Again, in this study, like the last we discussed here, we are looking at experienced (and in this case, young) runners; sprinters specifically. Again, they ran relatively short distances (20 meters). More than 1/2 the runners had “large” asymmetries, and they all had asymmetries of some type. Some athletes had injuries and some did not.
There wasn’t a difference in sprint performance over this short distance. This is not surprising in light of the previous paper we discussed; asymmetries seem to worsen over time (Hanley 2018). The level of compensation present (since these are experienced runners) may also be better; the folks that were uninjured having compensation patterns that were more in line with their anatomy, than the injured ones.
The asymmetries did not change. Thinking about anatomy, especially with hard deformities like torsions or versions, why would they? You can’t change the stripes on a tiger.
Injured and non injured athletes did not differ in asymmetry before or after the study. Again, why would they? We are talking about gait changes (or perhaps compensations). What is significant for one individual (tibial torsion, femoral retroversion, leg length discrepacy) may not be as significant as it for another, depending on the compensation present.
The study concludes “... kinematic asymmetries in the stride cycle were not associated with neither maximal sprint running performance nor the prevalence of injury among high-level athletic sprinters.” Note that they are talking about prevalence of injury, not incidence of injury.
We still think that asymmetry matters...
Haugen T, Danielsen J, McGhie D, Sandbakk Ø, Ettema G. Kinematic stride cycle asymmetry is not associated with sprint performance and injury prevalence in athletic sprinters. Scand J Med Sci Sports. 2018 Mar;28(3):1001-1008. doi: 10.1111/sms.12953. Epub 2017 Aug 15.