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Biomechanics and Posture

New Study Shows Peak Muscle Activation at 90 Degree Squat

The elephant in the room is that this study was performed using isometric maximal effort squats rather than a dynamic range of motion.  If these findings are only relevant in static positions, the concepts could be useful in the post-surgical setting.

If what is true for these isometric findings holds true for dynamic motion, it would direct box height selection in Box Squats as well as point out the need for some athletes to cultivate additional recruitment at end range.  Perhaps the use of Pause Squats or 1 and 1/4 squats at full depth for athletes (olympic lifters) who find themselves at angles approaching 140 degrees flexion.

Also, this could validate the use of partial depth squats and walkouts at above 1RM weight. . . interesting. . .

Here’s the link to the full text article-

Barefoot Running Part I: The Cheap Shoe Revolution

Taoist Proverb: “It is easier to put shoes on your feet than it is to wrap the earth in leather.”

I was not even familiar with the term “minimalist runner” when a guy on a mountain trail had the audacity to pass me while wearing a pair of rubber slippers.  I was only on mile 4 and working hard for it but I could see by his belt of empty bottles that he had run much further than that.  I chased him and his ridiculous footwear down and demanded answers to the following questions:
Q:  How many miles have you run?-
“18.” 
18?!!! I wasn’t letting him pass me now, not even at my car-  I ran all the way back to his car with him.
Q:  Isn’t gravel getting into your beige gardening slippers?-
“They’re Crocs and yes rocks get in but I stop every few miles and shake them out.”
Wow.  This guy was a beast.  It turns out that he competes in vertical marathons.  This guy runs up mountains in garden slippers for time.
I bought my beige Crocs at noon the next day.

I have always trained in indoor soccer shoes like Sambas.  Even with my excursion into Croc running, I personally have never fully committed to the barefoot lifestyle.  I fit into the much broader category of individuals who are intrigued by the idea.  Of those who enjoy the books and the blogs that trash the oppression of modern footwear technology but never totally follow those ideals into the filthy and sharp world of barefoot running.  I garden barefoot.  I sometimes deadlift barefoot.  I read books about barefoot running while barefoot but actually run barefoot?  No.  As I mentioned, it’s dirty and sometimes sharp out there.  I know my ancestors didn’t evolve in running shoes and barefoot is “natural” but so are sharks and hurricanes.  Furthermore my ancestors didn’t charge around on the refuse strewn pavement that our modern tribe does.
The topic of Barefoot running has several converging concepts from footwear and running mechanics to cultural and historical perspectives.    I have sat down to write this post dozens of times now and each time I go a different direction so I’m going to try and keep this simple.  This is the first of what will likely be many postings.  Rather than dive right into barefoot running, let’s start with comparing the merits of simple shoes  vs. the modern shoe.
For simplicity’s sake the “modern shoe” I refer to will be defined in this post as:  The shoe has an elevated and cushioned heel and pronation control features that can be tailored to foot type.
The “simple shoe” is anything from racing flats and Sambas to Vibrams.  Anything that protects the bottom of the foot without intentionally altering the motion of the foot.
Since the 70’s and the advent of Nike’s Swoosh, there has been a revolution in the running footwear industry.  We once had simple shoes that did nothing more than protect us from sharp


objects.  Four decades of technology and innovation have brought us motion control, arch support, inflatable parts-don’t forget the Reebok Pump, and heel cushions made of gel, air, foam and springs resulting in the modern running shoe.   The result:  nothing.  Today runners experience the same injury rate as they did before these technologies were introduced.

This broad sort of observational data can be misleading as industry advocates will point out.  There may be other factors at play such as the age, size and lifestyle of runners today vs those in the 70’s and before.  They will claim that modern shoes may be preventing what would otherwise be a large increase in running injuries- hard to prove.  Let’s get into some details and figure it out for ourselves.

This is a great topic because it is very difficult to demonstrate in a study the superiority of either barefoot/minimalist or the modern shoe. In my mind, the only way to demonstrate such superiority is to show a causative relationship resulting in greater injury prevention and improved performance. The data is there but great care must be taken in order to establish a causitive relationship. For instance an observational study that shows that those in worn shoes ran faster in a given race may do so because they run more often thus always having shoes that appear “worn.” Or, those same results may have been caused by the fact that people with injuries seek motion control shoes and it is the injury that is causitive, not the footwear.

