The Sci­ence of Run­ning

By Alex Hutchin­son Ul­tra-trail Phys­i­ol­ogy; Trail Phys­i­ol­ogy; Fight­ing the In­ter­fer­ence Ef­fect

Canadian Running - - DEPARTMENTS - alex hutchin­son

Ul­tra-trail Phys­i­ol­ogy

It’s “the world’s most chal­leng­ing moun­tain ul­tra­ma­rathon,” ac­cord­ing to the sci­en­tists who study it. And with 24,000 me­tres of el­e­va­tion and de­scent spread over 330 kilo­me­tres in the Ital­ian Alps, there’s a rea­son the Tor des Géants strikes fear in the hearts of run­ners and cu­rios­ity in the minds of re­searchers. What does it take to make it to the fin­ish line of a race whose course record is just un­der 68 hours and whose cut-off time is a mind-numb­ing 150 hours?

Re­searchers in Italy and Switzer­land con­vinced a 50-year-old trail vet­eran (and three-time Tor des Géants fin­isher) to serve as a guinea pig dur­ing the race. In ad­di­tion to ex­ten­sive phys­i­o­log­i­cal test­ing be­fore and af­ter, he agreed to wear a por­ta­ble oxy­gen-anal­y­sis mask dur­ing six of the race’s gru­elling as­cents, along with a gps sen­sor and a fin­ger-mounted oxime­ter to mea­sure oxy­gen lev­els in his blood. The re­sults, which were pub­lished in the jour­nal Fron­tiers in Phys­i­ol­ogy, of­fer a unique glimpse of the meta­bolic de­mands of multi-day races – and some sur­pris­ing twists.

The re­searchers ex­pected to see a pro­gres­sive de­crease in the run­ner’s “meta­bolic ef­fi­ciency” as he fa­tigued over the six days he was out there (his fin­ish­ing time was 125 hours and 19 sec­onds), mean­ing that it would re­quire more en­ergy to cover the same dis­tance or as­cend to the same el­e­va­tion. In fact, his best ef­fi­ciency val­ues were recorded on the fifth and sixth days of the race, when his fa­tigue was high­est. The rea­son, the sci­en­tists sus­pect, is that his stride got pro­gres­sively more ef­fi­cient as he elim­i­nated need­less up-and-down mo­tion and set­tled into a smooth (and likely dead-legged) run­ning style.

It’s al­ways a lit­tle risky to gen­er­al­ize too much based on the re­sults of a sin­gle case re­port, but this new data agrees with pre­vi­ous find­ings about how ef­fi­ciency changes over the course of long races. In par­tic­u­lar, stud­ies sug­gest that it’s your up­hill run­ning form that un­der­goes the most changes. This is, af­ter all, the part of the race that eats up the most meta­bolic en­ergy and takes the most time – in the Tor des Géants study, the par­tic­i­pant spent a stag­ger­ing 75 hours go­ing up­hill. The take­away, the re­searchers ar­gue, is that “in­cor­po­rat­ing long-last­ing lo­co­mo­tion train­ing… is manda­tory in the train­ing pro­grams of moun­tain ul­tra­ma­rathon ath­letes.” Run hills, the longer the bet­ter, and lots of ’em.

Trail Phys­i­ol­ogy (The Short Ver­sion)

What’s true for epi­cally long trail races like Tor des Géants doesn’t nec­es­sar­ily ap­ply to briefer chal­lenges. A re­cent pa­per in Medicine & Sci­ence in Sports & Ex­er­cise, from re­searchers in France, aimed to dis­en­tan­gle the phys­i­o­log­i­cal de­mands of “short” trail races, which they de­fined as any­thing less than the stan­dard marathon dis­tance of 42.2k. They put nine ex­pe­ri­enced trail run­ners through a com­pre­hen­sive bat­tery of tests be­fore run­ning a chal­leng­ing 27k trail race, then as­sessed which test re­sults best pre­dicted the race times.

