In most workout programs I follow one of the suggested exercises is decline sit-ups while holding a weight on you chest to increase resistance. I have read somewhere that to determine if you have true ab strength you should hold the weight behind your head.
So in the gym today I decide to try it. I can easily knock out reps with a 45 lb. plate on my chest but when I put it behind my head it was a struggle for my life to sit up once. So what gives. Someone give me some info. If you read this CW let me know whats up.