Any situp will work your abs, but you usually hit them with assistance from your hip flexors—those muscles on the front of your pelvis that raise your legs. To focus solely on your core, try the Janda situp, which requires only minimal use of the lower half of your body. DO IT ● Attach an exercise band around a sturdy object and lie on the floor. Now hook your heels behind the band and pull them toward you so your hamstrings contract and the band is tense. Perform a situp as normal. For even better results, go to dragondoor.com and buy the Ab Pavelizer II, an apparatus designed exclusively to help you master the exacting form of a Janda. WHY IT WORKS ● By contracting your hamstrings, you limit your body’s ability to use the hip flexors—so your ab muscles have to work extra hard. The more stimulus you apply to them, the better the six-pack you’ll build.