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Why crunches are a waste of time - and what to do instead


Crunches essentially target one core muscle – the rectus abdominis – by flexing the trunk in what is basically an ‘isolation’ exercise.

The rectus abdominis (RA) is a superficial muscle (known as the 6 pack muscle)  – it lies closer to the surface of the skin – which is why we can see it – and why most people target it.

 It does NOT actually:

- flatten the stomach

- heal abdominal separation (diastasis recti)

- alleviate back pain

- help pelvic floor issues

In fact - when worked mostly in isolation (when doing crunches or sit ups for example) it can make all of these issues worse.


Here's why:

Around every joint (including the spine and for the sake of this conversation, the ‘core’), there are  inner or deeper muscles, and there are some outer, or superficial muscles. 

It’s the inner unit muscles that provide stability at a joint, and do all of those things listed above.

And the rectus abdominis is an outer unit muscle. 


After we've had our babies (no matter how long ago)  it’s the deeper muscles of the core and spine - like the transverse abdominis and pelvic floor - that create stability, flatten the stomach, alleviate pain and close abdominal separation. 


When you’re pregnant it's recommended we avoid sit ups and crunches. Here's why:



The rectus abdominis attaches to the pubic symphysis – which, if de-stabilised during pregnancy, will cause pelvic girdle pain. 

Every repetition of a crunch is a contraction of the rectus abdominis – which means it pulls at the pubic symphysis. 

If it's unstable from hormonal changes, this can cause aggravation as the pubic symphysis won't be stable enough to withstand the line of pull.



The RA has a line of tissue running down the centre called the linea alba.  This widens and loosens during pregnancy to make room for the baby –  in severe cases it’s typically known as abdominal separation or DRAM.  A tighter rectus abdominis (which is of course what happens to a muscle if you exercise it) can cause a larger separation and can be harder to rehabilitate post pregnancy. 


Post pregnancy –

If you have some form of abdominal separation (diastasis recti) then a traditional crunch or sit up will exacerbate the gap.  As you're doing the exercise you'll either feel the gap increase, or you'll get a 'coning' shape down the line of your torso.

The aim when healing the core is that the muscles lift everything up and in.  This ensures there's no pressure on the pelvic floor or spine, that the pelvic organs are aligned correctly to avoid leaking and prolapse, and that diastasis recti heals.

When we perform a sit up without the inner unit working properly - our bodies push everything in our torso out and down.  Our belly pushes outward, which exacerbates abdominal separation, as well as placing pressure on the pelvic floor and organs.


What to do instead?

Deep core exercises that properly engage the pelvic floor, transverse abdominis and other muscles in the inner unit.



The Core and Pelvic Floor program takes women through 3 stages of exercise from core healing to core strength and performance. 

First month half price for a limited time.  No contracts. Get started for just $24 today.



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