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Achilles Tendon Rupture

David Beckham.  Arguably the most iconic professional footballer on the planet.  A point that hasn’t been overlooked by the likes of Adidas, Gillette and Armani.  A man who in my opinion has also probably done more for promoting certain sports injuries than anyone else.  In 2002 he literally taught every lay person in the UK what a metatarsal was.  The aircast boot was anecdotally referred to as the ‘Beckham boot’.  And I for one had a sudden influx of patients in my clinic presenting with foot pain and telling me in the first few minutes of the consultation that they thought it was their metatarsal.  And now he’s done it again.  The entire country is talking about the Achilles tendon.

Personally, I cried into my cornflakes on the morning of Monday 15th March as I read he had a suspected (at that time) Achilles tendon rupture.  If a similar heel injury was responsible for the death of Achilles during the Trojan war perhaps it didn’t bode well for David making a record breaking trip to South Africa in under 3 months time.

So what actually happened?

Sunday 14th March.  AC Milan are hosting Chievo in a Serie A game.  It’s the 87th minute.  David Beckham receives the ball in the centre of the pitch with plenty of space.  He takes a touch with his left foot, opens up his body and looks up to see where his team mates are as he is stepping back on his left foot…

If you look closely as his left heel nears the floor you can almost see it ‘pop’.  Watch David’s immediate reaction – he turns to see who is there.  I guarantee if he ever speaks of this experience he will explain the way he thought someone had kicked him.  After trying to take one step on it he knew he was in trouble.  He then feels the back of his ankle, and would not have felt the prominent firm tendon which he has probably felt every single day for the last 20 years.  At this point he would immediately have realised how serious his injury was.  Some newspapers report he looked over to the bench and made a ‘breaking twig’ gesture with his hands.  Within 48 hours he has been operated on by Professor Sakari Orava in Finland and knows his World Cup dream is over.

The Achilles tendon

The Achilles tendon is one of the most commonly ruptured tendons.1 It is well documented that it has a zone of hypovascularity, 2,3,4 which is an area of reduced blood supply and is located approximately 2-6cm up from the heel bone.  This zone of hypovascularity is the site of around 80% of all Achilles tendon ruptures.5 Despite the Achilles tendon generally being referred to as the strongest tendon in the human body, there is good research which actually disproves this and found that its material properties are instead similar to most other tendons.6 However we do know it has to cope with far more mechanical loading than most other tendons which may explain the relatively high incidence of Achilles injury.

The Achilles tendon can cope with loads of approximately 100N/mm2 and can be stretched approximately 8% of its length before rupturing.7 To put this into perspective, an Achilles Tendon with a cross sectional area of 90mm2 (which is about normal for an adult male) could theoretically cope with a force of approximately 1 tonne.  In a 75kg man (David’s current weight according to Google) this equates to twelve times his body weight.  So considering this tensile strength, how and why do they suddenly rupture?

All human tissues are what we term viscoelastic.  This basically means they will change shape (or deform) when a force is applied to them, but then return back to normal once the force is removed – a bit like an elastic band.  If they are deformed or stressed outside of the limits of their tolerance they will fail (in our elastic band example it snaps, in our Achilles tendon example it ruptures).  I explain this in a bit more detail on my website here.  When reviewing David’s mechanism of injury it is difficult to imagine the tendon being loaded with a force it couldn’t cope with (or equivalent to twelve times his body weight).  He was simply moving in a way he has done hundreds of times a day for almost two decades ; and therein may lay the key.

David has been playing the highest level of football for 18 years, ever since he made his professional debut for Manchester United back in 1992.  He has played for three of the biggest clubs in the World (four if you are a Preston North End fan).  He is the most capped outfield England player in history and has played in three FIFA World Cups.  This is undoubtedly a huge demand on the human body (and testament to what a conditioned athlete he is that he hasn’t been injured more in my opinion).  He is world renowned as being one of the best dead ball specialists in the modern game.  It is no secret that he often stays behind after training and practises his free kicks again and again.  And he is right footed.  So it would be reasonable to assume he has spent a lot more of his life balanced only on his left leg (just take a look at his left foot in the picture and imagine the strain on the Achilles tendon).  He certainly has the repetitive load history which could have led to some tendon/collagen deterioration, and it is my belief that the seemingly innocuous movement he made in the San Siro stadium less than a week ago was simply the ‘straw that broke the camels back’.

Unfortunately for David (and every English football fan) he was also in the right demographic for an Achilles tendon rupture.  It is more common in males 8, and more common between 30-50 years old.9 I don’t know David’s blood group (even Google can’t tell us that) but individuals with blood group O have been shown to be at higher risk of tendon rupture 10,11 so it would be interesting information to know.

