Don't Overwork Your Abs
"A lot of guys hit their abs every time they hit the gym," says Yuam. "That's why so few of them have six-packs." Your abs are like any other muscle group, and the same rule of muscle building applies: Don't overwork them. Lautner targets his abs only 3 days a week and does a combination of exercises to work his entire core. "The result is a balanced, more detailed musculature," Yuam says. One of his favorite combinations is the hanging leg raise to reverse crunch, holding for 7 to 10 seconds. That works your whole core, preventing a muffin top.
Source: Men's Health