biomechanics

Running Strong: Video Analysis, Running Re-education and Strength and Power Program for Runners

The Running

Strong Program

What is it?

A 4 session program to improve your running and decrease your chance of injury.

What is it composed of?

  • Detailed analysis of your running history and programming to find predictors of injury
  • High Speed Camera (240 frames/second) analysis of your running form
  • Pelvic Drop
  • Detailed functional evaluation of your physical function designed to find weak links
  • Custom created corrective exercise and performance based exercise program including 3 follow up sessions

Is it covered by insurance?

 

Yes.  I am both a physiotherapist and chiropractor.  Each session can be billed separately and our rates are well within the normal fees charged for regular physiotherapy sessions

The cost?

$400.00 for the initial 1 hour session plus 3 follow up sessions.

The timeframe?

The timeframe is surprisingly flexible.  Some people need a follow up session within a week of the initial evaluation.  Others might need a follow-up session within 3 weeks.  Having this flexible time frame allows us to tailor the program to your needs.

Can I work with my existing coach or personal trainer?

Absolutely.  In fact, this is encouraged.  I regularly work with running or triathlon coaches to create safer and better training programs.  If you already work with a personal trainer we can speak with your trainer about encorporating the running performance program into your existing exercise sessions.

About Me:

I am physiotherapist and chiropractor with a MSc in Exercise/Spine Biomechanics.  I have published more than 20 peer-reviewed academic papers on exercise science and injury.  I regular work with runners and multisport athletes from beginner's to Olympic athletes.  I currently write injury prevention articles for Triathlon Canada.  I am also an instructor with therunningclinic.ca - Canada's, if not the World's, leading course on the prevention and treatment of running injuries.  Last, I am the clinical director of Medcan's Run Well 3D Kinematic Analysis Program for Running Injuries.

Related Posts

1. Running Strength: Moving beyond the Core

2. Running Biomechanics: Clinical decision making in running analyses

3. Gait Modifications for Runners.

 

Core stability and low back pain: How stability exercises might help. Part Two

brain-running-on-treadmill.jpg

In part one of this post I very simple reviewed some of the ideas behind core stability and how I questioned their relevance to a patient's pain presentation.  In this follow up post I will briefly review how people with pain have different function than those without pain and give an opinion on how core 'stability" exercises may help with patients in pain in a manner that has nothing to do with stabilizing the spine.

What do we know and what can we do with patients with low back pain

- some patients with low back pain show delays in Tranny firing

- this delay can be correlated with the presence of low back pain

- changes in muscle timing occur with perturbations to the spine

-improvements in pain and function can occur and have nothing to do with changes in firing onset (see here )

-changes in firing onset can occur and have nothing to do with a motor control retraining plan (see Gary Alison's recent work here which he has been trumpeting this idea for more than a decade, here and here)

- some clinical prediction rules help identify who best responds to a "spine stability program"

- I published two literature reviews years ago that outline how peoples spines function differently with pain (Here and here). The research shows those with pain have differently behaving muscles, changes in proprioception, differences spine kinematics and differences in how they move

But so what if there are changes in function?  Do we need to know this to make improvements in pain?

None of the research suggests that these differences occurred before the pain nor does any research suggest that changing these dysfunctional parameters is necessary for pain resolution.  We probably don't need to specifically address these changes in function with our treatment and most of us aren't.  From the above list there are at least 8 means that the spine is "dysfunctional" as measured with some advanced biomechanical testing.  All of us do not do these testing on our patients yet we are often able to make them feel better.  What does this tell you about advanced testing? It probably isn't necessary.  Or is the test that is most important just the one that your clinic happens to have access to (I'm talking to you you people with Rehabilitative Ultrasound Imaging - I guess you have to justify the cost somehow :) )  We may just need to address the patient's pain, their beliefs, their attitudes, their activity levels and their habits and we will get changes in these functional outcome measures or we won't get changes in those outcome measures and we don't even need to.

These changes in how muscles work can definitely occur in the presence pain.  Where we are confused is correlation and causation. When did these changes begin in relation to onset of pain?  We have some suggestion that changing these motor control variables does not relate to improvements in symptoms (Mannion 2012).  So are these changes just a defense of the body rather than some defect?  They are assumed to be surrogates for stability but are they?

Maybe we should see them as secondary casualties in how our brain works.  The brain changes with pain.  Pain is an output of the brain.  So is motor control.  We can also see changes in swelling, heat, blood flow.  No one thinks that we have to address these secondary adaptations to help with back pain but we think we have to address the motor control or stability issues.  All of which can be secondary byproducts of the persistent pain experience rather than some original criminal mastermind of the patients pain.

 

What do I think my exercise prescription is doing

Breaking habits of motion, changing fear and building self efficacy

Directional preference, flexion intolerant, extension intolerant, activating neurotags etc. Patients have movements that hurt.  Sometimes they continually perform these movements and they keep hurting.  Maybe they were told that they were supposed to sit up straight, brace their spine, suck in their belly and always activate their lazy glutes.  And guess what, sometimes you have these patients relax, move their spine, sometimes slouch, sometimes put their feet up, stop worrying about their glutes and keep active and voila their pain feels better. Instead of "correcting" some stability problem we just gave the patient permission to move with a lot of variety.   We just broke a pain habit.