Recovery

Professor Orava tells us the operation was successful and David will make a full recovery.  I am no surgeon, and do not profess to know what procedure was performed, but in simple non surgeon speak the tendon would have been sewn back together (possibly requiring a graft of tissue from another part of his body).  A task which no doubt requires serious skill and expertise on the Surgeons part.

For David the worst is probably yet to come.  Long rehabilitation is a certainty, and from the sportsmen I have spoken to regarding their ruptures, the first two months are miserable and they wouldn’t wish the injury on their worst enemy.  Assuming there are no post-operative complications (incidence of deep vein thrombosis following Achilles tendon rupture is high12) many months of Physiotherapy await.  It pains me to say it, but David may have played his last game for England (I hope he proves me wrong).  He has almost certainly played his last game in a World Cup.  So, is his career over, or will he return to elite sport and be back to his best?  I wouldn’t like to say.  Recent research on recreational athletes suggested significant reductions in playing sports following a rupture.13 However, that was recreational athletes – what about the professionals?  A study showed that 32% of professional American Football players who sustained Achilles tendon ruptures between 1997-2002 never returned to play in the NFL and on average players experienced a greater than 50% reduction in power ratings following the injury.14

Get well soon Becks.  I genuinely hope to see you play again.

References

  1. Kannus, P., & Jozsa, L. (1991). Histopathological changes preceding spontaneous rupture of tendon. Journal of Bone & Joint Surgery, 73, 1507-1525.
  2. Carr, A. J. & Norris, S. H. (1989). The blood supply of the calcaneal tendon. Journal of Bone & Joint Surgery Br, 71, 100-101.
  3. Schmidt-Rohlfing, B., Graf, J., Schneider, U. & Niethard, F. U. (1992). The blood supply of the Achilles tendon. International Orthopaedics, 16, 29-31.
  4. Theobald, P., Benjamin, M., Nokes, L. & Pugh, N. (2005). Review of the vascularisation of the human Achilles tendon. Injury International Journal of the Care of the Injured, 36, 1267-1272.
  5. Lesic, A. & Bumbarsirevic, M. (2004). Disorders of the Achilles tendon. Current Orthopaedics, 18. 63-75.
  6. Wren, T. A. L., Yerby, S. A., Beaupre, G. S. & Carter, D. R. (2001). Mechanical properties of the human Achilles tendon. Clinical Biomechanics, 16, 245-251.
  7. McNeill Alexander, R. (1994). Human elasticity. Physics Education, 29, 358-362.
  8. Leppilahti, J., Puranen, J. & Orava, S. (1996). Incidence of Achilles tendon rupture. Acta Orthopaedica Scandanavia, 67(3), 277-279.
  9. Wapner, L. K. (1999). Achilles tendon ruptures and posterior heel pain. In: Kelikian AS (Ed). Operative treatment of the foot and ankle. Stanford, Connecticut; Appleton & Lange. P369-387.
  10. Jozsa, L., Balint, J. B., Kannus, P., et al. (1989). Distribution of blood groups in patients with tendon rupture. An analysis of 832 cases. The Journal of Bone & Joint Surgery Br, 71(2), 272-274.
  11. Kujala, U. M., Jarvinen, M., Natri, A., Lehto, M., et al. (1992). ABO blood groups and musculoskeletal injuries. Injury, 23(2), 131-133.
  12. Nilsson-Helander, K., Thurin, A., Karlsson, J. & Eriksson, B. I. (2009). High incidence of deep vein thrombosis after Achilles tendon rupture: a prospective study. Knee Surgery, Sports Traumatology, Arthroscopy, 17(10), 1234-1238.
  13. Kinner, B., Seemann, M., Roll, C., Schlumberger, A. et al. (2009). Sports and activities after Achilles tendon injury of the recreational athlete. Sportverletz Sportschaden, 23(4), 210-216.
  14. Parekh, S. G., Wray III, W. H., Brimmo, O., Sennett, B. J. et al. (2009). Epidemiology and outcomes of Achilles tendon ruptures in the National Football League. Foot & Ankle Specialist, 2(6), 267-270.

Foot Orthoses; Nomenclature

Foot orthoses are a source of immense discussion amongst health professionals and sports people, and as such are more than worthy of their own category on any Podiatry blog.  What is the difference between an off the shelf and a custom made device?  Do they weaken foot muscles?  Do we know how they actually ‘work’?  What does the scientific research tell us about them?  These are just a few of the topics I hope to blog about in the future.

