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:
@craigbpayne the knee went thru a different range but they didn’t model patellar contact stress. Ext load not what happens at surface
— Greg Lehman (@GregLehman) June 8, 2013
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
