Since your abs consist of the same type of muscle tissue as your other muscles, they are subject to the same negative effects caused by overtraining. One negative aspect of overworking your muscles is called muscle atrophy, or the actual breaking down of muscle tissue to a smaller size. The second potentially negative side effect of doing situps and crunches every day is that over time your workouts will tend to get less intense, and thus less effective at strengthening and toning your abs.
Types of Exercises
Crunches alone will not tone your abs. There are no specific exercises that target any one particular spot. For example, you cannot work out in hopes of toning your lower abdominal muscles exclusively. The key to a successful routine is to perform different types of ab exercises that will tone your entire core, while remain challenging for the muscles. You can include crunches as well as leg lifts and toe reaches.
Overall body fat reduction is another factor in achieving lean abs. This is achieved only through aerobic exercises. Examples include walking, running, stair-climbing, swimming and bicycling. Incorporate regular aerobic activity in addition to ab exercises for maximum results. The Diet Channel recommends five 30-minute sessions a week at the very least. Overtime, the expulsion of energy through cardiovascular exercise causes the body to eat up fat to maintain energy levels. The first place you will likely lose this fat from is the stomach. Reducing stomach fat allows your ab muscles to become more prominent. Ask your doctor before exercising, particularly if you are a newcomer, or if you have an underlying health condition.