Sometimes, patients get pain with flexion and for some reason they keep doing activities that flex their spines and they keep having pain.  Sometimes, we suggest that they move the opposite direction, try to find a position of relief and every hour they arch backwards for a few weeks.  Then we slowly have them start flexing their back again (because we don't want them to be afraid of flexion, its what we are meant to do) and now they can flex their spine without pain.  Are these patient's spines any more or less stable? Did their tranny start firing earlier? Who knows, they have less pain.  They began to move differently than what they were previously doing and this helped.  We broke a habit, found positions of relief, built confidence that they could move without pain and transferred that confidence over to other activities.

In some patients you can give them a full spine stability program aimed at buttressing their entire spine. The exercises feel good when doing them.  The patient gets more confident.  They feel stronger and even their pain decreases.  Did their spine's stability become more robust? Maybe.  Is this what caused less pain?  Probably not.  You got this patient moving, maybe you caused exercise induced analgesia.  You put them in control and they felt better.  It probably helped if you didn't tell them there spine was unstable before you gave the exercises.

 

What is my point?

Keep it simple. Adam Meakins (A sport physiotherapists at http://thesportsphysio.wordpress.com/  wrote a simple tweet

 

"In physio you cant go wrong if u do the simple things exceptionally well & save the fancy crap for show offs & bullshitters #ROM #power etc "

This might encapsulate my treatment philosophy in all its foul mouthed glory.  While the body is extremely complex and the pain experience difficult to fully understand our interventions can be quite simple.  We are not car mechanics where we are tightening something or loosening something.  We just provide some input into the body.  The body and brain then decide what to do with it.

I still advise bird dogs, side planks, front planks, curl ups, squats and all the exercises that are in the traditional North American stability paradigm.  Sometimes, I even check to see if you someone can suck in their belly button without other muscles turning on and if doing that decreases the pain in their back when they move their leg.  Do I think that any stability changes occur and this is causing their pain to decrease?  NO. There are other reasons that these movements help.

Do I think that all those planks are creating rigidity in the spine.  Of course not, this is much too simplistic.  So what the hell do I do and what do I think I am doing.

My approach and my rationale

All of the following assumes I have ruled out the nasty stuff.

1. Educate about pain.  Don't catastrophize.  Explain the difference between tissue injury and pain.  Explain that we are meant to move and that pain is normal and is not some indication that they are falling apart.  Explain that their scary x-rays and MRIs are poorly correlated with their pain.   Explain that pain is so much more than just the tissues in their back and reassure them that they can do something about it.

2. Touch them with your hands:  Move them, push, pull, rub, crack, traction, distraction, compression. Whatever.  Manual therapy has some neurophysiological pain modulator effect.  Skip the bullshit explanation about the complexity of the SI joint having an upslip, downslip, a shear or flare or whatever.  You can't feel this and you can't correct it.  But using your hands can modulate the perception of pain and can change muscle and joint performance.  This gets your patients confident that change is possible.

3. Move meaningfully.  What is important to your patients?  Find some movement related goal that is important.  Figure out a way to do this.  Set small goals related to this movement and achieve them.  They might have pain during this task but they know that pain does not mean damage and that they can do it.  Don't hammer them into fighting through pain so that they feel "Wind Up" the next day.  But keeping pushing that pain threshold up.  Keep empowering them.

4. Stress the body.  This is where I use exercise.  I find a movement that is painful.  I figure out someway to modify that movement so that it is not painful (think Mulligan).  Train that movement.  Start to break the habit of pain.  Pain is a habit.  If we activate a pain neurosignature with certain movements we can sometime modify that movement so that that neurosignature is not activated.  Do this.  This is where "spine stability" exercises can come in.  Get them working their achey back in ways that don't cause pain.  This is awesome they train a painful area without experiencing pain.  This decreases the threat associated with movement, decreases kinesiophobia and changes how they think about pain.

5. Train harder: pick a movement that is kind of related to their painful site but does not hurt at all.  Train the hell out of this.  This can be build confidence in their body.  For example, they might have shoulder pain but they can deadlift.  What a great shoulder exercise.  You work your entire body, train the shoulder but experience no nociception.  Hammer this.

6. Address beliefs: we need to understand what our patients think about their condition and how that impacts their psychosocial profile.  If they have some serious catastrophizing, fear avoidance, depression, perceptions of injustice etc this shit needs to be addressed.

An opinion on motor patterns

I have seen "faulty" motor patterns and I have also seen them "corrected" by doing exercises that have nothing to do with retraining the supposedly faulty muscles.  If a motor pattern is corrupted this pattern is most likely corrupted at the level of the brain.  If I train some movement, modulate pain with some education or mobilization we often see changes in these motor patterns.  But I didn't change these as a mechanic.  There was no tweaking at a local level of "muscle imbalances".  We aren't bloody puppeteers The imbalances get "corrected" via other means.  Or they don't get corrected and my patient is pain free and I know that "muscle imbalances" can certainly be normal variations of your complex system.

So just remember this mnemonic: KISDAS.  Keep it simple Dumb AsS.

 

Future posts and questions for research

Corrective Exercise: this approach, besides being an unethical cash grab for CE dollars by some questionable organizations by making good intentioned personal trainers and physios feel insecure, has a number of assumptions about human function that we all need to question.  I also want to investigate it because it is an approach that I kind of use daily (see my defense here of the lowly clamshell) although I try to simplify it and pain neuroscience it up a bit.  And besides, isn't "corrective exercise" what every good coach or therapist does automatically? Find a deficit and improve it?  Anyways,  corrective exercise has a number of interesting things that we can look at and I don't think it is worth completely discounting.  Here are some areas I hope to address:

1. It assumes that there is an ideal way that the body functions.  I think this is everything most physios, trainers and coaches do yet our research is so piss poor.  I would love a catalogue of articles that attempt to categorize the best way to move.  We need to settle this debate once and for all.  The catalogue might just show exceptions and the huge variety that is acceptable.  It might show that their instances when it is best to move on way over another.  I know it is more complicated than just avoiding knee valgus, keeping a neutral spine, not letting 'global movers" shut down "local movers" and assuming that all asymmetry is evil.

