Sure, everyone wants sexy six-pack abs, but the core muscles are responsible for much more than a few appreciative looks at the beach.

The core (composed of the oft-mentioned abdominals as well as the side, back, pelvic, and glutei muscles) provides a muscular framework that protects internal organs, aids movement, and lends balance and stability to the whole body.

To get a strong core, it's important to switch it up and keep the muscles guessing. Use the list below—broken down into bodyweight and gym equipment categories—to train the upper and lower abdominals, obliques, and work on deep core strength and stability (we termed this "stability" to keep it simple!). Mix and match the exercises to work on core strength, whether at the gym or working out at home.

Classic Bodyweight Core Moves

Medicine Ball

1. Med Ball Crunch

Lie face-up with knees bent and feet flat on the floor, holding the ball between palms with arms extended on floor behind head. Curl head and shoulders off floor, raising MB overhead and then in front of you as you sit up. Return to start position, raising ball overhead as you lower torso to floor.

Make it harder: Perform the sit-up holding the med ball at your chest throughout. At the top of your sit-up (when you're sitting up) perform a chest press by pressing the ball straight out in front of you. Keep you abs contracted and shoulders down.

2. Russian Twist With Med Ball

Sit with knees bent and together, feet flat, and hold a weighted ball in front of you. Lean back slightly and rest lightly on heels or lift feet completely. Rotate from side to side; touching ball to floor each time (turn your head to look where you're touching).

Targets: Obliques

3. Med Ball Plank

From a facedown position on the floor, place both hands on the medicine ball and push-up so your arms are fully extended, and legs are straight back behind you. You'll be in a high plank, except your hands are balanced on a ball, instead of the floor. Keep your abs tight, hips levvel, and shoulders down. Hold for 30 to 60 seconds.

4. Med Ball Woodchoppers

Stand with your feet hip-width apart, knees slightly bent, and hold the medicine ball with both hands. Bring the ball up and to the right on a diagonal so your arms are fully extended. In one fluid movement, bring the ball down and across your body to the left, allowing your back to naturally rotate to the left, and your knees to bend so you can get lower. You should finish with the ball about even with your left knee, your hips back, and your knees slightly more bent (ou do not need to be in a full squat). Return to the start position by bringing the ball up and across your body on the same diagonal. Repeat 8 to 12 times, then switch sides so you start on the left diagonal, and bring the ball down and to the right.

5. Med Ball Mountain Climbers

Being in a high plank position with both hands on the ball (for details on the plank, see above). From here, draw your right knee in to your chest, then your left knee in to your chest. Continue to alternate running knees to chest as quickly as possible while maintaining a tight core and level hips.

6. Reverse Med Ball Mountain Climbers and Plank

Begin in a facedown position with the med ball near your feet. Come into a high plank position with hands on the ground, wrists directly under shoulders, core tight, hips level, and legs fully extended behind you. Place one foot, and then the other on top of the ball so your feet are balanced on the ball. Stay here for 30 to 60 seconds to hold the plank.

Make it harder: From the plank position, bring right knee in to chest, then carefully place it back on the med ball and bring left knee in to chest. Continue to alternate as quickly as possible maintaining your balance throughout.

7. Med Ball Boat Balance

Sit upright with your feet on the floor, knees bent, and med ball close at hand. Bring feet off the floor and legs into a table-top position so your shins are parallel to the floor. Place the med ball on your lower shins, so it's balanced between your ankles and held in place by flexed feet. Lean back slightly for balance and raise extended arms to your side . Hold for 30 to 60 seconds.

8. Med Ball Twist

Lie faceup with legs extended and hold the ball at your chest. Raise legs straight up and contract your core (so you form an "L" shape). Extend your arms, lift your upper back a few inches off the ground, and rotate your upper body to the right, while your simultaneoulsy allow your legs to drop to the left. Return to center with extended arms, and bring arms to the left, while you allow your legs to drop to the right. Continue to alternate for 8 to 12 reps.

Make it easier: Instead of keeping your legs straight, bring them into a table-top position (shins parallel to the floor), and do not rotate your lower half.

9. Supermans With Med Ball Pass

Lie face-down on the floor, arms extended in a "T," and your right hand on top of the med ball. Raise up into a superman by lifting your upper back and feet off the ground a few inches and contracting your abs. Be careful not to put excess pressure on your low back. From here, pass the ball to your left hand by rolling it in front of you. While still holding the superman position, roll the ball back to the right hand. Continue to pass the ball from hand to hand for 8 to 12 reps.

10. Med Ball Toe Touch

From a face-up position, raise your legs straight up in the air (so your body forms an "L" shape). With the ball in both hands, extend it upward in the direction of your feet so your arms are fully extended. Holding this position, crunch up, raising your upper back a few inches off the ground, contracting your abs, and keeping your neck and shoulders relaxed. Roll back down and repeat, holding the ball in place throughout. Perform 8 to 12 reps.

Stability Ball

11. Stability Ball Crunch

Lie face up on a stability ball, ball under low back, with knees bent at a 90-degree angle. Cross arms across chest, feet flat on the floor, shoulder-width apart. Draw navel in, tighten glutes, and slowly crunch upper body forward, raising shoulders off the ball and tucking chin to chest. Slowly lower upper body over the ball.

Targets: Upper abdominals

12. Stability Ball Hip Thrust

Lie face-up on the floor with your knees bent and lifted over your hips, and place a stability ball between your knees. Extend your arms along your sides. Exhale and tuck your pelvis to engage the lower abs, curling your knees and ball toward your head and up toward the ceiling. When your hips are a few inches off the mat, slowly uncurl and return to start.

