Most fitness disciplines involve movement and that means only a limited amount of your available energy is actually reaching the area you want to condition. For example, sit-ups waste 80% of energy raising and lowering the upper body, and only about 20% reaches the abdominal muscles.
For exercise to be effective it must allow you to channel 100% of your available energy into the area you are working. This means for best results the exercise you choose should be stationary, and movement should be no larger than the muscles own contraction (approximately 1-2 millimetres).
Stationary positions will allow you to reach deep into the centre of all of your core muscles with isometric engagement where you’ll be able to condition your body in all three dimensions. Stationary positions also have a lower risk of injury, which means you’ll be able to relax and focus more on what you are doing and see results much faster.