Thinking of buying one of those ab machines or other ab gadgets as seen on TV? Abdominal and back exercises are important for a strong, healthy core. However, you don't need special equipment. Research has found no difference in muscle activity between basic crunches and exercises done on top-selling ab machines. Bottom line: You don't need to spend money to get an effective ab workout unless using a device helps to motivate you. If you do decide to buy something, an exercise ball offers an excellent way to work your core.