Lab Rat

Adding to the Ro­ta­tion

Canadian Running - - DEPARTMENT­S - By Mary­lene Vester­gom

We’ve all heard it. You need to change your shoes af­ter about 500k. But do you? What about sim­ply ro­tat­ing your shoes or vary­ing the sur­face you run on? Is this some­thing run­ners should con­sider?

“Peo­ple give these num­bers for when you should re­place your shoes, but there’s gen­er­ally no con­sid­er­a­tion of the run­ner’s body mass and shoe wear, so the num­ber is of­ten ar­bi­trary,” says biomech­a­nist Dr. Max Pa­que­tte, from the Univer­sity of Mem­phis.

A for­mer col­le­giate ath­lete in cross-coun­try and track at the Univer­sity of Guelph, Pa­que­tte is a strong be­liever in shoe ro­ta­tion to pre­vent in­jury. “Run­ning in­juries a re re­lated to the amount of mus­cle and skele­tal tis­sue load­ing. These tis­sues get over­loaded in some way, they are not given enough re­cov­ery time and get dam­aged.”

Although the sci­ence be­hind shoe ro­ta­tion is lack­ing, Pa­que­tte points to one study that was done by a group of sci­en­tists in Luxembourg and pub­lished in t he Scan­di­na­vian Jour­nal of Medicine& Sci­ence in Sports. It s aim was to de­ter­mine if run­ners who used dif­fer­ent pairs of run­ning shoes are at a dif­fer­ent risk of run­ning-re­lated in­juries. It turns out run­ners who got in­jured more of­ten used one pair of shoes dur­ing train­ing while those who used at least two pairs tended to get hurt less.

The study goes on to say, “the con­comi­tant use of dif­fer­ent pairs of run­ning shoes will pro­vide al­ter­na­tion in the run­ning pat­tern and vary ex­ter­nal and ac­tive forces on the lower legs dur­ing run­ning ac­tiv­ity. Whether the re­duced in­jury risk can be as­cribed to al­ter­na­tion of dif­fer­ent shoe char­ac­ter­is­tics, such as mid­sole den­si­ties, struc­tures or ge­ome­tries can­not be de­ter­mined from these re­sults and war­rants fu­ture re­search.”

Although some of us may think buy­ing more shoes is a ploy from run­ning shoe man­u­fac­tur­ers and spe­cialty run­ning shoe stores, this is not so, says David Korell, footwear mer­chan­diser for New Bal­ance Canada.

“We typ­i­cally say that ro­tat­ing two pairs of shoes ev­ery other day with dif­fer­ent off­sets within the same genre can help strengthen and adapt lower limbs in dif­fer­ent ways,” says Korell. “A per­son may wear one shoe with a thicker stack height and a cer­tain drop and a sec­ond shoe with less stack height and a dif­fer­ent drop, both from within the same cat­e­gory. That would be the healthy ap­proach and may just help con­trib­ute to run­ners stay­ing in­jury-free.”

Pa­que­tte agrees that the more vari­able the move­ment, the more you’re able to change where the forces are act­ing on the tis­sues of the body. If you run in a high heel drop shoe ver­sus a low heel drop shoe, ev­ery time the foot strikes the ground, the foot is go­ing to be in a slightly dif­fer­ent po­si­tion. By chang­ing the po­si­tion of the body, you’re ef­fec­tively chang­ing how forces are be­ing ap­plied. Just mak­ing small changes may be enough to al­low cer­tain tis­sues to re­cover by run­ning in a dif­fer­ent shoe.

“I do be­lieve chang­ing things up, whether it’s footwear or some­thing else like the ter­rain you’re run­ning on, is im­por­tant. When I ran at Guelph, I of­ten ro­tated up to five dif­fer­ent shoes: sta­bil­ity, a few pairs of neu­trals and a few rac­ing shoes that I would only run in oc­ca­sion­ally.”

The only equip­ment a run­ner has is his or her run­ning shoes. “Run­ners need to mix it up and not just their shoes,” says Janette Yee, ath­letic ther­a­pist at the Toronto Ath­letic Club. Although ro­tat­ing your shoes is a good idea, it’s not the only op­tion. “Run­ners should also try run­ning on dif­fer­ent ter­rain and sur­faces. This way your body doesn’t get used to the ex­act same de­mand.” Biomech­a­nist Dr. Ge­off rey Gray, founder and pres­i­dent of Heeluxe in Cal­i­for­nia, agrees. “It re­quires your body to ex­plore move­ment pat­terns and use them a lit­tle bit dif­fer­ently; I also feel it’s good to run at dif­fer­ent speeds. Chang­ing your shoes does cre­ate dif­fer­ent sen­sory-stim­u­lus, which helps our body to tune it­self to be a bet­ter run­ner.” As far as Pa­que­tte is con­cerned, the idea that run­ners need to change af­ter X amount of kilo­me­tres be­cause your shoe is get­ting tired and old tells us the whole shoe in­dus­try has made us weak. Per­haps the shoe isn’t the whole prob­lem. “Per­haps our feet are weak and lazy and they’re un­able to move in their nat­u­rally pro­tec­tive way and now we are more sus­cep­ti­ble to in­jury. In my shoe ro­ta­tion I’ve in­cluded a low heel drop shoe to pro­vide my feet with a type of ‘work­out’ if you will. I only com­plete short runs in those, but I do try to in­clude a less sup­port­ive shoe in my ro­ta­tion for that rea­son.”

Per­haps chang­ing the stresses on your body – whether it’s ro­tat­ing your shoes, run­ning on dif­fer­ent sur­faces or even tak­ing some time off – is worth ex­plor­ing. As for chang­ing your shoes af­ter a cer­tain num­ber of kilo­me­tres? Dr. Benno M. Nigg, pro­fes­sor emer­i­tus of biome­chan­ics at the Univer­sity of Cal­gary, says only you and your body can re­ally tell if you need to switch out your shoes. “Change them when they’re not com­fort­able,” says Nigg. “That’s my rec­om­men­da­tion.”

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