Phil demonstrating the proper technique to stimulate the rectus abdominus (abs). Notice how he is in control, not going fast and using his hips to provide momentum. Curling - flexing the spine on the concentric and then curling back down until the upper back touches - constant tension.
BIGGEST DUMB TECHNIQUES I SEE OFTEN - Even by shit coaches;
Back straight, no flexion, using their hips - not their abs, and going far too fast with momentum. Then they go and hold a weight!!! TRUST me... if you do this right you DO NOT need to hold a weight. Increase the decline to make it harder.