I love the Prone Cobra! I do that twice a week for sets of 5-8. I only hold it a for seconds each rep though. Never thought to hold it for a long period. I'll try that this week.
Before I started doing that, the swimmer (alternating raising an arm and opposite leg) and Cat Camel and reverse hypers, back raises, etc. I had all kinds of low back tweaks and whatnot. Since, I haven't hardly any trouble with my back. It's get sore of course, but not out whack like it used to sometimes just stepping off a curb.
I am Anton Zdravko Martin!
Best meet lifts: Sq 150 Kg (330 lb), Bench 120 Kg (264), DL 160 (352) @89 Kg (197)
Best gym lifts: Sq 375, Bench 280 (pause), DL 385 @205 or less
Goals beyond my wildest dreams, 600 Kg raw total, 200/160/240
Hack away at anything which isn't essential. Do what you love, and do it often. Fazc.
Everything competes for recovery so more assistance is not always the best idea. miked96