William Henry Bill Cosby, Jr. (born July 12, 1937) is an American stand-up comedian, actor, and author. Cosby's start in stand-up comedy began at the hungry i in San Francisco, and was followed by his landing a starring role in the 1960s television show I Spy. He was also a regular on the children's television series The Electric Company during the show's first two seasons.
Crunch on Exercise Ball: This exercise not only build your abs but also promotes balance and stability. Crunch on exercise ball is a highly effective exercise to build upper and middle ab muscles. Check out the proper way to do this exercise: Sit on the ball and keep your feet straight on the floor.
You will perform this exercise as a variation on ab crunches. The difference is that you always have both feet off the ground during these bicycle crunches. This makes bicycle crunches a bit harder, than standard ab crunches. Also, it tends to work the lower abs more. Typically, keeping your legs off the ground works the lower abs. Keeping your legs flat, on the other hand, works the middle abs. Interestingly, bicycle crunches also work the rectus abdominus muscle (upper abs). This is the highest set of ab muscles you have.