Forget sit ups (except for the half turkish getup) and ab machines. Try hanging from a pull up bar and bringing your knees up to your elbows. It's that simple. And that hard. My abs started cramping up after about rep number 25 (during round #2).
Workout of the day
3 rounds for time:
30 kettlebell snatches (53lbs/24kg)
21 box jumps
15 Knee to elbows
Time
14:03
Knees to Elbows
1/2 Turkish Getup
