What is a crunch and how do I do one?

How many crunches should I do a day for a workout?

What's the most amount of kilometers/miles you ever drove on a bike in one day? Mine's 31 miles.

How can one perform crunches? (It is an exercise)

Which one helps with getting rid of fat of the stomach?? People always give me mixed answers does anyone no the right answer??

What's the difference between them??

Wich one is better to get thicker legs running or riding a bike??

I know the 2010 is more expensive, but is there really a defference besides technology?

Would sit-ups & crunches make my boobs smaller? and I was just wondering.

Yeah,im slow...but how do crunches help our body? && how do push ups help our body? ♥Vero

Do sit ups and crunches realy help you lose weight?