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Category: Anatomy & Physiology (Page 2 of 2)

Hey Fitness People, Let’s Talk About the Serratus Anterior

Last updated: October 5, 2021

You can never know enough anatomy.

If you know your anatomy, you can apply it in unlimited different ways.

The problem is that schools don’t always go very in depth into anatomy. Trust me, I’ve been there (for nine years). My desire to change this was why I taught anatomy to exercise science students for two years.

One of the most neglected muscles in school anatomy curricula these days is the serratus anterior. I want to take you through the basic attachment sites, a few reasons why you should care, and then I’ll leave you a few ways you can train this muscle.

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Posture and Senses

In preparation for the Postural Restoration Institute course I’m doing this weekend, I have been reading through some of the course’s references.

Today, I wanted to talk about one I just read that shows you why sensory information is so important.

Inglis, J. T., Horak, F. B., Shupert, C. L., & Jones-Rycewicz, C. (1994). The importance of somatosensory information in triggering and scaling automatic postural responses in humans. Experimental Brain Research, 101(1), 159–64. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/7843295

This piece of work compared normal people to people who had lost feeling in both of their legs from having diabetes.

What they did was they had the subject stand on a piece of floor that was yanked out from under them. It moved 6cm backwards, causing a forward lean of their body relative to their feet. You can imagine how startling that might be. They wanted to see how these subjects responded to this postural sway. What they found was that people with less sensation in their lower legs:

  • Take longer to respond to postural demands.
  • Don’t respond as appropriately to postural demands when the ground moves faster.
  • Don’t respond as appropriately to postural demands when the ground moves further.

 

Longer Response Time

These people might appear slower or take longer to get things done because they can’t gauge the demands placed upon them as quickly as those with full sensation.

The figure below is a good visual of this finding. Each set of bars is a different muscle (three in total). The asterisk means the findings were statistically significant. The higher gray bars means it took more time for people with less sensation in their legs to respond to the moving floor.

The asterisk means the results were statistically significant. Higher bars means it took more time to respond. GAS = medial gastrocnemius, HAM = biceps femoris, PAR = paraspinals at the level of the iliac crest.

Less Appropriate Postural Response

As the demand for adjusting posture increases, people with less sensation don’t respond to the same extent as those with normal sensation. If the floor moves out from under you slowly, you would react with less UMPH. The patients have more UMPH (they try harder). If the floor moves quicker, you would scale your response to be stronger.  The patients don’t scale as well.

Think of this in terms of unpredictable slipping-and-falling accidents.

Now with respect to how far the ground moves out from under them, they tried harder than people with full sensation in their legs, but they didn’t adjust as well according to how far the platform was moving. These people were all over the place with their postural responses.

Also worth noting is that they produced higher forces, so muscular weakness is unlikely to be the cause of their postural response issues.

 

Interpretation

This is a simple study that shows the importance of sensory information. When we start talking about sensation, my brain immediately goes to the right foot.

Due to our asymmetries and our desire to stand on our right legs, the right foot turns outward (supinates). If it stays out there, then my right foot’s inside arch and big toe don’t get much sensory information.

Given this, it’s likely that their postural responses will not be as appropriate as someone who has “found” the floor. It’s not likely that they will fall, but they will have poorer responses.

These people might get tired more easily and react more slowly because they’re trying to hard and doing too much. Those muscles are freaking out when they don’t have to because their feet are telling them to do so.

 

Practicality

This is why we have to think about sensation when coaching. So if that right foot is rolling outward, tell them to stick it to the ground like a tree’s roots in the ground. Spread your toes out.

Just last night I had a client who showed this. She’s having trouble getting her right glute max to work when it should, and it makes her right knee hurt when she squats.

When I asked her to show me her squat, her toes start singing and dancing. As she squats down, the toes come up. Squat up, toes back down. It’s like I’m watching a game of Whack-A-Mole.

But when we cue her right arch to stay on the floor, her toes go down on both feet.

The sensation tells her feet that they can relaxxx. It also tell that to every other part of her body.

When you’re coaching someone, make sure you give the feet the respect they deserve.

You Want to Give Me a Mouthpiece for My Foot Pain?

UPDATE (11 Dec 2013): Click here to see more recent research.

The problem with having specialists in so many different areas these days is that the whole problem gets neglected.

Steve has foot pain. He’s referred to a podiatrist who says, “We need to open up your foot.” Foot pain comes back after surgery because his flat feet are being driven from the top down: an anteriorly rotated innominate, internally rotated hip, knee valgus, and excessive pronation at the feet.

But how far can we extend connections like these?

It’s not too difficult to get from the hip to the foot. Brian Rothbart doesn’t stop there. (2008; Rothbart 2008)

Poor “teeth coming together-ness” associated with foot position. If that isn’t cool, I don’t know what is.

Rothbart looked at the foot, the hip, and the cranium and drew relationships between them all. The summary is that when you look at a person (more specifically, a young Mexican subject), their more pronated foot is associated with shorter vertical facial dimensions on the same side.

Looking at it in more detail, a pronated foot is linked with an anteriorly rotated innominate via the mechanism I mentioned above. It is also associated with an anteriorly rotated ipsilateral temporal bone (think bringing the mastoid process up and making it less palpable, a.k.a. counterclockwise rotation in the photo below). The sphenoid is pulled downward, and the maxilla is pushed upward. There we have it: short face! There’s a helpful radiograph in the article linked above.

The skull
A right innominate

Pelvic bones and temporal bones look pretty similar, don’t they?

He briefly mentions a fix for malocclusions. Check out the video below for an introduction to Advanced Lightwire Functionals.

The DO lady in that video mentioned using the ALF to treat people with autonomic problems. The central goal of the Postural Restoration Institute – as I understand it – is to get at the nervous system. We want the body to have sufficient variability to do what it wants to do. We don’t want to be stuck on our right leg. We don’t want to be stuck in extension. We don’t want to be sympathetically toned up. Realigning your temporal bones, innominates, and feet are just neutrality acting on the nervous system.

Consider another article from Rothbart (2011) where he describes a foot condition.

On a side note, does anyone have a problem with him naming this condition after himself?

In people with Rothbarts foot, the first ray (that is, metatarsal up through big toe) hovers over the ground even when the talus is neutral. The big toe can’t feel anything underneath it, so when walking, the foot pronates hard to “find the floor”. These videos on rearfoot varus and forefoot varus can help you picture it.

The neurophysiological model which Rothbart proposes helps explain why proprioceptive insoles can make people better. Contrary to traditional orthotics that offer support, these insoles simply give the foot something to feel. Rapid pronation every time your heel strikes the ground holds the body in a state of extension. Good input on the bottom of the foot sent up to the cerebellum helps keep the person’s system neutral.

And as we already talked about, this can help a lot of things. From feet, to hips, to teeth!

Make sure you step back and look at the whole person when you’re helping them; getting too focal traps you into the specialist mindset. Better to be the person who sees everything than the person who misses the big picture.

References

Rothbart, B. a. (2008). Vertical facial dimensions linked to abnormal foot motion. Journal of the American Podiatric Medical Association, 98(3), 189–96. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/18487592

Rothbart, B. A. (2008). Malocclusions Linked to Abnormal Foot Motion. Positive Health Online. Retrieved from https://www.positivehealth.com/article/bodywork/malocclusions-linked-to-abnormal-foot-motion

Rothbart, B. A. (2011). Primus Metatarsus Supinatus (Rothbarts Foot): A common cause of musculoskeletal pain – Biomechanical vs Neurophysiological Model. Podiatry Review, 68(4), 16–18.

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