This first entry is going to be quite short but it was the first thing I was ever taught regarding orthoses so seems as good a place as any to start; and it is simply regarding correct and incorrect terminology.  This was drilled into me so religiously that unfortunately it made me a little bit pernickety about it.  So what should we call the things we issue people to wear in their shoes? Insoles?… Inserts?… Orthotics?… Prosthetics?  Certainly I’ve heard them called all these things.  The general rule for their naming is perfectly summed up by Ray Anthony at the start of his 1991 book:

It is an Orthosis

They are Orthoses

They are Orthotic Devices

They are not Orthotics

Funny really, as ‘orthotics’ are probably what I hear them called (by patients and healthcare professionals alike) with the most frequency, despite this being considered poor terminology.  Does this really matter?  I suppose not in the big scheme of things.  But I can’t help but cringe a little when I read or hear them referred to incorrectly – the legacy of a pedantic (but brilliant) university lecturer almost 10 years ago.

References

Anthony, R. J. (1991). The manufacture and use of the functional foot orthosis. Karger; Basel, Switzerland.

The supination resistance test holds particular interest for me as I am currently doing some research into it myself for my Masters degree at Manchester University.  To my knowledge it first appeared in the literature some 18 years ago (Kirby & Green, 1992).  It is a very quick and simple test to perform, but like most clinical tests will need to be performed many times on many different feet before the clinician will feel comfortable with it.  The main reason I feel it is so important is that it gives insight into the forces acting on the foot during weightbearing; something which we cannot physically see, and the importance of which are discussed in this blog.

Historically when examining the weightbearing foot all of our attention has been on its visual appearance (or posture).   Indeed these visual observations and measurements still form the main portion of an objective clinical assessment, and for many will also dictate the prescription variables for foot orthoses.  The potential problem with solely relying on visual alignment (or kinematics as they are referred to in biomechanics terminology) is that there is surprisingly little literature which shows that foot posture is actually predictive of injury.  What this means is that the pronated foot type is not necessarily as evil as we had previously thought.  Dr Christopher Nester of Salford University sums things up perfectly in his recent paper from the Journal of Foot & Ankle Research:

Rather than continue to apply a poorly founded model of foot type where the focus is to make all feet mechanically ‘normal’ we must embrace variation between feet and develop patient specific models of foot function.

In addition to this when we look at the research of how orthoses exert their effects (or ‘work’) it is clear that kinematic responses to orthoses are also variable and subject specific (Nigg et al, 2003; Huerta et al, 2009).  This means that not all feet will respond the same if given the same orthotic prescription.  And even if they did respond in a predictable way would this mean they would all get better?  Sadly not, as Zammit and Payne discovered in 2007, when they investigated the relationship between kinematic response to an orthotic device (how much it ‘realigned’ the rearfoot) and the reduction in the individuals symptoms; and found that there was no correlation between the two.

Confused? So was I.  I was taught that a pronated foot was a huge risk factor for injury.  I was then taught to measure how much it was pronated, write a prescription based on this number and the orthotic device I issued would duly realign the foot into ‘neutral’ and the patients symptoms would of course disappear.  It was a simpler time as you can imagine.

Not until I read an excellent research paper by Williams et al (2003) in the Medicine and Science in Sports and Exercise Journal did it start to make sense to me.  This research took a group of individuals and made them run in 3 conditions: no orthoses, ‘standard’ orthoses and inverted orthoses (between 15-25 degrees inverted).  It measured the kinematics (alignment) and the kinetics (the forces we can’t see).  The results were astounding – there was no statistically significant difference in rearfoot alignment between the 3 conditions.  However, when looking at the forces involved (particularly how hard Tibialis Posterior had to work) the more inverted an orthotic device was significantly reduced the demand on the soft tissues.  The inverted orthoses reduced this demand almost 4-fold when compared to the no orthoses condition.  Immediately we realised that our orthoses made people pain free by reducing damaging force, and not by ‘re-aligning’ them.

So what does all of this have to do with the supination resistance test? Well it is one of very few tests which give us insight into these forces (which may well be more predictive of injury risk and may better determine orthoses prescriptions than our visual assessment techniques do).  If a foot requires a large force to supinate it then it is assumed that a greater contractile force from extrinsic supinators, such as Tibialis Posterior, may be required functionally (does this increase injury risk?)  It may also dictate the sort of orthotic device which would be most appropriate.  The harder it is to supinate a foot then the greater force an orthotic device would need to cause a supination moment, and conversely the easier it is to supinate a foot then the lower the force required from an orthotic device.

So how is the test performed?

