[Arkan]

Ok, this is a 2 part answer:

Answering the actual thread question, crunches are the best for your abs but don't do them with your hands behind your neck (a good way to injure your neck and/or back) Instead, place your hands across your chest. As for your lower back, lie flat on your stomach and arch your back where both your legs and upper torso comes off the floor. I place my arms crossed just under my chin.

ok, 2nd answer that's not in the original question, Yes, a marathon sex romp can be a good form of excersize. Ever fuck the breath out of someone?? I did, the girl had to take her asthma pump !!