Training the central part of the torso, especially the abs, without overloading the spine as often happens with the classic Sit Up
This move isolates your core muscles, improves your balance, and improves functional fitness.
Continuous muscle tension and the taut and slightly raised position of the arms and shoulders
This exercise is very effective to strengthen trunk stabilizers and works synergistically on all muscle groups if done properly.
The crunch with knees to the chest, better known as double crunch, is an advanced level exercise for training the abdominal area and for the stabilization of the lumbar area.
This exercise is a variation of the classic crunch: with the forward thrust of the hands, more effort is exercised and this is why the abs, especially at the high end, are trained in a more intense and targeted manner.