@bad2thebone_kat and Felipe demonstrating a great exercise variation that turns the lame, traditional sit up into a highly effective tool for teaching athletes to brace the core during dynamic movement. This would be the third exercise progression after mastering Category 1 bracing exercises like the stationary standing and kneeling Palloff press.
Despite popular belief, and how "HORRIBLE" it apparently is for your spine and "posture" (whatever the hell that even means) there's absolutely nothing wrong with throwing in flexion based exercises to target the core...IF you know how to organize your spine and pelvis into the right position when doing so. Often times when performing exercises like the sit up and leg raise, athletes mindlessly pump out endless amounts of garbage reps with little regard to bracing. With the sit up Palloff press, athletes are FORCED to brace the core as hard as possible (if you don't, the band will pull you over), making this exercise 10x more effective at recruiting the abdominals through improved kinesthetic awareness and mind-muscle connection.
This exercise can be effectively progressed to challenge both anti flexion/rotation AND extension capacity.