Many intervention studies are flawed as well such as when a group of heel strikers is taught to run on the balls of their feet to see if they are faster and less prone to injury. Well they’re not faster and they often get hurt because in a short 2 week study they are thrown into taking the lion’s share of the impact in their untrained achillis tendon and gastrocs.  There are many clever studies out there that demonstrate a causitive relationship.  We’ll look at some that support and some that dismiss the utility of the modern running shoe.

The basic arguments for and against the modern shoe are as follows:
MOTION CONTROL-
Pros:
Proponents claim that the motion control shoe is necessary and helpful for those with severe pronation and other gait abnormalities.  This is a logical assumption but the data to support this claim is sparse.  I did however come across a study that indicates that the intervention of motion control shoes in severe over-pronators  lowers fatigue rates of certain muscles of the lower extremity (1).  This study does not demonstrate a reduced injury rate or improved performance but it is plausible that one could lead to another.
This is the perspective of Tim McConnell of West Seattle Runner who I briefly consulted with before writing this article.  He feels that “neutral” runners can get away with flats while pronators need more support.
Cons:
1)    Proponents of simple shoes point out that there is no evidence that the careful assignment of specific motion control shoes has any effect on injury rates or improved performance. (4) This is hard to believe given the massive resources available to the Research and Development departments of companies such as Nike and Adidas. An example of one such study is a recent and very large study of Air Force recruits in Basic training showed that assigning personalized shoes based on a foot shape evaluation did not improve injury rates when compared to placebo. (5)

2)   It’s “natural” to run barefoot.
Again, it may be true that bare feet is natural but before you march your Reebok Pumps to your local shoe burning keep in mind that Leprosy is natural and so are poisonous berries.  Nature has more interests than your health and safety.  Until there is some data to sink our greedy little teeth into we’ll curb this line of logic under the “interesting but irrelevant” category.