2. It assumes that isolated testing (e.g single leg squat, prone leg extension, single leg glut bridge) gives us some insight into altered functioning.  It then assumes that the altered functioning in some isolated test actually correlates with assumed altered functioning during some more meaningful performance task (e.g running, deadlifting, squatting).  I wrote a PhD proposal on this area and you would be surprised how poor our tests are at actually testing anything we think they are testing and also correlating with functional activities. Guess what? Did you know that the quadruped rock back test coupled with spine rotation actually does not "lock out" the lumbar spine and only result in thoracic rotation?  Crazy.  Or that the thoracic spine has just about the same amount of rotation capacity as the lumbar spine.

3. Muscle activation?  Such a neat, simple and prevalent idea.  Training some small movement (e.g squeezing your glutes during a bridge) while "turn on" some muscle during another activity.  I would love to see this idea put through a simple experiment.  Flippantly, it again views the body as something that is so stupid.  Certainly worthy of some good research.

4.   I would love to see a series of blog posts look at altered joint kinematics (what a corrective post assumes it is correcting) and how these alterations correlate with changes in pain or improvements in function. My big hesitation with the corrective exercise approach is that it complicates things and does not seem to recognize the uncertainty that exists in human function. Further, corrective exercise assumes that there is a limited way to "correct" the dysfunction.  aka. you need the "correct" corrective exercises.  I would suggest that there are a multitude of exercises or approaches that can influence pain perceived to becoming from a joint and the resultant aberrant kinematics.  Anyone want to look at this topic?

5. Of course we could also talk about foam rolling.   It is interesting that there does seem to be a shift in the rolling world to get away from the idea of digging out knots and adhesions and focusing on the possible neural aspect for the treatment mechanism.  But fascia is still king in some circles and I can't fathom why.

I would guess that if we look at the biomechanics and motor control literature we would find that our treatments can be much simpler, we would have lots of variety and many approaches would be successful.  We would not have to have incredible complicated solutions to simple problems (avoid the Rube Goldberg trap of exercise prescription).

 

Happy new year!  Anyone interested in collaborating on blog posts please email.

 

A Summary of Techniques to Change Impact and Joint Loading During Running

Purpose: To review some of the data on ground reaction forces during running, the significance of this physical loading and how loading can be modified. WARNING: this post is massive.  It is meant as a working and evolving repository of much of the research on this topic.  It is a compilation that I would like to update as more work is added. I use a post like this as a living reference library so I don't have to search through an entire article to get the gist of it.  It is not meant to win a writing award. Skip to the bottom for a summary.

What is in this post

1. Ground reaction forces (GRFs) overview

2. Relationship between GRFs and Injury

3. Modifying loading with step rate

4. Modifying loading with foot strike style

5. Modifying loading with shoe wear or going barefoot.

What are ground reaction forces and impact loading?

When the foot strikes the ground during running the ground produces a force back against the foot.  The force can be broken into three directional vectors:

1. Vertical

2. Forward - Backwards (e.g. "braking" and then "push off")

3. Side to Side.

Most of the research has focused on the Vertical loading so I will too.  Vertical loading looks like this:

The first peak in force is termed the impact peak and results from the collision of the foot with the ground.  We can also look at how quickly this force rises and when that peak occurs.  This is called the rate of loading.

The second peak is called the active peak.  It corresponds to the point when the energy absorption has stopped (the center of mass is at its lowest) and when we start to "push" off against the ground.

Relationship between ground reaction forces (GRFs) and injury

The relationship is contentious.  It is simple to assume that less load or less stress on the body leads to a reduction in injury risk.  But this does not always pan out.  The human body has the ability to adapt and the variability across runners' ability to adapt is huge. Simply, we don't know how much load is bad for an individual person.  You can even argue that loading is good in that this is what stimulates an adaptation in the runner (e.g. stronger bones, stronger soft tissue, a better nervous system?).  What the cutoff is between good loading leading to adaptation and too much loading leading to injury is our Holy Grail of Injury Prevention.  The concept of loading and loading rate on injury in runners could be a long post itself - I will just link to some articles below and briefly touch on this area.

There is some suggestion that the rate of impact loading is related to stress fractures in runners.  See this post here and the abstract here.   We also have some suggestion that decreasing peak loading can influence stress fracture risk (abstract here and here)

We also have some great research by Dr Irene Davis linking higher impact velocity (e.g rate of loading) with stress fractures (link here).  Dr. Davis has also published case series showing changes in loading rates with feedback during running (abstract here).

Some links to follow for more information on this.

Davis and company (here, here, here, an outlier here)

Other researchers showing no relationship with loading and injury ( here and here)

So How Can We Modify Loading During Ground Contact?

In the following sections we will take a look at three methods that are used to change loading during foot strike:

  1. Changing step rate
  2. Changing type of foot strike (i.e. rearfoot versus midfoot)
  3. Changing footwear (or foregoing footwear altogether)

In an upcoming post I will review what other changes occur when we attempt to make these changes to impact loading.  Changes don't exist in a vacuum.  They could lead to changes in running economy, muscular activation or other unintended consequences that could affect performance and maybe injury risk.

