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 may be learning the plank exercise for the first time or you may already use it regularly in your workouts. I have found it to be one of the most effective abs exercises I use. In fact, one research study found it to rank highly at #4 out of 13 exercises for the oblique abdominal muscles. Not only does it strengthen the abdominal muscles, but also works all the core muscles -- the back, hips, etc. I recommend starting with the first exercise and gradually increasing the seconds you can hold the position. Once you feel comfortable with the plank on your elbows, progress to the next exercise.