Lying Flat Raise
Beginners or persons with lower back injuries should avoid this exercise.

Lie flat on your back on a secure flat bench, with your buttocks at the edge of the bench.
Use your hands to secure your back on to the bench, either by your head, or lower down at your hips.
Keeping both feet together, with your legs straight, lift and lower in a smooth controlled action, taking 3 - 5 seconds to complete 1 lift and lower.
Aim to lift your legs to a right angle position with your body, with your buttocks raising naturally a few inches off the bench.
Avoid allowing your feet to come down to low, until you have adequate strength in your lower abdominals, as this can causes excessive strain on your lower back.
Aim to work for a comfortable amount of reps, focusing on good technique and a smooth slow action, rather than high reps at speed.
Throughout the movement, you shouldn’t let your feet touch the floor, as this will reduce the contraction within the abdominals.