The Bottom Line before the bottom

All three techniques are able to change impact loading and joint loading in some individuals but not in all individuals.  What we see in the research is variability and this leads to conflicting results across studies.  This is because there are other factors than the three above that influence the ground reaction force.  For example, you can change to a midfoot or forefoot strike and still overstride (see a neat video and case on this here).  The stiffness in our limbs can all influence impact.  This is what happens to some extent with kinematic changes with aging.  Older runners can have similar stride rates but still have greater impacts (for a brief review see here).  But lets look at some research.

A. Changing step rate

We can increase the number of steps we take while running.  Heiderscheit et al (2011) did such a thing (for detailed review of the study look here and here).  He increased step rate by 5 and 10%.  This is some of what they found:

At both 5 and 10% increases in cadence

  • decreased step length
  • decreased Center of Mass vertical excursion (less bouncing up and down)
  • decreased horizontal distance from the center of mass to the foot (i.e. less overstriding in front of you)
  • less knee flexion (excursion) during the foot contact (i.e. increases stiffness)
  • decreased energy absorption and energy production at the knee
  • decrease in the impact transient occurrence (there were times when runners did not have that sharp spike in ground reaction force plot)
    • decreased braking impulse

At a 10% increase in cadence only

  • decrease in foot inclination angle at contact (toes point down more)
  • decreased stance time duration
  • increased rating of perceived exertion
  • less hip flexion and adduction
  • increased knee flexion at initial contact
  • decreased peak vertical ground reaction force
  • decreased energy absorption at the hip

A note on the ankle

There was no change in the amount of ankle energy absorption when increasing cadence yet a huge decrease in the amount of energy absorbed at the knee.  This is most likely due to a lack of change in the ankle kinematics and how the foot struck the ground.  I would guess that changing cadence was not enough to change the type of foot strike.  If an individual went from a rearfoot to a mid or forefoot strike we would probably see more energy absorption at the ankle.  Take home point, is that a lot variables can influence impact loading.

A note on the initial impact loading and loading rate

The authors found that reducing step length decreased the occurrences of that sharp initial bump in the ground reaction force.  This is the impact transient and is what we most see in runners who heel strike - it is essentially the collision force with the ground. However, it was rarely seen (0-1 times in every 5 strides) only 56% of the time when increasing step rate by 10% (this lack of impact transient was seen 22% at preferred step length).  So notice this is just a trend in some runners.  If you notice with the study the authors did not calculate the average loading rate across all runners.  This is how we typically compare loading rates across interventions.  I would guess with the variability across the subjects we would not end up with a statistically significant change in loading rate.  Presenting the data in this way shows us that sometimes we get a change in the impact transient just not always.  As a refresher here is a lovely video of the loss of the impact transient with forefoot running.

http://youtu.be/XO4MruQov4Q

Hobara (2012 -abstract here ) had athletes run at 2.5 meters per second and also modified step frequency (increasing huge amounts of 15 and 30%).  They found decreases in:

  • vertical impact peak (VIP),
  • vertical instantaneous loading rate (VILR) and
  • vertical average loading rate (VALR).

The only issue with this study is how practical it is to have such a huge change in stride rates.  It is great for a proof of principle but we should question whether we want to do this in terms of running economy and even injury risk (i.e. you are taking a lot more strides thus increasing repetitions).

...and the other side of things (nothing is ever that simple)

But, these findings were mildly contrasted with another neat study that looked at changing a number of things (step rate, foot contact style and type of shoe) and the loading response.   Giandolini (2012)found the following when increasing cadence 10%:

  • no change in the rate of impact loading
  • no change in the impact transient
  • no change in the time that your foot is on the ground
  • a decrease in the aerial time (time you are in flight)
  • increase in stiffness (vertical)

These authors looked at the group average for changes in rate of impact loading.  They don't show their raw data so it is possible that there may have been some individuals who decreased their rate of impact loading and perhaps lost the impact transient during initial foot strike.  This would be consistent with the Heiderscheit study.

In this comprehensive study, these authors were also able to change a number of loading and kinematic variables with other interventions.  They did two other things - put runners in a racing shoe (versus a big bulky cushioned shoe) and had the runners switch from a rear foot strike to a mid foot strike.  They also combined all three changes (COMBI).    So why don't we take a look at this neat-o study along with other relevant studies that look at changing footstrike style.

B. Switching to a Midfoot Strike

The research suggesting changing foot strike influences loading variables

This simple change provided some pretty drastic results.  Giandollini et al (2012) found:

  • loss of the impact transient when switching (also found in the COMBI)
  • greater than 50% decrease in the rate of loading (also found in COMBI)
  • interestingly no change in step rate (this is of interest because we often assume that this happens with a midfoot strike.  We typically assume that running midfoot versus the heel naturally shortens the stride - suggesting that we can get changes in loading rates without decreasing stride length)
  • an increase in Gastroc (calf muscle) and Tibialis Anterior (shin muscle) muscle activity was found just before impact but not during impact.  However, the authors did not account for the electromechanical delay (i.e. the muscle turns on immediately but it takes time to take up the slack of the muscle to create force against the bones) that occurs with EMG muscle activity so we shouldn't conclude that the muscles are not creating less force during impact.  With the delay these muscles are creating force and are mostly likely contributing to the buffering of the impact loading response.

You can see a video version of this response in the video above from Dr. Lieberman.

