Crunches: Your Friend or Foe?



Let’s talk about crunches today -shall we??  Recently at the gym, I’ve had women telling me that they have read somewhere along the line that “all crunches and sit ups are bad for you.” So, I thought it was time to bring this subject to light.  While crunches and sit-ups (when done properly) aren’t necessarily “bad” for you, it’s a bit more complicated than that, and there are in fact times when they should be avoided.

Crunches and sit-ups are usually the “go to” exercises that many postpartum women resort to as a means to strengthen and “shrink” their midsection after pregnancy.  However, sit-ups and crunches aren’t generally recommended for postpartum women, especially when a Diastasis Recti is present.

Why? Well, to catch you up to speed –a Diastasis Recti is a separating and stretching of the abdominal muscles and weakening of connective tissue that joins the abdominal wall along the midline of your body, so you are left with a gap between the two sides of the abdominal wall and a core that doesn’t function well.  Diastasis Recti occurs during pregnancy as a result of hormones and increased pressure from the growing uterus pushing out against the abdominal wall.  A “DR” is actually pretty common among most prenatal and postnatal women and it’s nothing to be overly panic stricken about.  I’ve had a Diastasis with all three of my pregnancies, and most of my postnatal clients show some degree of a Diastasis Recti as well.  Just know that more often than not it can be healed with time and proper rehab exercises.

Now, getting back to why sit-ups and crunches aren’t appropriate for a postnatal mama! Sit-ups and crunches, when done poorly, can severely increase the intra-abdominal pressure of your core.  This increased pressure needs to go somewhere, and so it ends up pushing your organs outwards against that gap we previously talked about, and downwards onto your pelvic floor.  Think of your core as a softly inflated balloon.  Now think about what happens when you squeeze that balloon.  The pressure in the balloon (your core) has to go up, down, and sideways.  Believe it or not, you can actually see how you’re doing more harm than good to your core when doing crunches with a Diastasis Recti present.

If you look straight down and watch your belly as you perform a crunch, you will more than likely notice a doming, bulging, or pooching of the belly at its midline when you crunch up.  This is a CLEAR sign that things aren’t working right in your core and that you have a Diastasis Recti that needs to be fixed.  This can actually occur even years after you have had your baby!  And so -this is why I generally recommend against crunches or sit-ups until you have restored proper functioning of your core and pelvic floor, and this musculature is strong enough perform these movements correctly.

Another point to add to the discussion is that there are some physical therapists out there that will prescribe a modified version of a crunch (the curl-up) for their postnatal patients at some point during their recovery.  The thought process behind this is that the sheer motion of a curl-up (forward flexion of the spine) engages, shortens, and strengthens the most superficial abdominal musculature -the rectus abdominis -which has been stretched lengthwise as well as lateral wise and weakened as a result of pregnancy.  But here are a few big takeaways to keep in mind about this:

  • The physical therapist will most likely only prescribe a curl-up after his/her patient has shown that she is able to properly recruit the deepest muscles (diaphragm, pelvic floor, transverse abdominals, multifidus) of the core first.  It’s imperative that the mind-muscle connection of these muscles is re-established first so that proper stabilization of the spine and pelvis can occur, healing of a Diastasis Recti can take place, and the rest of the surrounding core musculature can do what it’s supposed to do and not have to compensate for the inner core musculature.
  • The physical therapist is also able to monitor and ensure that proper technique is being used and the right muscles are being recruited.

As I mentioned earlier, the problem is that there are many incorrect ways in which women (and men) perform a crunch and this only leads to worsening a Diastasis Recti or causing the pelvic floor to become even weaker. Like I mentioned above, the intra-abdominal pressure within the core gets managed ineffectively and it has to go somewhere inside the core, pushing out on the abdominal wall or pushing down on the pelvic floor.  Oftentimes, women will perform a crunch while holding their breath, sucking in their bellies, or not engaging the transverse abs and pelvic floor.  Another thing you will often see, especially in CrossFit classes (where proper form tends to very much get thrown out the window for sake of the fastest time or most reps in a workout) is that people won’t even use their abdominal muscles anymore to do a sit-up because they are moving so fast, their butts start bobbing up and down off the floor, and the hip flexors and lower back kick in to do the majority of the work.

