When doing lower ab exercises, is it more benefical to put feet on a bench or not? I've never understood why this is suggested.
I don't really know why it is more beneficial to put your feet up on a bench. It must be something with the position of your muscles prior to starting a workout. But i do not think this is important because the best way to know if something is beneficial to your abs or not is by doing an exercise and "feeling" the tension of your muscles.
As for "lower ab exercises" as you said, i think that is a common misconception to target ab muscles. My workout trainer told that abdominal muscles are just one strip of muscles so when you are exercising abs you are targeting all of your abs. So there is really no point in targeting lower or upper abs.
How long have you been doing abs? And how exactly are you performing them? Do you eat any specific food ?
Hope to hear from you soon