...again it is never that simple.  Similar research has found different conclusions

Laughton, Davis and Hamill (2003) investigated fifteen habitually rearfoot strike runners and then converted them to a forefoot strike pattern in a single session.  The authors found:

  • increased average peak vertical ground reaction force
  • increased Anterior to Posterior GRF
  • Increased Anterior to Posterior loading rates
  • no difference in average or instantaneous GRF loading rates

some other findings:

  • increased dorsiflexion and calcaneal eversion excursion
  • decreased centre of mass excursion during foot contact
  • increased knee flexion at initial contact
  • decreased knee flexion excursion
  • increased knee and leg stiffness
  • decreased ankle stiffness

WHOA...this is very conflicting.  Sure is.  It again stresses that changing a single variable is not sufficient to change other variables. Changing to this type of forefoot strike pattern either increased peak loading, no change in loading rates, increased braking forces and increased knee and leg stiffness.  We don't know if stride rate changes but the increased anterior-posterior forces suggest that the forefoot striking may have been related to overstriding.  Last, in this particular study the forefoot strikers were not permitted to let their heels hit the ground.  They essentially ran on their toes.  The Giandollini suggests that converting to midfoot strike can be beneficial (in terms of impact and force variables) but there may be a correct way to do this.  i.e. don't just run on your toes

Further research showing variable impact loading with changes in footstrike

Becker et al (2012) in an abstract presented at the ASB 2012 concluded that foot strike pattern does not predict loading rates during shod or barefoot running.  With a subject population of 11 (this study was reported as ongoing so it looks like it may be more robust in the future).  The authors measured vertical impact loading rate and strike pattern in the runners when they ran either shod or barefoot.  What they were able to evaluate was how footstrike pattern related to VILR in quite a novel way.  The participants were not told to attempt to change their foot strike pattern.  Rather, they had people either run with their shoes or in barefoot and measured their footstrike pattern with something called a Strike Index while also measuring their VILR.  With these two measures in hand they determined how foot strike pattern related to VILR because some people would naturally change from a rearfoot pattern while shod to a forefoot pattern while barefoot.  So, there were few permutations on what could happen.  Here is a sample of what I see as relevant and check out the chart below for all the details.

Lets look at those instances where people RFS while shod but ended up switching to a forefoot strike while barefoot:

  • 12/16 switched from a RFS to MFS/FFS while 4/16 remained RFS while barefoot
  • of the 12 that switched 5 of them significant increased their VILR while 7 had no change.
  • of the 5 that showed changes when going to a MFS/FFS while barefoot all of them showed increases in loading rates while non showed decreases.
  • Figure 1 below shows no loss in the impact transient in subjects running with a midfoot strike

The flow chart below shows what happens to the vertical loading rate to individual runners when they either change to a midfoot/forefoot strike (MFS/FFS) while barefoot or remain heel striking (RFS)

The bottom line from this study is that a mere shift to a MFS/FFS is not sufficient to get less VILR.  This study is also confounded with the shift from the shod to barefoot but it again suggests that is not a sufficient condition to automatically assume you will get less loading rates.  Big limitation: there was no training or time allowed for habituation.  This is short term study and may not reflect what happens with motor learning over time. 

C. Impact and loading changes when we change our shoes

 I will cut right to the chase here.  Changing your shoes is not always enough to get changes in loading variables.  Big bulky shoes are knocked under the assumption that the ass of the shoe gets in the way and forces runners to land on their heels and overstride.  We assume that replacing these shoes with lighter shoes (and less of a heel to toe drop)  will lead to a change in how we run to avoid heel striking  (due to pain) and overstriding.  Lets look at the research on what happens in different shoes.

Possible Study Outcome #1: Traditional versus minimal shoes lead to variable changes in loading

Goss et al (2012) Accuracy of self-reported footstrike patterns and loading rates associated with traditional and minimalist running shoes (ASB 2012).

These authors looked at 57 runners who ran in either traditional running shoes (n=22) or minimalist running shoes (n=35).  There were no details on what these minimal shoes were.  The authors measured ground reaction force and were classified into either a rearfoot or forefoot runner.  This gave three categories of people: 1. rearfoot striker with traditional shoes (TSR) 2. Midfoot striker in minimal shoes (MSA) and 3. rearfoot striker in minimalist shoes (MSR).  Before doing the assessment they also asked the runners how they thought they struck the ground.  Here is what they found:

  • 1/3 of experienced minimal shoe wearing runners misclassified their running footstrike - they thought they were midfoot but they were hitting their heel.
  • the MSA group (midfoot minimal) had the lowest average vertical loading rates (52.8 BW/s), traditional shoe rearfoot strikers were next (68.6 BW/s) and the rearfoot strikers with minimal shoes had the highest loading rates (107.8 BW/s).
  • there was no change in peak ground reaction force across groups
  • vertical ground reaction force curves were different between groups.  Noticeable there is less of the impact transient in minimal shoes regardless of footstrike but midfoot striking with minimal shoes leads to the gentlest of loading rates.  See chart below.

Possible Study Outcome #2: Shoes versus barefoot lead to increases in joint loading

Kerrigan et al (2009) looked at the influence of running shoes on lower extremity joint torques in standard running shoes and barefoot (n=68).  They found increases in the following joint torques when going from barefoot to shod:

  • hip adduction
  • hip external rotation
  • knee flexion, knee varus, knee internal rotation
  • ankle internal rotation

In terms of ground reaction forces there were increases with shod running in:

  • medial to lateral GRF and Vertical GRF

with a decrease in the minimum anterior to posterior GRF

Stride length was found to increase from 2.15 meters (barefoot) to 2.29 meters (shod) although the authors suggested that this accounted for only a small percentage of the changes in joint torques.

