One of my favorite machines at the gym is the seated leg press machine. There are so many squats and lunges I can do before I get bored, so the seated leg press is a great way to also work the upper muscles of the leg.
What is it: A seated leg press machine
Area of body it works: Quads, hamstrings, glutes and lower back
Why: It's a great way to work out your legs as it works a lot of the major muscles in the legs.
How: Start by adjusting the seat so that your legs are bent at a 90 degree angle for your starting position. Position your feet about shoulder width apart. Press the weight with your legs until they straighten out (knees still slightly bent), but be sure that you don't lock, buckle or bow (inward or outward) your knees at any point. After pressing, slowly bend your knees back to a 90 degree angle. Do not ever lift your booty from the seat. On most modern models the platform does not move but your seat will slide backwards, on older machines the platform moves - either way, keep your form the same.
Fit's Tip: If the seat reclines, then make sure it is in a position so that you do not feel any kind of a strain in your lower back, particularly if you are going to do high resistance, low reps.