This suggests that not only does crunch not produce better outcomes, but it may actually make games worse where it is used. (ndark.wordpress.com)
The age - old question in bodybuilding is whether it is better to do crunch exercises in a slow and controlled manner, or at faster speeds. (fitnessandpower.com)
To do this crunch variation, lie face up with your knees bent, feet flat on the floor, and palms facing down underneath you. (health.com)