Possible Study Outcome #3: Minimal shoes lead to increases in joint loading

Logan et al (2012 - ASB Abstracts here) GROUND REACTION FORCES BETWEEN RUNNING SHOES, RACING FLATS AND DISTANCE SPIKES IN RUNNERS

The authors compared the three different shoes and aspects of the ground reaction force (Impact peak (BW), loading rate (BW/s), peak braking and propulsive force (BW), peak vertical force (BW), stance time (s), and vertical stiffness (BW/m)) in runners (n=18) who were all habitual rearfoot strikers.  Further, these runners were college track athletes running between 5.67 -6.7 meters/s.  This is fast considering that running around a 5 meter/second pace will have you run 5 km in 16:40.   They found:

Impact peak and vertical stiffness significantly increased between running shoes and spikes. Differences between stance time and loading rate approached significance with trainers being lower

This again is interesting.  I don't know if these runners changed their foot strike with any of the shoes but it reiterates that changing shoes to a more minimal shoe is enough to positively lower loading variables.  In this case it increased them.  I would assume that these runners were still heel strikers despite the change in shoe.    This group shows that you can have less of an impact peak, less vertical stiffness and a trend to having less loading rate with a trainer than with more minimal shoes.  Take home point here is that our movement patterns involve motor learning...motor learning involves effort, time and conscious attempt to change how we move.

Possible Outcome #4: Shoe differences are minimal but going barefoot decreases loading variables.

...and now a contrary view Hamill et al (2011  with a detailed review here) in a study titled "Impact characteristics in shod and barefoot running".  The authors compared barefoot running with running shod in three different shoes of different sole thickness (1. A shoe with a 4mm heel and 0 mm forefoot; 2. a shoe with 12mm heel and 8mm forefoot and 3. a shoe with a 20mm heel and 16mm forefoot). The authors looked at the immediate response with these different shoes.  Again, there was no training or attempts repatterning a gait stride. Their results in a nutshell were:

  • switching to barefoot leads to an anterior footstrike pattern
  • barefoot leads to less 50% of the loading rate of all footwear conditions
  • impact peaks are still common with minimal shoes (a 4mm drop and very little thickness)
  • there is a trend to decrease loading rate with decreasing shoe midsole thickness
  • in general, shoes of different midsole thickness did not have different loading variables as runners in all shoes did not change their footstrike pattern

Possible Outcome #5: Minimal shoes show no effect on impact loading

The Giandollini (2012) study compared standard cushion shoes with a racing shoe (important note: the racing had a large heel to toe drop of 10.8 mm - thus some may not call this a minimal shoe despite there being less mass).  The authors trained the participants and had them run at the same speed with the two different shoes on.  The authors found no difference in loading rate, time to peak vertical load and peak vertical loading. The authors suggest that individuals continue to use a heelstrike style of running and that the minimal shoe did not coerce the runner into changing their running style.  What I find interesting is that even though the racing shoe is much lighter with less cushioning there are no adverse consequences to running with a similar style compared with the  normal cushioned shoe.  Below is a nice graphic representation of all of Giandolinni's interventions on the vertical ground reaction force.

Brief Summary of changing gait variables to influence impact loading

All methods can influence of impact and joint loading but not consistently.

Increasing step rate can decrease joint loading but does not always lead to a reduction in the impact transient or rate of impact loading

Changing to a midfoot strike does have evidence to change impact loading variables but again in some individuals we won't see any change

Changing to a midfoot strike may also result in other factors that increase the strain on the tibia (link here for a start to this interesting idea).  We can't say with certainty that everyone should be doing this change.  A follow up post must and will address this area.

Changing your shoes to lighter weight or minimal shoes also has variable effects.  Most importantly, instances can exist where your loading can increase when going to lightweight, minimal shoes.  Most likely due to maintaining the running style that you have adopted when running in your previous cushioned trainers

The Giandollini et al (2012) study is really quite lovely.  They look at as many variables and interventions that you can reasonable look at.  They show how many techniques of what we think might change impact don't consistently change impact and they also provide insight into the "whys" of this.  I also like their conclusion (probably because it agrees with something I wrote last year on barefoot running and foot strike style and I need reinforcement :) ) where they write:

our results show that running "barefoot-like", i.e. with a midfoot strike pattern may be an effective solution to reduce the magnitude of impact, as quantified through the loading rate

Related Posts

Running economy, barefoot, minimal and traditional shoes

Barefoot and foot strike style running biomechanics review

Running injury prevention

Postural correction and changing posture. Can we treat our patients like puppets?

Audience: Therapists and Strength CoachesPurpose: To justify the use of a variety of exercises (even general exercises) for training, rehabilitation and injury prevention and question the application of movement specificity principles.

The Gist of this Post: Specificity of training is an important component of rehabilitation and strength and conditioning but I think the application of specificity can be taken too far when we attempt to mold our posture.

A related post by Tony Ingram touches on many of these ideas in relation to pain and posture.

