The fu­ture of gait anal­y­sis

Canadian Running - - THE SCIENCE OF RUNNING -

At last year’s World Track and Field Cham­pi­onship in Lon­don, sci­en­tists from Leeds Beck­ett Univer­sity de­ployed 49 high­speed cam­eras around the sta­dium and along the marathon course to record the move­ments of the best run­ners in the world. The re­sult was billed as “the largest biome­chan­ics study in the sport’s his­tory,” and it re­vealed some sur­pris­ing in­sights.

For one thing, more than 70 per cent of the 1 48 male and fe­male marathon­ers landed heel-first with each st ride–a much­ma­ligned ga it pat­tern that some crit­ics der ideas in ef­fi­cient. But ap­par­ently many of the best run­ners in the world, in­clud­ing the top four fin­ish­ers in the men’s race, are heel-strike rs. There were also some sur­pris­ingly quirky gaits on dis­play: women’s 10,000m cham­pion Al­maz Ayana, for ex­am­ple, had an asym­met­ric stride with one leg reach­ing 20 cen­time­tres far­ther than the other.

As fas­ci­nat­ing as this data is, there are two draw­backs. One is that few of us will ever have a team of sci­en­tists por­ing over high­speed cam­era data of our strides. The other is that, even for the lucky run­ners who get this treat­ment, it’s not al­ways clear what to do with the re­sult­ing data. Should Ayana, who al­ready holds the 10,000m world record, try to make her stride more sym­met­ric? Or should the rest of us try to em­u­late her awk­ward-but-fast gait?

One pos­si­ble vi­sion for the fu­ture comes from re­searchers at the Univer­sity of Cal­gary, who de­ployed a sim­ple, wear­able ac­celerom­e­ter on run­ners, with the re­sults an­a­lyzed by a com­puter us­ing “ma­chine learn­ing” to de­tect which gait traits are most im­por­tant. The study, which was pub­lished in the Jour­nal of Sports Sciences, showed that the com­puter could tell the dif­fer­ence be­tween “recre­ational” and “com­pet­i­tive” run­ners (as clas­si­fied based on their race times) with bet­ter than 80 per cent ac­cu­racy.

Un­der­stand­ing t he gait dif­fer­ences be­tween recre­ational and com­pet­i­tive run­ners is use­ful be­cause the lat­ter group tend to be more in­jury-proof, es­pe­cially in the knee and hip ar­eas. The main dif­fer­ences be­tween the two groups showed up in their con­sis­tency: for com­pet­i­tive run­ners, the forces and ac­cel­er­a­tions and lower-leg move­ments in one stride are al­most iden­ti­cal to the next stride. In­ex­pe­ri­enced run­ners, in con­trast, tend to have more stride-tostride vari­a­tion. And that, lead re­searcher Chris­tian Cler­mont ex­plains, of­fers a sim­ple tar­get for fu­ture wear­able de­vices to start track­ing: don’t worry if you’re heel strik­ing, as long as it’s con­sis­tent.

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