Sit ups/ crunches vs F1

Sit ups and crunches are often said to be bad exercises because of the stress it puts on your lower back, makes the hip flexors tight etc. However, F1 contains many exercises (in FL and MN) that are similar to crunches and sit ups. 

 

Could someone explain why THE F1 exercises are better than sit ups/crunches and if they have the same negative effects as them?

I'm not aware of ANY exercises in F1 similar to sit-ups.  We have isometric holds, rocks, etc.  Nothing similar to a sit-up that i can see.

You have to take in account that research is done on the general population and general population is unhealthy. If your bodies have mobility or stability problems then of course sit-ups will make it worse. Just like how people consider dips bad. It's bad if you have shoulder problems and you can't control the range of motion. You also consider some people will do endless reps without even progressing further or doing incorrect techniques.

This is a good video about situps, 
http://www.youtube.com/watch?v=H3Mod-66D-o

Decent video I agree with what he is saying. I would like to add some comments though. Crunches tend to be where people do the most damage. Where the focus of the movement is really only on a few vertebrae in the lumbar spine. The legs and hips are actually held pretty rigid in that movement.

The movement in foundation revolves around folding the body in half. This should be focused at the hips. And the body folds pretty naturally. Also the movements should be controlled and not jarring like people often do with high rep crunches.

In f1, we also PPT in these exercises like tuck ups and hollow body holds. When the vast majority of people do sit ups and crunches...they've never heard of the term PPT. Just try a hollow body in an arch and you might feel that lower back pain people talk about. If I had a nickle for every arched back sit up I've seen...I'd be on a plane to the next seminar.