Crunches are a mom’s go-to exercise to try to get her belly back. But no matter how many she does or how hard she tries they simply don’t get the job done. A flat belly seems elusive.

This mommy mystery is usually chalked up to stretched–out muscles, laziness (arrgh-never call a mom lazy), or just “the way it is” after having a baby. But the culprit may lie in a mom’s attempt at a solution-the crunch.

The abdominals connect the ribs to the pelvis, and are separated into layers. A crunch primarily strengthens the two superficial layers of abdominals. The first, most superficial layer, is the Rectus Abdominis. When toned, the Rectus creates the 6-pack. The second layer includes the External and Internal Obliques, and they will define a waistline when strong.

Sign me up, that’s exactly what I’ve been looking for. So what’s the problem?

The Core, which includes the deepest abdominal layer, the Transversus Abdominis (TA) is responsible for contracting before the crunch begins to maintain the position of the pelvis. This gives the Rectus and Obliques something sturdy to pull against to lift the upper body off the floor. Without an active Core, the pelvis will give in to the pull of the Rectus and Obliques, tipping the front of the pelvis up toward the ribs. The result? The abdomen collapses and resembles an accordion as you pull up into the crunch. Repeat crunches WILL train the Rectus and Obliques, but it trains them to be shaped like an accordion.And nobody likes a polka.

Pregnancy takes a toll on all of the muscles of the Core (there are three others in addition to the TA), and without specific exercise to reorganize and wake up a Core after pregnancy, it can stay asleep for years, even decades after having a baby. Crunches won’t awaken a sleepingCore, they will actually reinforce its slumber. Overtime, that tipped-up pelvis that comes from repeat crunches becomes the norm and actually shortens the distance between the ribs and front of the pelvis. This pulls moms into a postural slump to the front and tucks the bum under in the back. Studies have shown that in a tucked-under bum posture, the Core is dormant.

Disappearing bum, lousy posture, accordion belly, sleepy Core…sound familiar?

So what’s a mommy to do?  First, no more crunches.  If you want a flat belly, activating your TA is the key.  The TA contributes to keeping the pelvis and spine sturdy, but it also flattens the abdomen and cinches the waist. Often women are told to “hollow” their belly or pull the navel to the spine to activate the TA.  Beware, this often leads to tucking the bum under, a major Core no-no.  Instead, focus on deep lower abdominal tensioning at the end of a long exhale for accurate activation of TA.  Once your Core is awake and active again, choose safer and more effective abdominal work like planks, side planks and swimming.

Finally, become aware of your posture throughout your day.  Alignment is critical to the activation of the Core. A few great planks cannot beat an entire day of slouchy, tucked-under posture that keeps the Core quiet. Instead think of posture as your new gym and a big part of your Core conditioning program.

Now a flat belly is within your reach.

If you have any questions, please feel free to contact me at julie@interiorfitness.com. Follow me @interiorfitness .