Extend your self only to the horizontal position to begin with, Once you are comfortable, then drop as far back as possible.
Always have a spotter to help you incase you get stuck and can't get back up.
Strat slow to prevent injury.
Position yourself on your glute ham machine or back extension machine. Place your feet under the padded supports and flex your feet so that your toes pull back towards you. Scoot back on the seat so that the front end of the padding is just above the backs of your knees.
Tighten the quadraceps muscles, buttocks and abdomen, crossing your arms over your chest and slowly lower yourself backwards as far as you can while extending your back. If you feel uncomfortable or feel that you have dropped to far, have your spotter lift you up gently until you can lift on your own.
Push down with your knees, engage your abs and lift your arms to generate the power to lift yourself into the GHD sit-up. When beginning new exercises, start slow to prevent injury.
Don't bend your knees while coming up, to prevent lower back pain.