In stan­dard road marathons, which take a sim­i­lar amount of time to com­plete, per­for­mance can be pre­dicted pretty ac­cu­rately with three pa­ram­e­ters: max­i­mal oxy­gen con­sump­tion (VO2­max), lac­tate thresh­old and run­ning econ­omy (a mea­sure of ef­fi­ciency). But these three pa­ram­e­ters, which col­lec­tively make up the “clas­sic en­durance run­ning model,” could ex­plain less than half of the vari­a­tion in fin­ish­ing times in the trail run­ners. The spe­cific chal­lenges of trail run­ning – ter­rain, foot­ing, hills, mud – mean that suc­cess­ful run­ners need other char­ac­ter­is­tics.

Two ad­di­tional pa­ram­e­ters al­lowed the re­searchers to make bet­ter per­for­mance pre­dic­tions about the trail run­ners. One was their run­ning econ­omy mea­sured on a 10 per cent up­hill slope rather than on level ground. Be­ing an ef­fi­cient run­ner on the f lats doesn’t nec­es­sar­ily mean you’re ef­fi­cient on hills, and the best trail run­ners have ap­par­ently learned to min­i­mize wasted mo­tion while climb­ing.

The sec­ond new pa­ram­e­ter was “lo­cal mus­cle en­durance,” which was tested with a se­ries of 40 all-out leg ex­ten­sions. Run­ners whose strength de­clined the least from start to fin­ish of this test per­formed bet­ter in the trail run – a sign, the re­searchers sus­pect, that strong legs are par­tic­u­larly im­por­tant for pro­pel­ling run­ners up and down hilly ter­rain. The take­away, in the end, is much like the Tor des Géants study: runs hills – and lots of ’em.

Fight­ing the In­ter­fer­ence Ef­fect

Putting on mus­cle isn’t par­tic­u­larly easy for most peo­ple, but run­ners have long har­boured the sus­pi­cion that it’s es­pe­cially hard if you’re do­ing a lot of en­durance train­ing. Stud­ies have mostly backed this idea up, and there’s even ev­i­dence that the cel­lu­lar sig­nals that trig­ger en­durance gains in­ter­fere with the sig­nals that trig­ger mus­cle growth. In peo­ple do­ing iden­ti­cal strength train­ing pro­grams, in other words, those who run more will gain less mus­cle.

As re­searchers learn more about molec­u­lar sig­nalling, they’re start­ing to come up with ideas on how to com­bat this in­ter­fer­ence ef­fect. A se­ries of stud­ies by Keith Baar, a Cana­dian-born re­searcher at the Univer­sity of Cal­i­for­nia Davis, sug­gests that one of the key is­sues is caloric deficit, which trig­gers a sig­nalling cas­cade that hin­ders the for­ma­tion of new mus­cle pro­tein. Even if you’re get­ting enough calo­ries over­all, com­bin­ing both strength and en­durance train­ing means there will be times dur­ing the day when you’re short on calo­ries and get­ting less post-train­ing adap­tion.

Baar’s prac­ti­cal tips in­clude mak­ing sure you fully re­fuel af­ter a run be­fore start­ing strength train­ing, and aim­ing to spread your pro­tein in­take through­out the day to en­sure you’re never short of amino acids. He also sug­gests lift­ing rel­a­tively heavy weights that push you to fail­ure within less than a dozen reps, which max­i­mizes the sig­nals for mus­cle growth while min­i­miz­ing calo­ries burned and meta­bolic stress. These fac­tors prob­a­bly only mat­ter if you’re train­ing at least four times a week and push­ing hard in some work­outs – but if you’re strug­gling to main­tain your mus­cle mass, they’re worth con­sid­er­ing. Alex Hutchin­son is one of the most re­spected sports sci­ence writ­ers in the world. His lat­est book, En­dure, is avail­able now.

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