Donkey Kick Back Exercise
These are a great exercise for your lower back. Lie face down on a gym bench so that only your upper body is on the bench, and from your waist down is hanging off the bench. Grip the bench so your upper body is securely held on the bench. Now slowly press your legs back until your body is straight then hold for a second then lower your legs and bend your knees until your shins are nearly touching the floor.