Ab exercise compliment everything. Try and stay away from movements that are dependent on lumbar flexion (crunches are the best example) and you should be good.
McGill and those who ascribe to his research findings tend to stick to movements that teach: extension, resistance to flexion, rotation, resistance to rotation. this tends to fit as cable rotation/anti rotation exercises, planks, roll outs, plank variations, and sometimes reverse crunches. I also like TGU Sit Ups as well.
And if you don't think kettleball squat cleans are difficult, I say, step up to the med-ball
- CJ Kim