Despite what I’ve said above, I don’t think that crunches inherently are a bad exercise when done PROPERLY and PERIODICALLY/ IN MODERATION, and AFTER you have healed a Diastasis Recti.  But -most of the time they are done improperly and are performed WAY TOO often as a part of most people’s workout programs.

Something else to consider: most of us already suffer from a very slouched over posture through the shoulders and upper back from all of the sitting we do on a daily basis.  So why should we choose to do an exercise like a crunch that is only going to continue the cycle?  Remember, a crunch shortens the distance of the rectus abdominis (our 6 pack); so, by doing crunches we are only allowing ourselves to be pulled into an even more forward, slumped over position.

In the end, there are FAR MORE effective ways to train the core besides sit-ups and crunches.  Focus instead for the most part on exercises that require you to have to stabilize the spine and pelvis.  These exercises will give you much more bang for your buck than sit-ups and crunches.


I realize that many of you just can’t seem to shake these exercises, so let’s go over a few pointers for how to properly do a crunch, and signs or symptoms to look out for that will tell you that your core isn’t just right yet for these or many other exercises.  Please notice one other thing: I have veered away from discussing sit-ups because -well -these are just plain bad for the lower back.  The lumbar spine is not made to flex as much as is required for a full sit-up.  At least with a crunch, you are primarily flexing the thoracic spine, which is built for a bit more flexion.  Anyway, let’s continue on –

  1. First and foremost, you need to be able to engage your deeper core muscles effectively. To see if you are able to do so, try this little exercise on for size:



  • Lie on your back with knees bent up and feet flat on the floor. Place the heels of your hands on top of your hip bones and then place your fingers in the space right above your pubic bone.
  • Inhale through your ribcage and feel your pelvic floor expand. On your exhale, pull the pelvic floor up and SOFTLY draw the abs (space underneath where your hands are resting) in while engaging the pelvic floor. When you engage your pelvic floor muscles and transverse abs correctly, then you should feel a contracting of the muscle underneath your fingers.  This contracting of the abs should be felt as a downward motion and not a bulging or pushing out on your fingers.
  • If you find that your stomach pushes out when you do this, or you are holding your breath or straining to do so, then your transverse abs are not engaging properly, and some isolation work needs to be done to make sure they are firing properly.
  1. DO NOT hold your breath.  Inhale before you crunch.  Exhale and engage as you are crunching.
  1. SLOW DOWN and take your time so that you can focus on your breathing and engaging of your transverse abs and pelvic floor.
  1. Start out small with your intensity/range of motion and levers (outstretched arms, legs straight, one leg in the air, both legs in the air, holding a weight, etc.). At first, only focus on SLIGHTLY lifting your shoulders and head off the ground with your legs bent and feet flat on the floor.  If you can’t engage your transverse abs and pelvic floor with even this smallest bit of range of motion, then you sure as heck won’t be able to properly engage the core with even greater range of motion and longer levers, and have no business doing so either.
  1. Other signs or symptoms that you aren’t ready for crunches or more strenuous exercises:
  • Pain in your lower back, pelvis, abdomen, or hips.
  • A bulging or doming ANYWHERE along your abdomen during exercise.
  • Any feelings of heaviness or bearing down in the pelvis.
  • Any bulging from the vagina or rectum.
  • You leak urine or feces when you laugh, cough, sneeze, you leak urine as your rushing to the bathroom, or with any other activities of high impact like jumping or running.

So, in sum, I generally do not recommend that my prenatal and postnatal clients do sit-ups or crunches. If their cores and pelvic floors are fully rehabilitated following pregnancy, we may be able to talk about gradually incorporating a FEW crunches sporadically into workouts. However, proper form is crucial. You will have worked very hard to get your core and pelvic floor back and in good shape -and it would be a great shame to undo all the progress you’ve made.

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