 
3)    Proponents of cheap/simple shoes aslo point out the proprioceptive inhibition  of bulky footwear-
Anyone who suffers from chronic ankle sprains is aware of the importance of proprioception at the ankle.  Proprioceptive nerves tell your brain where your feet are when you are not looking at them.  Severe ankle sprains tear these nerves and they only grow back to their pre-injury state if rehabilitated with balance exercises.  Studies show that the relatively bulky modern shoe decreases the brain’s capacity to know where the foot is in space while running and the study points out that it is this decreased proprioception that leads to running injuries in later years.(3)
HEEL CUSHIONING-
Pros:
Proponents point out that the perceived level of impact is diminished while running in a heel cushioned shoe allowing a heel strike and a longer stride.
Cons: 
Advocates of flats, vibrums, barefeet etc.  point to the fact that the body has its own mechanisms for reducing impact that are retarded by the built up heel of the modern shoe.  There are several proposed mechanisms by which this happens.  Here are a few that I find most interesting:
1)       A recent study (2) by Kong et al compared ground impact forces of built up heels vs. lower heels in a novel and clever way.  They compared impact forces of new vs. worn shoes.  What I like about this study is its clever design allows us to eliminate a lot many distracting variables because these old shoes are the same in all ways except they are slightly lower profile and have a decreased capacity to absorb the impact of heel strike.  The findings:
“As shoe cushioning capability decreases, runners modify their patterns to maintain constant external loads. The adaptation strategies to shoe degradation were unaffected by different cushioning technologies, suggesting runners should choose shoes for reasons other than cushioning technology.”
So there you have it.  New shoes are no better than old worn-out shoes thus the modern shoe is a waste of money that robs you of your innate ability to run light as a deer right?  Not so fast.    The way that the lower extremity modifies to absorb the shock in the absence of adequate heel cushioning is by activating the gastroc and taking the impact through the achillis tendon.   Just ask the over eager reader who gets all excited after reading this article and goes out for a brisk 5k on the balls of their feet tomorrow how their achillis tendons feel.  It takes time to build up that strength.
So there.  Now we have it.  The modern shoe is superior because it allows us to expend our muscle energy running rather than mitigating impact forces.  We can finally put this issue behind us.  Again.  No. The fact that those muscles are at rest during the running stride may be what causes high impact forces and is the source of potential injury.
 Think of it like this:  if you get up off of your chair now, stand on your table or desk next to your monitor then jump to the ground you will probably be OK especially if you tense your muscles and brace for impact causing you to land quietly.  This is analogous to expending energy in stance phase of the gate in worn shoes.  If you instead attempt to “save energy” by strapping on some new shoes and step off the desk completely relaxed and land unbraced into your heels at impact, even a fall from that modest height will cause injury.  Another great analogy is anyone unfortunate enough to have done wallballs.  It feels great to rest with your arms by your sides while that #20 ball is falling toward you doesn’t it?  We all learn sooner or later that it is far less taxing to stay tensed and ready to decelerate that ball.
2)      This bracing phenomena occurs in the muscles of the lower leg and foot millimeters from the ground and is not present when wearing a modern shoe that prevents the bottom of the foot from ever getting close to the ground.  (6)  Tension in muscles at impact prevents vibration of those tissues and may decrease fatigue rates.  Thus the purpose and popularity of single-ply recovery suits in sports such as crossfit.
3)      Just the THOUGHT of heel support makes you a worse runner! (7)  This is the most interesting study I came across so I saved it for the end to reward you loyal barefoot blog readers:
Here is a summary of the study from http://www.sportsscientists.com/.
In 1997, Robbins and Waked (7) made people step onto a material that was the same as is used in the midsole of running shoes. They did this a number of times, but the difference was that they were either told that the material was a state-of-the-art cushion, with all the latest technology to minimize injury (they even drew graphs and made up fake endorsements from athletes), or they were warned that it was the same as the material used in cheap shoes, responsible for many injuries. This is the WARNING trial shown in the graph below. Effectively, they were evaluating how belief about cushioning affected impact.

    It turned out that when subjects thought they were landing on the soft, high-tech material (Deceptive trial), the impact forces were actually HIGHER than in the Warning trial when they expected the cheap and ineffective material. And barefoot had the lowest impact forces of all. The other amazing finding, as is shown in the graph above, is that in the barefoot and cheap material trials, the impact forces get lower and lower as the subjects repeat the step, which shows a learning effect that is not present in the ‘Deceptive’ trial where subjects thought they were landing on a soft material. So this is remarkable – it shows how an expectation of impact can actually alter impact, and again, it supports what Benno Nigg and others are saying about anticipation of impact, with the ability to adjust muscle activity to defend some other variable.

I had a similar experience yesterday at West Seattle Runner with owner Tim McConnell when he was gracious enough to let me try on nearly all of his shoes as research for this article.  His shop is a great one-stop shop for all of your pre-race needs.  I wish I would have gone in there for his super-powered gummies before my cheap shoe marathon experiment last month.  Anyway I tried all of his top-end modern shoes with novel forms of the raised cushioned heel and they felt great, like walking on a water bed, but I found that I ran differently in each pair.  These felt nothing like the flats I usually wear and I found myself relaxing my gastrocs and heel-striking hard to feel the cushy bounce of the gel sole.
Conclusion:
I’d say that round one went to Cheap Shoes but this is not really a conclusion as much as a starting point.  If you are compelled to experiment with these ideas my advice is to take it slow.  If your feet are deconditioned by support shoes and a raised heel, it will take time for your body to develop the strength to become its own shock absorbing system especially in the achillis tendon and gastrocs.
I forwarded this posting on to a few friends in the shoe industry with the invitation to write a response posting or leave me a vigorous tongue lashing in the comments section so expect more to come on this topic. Your feedback as always is welcome in comments.
1)
1)Am J Sports Med. 2010 Mar;38(3):486-91.

Motion control shoe delays fatigue of shank muscles in runners with overpronating feet.
Cheung RT, Ng GY.

 
2)Br J Sports Med. 2009 Oct;43(10):745-9. Epub 2008 Sep 18.

