Sit-Ups Vs Crunches: Why Are These Ab Exercises Bad For You?

By | August 10, 2011

Sit-ups and crunches are the 2 most commonly performed ab exercises. Since almost everyone who wants a flat stomach or 6-pack abs does them, they should be effective, right?

Yes, for damaging your back.
No, for training your abs.

Let’s take a look at each of these 2 ab exercises, to see how they cause more harm than good.


When performing sit-ups, the illiopsoas muscle is mainly responsible for flexing your torso towards your thigh. The illiopsoas is made up of 2 muscles: psoas and iliacus. The psoas originates from the lower back and the iliacus originates from the thigh bone. Both muscles end at the same point.

During repeated sit-ups, the illiopsoas pulls on the lower back while there is little or no ab engagement. This can cause lower back pain and poor posture. The constant flexing of your spine causes it to become weaker and prone to injury. In addition, your core muscles are not being trained to support and stabilise your spine.


Many people would have performed the crunch, not just once or twice, but countless of repetitions. They often do so by going into full spinal flexion. This puts tremendous load on the spinal discs, which can result in disc herniation or bulging.

“Realize that the spine discs only have so many numbers of bends before they damage,” says Dr Suart McGill, professor of spine biomechanics at the University of Waterloo in Canada and a back-pain clinician. Repeated spinal flexion and bending of the disc increase the risks of disc injury and back problems.

Spinal flexion can lead to a hunch back and/or protruding head. This is not only unsightly, but can eventually lead to poor posture and lower back pain. It’s no wonder that some of the guys at my gym who often perform endless crunches, have rounded backs.

Training the rectus abdominus with repeated sit-ups and crunches while ignoring other core muscles can result in a protruding belly. For good-looking, strong abs, you need to train all of the core muscles (obliques, transverse abdominus, rectus abdominus and back extensors).

A word of advice…

You should stop or avoid doing sit-ups and crunches:
- if you feel back pain after performing them
- if you suffer from lower back pain/injury or other back problems
- even if your back may seem healthy and you feel no pain from performing them (to prevent damage to your spinal discs)

Ab exercises that really work

There are many non-specific ab exercises that are more effective than sit-ups and crunches, to train your core muscles. Not only do these exercises help to develop flat or six pack abs, but also improve core strength and stability. Check out –> Ab exercises that really work

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