This is often something people feel that helps them have a flatter abdomen. The muscles beneath the fatty tissue do strengthen with exercise but working your core is not a cardio activity within itself. If you are focused on getting your abdominals is shape you will want to focus very much on changing the way you eat. Cardio helps burn fat during the workout but weights and strength training burns more calories while you rest. The more muscle you have the more you will be burning fat while you sleep. Still, your food intake, type, amount, times you eat all play a key role in the amount of fatty tissue you will retain or lose.