 

Running in new and worn shoes: a comparison of three types of cushioning footwear.
Kong PW, Candelaria NG, Smith DR.

University of Texas at El Paso, El Paso, TX, USA. venikong@yahoo.com
 
3)Age Ageing. 1995 Jan;24(1):67-72.

 

Proprioception and stability: foot position awareness as a function of age and footwear.
Robbins S, Waked E, McClaran J.

Department of Mechanical Engineering, Concordia University, Montreal, Quebec, Canada.
4)
Br J Sports Med. 2009 Mar;43(3):159-62. Epub 2008 Apr 18.

Is your prescription of distance running shoes evidence-based  Richards CE, Magin PJ, Callister R.

5)No effect of shoe/injury rate.  Am J Prev Med. 2010 Jan;38(1 Suppl):S197-211.
Effect on injuries of assigning shoes based on foot shape in air force basic training.
U.S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland 21010, USA. joseph.knapik@us.army.mil
6)
 Nature. 2010 Jan 28;463(7280):531-5.

Foot strike patterns and collision forces in habitually barefoot versus shod runners. Lieberman DE, Venkadesan M, Werbel WA, Daoud AI, D’Andrea S, Davis IS, Mang’eni RO, Pitsiladis Y.

7) Br J Sports Med.  1997 Dec;31 (4): 299-303
Hazard of deceptive advertising of athletic footwear.

 

Sit Up Straight! The Brugger Relief Position isThe World’s Best Micro Break

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Does the picture of the guy in the headband look familiar? If you have a job it probably does. We live our lives in flexion. We wake up. We drive to our place of business and we hunker down over our work and drive home after a long day to have a meal and fall into a comfortable piece of furniture.

Whether you suffer from a stiff back and tight shoulders or you are an athlete who has difficulty maintaining lumbar extension during a heavy deadlift, intervening on this chronically flexed lifestyle will make you stronger, decrease your frequency of injury and help you remain strong and mobile into your later years.

In addition to causing aches and pains and diminishing the strength and functionality of the spine, increased thoracic kyphosis (flexion) is associated with increased mortality rates and subjective poor health in elderly populations. *

OK- I think you get the point now that slouching isn’t good but your mom has been telling you that for decades to no avail. What is useful about this posting is the solution: The Brugger Relief Position as pictured below is your tool to have balanced biomechanics in the context of your imbalanced lifestyle. This position is not intended to be held all day. It is a vigorous static exercise meant to tip the scale of your equilibrium back to neutral: 2 hours in a passive flexed position + 20 seconds in active extension = Balance.

Here’s how it works:
Best results when performed hourly (try setting your outlook calendar to remind you), or 8x per day and held for 20 seconds each bout.

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1) Actively engage the muscles of your foot arches by pressing your toes down and scrunching the aches of your feet up and off of the arch support in your shoes.

2) Push your hips back.

3) Drive your chest forward. The image to use here is a hollowed back as though sitting against a beach ball.

4) With your elbows at your sides, rotate your hands away from your body and supinate your hands (turn them all the way upwards)- remember, this is not a relaxation position. This is work. That is why 20 seconds of effort can neutralize hours and even days of destructive habits.

5) While gazing directly forward, pull your chin back into your neck. When done correctly this will give you the appearance of having up to four chins.

6) This is the most important part; Lower Your Shoulders. They won’t go far, maybe a quarter inch down. You will know when you have it when you feel the muscles below your shoulder blades feel tight and crampy. You’ll also feel a stretch that goes up to the base of the skull.

7) Start from the bottom at your feet and redouble your efforts to push a little further with each step. You can always go a little further.

This is the best micro break around and it is effective even when only held for a moment. It directly addresses and counters the postural strains that had you needing a break in the first place. What I like about it is that it changes your posture without you having to consciously “sit up straight.” It changes the tone of your muscles so that through sustained efforts over time your natural resting posture is stronger and more erect.

*Environmental Health and Preventive Medicine
Publisher Springer Japan
ISSN 1342-078X (Print) 1347-4715 (Online)
Issue Volume 12, Number 6 / November, 2007