The leg press is one of the best exercises for overall strength and development of your legs. First, sit in the seat, positioning your feet about shoulder width apart and chest high on the platform. Adjust the seat height by pulling the handle and sliding forward until your thighs are parallel to the platform. This is your start position (make sure that your lower back is pressed firmly against the back of the seat). With your feet flat, slowly press upward until your legs are fully extended but short of locking. Slowly return to the position where the weight almost touch the weight stack. The breathing pattern for this exercise is to exhale as you press up and inhale as you return to the start. Again, you will have to experiment to find a weight with which the last three repetitions are difficult to perform.
If you are new to strength training do 2 sets of 12 repetitions. If you are a veteran of strength training do 3 to 4 sets of 10 repetitions.