Malisoux L, Gette P, Delattre N, et al. Gait asymmetry in spatiotemporal and kinetic variables does not increase running-related injury risk in lower limbs: a secondary analysis of a randomised trial including 800+ recreational runners.

The full article can be found here.


Tell us more about yourself and the author team.

With my mentor and former head of the unit, Daniel Theisen, we have worked for more than 10 years in Sports Sciences at the Sports Medicine Research Laboratory of the Luxembourg Institute of Health. Amongst others, we have conducted several randomised trials investigating the effect of running shoe features on injury risk in leisure-time runners. Our longstanding relationship with the sports equipment manufacturer Decathlon was made possible thanks to Nicolas Delattre’s great work, open-mindedness, and the trustful collaboration we have built. We also benefitted from the clinical and scientific expertise of Dr Axel Urhausen and the tremendous work done by Paul Gette regarding data processing in the lab.

What is the story behind your study?

When we designed our study on the effect of shoe cushioning on injury risk, we also aimed to understand the underlying mechanisms that may explain a potential protective effect of shoe cushioning. So, not only did we follow up with more than 800 leisure-time runners for 6 months regarding their injuries, but we also boldly decided to test every participant on an instrumented treadmill at the start of the study. We knew that this dataset would be unique worldwide and that it would allow us to look at the effect of shoe cushioning on timing and magnitude of ground impact forces, investigating how running biomechanics relate to injury risk. Of course, we first worked on the questions about shoe cushioning. In the following stages, we addressed other clinically relevant questions on the relationship between running biomechanics and injury risk.

In your own words, what did you find?

Differences in spatiotemporal and ground reaction force characteristics between the left and right leg were unrelated to running injuries in our group of healthy runners. This was somewhat unexpected, as many believe that asymmetries in running mechanics represent a risk factor for injury. Of course, our results should be confirmed by further studies, including leg movement analyses, which we did not perform here. Also, our conclusions are valid for recreational runners and may not necessarily hold for elite athletes. Still, we provided solid evidence that asymmetry in spatiotemporal and kinetic variables is not worth systematically investigating without physical complaints. On the contrary, some degree of asymmetry may even be beneficial. After all, the human body is not a machine that works perfectly symmetrically.

What was the main challenge you faced in your study?

The main challenge was the sheer scale of the study. Recruiting and testing 874 runners in our lab required a 6-month commitment of working from 7 am to 7 pm 5 days a week. Also, the parent study was a randomised, double-blind study, so managing the randomised shoe allocation without the study participants nor the researchers knowing who received what type of shoe was challenging. Finally, the 6-month follow-up of such a large study group was very resource-intensive. We were very fortunate that the whole team rolled up their sleeves, including postdocs from other projects, research assistants and a master’s student, to make this project a huge success.

If there is one takeaway message from your study, what would it be?

Do not mind your asymmetry if you have no physical complaints. In other words, do not repair what’s not broken!

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