  1. The patient is asked to stand in a relaxed position on two feet
  2. They are instructed to relax their feet during the test, and not help in any way
  3. The clinician places the tips of the index and middle fingers just beneath the navicular
  4. The clinician pulls directly upward (parallel to the tibia)
  5. The clinician notes the magnitude of force that is required to supinate the foot from its resting position
  6. The test is performed on the other foot

When done in this clinical setting the test is a little subjective, but with repetition gives the clinician a good idea of the forces involved (and despite its subjectivity may still offer more important information that visual assessment).

The research team at La Trobe University in Melbourne took this one step further and built a machine which quantitatively measured this supination force in Newtons.  They found some fascinating results:

  1. The manual version of the test (as described above) is reliable for experienced users
  2. The amount of force required to supinate a foot is only weakly related to how pronated it is
  3. The amount of force required to supinate a foot is highly correlated to the subtalar joint axis position (I won’t go into this now – it is worthy of its own blog entry and will get one in due course)
  4. Body weight explains about a third of the force required to supinate the foot

These findings are what we see clinically when performing the test – the force to supinate feet is variable, and does not seem to be hugely influenced by body weight (I have experienced a 13 year old girl who weighed 7 stone have a higher supination resistance than a 19 stone rugby prop forward).

The team at La Trobe have also done much research which has not been published yet (personal communication with Craig Payne) and one which interests me particularly.  They took 28 individuals all who had problems with only one limb and all of which had been previously considered to be due to ‘excessive pronation’.  They recorded the Foot Posture Index (a protocol which classifies feet into categories based on visual observations) on the injured side versus the uninjured side, and then measured the supination resistance on the injured side versus the uninjured side.  They found that when looking at foot posture the injured side was more pronated in 15 out of the 28 subjects.  However when looking at supination resistance it was higher on the injured side in 25 out of the 28 subjects.  Does this tell us that supination resistance is more predictive of injury that foot posture? Well not quite as it was a cross-sectional design, but it certainly suggests this is worth investigating further in a prospective study.

The supination resistance test is probably now one of the key things from my assessment of patients which dictates my orthoses choices.  I pay more attention to it than I do the foot posture.  However further work is required to fully understand supination resistance and whether it is prospectively predictive of injury risk (or can validly be used to determine dynamic kinematic responses to different levels of force from foot orthoses).

References

Picture from: Kirby, K. A. (2002). Supination Resistance Test. Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002 (pp. 155). Payson, Arizona: Precision Intricast, Inc.

Huerta, J. P., Moreno, J. M. R., & Kirby, K. A. (2009). Static response of maximally pronated and nonmaximally pronated feet to frontal plane wedging of foot orthoses. Journal of the American Podiatric Medical Association, 99(1), 13-19.

Kirby, K. A., & Green, D. R. (1992). Evaluation and nonoperative management of pes valgus. In S. DeValentine (Ed.), Foot and Ankle Disorders in Children (pp. 295).  New York: Churchill Livingstone.

Nester, C. J. (2009). Lessons from dynamic cadaver and invasive bone pin studies: do we know how the foot really moves during gait? Journal of Foot & Ankle Research, 2 (18)

Nigg, B. M., Stergiou, P., Cole, G., Stephanyshyn, D., Mundermann, A., & Humble, N. (2003). Effect of shoe inserts on kinematics, centre of pressure, and leg joint moments during running. Medicine & Science in Sports & Exercise,35, 314-319.

Noakes, H., & Payne, C. B. (2003). The reliability of the manual supination resistance test. Journal of the American Podiatric Medical Association, 93 (3), 185-189.

Payne, C. B., Munteanu, S., & Miller, K. (2003). Position of the subtalar joint axis and resistance of the rearfoot to supination. Journal of the American Podiatric Medical Association, 93 (2), 131-135.

Payne, C. B., Oates, M., & Noakes, H. (2003). Static stance response to different types of foot orthoses. Journal of the American Podiatric Medical Association, 93 (6), 492-498.

Williams, D. S., McClay Davis, I., & Baitch, S. P. (2003). Effect of inverted orthoses on lower-extremity mechanics in runners. Medicine & Science in Sports & Exercise, 35, 2060-2068.

Zammit, G. V., & Payne, C. B. (2007). Relationship between positive clinical outcomes of foot orthotic treatment and changes in rearfoot kinematics. Journal of the American Podiatric Medical Association, 97, 207-212.



I first came across the Lunge Test back in 2006 whilst reading a thread on Podiatry Arena.  It was at a time that my thinking was changing significantly with respect to what I had been taught during my undergraduate degree (2000-2003) and consequently the way I assessed my sports patients.  As undergraduates we were taught how to assess an ankle joint, and this primarily consisted of testing its range of motion by seeing how much you could push the foot towards the leg (a motion we call dorsiflexion), from a starting position with the ankle at 90 degrees, when a patient was lying supine on the examination couch.  We were looking to see if the patient had 10 degrees of dorsiflexion from the starting postion – a golden figure which was considered ‘normal’ at that time and which we were informed all individuals required.

