You use them hard in a golf swing, tennis stroke and even throwing a Frisbee. There are a few areas of the mid section that you need to work to ensure balance in strength between the muscles. The rectus abdominus and the obliques. The rectus muscles are the ones that form the six pack or in some cases the eight pack of muscles in the front. The oblique area is the one termed love handles on the sides.
Crunches are great, because of ease and technique, but here is one that is better.
Try sitting on the floor with your knees bent and your feet flat on the floor. Hold that position while breathing slowly and consistent. Try holding for 3-5 sets of 30seconds to a minute. With your left hand behind your neck for comfort, try reaching up to the outside part of your left foot with your right hand. When your abdominals and obliques are strong you should be able to reach up to your foot, but if not try reaching for the side of your lower leg.