Back Health and “Six Pack” Abs: Anti-Extension at it Finest

My previous post outlined the various movements that your spine is capable of going through.  I also talked at length about how core function ultimately comes down to “anti-movement” rather than creating movement.  This means that the most basic function of your core musculature is to stabilize the spine and resist excessive movement outside of neutral.  This point can not be understated, and it is one of the most misunderstood topics in fitness today.  My most recent post broke core function down into 4 main components of anti-movement- Anti-Extension, Anti-Flexion, Anti-Lateral Flexion, and Anti-Rotation.  Today’s post will more closely examine the commonly-used component: Anti-Extension.

What is “Anti-Extension?”

Anti-Extension is your ability to resist the lumbar (lower back) spine’s tendency to move into an excessively extended position.  In my introduction to core anatomy, I mentioned that most people live with a slightly extended lumbar spine position, and this is completely normal.  Those of us who spend much of our day on our feet- construction workers, personal trainers, professional athletes, etc. live in slightly more extension than normal, while those who spend much of their day sitting at a desk live in a slightly less-extended position.  Regardless of where you start though, the idea with core training is to get as close to neutral as possible and to stay there while you train.

To get an idea of what anti-extension feels like, get a partner and face each other.  Extend your arms straight out in front of you with your hands about shoulder height while your partner does the same and put your palms against theirs.  Have your partner gently push into your hands and don’t let them knock you backwards.  If successful, have them push a little harder, a little harder, etc. until you’re unable to maintain a nice tall posture.  Your partner was exerting an extension force on your lumbar spine and your core musculature (along with your arms, shoulders, etc.) was creating an anti-extension force to keep you upright.  Notice, you didn’t have to think about this too much.  It just happened.  That’s the beauty of normal abdominal function– when core muscle function is working properly, it happens at a subconscious level that does not require much thought.  There is a fantastic internal feedback mechanism at work where you sense a force placed on your body, and your body simply reacts to it.  You don’t crunch, you don’t hollow your belly, you don’t “activate” your transverse abdominis.  You just don’t let yourself get knocked over.

What muscles are involved with anti-extension?

There were several muscle groups involved with the example above and the total muscle groups involved will depend on the exact task at hand, but let’s narrow this down to the muscle groups that are most directly involved with anti-extension forces:

The Rectus Abdominis (RA)
The beautiful, wonderful rectus abdominis.  When this muscle is strong and doesn’t have a bunch of fat laying over top of it, this is the “six pack” muscle that everyone desires.  The RA runs from the xiphoid process (tip of the sternum) and 5th, 6th, and 7th ribs all the way down to the crest of the pubic bone.  It is innervated by the inferior intercostal and subcostal nerves.  If you look the RA up in most texts, function of this muscle is said to be flexion of the trunk.  This is where crunches, sit-ups, curl-ups, etc. come from.  And indeed, the RA does flex the trunk.  But knowing what we now know about spine health, the trunk does not need to be flexed repeatedly during workouts.  The much more important function of this large, powerful muscle is to resist extension through the lumbar spine.

Transverse Abdominis (TVA)
transverse abs
This picture illustrates the layers present in your core musculature.  On your right side of the picture, we see the RA and external oblique muscles (more on the obliques later).  On your left, we see the RA removed, revealing two muscles that lie deeper, or closer to your internal organs.  These muscles are the Transverse Abdominis (TVA) and internal oblique.  The TVA has received a lot of attention in certain circles lately as a cure-all muscle for back pain and breathing disorders.  The problem with is that, like with the RA and crunches from years ago, people have now begun to try to isolate the TVA by practicing what is known as the draw-in method of core activation.  Basically, just suck your belly button in towards your spine and ta-da! you just “turned on” your TVA!! Congrats!  Except, wait, your back still hurts every time you stand or do anything….shoot.  The problem with this approach is that your TVA does not function by itself when you’re not thinking about it, nor does your RA, nor does any muscle for that matter.  Your muscles are constantly working together to perform every task you ask them to on a daily basis, so isolating this one particular core stabilizer is clearly the wrong approach.  Now, you should have the ABILITY to draw in your belly button, and if you don’t, further investigation is warranted, but nobody is getting strong doing draw-ins and nobody is getting out of back pain doing draw-ins.  Instead, one must learn how to properly stabilize the trunk through a process known as “bracing,” which recruits not only the TVA, but also the RA, the obliques, the spinal erectors, the paraspinals, etc. etc.  More on bracing later.

