Crunches, Abdominal machines, Sit-ups, Ab-crunchers, all are fantastic. But sorry, they will not get you six-pack abs. Most of you at the local fitness center looking to trim your stomach are doing cardio (treadmills, cycles, etc.) and then heading to whatever abdominal machine they have. This is because of one of the biggest myths in the fitness world: “There is no such thing as spot reduction.”
Spot reduction is the idea that exercising a body part will reduce fat for that body part. The belief that exercising legs will slim those thighs. Or dumbell curls will rid the fat hanging off your arms. Or doing crunches will make you flatten that stomach. By themselves, none of them are true. You are exercising muscles and not exercising fat. All exercise will burn calories and therefore fat but not in any single body location.
You may already have 6-pack abs but they are covered up in fat. You do need to burn that fat off your stomach to expose those abdominal muscles. That is the most important step in getting that perfect stomach. It is through TOTAL exercise and not any single exercise. Exercising your arms, legs, back, chest and ab muscles will together burn fat over your entire body including your stomach.
You can do do the crunches or ab machines but if you really want your stomach to look better you need to also work all your other muscles. The second part of the equation is to build toned ab muscles so it is important to exercise them. But only until you remove the fat covering you be able to see they exist.