Give your hip flexors a break...

Here's a quick hint.

Give your hip flexors a break...

Anytime you draw your legs toward your midsection—reverse crunches, V-ups—you emphasize the lower portion of your abs. These moves also stress your hip flexors, the muscles on the front of your thighs. When these muscles are involved, your abs exert less than full effort, and you end up with tight hip flexors.

Overcome this tendency by pretending there's a glass of water resting just below your belly button. Before bringing your legs up each time, imagine not tilting the water all over you. Let the water tilt more toward your legs first. This redirects your body positioning, so the effort stays concentrated on the lower abs, making you work better and not stressing out your overworked hip flexors.