To crunch or not to crunch, that's the question

There is a lot of crazy advice out there on the internet.

After all, that's one of the main reasons that you guys look to me – for sound advice that is backed by credible science.

One of the craziest recommendations that I am seeing lately is fitness "experts" warning that crunches are DANGEROUS!

What?!

Yes, there is an entire camp of fitness "experts" that claim that crunches are bad for your spine and that you should completely stop doing them. In fact, over a year ago our online editor for muscleandfitness.com posted an article by a so-called fitness expert that warned our readers against doing crunches. I was horrified when I saw the article on our website and had the online editor remove it promptly. I was shocked that anyone would be so idiotic to think that doing crunches is bad for your back. That's like warning people to stop doing curls because they are bad for your elbows! But I quickly learned that this guy was not alone and that there is a whole slew of fitness "experts" claiming the same ridiculous thing.

But don't just take my word for it.

Luckily, the National Strength & Conditioning Association's (NSCA) Strength and Conditioning Journal published a review paper on whether or not the crunch is a dangerous exercise. Here is a summary of what they found:

There is research showing that when you flex your spine forward, like you do when you do a crunch, it can cause damage to the spinal discs.

However, all of this research was done in animal spines and in vitro! In vitro basically means "outside the body". So basically these studies were done in isolated animal spines. There are many problems with this technique.

For starters, the majority of these were done with the cervical (neck) portion of pig spines and not even the lower back portion.

There is a big difference between the spine in your neck and the spine in your lumbar (lower) back. A BIG difference!

Another problem is the fact that in the body there are muscles that support the spine and take much of the load and reduce the stress on the spine and discs.

There are no muscles working with the spine in an isolated animal spine.

Another issue is that when you do a crunch you increase the pressure inside the abdominal cavity.

An increase in pressure inside the abdominal cavity reduces the stress on the spine and discs. An isolated animal spine has no abdominal cavity working with it and therefore no extra pressure to support it.

So most of these fitness "experts" claiming that crunches are bad for your spine are making these conclusions based mainly on this ridiculous research in pig cervical spines.

What they forgot to read were all the studies showing that flexion of the spine is actually beneficial to the discs, as the Strength & Conditioning Journal article points out. Research shows that flexion of the spine increases nutrient delivery to the discs. And research also shows that exercise programs involving spinal flexion have been proven to reduce low back pain and increase flexibility of the spine. Not to mention that the ONLY way to increase muscle hypertrophy of the major midsection muscles – the rectus adbominis (the abs) and obliques as well as their strength is by doing exercises with resistance that involve spinal flexion!

So if you read in a book, or magazine, or online that you should stop doing crunches, get a good laugh, and ignore it.

Crunches and other ab exercises that involve flexing the spine are one of the healthiest things you can do for your back and your body.

In my opinion, I think that these fitness "experts" that warn against crunches are just looking for excuses not to train their abs.

And I'll bet that the majority of them have less than impressive abs.

A few tips on when not to do crunches:

Do not do crunches within the first hour of waking up.

When you sleep, loading on the discs is reduced. This allows them to absorb more fluid. When you wake the pressure inside the discs is 240% higher than before going to bed. This increases bending stresses at the discs by 300%. As the day goes on, the discs become more elastic and flexible in bending. If you workout when you first wake up, do your ab work at the end of your workout.

Do not do crunches after prolonged sitting.

After sitting for long periods discs gain height and decrease lumbar range of motion, which can increase the risk of injury. So if you sit at a desk all day and then sit in your car driving to the gym, do not train abs as soon as you get to the gym. At the very least, warm up on the treadmill for 5 or 10 minutes. Or better yet, save the ab training for the end of the workout.

Reference:

Contreras, B. and Schoenfeld, B. To crunch or not to crunch: An evidence-based examination of spinal flexion exercises, their potential risks, and their applicability to program design. Strength and Conditioning Journal 33(4):8-18, 2011.

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