The more I read the more I discovered that 10 degrees as a normal value was erroneous (infact it was not possible to even find the reference that this figure originated from).  What happens if you walk slower, or faster? What happens if you run? Was 10 degrees still valid?  The truth was that ankle range seemed to be hugely variable, and both subject and activity specific.

Then there was the actual method of assessing the ankle range – how hard should we push the foot when measuring dorsiflexion? Common sense would suggest we should apply as much force to the foot as is applied during gait.  Could we physically apply this much force?  Probably not.

At the same time I was trying to take in the bombshell that 10 degrees of ankle dorsiflexion was no longer something I needed to worry about I was reading a lot of work by Dr Kevin Kirby; a Sacramento based Podiatrist and Professor of Biomechanics who was pivotal in highlighting to me (amongst many others I’m sure) the importance of thinking more like an engineer.  In the discipline of engineering terms such as flexibility, mobility and rigidity are not used as they lack the precision to be mathematically quantified.  Instead the term ‘stiffness’ is used, and this describes motion or deformation in response to an externally applied force.  So when applying this concept to the ankle joint instead of reporting simply how much it moves (its range), we should instead consider how much it moves when various forces are applied to it (its stiffness).  Given that the foot and ankle are predominantly asked to perform their daily functions during weightbearing activity ‘stiffness’ seems much more relevant than non weight bearing range of motion.

So after abandoning non weightbearing ankle range and the mythical 10 degrees of dorsiflexion from my thought processes, and getting my head around the concept of stiffness Vs range of motion I stumbled across the Lunge Test – a weightbearing assessment of the ankle joint range which factored in the individuals body weight.  This is a test which has been shown to have very good reliability / repeatability (Bennell et al, 1998) and prospective studies have also shown it to be predictive of injury (Pope et al, 1998; Gabbe et al, 2004).  There are actually very few clinical tests we perform which have been shown to be prospectively predictive of injury so this is a test which should certainly not be left out (especially when screening uninjured sportsmen and women).

So how is the test performed?

  1. Patient stands against wall with about 10cm between feet and wall.
  2. They move one foot back a foot’s distance behind the other.
  3. They bend the front knee until it touches the wall (keeping the heel on ground).
  4. If knee can not touch wall without heel coming off ground, move foot closer to wall then repeat.
  5. If knee can touch wall without heel coming off ground, move foot further away from wall then repeat.
  6. Keep repeating step 5 until can just touch knee to wall and heel stays on ground.
  7. Measure either: a) Distance between wall and big toe (<9-10cm is considered restricted) or b) The angle made by anterior tibia/shin to vertical (<35-38 degrees is considered restricted)
  8. Change the front foot and test the other side (symmetry is ideal)

It is worth remembering that there are some validity issues with the wall to big toe measurement with respect to the proportions/ratios between an individual’s leg length and foot length.  Anyone who is very tall is likely to have the minimum distance required and anyone who is very short will probably not have the minimum distance; therefore it is generally considered better practice to use the tibial angle when interpreting the results.

So what does this test mean?

A restricted Lunge test essentially suggests there in an increased ankle joint dorsiflexion stiffness.  Research tells us this may increase an individuals risk for lower extremity injury.  It is also something which will often be considered by a Podiatrist when recommending footwear or foot orthoses for someone who is already injured.  The test is generally performed when shod (to allow for the heel height differential of the shoe) and whilst wearing orthoses; modifications are made as required in order to achieve an appropriate tibial angle.  It may also dictate the appropriateness of concurrent joint mobilisations or a soft tissue stretching programme.

References (please contact me if you would like a copy of any article)

Bennell, K. L., Talbot, R., Wajswelner, H., Techovanich, W., & Kelly, D. (1998). Intra-rater and Inter-tester reliability of a weightbearing lunge measure of ankle dorsiflexion. Australian Physiotherapy, 24(2), 211-217.

Gabbe, B. J., Finch, C. F., Wajswelner, H., & Bennell, K. L. (2004). Predictors of lower extremity injuries at the community level of Australian football. Clin J Sport Med, 14(2), 56-63.

Kirby, K. A. Foot and Lower Extremity Biomechanics Volume 3: Precision Intricast Newsletters, 2002-2008. Precision Intricast: Payson, Arizona, 2009, p50.