Background

The godfather of specificity was a former professor of mine, Digby Sale.  For a brief review see here.  Very briefly the research suggests:

"Evidence supports exercise-type specificity; the greatest training effects occur when the same exercise type is used for both testing and training. Range-of-motion (ROM) specificity is supported; strength improvements are greatest at the exercised joint angles, with enough carryover to strengthen ROMs precluded from direct training due to injury. Velocity specificity is supported; strength gains are consistently greatest at the training velocity, with some carryover. Some studies have produced a training effect only for velocities at and below the training velocity while others have produced effects around the training velocity"

Another great review article is by Cronin et al (2002) link here:  A quick quote from the abstract:

"It has been suggested that training at a specific velocity improves strength mainly at that velocity and as velocity deviates from the trained velocity, the less effective training will be. However, the research describing velocity-specific adaptation and the transference of these adaptations to other movement velocities is by no means clear".

My thesis: The applications of specificity can be taken too far in three ways

1. The repeated performance of an exercise leads to plastic deformation of tissues or changes in motor control that cause significant changes in posture and movement capabilities (aka form).

I question if the body is really this malleable and ahem, stupid.  It assumes that consistently training certain movements makes you move in that specific way and you lose the ability to move in other ways (i.e. your posture and form become changed).   I believe it is an inappropriate extension of you become what you train.  It is a training belief related to the idea that hip flexors become shortened because we sit all day (see a previous post here).  I don't doubt that you can train habits of movement that might carryover into other tasks.  What I question is whether are tissues are so readily plastic and they can't control their destiny because of some passive changes in the make up of the tissue. 

An example...

I was listening to a podcast where the speakers objected to what they felt was the rampant, unjustified, often silly and apparently detrimental usage of the front and side plank (bridge) by physiotherapists and trainers the world over.   What the speakers argued was that performing these repetitive planks with no motion between the hips and the thorax would somehow create runners that will run like robots and lose the ability to dissociate the hips from the thorax.  As if twenty minutes of planking a week will somehow carryover to the automatic movements that occur during running.

I just don't buy this and consider it such a pessimistic and wholly unfounded structural view of the body.  It assumes that the body is stupid and a few minutes of planking will somehow override what ever neural control mechanisms, not to mention physical forces, that create subtle movement in the spine when we run. 

A brief review of 3D spine kinematics during running can be found here (Schache et al 2002 ) and here (Saunders et al 2005).

We don't change form through simple exercises...or do we?

The belief that planking makes you rigid and run like a robot has not been tested but assumes that planking will somehow stiffen up all the muscles of the trunk within the neutral zone and also cause our brain to change the automatic way in which it recruits muscles during locomotion.  That is some powerful planking to override our nervous system like that.  It is very difficult to change running kinematics even when we try to change running kinematics by volitionally changing our posture.  But somehow, a little bit of planking can do this despite us trying to run normally. 

Same holds true for the knock on the curl ups.  I think it is a fair to critique curl ups  for other reasons (e.g. there are better exercises, you may not think they are functional, you don't like the idea of compressing a disc with some flexion) but I don't think we can turn people into kyphotic zombies.  Unless you've been bit by a Kyphotic zombie and those are biochemical changes not biomechanical. Curl ups get critiqued because it is assumed that doing a lot of curl ups will end of shortening the rectus abdominis and will therefore be constantly flexed.  I just don't see any research suggesting that this happens.  While we might increase the stiffness of the rectus abdominis this is different than making that muscle shorter at its resting length.  The muscle has a stress strain curve where there is hardly any resistance to movement around its resting length (i.e. the neutral zone) while strength training might shift that curve if stiffness increases it still has a "toe region" of the neutral zone where hardly any passive force is created.  Certainly not enough to crank down the thoracic spine and all of the other opposing muscle groups

Some Research on changing posture and form through exercise

Here is a sampling of studies looking at both strengthening and stretching programs designed to change Scapular position or posture in general .  This is ridiculously difficult to do.  None of the following studies were able to do it:

- a review here by Con Hrysomallis looking at Shoulder position  http://www.ncbi.nlm.nih.gov/pubmed/20072041

- a review by Hrysomallis looking in general at the ability to change posture: http://www.ncbi.nlm.nih.gov/pubmed/11710670

-Wang et al (1999) Stretching and strengthening exercises: their effect on three-dimensional scapular kinematics.: http://www.ncbi.nlm.nih.gov/pubmed/10453769

- McClure et al (2004) Shoulder function and 3-dimensional kinematics in people with shoulder impingement syndrome before and after a 6-week exercise program: http://www.ncbi.nlm.nih.gov/pubmed/15330696

-Hibbard et al (2012) Effect of a 6-Week Strengthening Program on Shoulder and Scapular Stabilizer Strength and Scapular Kinematics in Division I Collegiate Swimmers: http://www.ncbi.nlm.nih.gov/pubmed/22387875

Serendipity of the internets

I have been writing and thinking about this post for months and along comes a post from Bret Contreras arguing that strength training alone does not change form. He argues that motor control training changes form.  This is a component of what I am trying to say.  Here is a link to Bret's piece

MY ARGUMENT DOES HAVE SOME RESEARCH AGAINST IT...Sort of

BUT...to weaken my arguement (and engender some healthy doubt or hope :) ) there are some papers that do show a change in posture albeit inconsistent. 

 1. Here is a great paper by Scannell and McGill(2003) - Stu does all the great stuff!

But, there was not a change in the stiffness of the spine nor did this lordotic static change carryover to a functional task

There were no changes in the size and location of the NZ of each group recorded during the mid-training and posttraining tests.

