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How to do a side crunch — one of the best exercises for the obliques

a photo of a woman doing a side plank
(Image credit: yacobchuk)

In what can seem like a never-ending quest for middle whittling, there are some basic core moves you should ab-solutely be doing (see what we did there?). 

Seriously, though, tummy-toning theories aside, if your goal is a slimmer waist, then the side crunch should definitely be part of your abdominal repertoire. Why? Well, when it comes to ab work, you need to make sure you challenge all the muscles in the core region (there are four main abdominal muscles (opens in new tab)). And it turns out the biggest ones — the obliques — wrap around the side of your body.

“Most core exercises focus primarily on the anterior portion of your abdominals, the rectus abdominis,” says Triana Brown, Senior Manager of Talent and Product Development at [solidcore] (opens in new tab). “The side crunch allows you to target the obliques, lateral muscles which tend to be underutilized and weaker.” 

In other words, if you want to get a handle on your middle, you may need to come at things a little sideways.

Looking for more workout inspiration? We've found the best ab workouts here, as well as the exercise that is better than crunches and sit-ups at sculpting your abs, and the ab exercise that targets the deep core muscles.

Why work the obliques?

Aside from wanting to tighten your belt a couple notches, there are very practical reasons for strengthening your side abdominal muscles. 

The internal and external oblique muscles are responsible for lateral flexion and rotation of the torso, meaning they facilitate movements like reaching sideways to scratch your leg or throwing something heavy over your shoulder. “The obliques help stabilize and protect the spine,” says Brown. “Strengthening these muscles will make daily movements more efficient.”

On an aesthetic level, depending on an individual’s diet and body fat percentage, toned obliques can help give the appearance of a trimmer waistline. Coupled with a developed rectus abdominis (which is the most superficial muscle contributing to the six-pack look), defining the obliques will clinch your midsection cinch. 

How to do a side crunch

Proper form is important to get the most out of this—or any—exercise. Here’s how to do it right!

Step 1: Lie on your left side. Head rests on the mat. Extend legs long, stacking your hips and legs, right over left. 

Step 2: Extend your left arm straight out from your shoulder so it’s perpendicular to your body, palm touching the floor. Curl right arm up to your head, bringing fingertips lightly behind your right ear. 

Step 3: Using your left hand as an anchor, contract your right oblique muscles to lift your head, shoulder, and torso towards the ceiling. Bend your knees as your right elbow drives towards right hip, pointing towards your heels.

Step 4: Slowly lower torso and legs to starting position. 

Step 5: Complete 7 to 10 repetitions before switching sides.

For best results, Brown suggests you incorporate this exercise into your workouts two to three times a week. Start with three rounds of 7 to 10 reps on each side.

10 tips to get the most out of this move

  • If the move feels too difficult at first, modify it by not lifting the legs at all. Focus only on the lift of the head and torso by engaging the obliques. As that gets easier, try adding just the top leg, keeping the bottom leg stationary and glued to the ground. Eventually, build up to lifting both legs. 
  • Focus on bringing your right rib towards your right hip with every rep. Imagine squeezing an orange that is sitting slightly above your right hip. 
  • Don’t pull on your head. Use a light touch of the hand behind the ear to prevent any strain in the neck or traps. 
  • Try not to cheat by pressing your arm into the floor instead of using your obliques to lift you up! 
  • Exhale as you raise up, inhale as you lower down. Breathing correctly enhances efficacy. 
  • For more tension in the lateral/side portion of your oblique, keep shoulders and hips facing forward rather than the ceiling. For more tension toward the midline of your core, shoulders can rotate toward the ceiling slightly. 
  • Ready to make it harder? Add a pause at the top. When the elbow is close to the hip, hold for 1 to 3 seconds before lowering. 
  • Kick it up another notch by focusing on your tempo. Take 2 to 4 seconds to lift the torso. Hold for 2 to 4 seconds at the top. Lower down with control taking 2 to 4 seconds. Slow and steady wins the sculpting race. 
  • For the most advanced variation of this move, keep the legs completely straight as you lift up instead of bending the knees so it becomes more of a side V. 
  • As you notice progress (i.e. the reps become easier to accomplish or fewer breaks are taken between sets), apply amplifications, increase the rep count or add more rounds.   

Kimberly Dawn Neumann is a multi-published writer whose work has appeared in such outlets as Forbes, Cosmopolitan, Fitness, Women’s Health, Prevention, Redbook, Real Simple and more. A Summa cum Laude graduate of the University of Maryland’s College of Journalism, she is also a life coach and fitness professional with certifications from the Coach Training Alliance, the American Council on Exercise, and Yoga Alliance. This NYC-based overachiever has also published two books and performed on Broadway. She meditates twice daily to keep everything in balance.