Pope, R., Herbert, R., & and Kirwan, J. (1998). Effect of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in Army recruits. Australian Physiotherapy, 44(3), 165-172.

Barefoot Running

It seems that barefoot running is a particularly hot topic at present, and no matter where you turn you are reading things about it.  In the last several weeks it has turned up on thousands of blogs, in magazines and even made it onto the BBC News.  There have been all sorts of sensational headlines and quotes regarding barefoot running, but what is the truth?

Firstly it should be mentioned that when we talk about barefoot running we are usually also referring to running in ‘minimalist’ shoes such as Vibram Five Fingers or Newton runners (to name but two).  This is not a new debate, and has been raging on for quite some time – the reason for the media hype recently is due to two studies which were published within a month of each other back in Dec 2009/Jan 2010.  Unfortunately what followed was some terrifically inappropriate and inaccurate reporting by the media, and some energetic and passionate use of these misrepresented facts by the barefoot running community.

I am often asked whether (as a Podiatrist) I feel threatened by barefoot running.  The answer is a clear no.  I have no bias and I go where the research tells me.  However rather than just read someones one line summation of a research paper I instead read the entire paper thoroughly myself, and critique the methodology and conclusions made.  Things in my head are kept strictly objective and factual.  This blog entry intends to take a look at the two articles responsible for the recent media circus:

Kerrigan, D. C., Franz, J. R., Keenan, G. S., et al. (Dec 2009). The Effect of Running Shoes on Lower Extremity Joint Torques. PM&R, 1 (12), 1058-1063.

What did they do?

They took 68 runners who usually ran in shoes.  They put them all in what they called a ‘neutral’ running shoe and made them run on a treadmill.  They then made them all run on the treadmill again (at the same speed) but barefoot.  They measured the torques at the hip knee and ankle in both conditions.

What did the media/barefoot running community report?

Headlines usually were along the lines of: ‘Running Shoes Cause damage to hips, knees and ankles’

What are some of the problems with this research?

(1) The shoes every runner was given were a pair of Brooks Adrenaline.  This is clearly a ‘Stability’ shoe and not a neutral shoe.  When researchers are getting such simple facts as this wrong it is a concern.  Not to mention the fact that this may not have been an appropriate shoe for all 68 runners (nor a shoe some of them may have been used to) and little things like this seriously question the validity of the results obtained.

(2) None of the 68 runners were used to barefoot running.  This could account for why the torques were so much lower (someone running barefoot for the first time is bound to be more tentative about striking the ground).  Would it not have been a better idea to use habitual barefoot runners?

(3) This was performed on a treadmill.  Can the results therefore be extrapolated to overground running?

(4) The main author, Dr Kerrigan is a 100% equity holder in JKM Technologies and is the developer of a new and upcoming running shoe technology (the CDC suspension system).  This potential financial conflict of interest was not stated.  Some may think it suspicious that research produces conclusions which are geared towards the eventual release of a ‘barefoot technology’ shoe product.  Watch this space…

Lieberman, D. E., Venkadesan, M., Werbel, W. A. et al. (Jan 2010). Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature. 463, 531-535.

What did they do?

They had 5 groups of different runners (some barefoot runners, some shod runners, some from USA, some from Kenya).  They had them all run at preferred speed on the track and data on the foot position and forces were recorded.

What did the media/barefoot running community report?

Headlines were usually along the lines of: ‘Barefoot runners are less likely to experience serious injuries’ or ‘Running barefoot is better for you’

What are some of the problems with this research?

(1) This study had absolutely nothing to do with injury.  It was a comparison of barefoot and shod running.  I honestly have no idea how injury can even be mentioned when discussing this research.

(2) The statistical analysis is flawed.  Unforgivably they only compared 2 out of the 5 groups, and interestingly these were both groups of runners from the USA (despite most of the pictures from the study and alot of the discussions focusing on the Kenyan runners).

(3) They also did not have any age group controls between the 2 groups they compared.  The barefoot group (8 runners) had an average age of 38 years old.  The shod group (8 runners) had an average age of 19 years old.  How can you compare data between 2 groups when one is almost twice as old as the other?

(4) Findings based on a sample size of just 8 runners (even if the statistics were correct) are really not poweful enough to extrapolate to an entire population.

(5) The study was partially funded by Vibram Five Fingers.  Was there a financial conflict of interest?

Very interestingly even the authors of this study (to their credit) are acknowledging that the media has misrepresented their findings:

There are many discrepancies between the way some of the press has reported our paper and what the paper actually reports…we present no data on opinions on how people should run, whether shoes cause injuries, or whether barefoot running causes other kinds of injuries.  We believe there is a strong need for controlled prospective studies on these problems.

