You might feel like your abs are divided into a lower and upper region, but in reality, your rectus abdominis — or front sheath of abs — is one long muscle. It's segmented by tendinous creases, which gives you a six-pack look, and may make you feel that it's made up of separate muscles. Technically, however, you can't independently contract the upper and lower region of the muscle.
Sit-ups refer to a very specific move: You lie on your back with your knees bent and lift your torso up to touch your legs. This move activates primarily the upper portion of the rectus abdominis as you lift your head, neck and shoulders off the floor.
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No sit-up, even on an incline, will predominantly activate the lower portion of the rectus abdominis, but other ab exercises will. The following moves will help target the lower portion of your abdomen.
Although the whole rectus abdominis works during this move, you will probably feel it most in the lower abs.
Lie on your back. Extend your arm out to the sides of the room to anchor your upper body on the floor. Bend your knees and raise them up so your shins are parallel to the floor.
Pull your belly in toward your spine as you exhale and lift your hips up off the floor. Draw your knees in toward your chest as you squeeze.
Inhale and release to the starting position to complete one repetition.
Hanging Leg Raise
The hanging leg raise works the entire rectus abdominis and the hip flexors, so you feel it in the lower region of your belly.
Hold onto a high pull-up bar, or use arm straps to hang from the bar. Extend your legs completely.
Pull your knees up toward your chest by flexing your hips.
Return to extended legs and hips to complete one repetition.
Stability Ball Jackknife
Use an inflated stability ball for this exercise.
Get into a push-up position with your hands on the ground and the tops of your feet and ankles on the stability ball. Draw your belly button into your spine and keep your torso as a straight line from your head to your feet.
Keep your back rigid as you roll the ball toward your chest by bending your knees.
Roll the ball backward to straighten your legs and complete one repetition.
Criss-Cross Mountain Climbers
This move activates your whole body, but places a special emphasis on the lower portion of your rectus abdominis. Go at a quick pace for 30 to 60 seconds to raise your heart rate, too.
Put your body into push-up position, balanced on your hands and feet and torso rigid.
Lift your right leg and pull the knee toward your left elbow. Put the foot back down.
Repeat by pulling the left leg to the right elbow to complete one repetition.
Keep In Mind
Your lower stomach area can be a place where fat is stored. No matter how muscular your abs are, if there's a layer of padding covering them — you won't see the definition. But, no one exercise will directly trim that specific area — spot reducing is just not possible.
To reduce fat all over your body, including your lower belly, follow a diet that focuses mostly on lean proteins, such as chicken and fish, as well as vegetables and small amounts of whole grains. Regular cardio and total-body strength training also helps you lose body fat all over, so your lower abs look lean and defined along with muscles on the rest of your body.