Relative to the pretraining test, all 3 groups sat in more lumbar flexion during the mid-training test (P=.005) (lumbar flexion increased by 4° in subjects with hypolordosis, by 5° in subjects with hyperlordosis, and by 5° in control subjects) and the posttraining test (P>.5) (flexion increased by only 1° more in all 3 groups relative to the mid-training test results). The changes in the sitting position between the pretraining and mid-training tests were seen in all 3 groups and therefore cannot be considered a treatment effect

Above Figure Description: The changes in the neutral zone (depicted by the black bars) and the lumbar position during sitting, standing, and walking (50% level of the amplitude probability distribution function) across the pretraining test (1), mid-training test (2), and posttraining test (3) are shown. The subjects with hyperlordosis stood in less lumbar extension during the mid-training and posttraining tests. Subjects in all 3 groups sat in more lumbar flexion during the mid-training test. No changes in the lumbar spine position during walking were found during the mid-training and posttraining tests. Positive values greater than the neutral zone represent extension.

An interpretation of the Scannell Paper

The Scanell paper certainly shows a change in resting posture (e.g. lordosis) but we see no change in lordosis during functional activities nor is their change in the stiffness of the spine.  This suggests that we aren't changing passive properties of the spinal tissues with these exercises but we are doing something else to change resting posture.  Did the participants change habits while doing the exercises and became more comfortable standing in a more neutral posture?  Was their standing posture a choice?

What I take from the conflicting research is that if there is a change in form with basic exercise it is not robust nor is it consistent.  And there is not sufficient information or even biological plausibility to assume that doing the plank daily for 3-5 minutes will somehow result in all of us moving like robots during an activity like running which appears governed by more central patterns.  I can't even imagine trying to run with a non-moving spine.  

A few more papers showing changes in posture with exercise:

2.  Misconception #2: Exercises must be specific in terms of every variable to be considered "specific"

This happened to me when I was trying to publish a paper on strength and conditioning for golf and I had the pickiest reviewer who kept saying that none of the exercises I was advocating as being specific to golf (e.g cable chops, one arm cable punches/pulls, weighted swings, med ball rotational tosses, Swing fan swinging) were specific to the golf swing as they all either had slightly different mechanics or different speeds.  I believe that I asked if a weighted sled exercise was specific to running and I was told that no it was not. I just think it is realistic to assume that a definition of specificity recognizes that some differences in terms of velocity or kinematics is acceptable and that we will still get benefits in the task we want to improve.  The early papers mentioned by Behm and Sale and by Cronin et al certainly support this.

3. Misconception #3: Non-specific or general strength exercises can't carry over to performance/injury reduction for specific tasks.

This is essentially the opposite of number two.  It is a pretty big debate and would rear its head with those arguing for functional exercises versus non specific exercises.  You could also ask "Are specific or functional tasks always better than general exercise?".  MOst of the time people assume (myself included) that specific tasks are better but I think we would ignoring a lot of research that suggests otherwise.

 A specific example can be seen in respect to doing a plank exercise for a runner.  Obviously, no runner gets into this position.  It is not specific in terms of body position with respect to gravity, the movements of running and certainly not velocity.   So the knock against this exercise is that it is not specific to running and therefore can't help the runner.  And I say, who cares? Why does it have to be specific to running? Can't an exercise give us benefits that carryover to other tasks?  Of course they can.  The plank obviously trains the trunk muscles and the lateral hip muscles.  We know that many runners with pain have weak abductors (whether this is a cause or correlation is hotly contested) and at the same time we have some evidence to suggest that training the hip musculature (with exercises that are nothing like the running movement) can be effective in returning people to running and decreasing pain in those with knee injuries. 

What is the mechanism for non-specific exercise benefits

Interestingly, the reason why these exercises are effective often has nothing to do with the purported biomechanical rationale for training the hip musculature in runners.  Specifically, we can advocate training the hip musculature under the assumption that this might change hip valgus and femoral internal rotation during the stride as there is some evidence to suggest that these mechanics are occasionally linked with knee dysfunction.  However, when we implement these hip exercise programs (again with exercises that are basic and totally not specific to running) we will see decreases in pain and return to running WITHOUT changes in the assumed dysfunctional mechanics (check out these papers here, here, here,  here  and here). Of course there are some studies showing that form does change (here and here - albeit no change in kinematics, just moment)  To me, this suggests that there is something generally beneficial about these exercises and that specificity does not have to occur.  But, if you want to change running form than the intervention should probably specifically try to change running form through feedback and training. (see here, here and here)

In terms of performance, I am biased, I do like creating exercises or stealing them that are somehow specific to the task at hand.  However, I recognize that there is a great deal of research that shows that exercises that are not specific to the sporting task can still improve performance (e.g. squats for sprinters).  Again, arguing that specificity is not always necessary.   My main point is the body craves variety and our programming and rehabilitation should reflect this desire.  We don't  have to be so rigid in our prescriptions or believe that there is only one way to get benefits.  The body adapts, lets exult in this.

Future Posts Related to this Topic

This post is a bit of a jumble with a lot different ideas.  I have few posts written half-assed in my head that are related. If anyone wants to write any of the following with me please let me know.  Or stay tuned for these upcoming posts.

These posts will ideally be a gathering of information that generates questions.

1. A catalogue of exceptions to the Joint-by-Joint Approach.

This post will use the framework of the joint by joint theory to consider the research that looks at injury risk factors.  It is not so much a critique of the approach but more a means to understand it limits and explore how it can still be useful.

2. A catalogue of examples that support the Joint-by-Joint Approach

3. Is there an optimal way to move? A catalogue of theories and evidence for ideal movement 

4. Can form be changed with via mechanical changes in tissue?

5. Changing running form through feedback and training.