We live in an age where rock-hard, six-pack abdominal muscles are the goal of many workout enthusiasts. We all want that washboard look, but which ab exercises actually work? There are two sets of muscles to target: the rectus abdominis muscles (the ones you engage during regular situps, that run from your sternum to your pelvis) and the transverse abdominis (the deepest ab muscles that wrap around the spine and help stabilize your core).

It’s important to remember that you can’t spot-reduce your abdominals. You have to lose the layer of fat over the abs for your abs to show through. Cardio workouts and a good diet are key to success.

Try these nine ab exercises as part of your overall fitness regimen.

Pilates targets your core muscles, working your abdominals in repetitive exercises. For instance, “the 100” is a modified crunch that you hold for 100 counts. There are also machines, such as the reformer, that strengthen and stretch your deep stomach muscles.

Perhaps all the funky looking equipment intimidates you. Luckily many gyms now offer Pilates mat classes. Pilates is low-impact, so it’s a great choice if you’re looking for a gentle joint exercise that is a killer ab workout.

Plank poses are very effective at tightening your tummy, whether you do these types of exercises in a yoga class or as part of your gym workout. The classic plank pose involves lying down on your stomach, then raising all your body weight up on your toes and forearms or hands in a “plank” position. You then hold the pose for as long as you can. You can change it up by doing a side plank (put all your weight on one forearm or hand and the sides of your feet), or by doing back leg lifts while in the traditional plank pose.

The sparring and jabbing you do while boxing engages both sets of ab muscles. Boxing is a solid option for overall fitness. Your midsection will transform when you focus on getting your form right. Many gyms offer boxing fitness classes, and your local boxing ring may have private coaches for one-on-one training.

Both balls and boards offer a way to further engage both sets of ab muscles, while doing simple exercises such as pushups and squats. Proper form is paramount when using these exercise balls and balance boards. Most gyms offer classes, so take advantage of professional instruction if you can.

You need to add fat-burning cardio into your routine to get your abs to show through. Pick an activity that interests and motivates you, such as running, walking, swimming, or spinning. Aim for either 150 minutes per week of moderate aerobic exercise or 75 minutes of vigorous aerobic exercise, per the CDC.

The bicycle motion works both sets of ab muscles. This exercise can help carve out a toned midsection when done with proper form. Be careful not to strain your neck when doing it.

Lie down on a mat and place your hands behind your head, gently supporting your head with your fingers without pulling. Bring your knee up to your chest, while rotating your upper body to meet your knee with the elbow of your opposite arm (see photo). The opposite leg will go straight out. Switch to the opposite side, “cycling” the legs. Do one to three sets of 12 to 16 repetitions each.

The traditional crunch is now largely considered an ineffective ab exercise and a potential cause of back pain. However, the pullup motion done in a “captain’s chair” (an elevated pullup chair) is still considered a highly effective way to tone your midsection.

This tried and true exercise involves hanging from a pullup chair and raising your legs in front of you, bending at the hips. Always be sure to use proper form. Lower your shoulders and lengthen your neck as your starting position.

This ab exercise is done standing up. Stand with your feet hip-distance apart and your hands on your hips. Twist your upper body to the right side, then go back to center. Repeat on the left side, then go back to center. Work up to three sets of 15 reps.

One way to add more to this exercise is to grab some small hand weights and place your arms out to the side while doing the twists.

You may not think of lunges as targeting your abs, but these exercises are very effective all-over body toners, especially for your “core” muscles. Stand with your feet hip-width apart, then step forward into a lunge position. Make sure to keep your back knee about 3 inches off the ground. You can add small dumbbells for a little more intensity.

Remember that it’s not all about spot-training when it comes to your abs. Keep your calories in check and work frequent cardio workouts into your routine. Keep your whole body in mind as you work toward an enviable midsection.