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  • Writer's pictureJen Curtis

Prenatal Fitness Series - #4

Prenatal fitness dos and don'ts series

Pre- and Postnatal fitness is not usually as black and white as people make out. Most exercises have good and bad aspects, and will be appropriate for different people.

In this series we're going to look at specific exercises and the pros and cons of doing them during pregnancy, so that you can decide for yourself if it's worth it.


PROS - Requires no equipment - Requires little instruction - If you are in the early stages of pregnancy and your belly is totally flat and fully functioning and you have no pelvic floor issues, the crunch may have some value in strengthening/using the rectus abdominus (6-pack muscles).

CONS - If you are in the later stages of pregnancy and you are starting to show or have a huge belly with a growing baby inside, your abdominal muscles will not be working properly to flex the spine as they are stretched around a bump. You will likely stretch the connective tissue more and cause/worsen a diastasis recti (DR, or separation of the abdominal muscles) and/or use other muscles to compensate.

- many women do crunches incorrectly: they hold their breaths and bear down as they do the movement. This can put tremendous pressure on the pelvic floor and cause a whole host of dysfunction. - If you are still in the early stages of pregnancy but have DR from a previous pregnancy, you will not be able to perform this exercise safely. If you cannot contain the pressure in your abdomen, your belly is likely to pop out, like in the pictures below. If this is happening, you are doing more damage, widening the gap between your abdominal muscles. - If you have any pelvic floor issues (this could be peeing yourself when you sneeze or run, or POP - pelvic organ prolapse, or even just mild pain, discomfort or heaviness) you will likely be pushing all the pressure down onto the weak pelvic floor, worsening your condition. - If you have poor posture and are hunched over from feeding and carrying your baby, or work at a desk most of the day, this is going to make your posture worse, reinforcing those bad habits.

CONCLUSION Crunches were hugely popularized quite a few years back when we realized that full sit-ups using a lot more hip flexors than "core". Pilates has further popularized this exercise, but the truth is it really has very little value in strengthening the core. The crunch really only strengthens spinal flexion - and while it can be part of a well-rounded training programme, it gives you little bang for your buck and there are many exercises that are much more effective at training and strengthening the core. In truth, spinal flexion is just one movement that the core muscles are capable of producing (along with side flexion, extension and rotation) and really their forte is in stablizing us centrally (proximal stability) while we create movement outwards from this base (distal mobility).

The fitness industry has moved away from this kind of training and focuses more on planks and functional training, but the legacy of the crunch still remains and it is difficult to convince women not to do it. Often, they love to "feel the burn", even if it is doing little to really get them the flat stomach they crave.