Are crunches and sit-ups the best exercises for getting a flatter stomach?
Updated: May 19
I used to be a crunch and sit up queen, back in the days when I wore neon g-string leotards over bike pants to teach fitness classes. ( You can laugh all you want, but it was super hot and fashionable in the ’90s ).
It used to be that 5 minutes of sit-ups, crunch variations for that burn-y feeling in your abs was seen as the best and most effective training to strengthen your core and flatten your stomach.
People would actually complain if I didn’t do crunches at the end of a class because then they “hadn’t worked their Abs.”
No More Crunches
I haven't trained crunches in years. Even I before I had a diastasis and needed to avoid them as I healed, there were lots of other core exercises that I preferred.
I almost never programme them for my clients either. They just aren’t the best or most effective exercise for core strength.
Crunches and sit-ups mostly work the front of your abs (the rectus abdominals) these are the muscles that you can see on people with 6 pack abs.
The 6 pack muscles are really just the outer layer of your core and are used to pull your body forwards and down when you are standing up (just like when you do a crunch).
These days most of us spend more than enough time bending forwards into flexion -
We are looking down at our phones, rounding forwards while driving the car or while holding and feeding a baby.
You don’t need to get stronger bending forwards.
What you really need is to strengthen all your core muscles and learn to control your inner core pressure if you want a firmer, flatter tummy.
Your deep core muscles function like a corset, creating stability in your hips and lower back.
If your Rectus Abdominal muscles get too strong, your Transverse Abdominals (part of your deep core) can become underactive , leading to hip and lower back pain.
For more info on internal core pressure read : How to really heal a Diastasis
What are Crunches good for?
Crunches are great for showing how you like to load your core and they are awesome for seeing an imbalance in your ab muscles.
All rectus muscles working in a crunch will cause your abs to bulge up.
If you are bearing down on your core and pelvic floor (because this is the easiest way for your body to create core strength) then you will see this as well.
As you can see here, my belly is bulging up as I put pressure downward onto my pelvic floor (-Hello to leaking when you cough or jump due to a stressed pelvic floor ) and just use my rectus muscles to crunch up.
When your deep core muscles are engaged and working together with your rectus, rather than letting it take over, the crunch looks like this.
You can see that my stomach is firmer and flatter and there is no bulging.
My pelvic floor is also a lot happier as it doesn’t have to work against the pressure from improper loading.
Given that you want to strengthen ALL your core muscles to get a flatter tummy, there are lots of other core exercises that are a better choice than crunches or sit-ups.
(The exception being if you have to pass a sit-up test for some reason like in the Police or Military).
If you do want to do crunches or sit-ups, because for some strange reason you love them, it all comes down to using the correct technique and proper core activation.
Crunches aren't a “bad” or dangerous exercise but there are so many other exercises that will help you build core strength and help you get a flatter belly faster.