RE: Hyper extensions
I have had lower back problems in the past, and ended up having discs removed. The physio recommended hyperextensions twice a week for me, and I've been doing them for six years, on and off.
I find that if I miss a couple of weeks, my back seems less supple. I started with two sets, 10 reps, twice a week, with my arms crossed, and my hands on opposite shoulders, working up to three sets of 10 reps, with a plate held against my chest.
I find I get a better workout if I push my head back towards the hyper machine as far as possible at the bottom end of the movement - a lot of people stop short of full ROM IMHO.
Six packs are for WIMPS - I've got a firkin!!!!!