The Return of the Sit Up?
Whaaat?!?!
Sit ups and crunches are one of the most unproductive exercises you can do to work your core. If you think about the most important functions of the core muscles you’ll likely end up with these 2 answers:
- Stabilize and protect the spine from excessive movement
- Force transfer from the lower body to the upper body
That being said, you can now appreciate why exercises that encourage motion at the spine are not the most productive ones when you want to work your core for functional and sports performance purposes. That’s why exercises such as planks, belly presses, and chops and lifts variations are far better options.
But what if sit ups and crunches actually served a purpose?
Before you ask, no, I’m not crazy.
One of the big differences between exercises that recruit your trunk muscles isometrically (planks, etc), and crunches and sit ups is the shortening of the muscles during the exercise.
If you perform too many crunches and sit ups, there is a c0ncetric action on the rectus abdominis that will most likely shorten the muscle in the long run. Because of the rectus’ attachment on the ribcage, it might pull you into a bigger kyphosis.
The guy probably did too many crunches…
What might be beneficial with these exercises might be more in regards to the oblique muscles. During a sit up or a crunch, the obliques pull the lower ribs down via their upper attachment, and posteriorly tilt the pelvis via their lower attachment on the illiac crest.
For somebody who presents with a significant rib flare and an anterior pelvic tilt, it might not be a bad idea to include a low volume of these “evil” exercises with a rehab purpose to correct the issue. We’re not talking about doing 100′s of crunches per day here.
This really is the only situation in which I might consider using a couple sets here and there with an athlete, though.
For this purpose, I like the straight leg sit ups for the way it recruits the internal and external oblique.
But again, this is something I would use only for rehab or prehab purposes, and the bulk of my core work would still be variations of planks, belly presses, un-even carries, etc.
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[...] was thinking about this while writing my last post The Return of the Sit Up?. It’s funny how trends change in the fitness industry. One day HIIT (high intensity [...]
can you please be more specific about why do you think that straight leg sit ups can be a good benefit in a rehab or prehab situation?
I dont see any benefit but I´m looking forward for your explanation.
My comment is you have to have a great deal of mobility in order to do this movement. Great hip mobility on both hips left and right – flexion and extension-, great muscle elasticity on your posterior chain, etc…
that´s my view of this exercise. perhaps in a person with gret mobility it can work but.
i´m looking forward to reading your explanation.
thank you
Luis Iglesias (Spain)
Luis, like I mentioned in the post, the downward pull of the internal obliques on the ribcage, and the contribution to posterior pelvic tilt of the external obliques are the 2 main reasons why I feel this CAN be a beneficial exercise in the cases of people with a significant anterior pelvic tilt combined to a vicious rib flare. I’ve seen good results with it recently even though it’s far from being a staple in my programs.
Hope this helps.
David