Research on core training has become confusing as of late. Are isometric exercises like planks and bridges the most effective way to train the core, or is there still a case for doing crunches?
Although most studies support core and functional exercises over traditional crunches for low-back health and sports applications, one recent study actually showed that crunches were superior to the traditional “pike” core exercise (basically a jackknife) in isolating the rectus abdominis while eliminating assistance from the quads.
So what does this mean? While stabilizing exercises like the plank build endurance in the core muscles to brace posture, they’re not going to provide the right stimulus for building muscle mass in the abs. Crunches — especially weighted ones — might be the way to go for someone who wants to develop her six-pack without getting help from her hip flexors. Most sports don’t use this crunching motion, however, so for the athlete, more functional exercises like woodchoppers will serve her better.
Your best bet: Though research has not yet been able to pinpoint a single perfect exercise to activate all core muscles at once, keep your abs guessing by switching up your moves often. Use a program for no more than four to six weeks, and change your workout variables such as sets, reps, rest time and equipment to keep things fresh.