Your abs are put together with 4 different muscle, the External Abdominal Obliques, Internal Abdominal Obliques, Rectus Abdominus, Transverse Abdominus. With these 4 movements we are focusing primarily on your Rectus Abdominus which are the muscles you see in 6-packs abs.
Keep in mind that anytime you want to see definition in your abdomen it requires proper nutrition first and then strengthening exercises that focus on building up those muscles. You could perform all the crunches in the world, but will not see a difference unless you eat properly and loose the excess weight over those muscles in your abdomen.
Opposite Arm & Leg Raise: Start in a seated position with both hip bones flat on the floor. Straighten your back and bring it behind you at a 45 degree angle. Lift your Right arm up so it is parallel with you right shoulder and your right leg a couple of inches off the floor. Lift your left arm to the side of your head and your left leg is lifted and bent at a 90 degree angle. In a smooth motion bring your right arm and leg up and your left side down. That is one rep. * You are performing the same motion on each side. As one side goes up the other side comes down.
Plank Twist: Begin in a full plank position with your feet hip width apart. Bend your right knee across to the left as you slide your right foot up to the inside of your left knee (your hips should turn to the left). Slide your right leg back to start and then repeat to the left. That’s one rep. * During the twisting motion your primary muscle you will be using is your external oblique muscles. I love this movement because it incorporates the entire core musculature.
Frog Press: Lie faceup with your knees bent and turned out, feet are flexed, and heels pressed together. Lift your head and shoulders off the floor. Reach your arms outside of your hips and palms are facing down. Press out through your heels and extend your legs 45 degrees, squeezing the backs of your knees together. Inhale and bend your heels back into your body. That’s one rep.Inchworm Plank: Begin in a full plank position with your hands and feet positioned shoulder width apart and your core is tightened. Begin to slowly lift hips as feet “walk” in toward your hands, taking small steps on the balls of feet until hips are in a full pike position. Walk back out to start position. That is one rep.