The leg press is an exercise machine which can be found in any gym. Like all exercise machines, the leg press is designed to kill you in a painful and humiliating manner. If someone manages to use the leg press for a few minutes without being squished into a pancake, then that person might say that he or she is doing a "workout."

Imagine lying at the bottom of the slope on a roller coaster, with your back on the tracks parallel to the ground, and your legs resting against the rise. The car, filled with large, burly men, is teetering at the peak of the hill and begins hurtling toward you. The only way you can prevent a ton of weight from breaking your knees and flattening your rib cage against the tracks is by pushing the car away from you with your two weak, spindly legs.

If, by some miracle, you manage to do so, your struggle still isn't over! Now you are expected to straighten out your knees to guide the car back to the top of the mountain. You are not permitted to use a crane or a helicopter. Burly men being what they are, however, they will get scared while they are up there, meaning that you will have to bend your knees to guide them down slowly toward the ground once again. As you do that, they will gain confidence, and ask to be pushed back to the top. You are expected to go through this raising/lowering process between eight and fifteen times.

The 'car' on a leg press is actually called a sled, which might fool anyone who hasn't read Calvin and Hobbes into thinking that using it is a fun exercise that won't hurt anybody. The burly men are the plates or the weights on the weight stack, which add as much resistance as you can handle to the exercise. Usually there is a small rubber stop placed halfway down the track which, in theory, prevents the sled from crashing into your fragile body; I am deeply suspicious of it, however, since it is only about an inch square, and the sled weighs eleven hojillion pounds.

The leg press exercises the quadriceps (which ordinary people call "thighs"), along with the glutes (Latin for "butt muscles") and hamstrings (a word which also means "attack a horse's legs so it can't move any more," though surely that's just a coincidence).

Here is a blurry, animated picture of somebody using a leg press: http://www.exrx.net/WeightExercises/Quadriceps/SL45LegPress.html