers, as they are often called, are a great cardiovascular exercise, without the high impact on your joints, that you can get from running etc. Elliptical trainers have a smooth movement that works the large muscles in your lower & upper body. Changing the direction of movement, the incline and resistance level, you will tone your gluteals (buttocks) quadriceps (thighs) calves, hamstrings, and hip flexors. In particular they work your thighs and buttocks better than most other exercise machines.