Targets: Lower abdominals

13. Stability Ball Knee Raise

Lie face-up on a stability ball, with your hips lower than your shoulders. Reach back and grab something stable, such as a bench. Lift and bend your knees so that your feet are off the floor and the lower parts of your legs point ahead. Using your abs and hip flexors, bring your knees toward your chest.

Targets: Lower abdominals

14. Stability Ball Upper Body Rotation

Place your feet on the ground shoulder-width apart and lean back on SB. Place palms together and extend your arms towards the sky. With your shoulders centered on top of the ball, rotate your torso and arms to the right, return to center, rotate to the opposite side.

Targets: Obliques

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15. Stability Ball Roll Out

Begin by placing your forearms on a ball and balancing your feet on the ground. This will look and feel like an incline plank. When you've mastered balancing on the ball, slowly roll the ball away from you by extending your arms out to a comfortable position. Roll back to starting position.

Targets: Stability

16. Stability Ball Pike

With your feet down, support your body in a push-up position with your lower legs on a ball. Raise your hips as high as you can toward the ceiling as you contract your abs. Hold and then slowly release back to starting position.

Targets: Stability

17. Stability Ball Tuck

Start in a pushup position, with your palms flat on the floor, shoulder width apart, and your shins on a stability ball. Pull your knees toward your chest, keeping your black flat and core engaged, until only your toes are on the ball. Straighten your legs to roll the ball back to start.

Targets: Stability

18. Stability Ball Crunch & Twist

Sit on the stability ball facing the wall, then lie back so the middle to small of your back is resting on the ball. Place your feet hip-width apart with your knees bent to a 90 degrees; cross your hands over your chest. Curl up and twist through the waist to the right, return to center, curl down. Alternate.

Targets: Stability

Gym Equipment

19. Hanging Knee Raise

Hang fully extended from a chin-up bar, palms facing out and your hands a little farther than shoulder-width apart. Raise your knees toward your chest, curling your pelvis upward at the end. Make it tougher by keeping your legs straight instead of bending your knees.

Targets: Lower abdominals

20. Cable Rotation

Stand with feet shoulder-width apart, knees slightly flexed, and toes pointing straight ahead. Hold a cable with both hands directly in front of chest, arms extended and shoulder blades retracted and depressed. Draw navel in, tighten glutes, and rotate body away from the weight stack using abdominals and glutes.Allow back foot to pivot. Slowly return to start.

Targets: Obliques

21. Long Arm Weighted Crunch

Lie on your back with your knees bent. Hold a light dumbbell in each hand and stretch your arms straight back behind you. Crunch your rib cage toward your pelvis.

Targets: Upper abdominals

22. Straight Leg Raise

Lie face-up on a bench with your glutes at its edge. Extend your legs, keeping them parallel to the floor. Grasp the sides of the bench, or near your hips. Keeping your legs as straight as possible, raise them slowly until you're in a jackknife position. Your head and shoulders shouldn't move. Make sure your abs do all the work. Unfold your body slowly, lowering your legs back to the start position.

Targets: Lower abdominals

23. Weighted One-Side Crunch

Lie with your knees bent and feet flat on the floor. Hold a dumbbell by your left shoulder with both hands. Curl your torso up and rotate to the right. Lower yourself; finish the set, then repeat, placing the dumbbell next to your right shoulder.

Targets: Obliques

24. Standing Torso Rotation

Stand with your feet shoulder-width apart, knees soft. Hold dumbbell with both hands, extending your arms straight out in front of you at about shoulder height. Contract your abs and twist to you right as far as comfortably possible, keeping your arms straight as you go. Reverse the motion by rotating all the way to your left to complete one rep.

Targets: Obliques

​25. Standing Cable Crunch

Attach a rope handle to a high cable pulley. Stand with your back to the weight stack, and hold the ends of the rope behind your head. Crunch down.

Targets: Upper abdominals

26. Seated Ab Crunch

Sit on the edge of a stable chair or bench. Place your hands in front of your butt, and grip the sides of the seat. Lean back slightly and extend your legs down and away, keeping your heels 4 to 6 inches off the floor. To begin the exercise, bend your knees and slowly raise your legs toward your chest. At the same time, lean forward with your upper body, allowing chest to approach your thighs.

Targets: Lower abdominals

27. Oblique Hanging Leg Raise

Grasp a chin-up bar with an overhand grip and hang from it at arm's length, with your knees bent. Keep your knees bent and lift your right hip toward your right armpit until your lower legs are nearly parallel to the floor. Pause, then return to the starting position, and lift your left hip toward your right armpit.

Targets: Obliques

28. Captain's Chair

Stabilize your upper body by gripping the hand holds and pressing your lower back against the back pad. The starting position begins with you holding your body up with legs dangling below. Slowly lift your knees in toward your chest. The motion should be controlled and deliberate as you bring the knees up and return them back to the starting position.

Targets: Stability

29. Bar Crunch

Hold a body bar, arms shoulder width apart and lie on a bench with your knees bent and your feet together. Extend your arms so the bar is directly above your chest. Without bending your elbows, crunch up by lifting your upper back and shoulders off the bench and extend the bar to the ceiling. Slowly return to start.

Targets: Upper abdominals

30. Incline Reverse Crunch

Lie on an incline board with your hips lower than your head. Grab the bar behind your head for support, or simply grasp the sides of the bench. Bend your knees slightly and hold your feet together. Raise your knees to your chest by lifting your hips and crunching them inward. Pause, and lower your hips back to start.

Targets: Lower abdominals

Don't forget that nutrition contributes to more than half (possibly even 80%) of the results. Without eating the right stuff (and maybe penciling in some cardio, too), those infamous "six-pack abs" won't happen, regardless of how many medicine ball crunches and pikes get done.

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