Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers

One thing that I have been consistent in saying is that different running forms load different tissues differently. From a clinical perspective, this is not a matter of one ‘form’ being better than another, its about what gait changes can be made to reduce the load on any tissues that there are problematic issues with. To blindly advocate one approach over another does not make sense. There is also the principle that you can’t reduce the load in one tissue, without increasing it in another¹. I have already written about what injuries are possibly more common in what running form, even though it now appears that there is probably no global differences in injury rates between forefoot strikers or minimalist runners compared to heel strikers. Now we have this study was just pre-published:

Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers
Kulmala, Juha-Pekka; Avela, Janne; Pasanen, Kati; Parkkari, Jari
Medicine & Science in Sports & Exercise: 6 June 2013
Purpose. Knee pain and Achilles tendinopathies are the most common complaints among runners. The differences in the running mechanics may play an important role in the pathogenesis of lower limb overuse injuries. However, the effect of a runner’s foot strike pattern on the ankle and especially on the knee loading is poorly understood. The purpose of this study was to examine whether runners using a forefoot strike pattern exhibit a different lower limb loading profile than runners who use rearfoot strike pattern.
Methods. Nineteen female athletes with a natural forefoot strike pattern and pair-matched females with rearfoot strike pattern (n = 19) underwent 3D running analysis at 4 m/s. Joint angles and moments, patellofemoral contact forces and stresses, and Achilles tendon forces were analyzed and compared between groups.
Results. Forefoot strikers demonstrated 1ower patellofemoral contact force and stress compared to heel strikers (4.3 +/- 1.2 vs. 5.1 +/- 1.1 body weight, BW; P = 0.029 and 11.1 +/- 2.9 vs. 13.0 +/- 2.8 Mpa; P = 0.04). In addition, knee frontal plane moment was lower in the forefoot strikers compared heel strikers (1.49 +/- 0.51 vs. 1.97 +/- 0.66 Nm/kg; P = 0.015). At the ankle level, forefoot strikers showed higher plantarflexor moment (3.12 +/- 0.40 vs. 2.54 +/- 0.37 Nm/kg; P = 0.001) and Achilles tendon force (6.3 +/- 0.8 vs. 5.1 +/- 1.3 BW; P = 0.002) compared to rearfoot strikers.
Conclusions. To our knowledge, this is the first study to show differences in patellofemoral loading and knee frontal plane moment between forefoot and rearfoot strikers. Forefoot strikers exhibit both lower patellofemoral stress and knee frontal plane moment than rearfoot strikers which may reduce the risk of running-related knee injuries. On the other hand, parallel increase in ankle plantarflexor and Achilles tendon loading may increase risk for ankle and foot injuries.

This study clearly showed that in female runners the heel strikers had increased knee loads and less ankle loads and the forefoot strikers had lower knee loads and higher ankle loads. This simply means that heel strikers load tissues differently to forefoot strikers and will therefore, theoretically, have a different injury risk profiles. As I keep saying, ‘its 6 of one and half a dozen of the other‘.

I am a little intrigued about the choice of title of the paper. It is “Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers“, which is correct as that is what the study showed; but the title of the article could also easily have easily been: “Forefoot strikers exhibit higher Achilles tendon loading than rearfoot strikers“, which is also what the study showed; or it could have been “Rearfoot strikers exhibit lower Achilles tendon loading loading than forefoot strikers“. Get the point I am making? As this is a science based publication, the title should probably have been something like: “Differences in knee and ankle loads between forefoot and rearfoot strikers“.

The interpretation of research in social media is always something I like to monitor. I will wait to see what happens with this study. For example, of course those who have rejected other studies that they just did not like results of because of what they consider to be small sample sizes will automatically reject this study (eg see the comments section on this study). I have no problem with the sample size of the this study, due to the power analysis and statistical significance.

Also of note in this study is that they found no differences in cadence between the rearfoot or forefoot strikers.

As always, I go where the evidence takes me until convinced otherwise.

POSTSCRIPT:

 

POSTSCRIPT:
Above I wrote:

I am a little intrigued about the choice of title of the paper. It is “Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers“, which is correct as that is what the study showed; but the title of the article could also easily have easily been: “Forefoot strikers exhibit higher Achilles tendon loading than rearfoot strikers“, which is also what the study showed; or it could have been “Rearfoot strikers exhibit lower Achilles tendon loading loading than forefoot strikers“. Get the point I am making? As this is a science based publication, the title should probably have been something like: “Differences in knee and ankle loads between forefoot and rearfoot strikers“.

Here is the title they used when they presented the research at a conference: Effects of striking strategy on lower extremity loading during running.

1. With the exception that loads can be reduced if you loose weight.

Kulmala, J., Avela, J., Pasanen, K., & Parkkari, J. (2013). Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers Medicine & Science in Sports & Exercise DOI: 10.1249/MSS.0b013e31829efcf7

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About Craig Payne

University lecturer, runner, cynic, researcher, skeptic, forum admin, woo basher, clinician, rabble-rouser, blogger, dad. Follow me on Twitter, Facebook and Google+

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4 Responses to Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers

  1. Brent June 8, 2013 at 3:13 pm #

    Interesting that I got your attention with the sample size issue…I find this to be a limiting factor with many studies in Homo sapiens. My main point of criticism with all of these studies is that it seems almost impossible to get a definitive answer. So why not just leave it alone and let people have fun doing whatever style of running they prefer?

  2. Craig Payne June 8, 2013 at 8:26 pm #

    I raised the sample size issue to be facetious as I see so many reject a study that they do not like based on the sample size, but are happy to accept the results of study with an even smaller sample size if they like the results of the study! They just showing their ignorance of sample size calculations, power analysis and effect sizes.

    You right about leaving runners alone to run the way they prefer (with one proviso*). The evidence from all the most recent studies that have appeared in the last 6 months is that there is no advantage of minimalism or forefoot striking over shoe or heel striking. In these most recent studies, the running economy is the same and the injury rates are the same. Even the above studies shows, as i said, 6 of one and half a dozen of the other. This is why I prefer to rely on what the evidence says rather than the blind religious like fanaticism of those who tout Pose, Chi, Barefoot, Minimalism, Maximalism, Evolution, Alexander, Whatever as *the way* to run and try and impose those views on all because it worked for them!

    *The one proviso is that I see runners clinically and will often give advice on what they may need to look at changing something(s) to help reduce the load in the problematic tissue to manage an injury long term. They may or may not want to change – its up to them. Sometimes I do see a more significant flaw in the running form – especially in an aspect of the technique that there is a pretty good consensus (even among the fanatics) that what I am seeing is not necessarily good running form (it may or may not be related to their injury) – in which case, I send them on to a running technique coach for further discussions.

    • Mark Richard July 5, 2013 at 11:52 pm #

      Better than sitting on the fence

  3. Ronald Lavine, DC December 28, 2013 at 3:09 pm #

    Good summary of this article, Craig, and a useful critique of the choice of title. I experimented with a forefoot landing style for a while and discovered for myself the possible Achilles tendon loading issues – my calves were killing me!

    Fortunately, my body was able to adjust without it becoming an injury. Nonetheless, I’ve gone back to a rearfoot strike style. Not sure exactly why. I’m not that serious a runner anyway – the longest I’ve ever competed is in a 5K.

    I subscribed to your feed and look forward to more good info. Thanks.

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