The website can be viewed in full here: http://barefootrunning.fas.harvard.edu/index.html

Some final things to consider about barefoot running in general:

  1. Why do no elite runners run barefoot if it is so beneficial?
  2. Every person is individual and what works for one does not work for all.  Not all runners need to strike on their forefoot to be the most efficient runners. For the majority of long distance runners at their normal training speeds, rearfoot striking is actually the preferred manner of running.
  3. Trying to make someone who is naturally a rearfoot striker into a forefoot striker may injure them.
  4. A runner who is a rearfoot striker at 10:00 min/mile pace may be a forefoot striker at 5:00 min/mile pace.  Running speed changes foot strike pattern.

In summary, what are the actual facts currently known about barefoot and shod running?

  1. Running barefoot/minimalist strengthens the intrinsic or postural muscles in the feet and lower leg…. probably, but not absolutely established.. seems sensible though.
  2. Running barefoot/minimalist increases proprioceptive awareness and balance.
  3. Running barefoot/minimalist forces a change in mechanics to adapt to the forces of on the feet.
  4. There are no clinical trials that show an effect of barefoot/minimalist running for a prolonged period of time.
  5. There are no research studies that prove that wearing traditional running shoes increases injuries or that barefoot/minimalist running reduces injuries.

So there you have it… the answer is that with respect to running barefoot and running shod, we don’t actually know which is better for you, or which puts you at greatest risk of certain injuries.  What we do know is that certain groups within the barefoot community (usually with their own agenda or sometimes financial interest) continue to promote their beliefs with poor information.  Whether they don’t bother reading the research themselves, or whether they do read it but through their own ‘lens’ who knows.

I would like to thank Mr Simon Bartold, Prof Craig Payne and Dr Kevin Kirby, without whom my own thinking on this subject would not be the same, and this blog entry would not have been possible.

For more in depth reading of both sides of the ‘discussion’ see the following pages:

Podiatry Arena discussions on barefoot running

Barefoot Running is Bad Blog

Newton Running Blog

Run Natural Blog

Fit Flops

Several weeks ago I was e-mailed by an online sports and outdoor footwear retailer and asked for my opinion on Fit Flops, possibly to be shown on their website.  They asked me for my honest opinion “whatever that may be”.  Now I have no personal vendetta against Fit Flops and am fully aware that (anecdotally at least) many many individuals find them very comfortable.  However I was pretty certain that a footwear company would not publish what I wrote about Fit Flops; given that they had a vested interest in selling them and I was certainly not going to validate the unsubstantiated claims that they boast:

I was quite suprised to see this week that the article had actually been published on the companies website blog.  However, perhaps I was less suprised to see that I had been ‘edited’.  I have pasted below the original manuscript exactly as I sent it to them:

Fit Flops – my thoughts by Ian B Griffiths, Sports Podiatrist.

The fit flop is one of the latest types of footwear to hit the stores backed up by significant marketing by the shoe company which produced it.  But what does it promise and can it deliver?  Surely it must be true or the media wouldn’t get hold of it and further promote the marketing claims… right?

Firstly let’s look at some of the alleged benefits of wearing Fit Flops:

(1)    Destabilisation of the feet to create continuous leg muscle tension

(2)    Increased leg, calf and gluteal muscle activity

(3)    Improved posture

(4)    Barefoot walking gait mimicked

(5)    Improved muscle tone

Now I cannot prove that Fit Flops do not do any of the above.  But I do not have to as that is not the way that the scientific method works.  It is the duty of the company making these claims to prove them to be true – not anyone else to prove them untrue.  By proof of course we mean well designed scientific studies (the gold standard being randomised controlled trials) which are then published in peer reviewed scientific academic journals.  So do Fit Flops have numerous studies backing up each of the above claims? No. They do not.

Their ‘research’ (as far as I can make out from their website) consists of studies carried out within a 3 month period at Salford and South Bank Universities.  There are no published studies that I can find regarding the Fit Flops.  This ‘research’ was of course carried out by the two individuals who developed the Fit Flop.  Am I suggesting their results are false and they are biased? No, but I am saying we all need access to these results and the statistical tests which were applied so we can critically analyse the conclusions drawn and decide for ourselves.  General words of advice – do not believe anything a shoe company tells you about their shoes unless it has been confirmed by an independent scientific study.

One study which has gone through the above peer review process is a paper published in 20081 which showed that normal flip flops actually increase the pressures under the heel and the ball of the foot when compared to athletic shoes, and therefore increase the risk of foot deformities.  Now whilst this was not a fit flop, you cannot disagree that the fit flop bears more resemblance to a flip flop than an athletic shoe.  Just some food for thought.