Stop Doing This:
This point should be pretty clear by now, but most people should not be doing crunches, sit-ups, curl-ups, etc. of any kind on anything close to a regular basis.  Research shows that a traditional sit-up imposes approximately 730 pounds of compression force on the spine (McGill). Common variations aren’t much better including the straight leg sit-up (788 pounds), bent leg sit-up (753 pounds) and cross-knee curl up (666 pounds).  It’s time that these exercises make their way out of regular exercise programming for good.  They treat the RA as if it ever functions in isolation outside of the gym (it doesn’t), and they put a ton of stress on the spine.  These exercises also tend to become very easy very quickly, making it necessary to constantly add repetitions or load to an already ineffective and dangerous task. Taking a risk-reward audit of any of these exercises shows a whole bunch of risk with very little reward.  Very similar or perhaps even better muscle strengthening can take place by getting rid of these exercises and all of their variations, and instead using…

Start Doing This:
Planks and the many variations of planks.  One of the most basic exercises to build anti-extension stability is known as the forearm plank.  Get into the same position you were just in for the anti-extension example above.  Standing tall, keep your eyes looking straight ahead and reach your arms straight out ahead of you.  Keep your posture perfect and now bend your elbows so that your hands are roughly in line with your head and your elbows are in line with your shoulders.  This is your plank position.  Keep that nice, tall posture and bring yourself down to the floor, supporting your weight evenly between your toes, elbows and palms, and now you’re planking.  Do not allow yourself to lose the position that you had while you were standing tall.  Some shaking and sweating is normal and to be expected, but allowing your lower back to sag towards the floor, or allowing your butt to hike up in the air is unacceptable.  If somebody took a picture of you from the side, and then turned that picture 90 degrees, you should look exactly how you did while you were standing.  It’s as simple as that.

Hold that position as long as you can, up to about 1 minute.  Once you can hold that position for a minute, it’s time to make the plank more interesting- Start by rocking your weight forward (towards your hands) and backwards (towards your heels), using your toes as a pivot point.  Again, nothing about your posture changes, just your weight distribution.  Once this becomes easy, try taking a step or two back away from your elbows without changing anything else and hold that position for long as possible.  Lengthening that lever arm makes the challenge on your core much greater.  Variations to this exercise are only limited by 2 things: 1) Your ability to maintain that neutral posture that you found while standing and 2) your creativity.

Planks and their variations are extremely effective at producing core muscle activity to enhance strength, endurance, etc., while also keeping the body where it wants to be- in a neutral spine position.  They produce significantly lower loads on the spine, resulting in a safer and more effective bang-for-your-buck workout.  The plank is far from the only exercise we’ll use to improve your extension stability, but they’re a great place to start.  Together with the other 3 components of core function, this extension stability will put you on the fast track to a healthier back, better fitness, and better performance.

A quick note about the “Six Pack:”  It doesn’t matter what exercise you choose- pick crunches, sit-ups, planks, hanging leg raise, etc.  Whatever exercises you choose to strengthen your core will only take you as far as your diet lets you go in terms of being able to see the definition in your abs.  You will NEVER out- exercise your nutrition, and no amount of sit-ups, crunches or planks will get rid of the extra belly fat that is covering the muscle.  Spot reduction does NOT work and “feeling the burn,” is NOT you burning fat.

My next several posts will take a similar approach to anti-flexion, anti-lateral flexion and anti-rotation training.

Thanks for reading,


Ultimate Back Fitness and Performance. Stuart McGill Wabuno Publishers. 2004. Waterloo, Ontario Soft Cover


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