The crunch is the most popular ab exercise for one reason: anyone can do it. Trouble is, that doesn’t mean it’s the most effective ab exercise. After all, would you rather be using the abdominal workout of an out-of-shape housewife or the ab workout of an Olympic gymnast?Enter the hanging leg raise. Consider this movement the gold standard for all abdominal exercises, just as the pullup is for your back. Although most gymnasts have probably never bothered with a crunch, they’ve been performing variations of the hanging leg raise for decades. It works like this: as you hang from a bar, you curl you