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The situation: You're doing cardio and strength training to burn fat all over your body, but in the meantime, your core routine is the standard plank, held for a long time.

What that has to do with belly fat: We love planks, and so do fitness experts, because they strengthen the muscles deep in your core that help support your spine. But a static plank (i.e., just holding steady, on your hands or forearms) should be one of many ab moves in your arsenal—not the only one. By adding movement to your plank, you become less stable, and your abs have to work harder to maintain your balance. So once those abs are revealed, they're more toned. Focus on reps over time— Jessica Matthews, American Council on Exercise (ACE) certified personal trainer and assistant professor of exercise science at San Diego Miramar College, says 30 seconds with good form is all you need, and a study in the Journal of Strength and Conditioning Research found that repeated holds for as little as 10 seconds are still beneficial.

What to do about it: Do shorter planks, focusing on versions that include movement to challenge your core more. (We've got 15 ideas here.) Two more of Matthews' favorite ab moves: The wood chop, and its reverse, the hay barreler. And don't discount much-maligned crunches. It's true that they work fewer overall muscles than planks and they're not recommended for people with lower back issues, but research funded by ACE found that they effectively work your six-pack muscles (crunches even beat other moves like boat pose, bicycle crunches and, yes, the standard plank, when it came to activating upper abs).