Hey

My abs get a good amount of work through my lifting, Krav class and cardio regimens. But I try and do some iso work a couple of times a week. Takes me literary less then10 minutes to tear them up pretty good so if I have some time left over at the end of a workout session I'll get some plank type work in.

I use free weight/body weight compound exercises for strength training, go to Krav classes so already engage in lots of core work. I also include core exercises such as planks, pallofs, roman chair/hanging leg raises, ball/ab wheel rollouts, stability ball Russian twists, chops, walkouts, land mine rotations 1-2 times/week for 10 - 15 mins. On top of this, I also sometimes do exercises on unstable surfaces such as bird dogs on stability ball, single arm shoulder press or clean & press kneeling on a stability ball; cable/dumbbell squat & press/row on a bosu, etc.