So why would a shoe company promise us all these things if they weren’t true? The cynical amongst us may assume it was to sell lots of them and make money.  Given the busy lifestyles people have nowadays, coupled with the human instinct to get quick results if at all possible you can see what a potentially lucrative idea a shoe such as the fit flop is.  Assuming you wanted to improve your fitness and get more toned buns which of the two below options sound more attractive (be honest):

Option A: A calorie controlled diet, cycling to work everyday, and visiting the gym 2-3 times a week to do a full lower limb resistance workout including straight leg hip extensions.

Option B: Just buy an expensive pair of shoes and ‘exercise while you walk!’

Having said all this there are certain circumstances in which this type of footwear may be beneficial (in my opinion).  Individuals who have arthritic changes or restrictions at the ankle joint or the big toe joint may well benefit positively from a shoe which allows the body to pass over the foot in a more fluid manner (a bit like a rocker bottom sole) as less joint movement is generally thought to be required.  They may also provide some relief for individuals with plantar fascia or heel pain – as any shoe with a raised heel has been shown to reduce the tensile loads in the plantar fascia.  The EVA construction will also afford the wearer more shock absorption which is certainly preferable to walking barefoot around the house, particularly on hard wooden floors first thing in the morning (first step pain being quite common in some presentations of heel pain).

To conclude, the human body has vast variability.  With regards to Fit flops some will love them, and some will hate them.  For some they may well be beneficial, and some they may well be detrimental.  What shouldn’t be done is a blanket approach to their marketing which seems to encompass all (and which also states facts which are unproven thus far).  I do not want anyone to think I am just getting at Fit Flops – all of the above could just as easily be applied to the MBT or the Shape Up from Sketchers.  These are my personal (and professional) opinions and I have no financial interest in any products.

1 Carl, T. J., & Barrett, S. L. (2008). Computerised Analysis of Plantar Pressure Variation in Flip-Flops, Athletic Shoes, and Bare Feet. Journal of the American Podiatric Medical Association. 98(5), 374-378.

Now you have seen this as I sent it to them originally – take a little look at it as it was published here: http://blog.fitnessfootwear.com/fitflops-by-ian-griffiths-sports-podiatrist/ See if you can see the  changes they made (and decide for yourself why they made them).  A bonus point for those who spot the not so subtle ‘completely putting words into my mouth’ trick.  EDIT: I did actually post a comment on the Fitness Footwear blog in response to the article ‘I wrote’ for them at the above link.  I merely supplied a link back to this blog entry here, and invited readers to see the original article as I intended it to be read.  You won’t see this comment on their site however, as after 4 days of it awaiting moderation it then disappeared.

What can be learnt from this? Well if you aspire to write articles for websites, newspapers or magazines then what you send them will most likely not be what you eventually read in print.  And the worst bit about this apparent ‘editorial/artistic license’ is that it will still have your name attached to it and everyone will think you wrote it.

If you are a consumer reading reviews on websites and in magazines then treat them with a healthy dose of cynicism, as what you read is not necessarily the most factually correct information (dare I say it is sales patter or financially motivated marketing hype?).  In a nutshell do not believe everything you read.  I certainly don’t believe what I read… even if it was I who wrote it.

Such is the nature of my profession that certain discussions or topics seem to come up time and time again.  It may shock some to hear that within the fields of Podiatric Medicine and Sports Injury we (the so called specialists) do not always all agree with each other.  Now more than ever it is important to try and stay abreast of all the latest research and to critically analyse it.  We should not just believe what we hear or what we read; we should question it and see whether the conclusions are solid and founded or whether it is simply a sensationalisation to grab headlines or sell a product (more on marketing hype later).

In the coming weeks and months on this blog I hope to cover some of the discussions which I have on a daily basis – whether I am with my sports patients in clinic or dissecting journal or newspaper articles with friends and colleagues.  I will present my opinions on hot topics (amongst others) such as barefoot running, how orthoses actually work, and whether or not the ‘normal’ foot or ‘perfect’ gait exists.  No doubt along the way I may plagiarise some of the thoughts and anecdotes I have learnt from good friends and colleagues over the years (and continue to do so) but I will try to credit or reference them accordingly.

Another more personal reason for the conception of this blog is that it seemed to me that it is the only way to have an unedited say.  Having written for newspapers, websites and magazines in the past (more on ‘Runner’s World’ to come) it is the unfortunate truth that the manuscript you send in is often not the one you read by the time it is in print with your name attached to it.  From now on anything I have published will appear here – in its full unedited original format.

I hope you enjoy reading my slightly geeky ramblings as much as I will enjoy writing them.

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