Gene play

The Olympics are a great nat­u­ral lab­o­ra­tory for the cu­ri­ous minds who want to un­ravel the ge­netic un­der­pin­ning of sports per­for­mance. Sci­en­tists are peer­ing into the genomes of top ath­letes to find out which genes can spill their se­crets of suc­cess. Novel

Down to Earth - - CONTENTS -

Do su­per ath­letes have spe­cial genes?

ELITE ATH­LETES hold a spe­cial at­trac­tion for ge­neti­cists. They are the finest spec­i­mens of phys­i­cal per­for­mance that can re­veal the clues to what sep­a­rates the champs from the chumps. Sci­en­tists first tried to doc­u­ment ge­netic mark­ers for sports per­for­mance dur­ing the 1968 Mex­ico Olympics. With ad­vances in ge­netic tech­nol­ogy in the 1990s, they be­gan look­ing at spe­cific genes in the dna. That was the time when the world re­dis­cov­ered Eero Män­tyranta, a Fin­nish cross-coun­try skier who had re­mained on top of his game in the 1960s, win­ning seven Olympic medals. Fin­nish re­searchers found out that Män­tyranta had a rare ge­netic mu­ta­tion that made his body pro­duce more than nor­mal red blood cells. This meant his blood could carry large amounts of oxy­gen to burn fuel and pro­duce en­ergy. Small won­der he would at times beat his com­peti­tors to the fin­ish line by, not split sec­onds, but tens of sec­onds.

That was the first di­rect ev­i­dence of genes pro­vid­ing a win­ning edge to a sportsper­son. But mere mu­ta­tions are not what ge­neti­cists are con­cen­trat­ing on. Their am­bi­tion is to trans­late the en­tire ge­netic bi­ble of ath­leti­cism. They want to iden­tify all the genes that shape what we call in­her­ent tal­ent. They are sift­ing through the genomes of hun­dreds of elite ath­letes. So far they have iden­ti­fied more than 200 genes that could be re­lated to phys­i­cal per­for­mance. These are the genes that in­flu­ence traits from mus­cle strength to car­diores­pi­ra­tory en­durance to ex­er­cise in­tol­er­ance. Some com­mer­cial ven­tures even of­fer to screen your dna and tell you what kind of sport you should try your hand at or how you should train.

Sci­en­tists have also stud­ied twins and fam­i­lies to see which fit­ness traits are heri

ta­ble, and how her­i­ta­ble. “We know from twin and fam­ily stud­ies that there is a ge­netic com­po­nent to phys­i­cal per­for­mance. This ap­plies to en­durance and strength-based mea­sures of per­for­mance,” Claude Bouchard, di­rec­tor of the Hu­man Ge­nomics Lab­o­ra­tory at Pen­ning­ton Bio­med­i­cal Re­search Cen­ter in Los An­ge­les, usa, tells Down To Earth ( dte). “What is the ex­tent of the ge­netic com­po­nent is not fully un­der­stood. The her­itage Fam­ily Study span­ning two gen­er­a­tions and hun­dreds of fam­i­lies] sug­gests that the ge­netic com­po­nent for en­durance per­for­mance may be as high as 45 to 50 per cent of the over­all in­di­vid­ual dif­fer­ences ob­served in the pop­u­la­tion.” Fifty per cent! That would mean an en­durance ath­lete is half born.

So is it the genes that stir Bri­tish swim­mer Keri-Anne Payne to say, “I was born to swim”? Payne says her par­ents were good swim­mers too. And didn’t Pele fa­mously say, “I was born to play foot­ball, just like Beethoven was born to write mu­sic and Michelan­gelo was born to paint”? Re­mem­ber his fa­ther was also a foot­ball player.

IS THE GENIE IN THE GENES?

Phys­i­cal per­for­mance is a com­plex trait un­like, say, skin colour, which is coded by a few genes. It re­sults from a com­plex in­ter­ac­tion of many genes with vary­ing in­flu­ence. Sci­en­tists be­lieve a large num­ber of them are yet to be iden­ti­fied. “While many genes have been ten­ta­tively as­so­ci­ated with per­for­mance-re­lated traits, few if any have risen to the level that would be called con­clu­sive,” writes ex­er­cise phys­i­ol­o­gist Stephen M Roth in Ge­netic and molec­u­lar as­pects of sport per­for­mance, a vol­ume of the En­cy­clopae­dia of Sports Medicine. “We do not know enough about them, ex­cept two genes, actn3 and ace,” says Nir Enyon, who

leads re­search on genes and per­for­mance at the Vic­to­ria Univer­sity in Mel­bourne. He is part of a dna biobank ini­tia­tive that aims to col­lect more than 1,000 dna sam­ples from all over the world to try to un­der­stand the genome of the best Olympic ath­letes.

So while genes play a big role in ath­letic per­for­mance, sci­en­tists are still far from pre­dict­ing suc­cess or spot­ting tal­ent. Two re­searchers in the UK, Al­lun Wil­liams and Jonathan Fol­land, tried to fig­ure out, sta­tis­ti­cally, how many peo­ple have the per­fect ge­netic pro­file for en­durance sports. They chose 23 ge­netic variants closely as­so­ci­ated with en­durance and ran an al­go­rithm. To their sur­prise they found that the chance of car­ry­ing all the 23 gene variants was one in a thou­sand tril­lion! Even to find a sin­gle per­son with just 16 of the gene variants, one will have to screen al­most the en­tire hu­man pop­u­la­tion. What’s more, the re­searchers ob­served, “There was con­sid­er­able ho­mo­gene­ity in terms of ge­netic pre­dis­po­si­tion to high en­durance po­ten­tial, with 99 per cent of peo­ple dif­fer­ing by no more than seven geno­types from the typ­i­cal pro­file.” In other words, ge­net­i­cally speak­ing, most of us dif­fer very lit­tle in ath­letic prow­ess and none is per­fect.

Take actn3 gene, the so-called sprint gene, al­though there is no sin­gle gene for speed or power. It reg­u­lates the func­tion of fast mus­cle fi­bres that help pro­duce bursts of en­ergy re­quired in sprint­ing, weightlift­ing and foot­ball. Its ver­sions come in three com­bi­na­tions and roughly ev­ery third per­son has the most favourable com­bi­na­tion for sprint­ing. It’s that com­mon.

But when it comes to the top level ev­ery gene counts. Among Olympic-level sprint­ers, in­di­vid­u­als with the least favourable com­bi­na­tion of actn3 are not to­tally elim­i­nated but their pro­por­tion is much smaller than in the gen­eral pop­u­la­tion. As Daniel MacArthur, one of the ge­neti­cists be­hind the actn3 stud­ies, ex­plains in an ar­ti­cle in Wired, “this large ef­fect is due to the ex­cep­tion­ally strong se­lec­tion that oc­curs dur­ing the slow climb to the Olympic level. The vast ma­jor­ity of ath­letes who start that climb will never make it to the top; those who do will be the tiny mi­nor­ity who have nearly ev­ery­thing in their favour, in­clud­ing the right genes. So su­per-elite ath­letes need to have the right actn3 com­bi­na­tion, but they also have to have a whole host of other fac­tors work­ing in their favour—this one gene is just a mi­nor in­gre­di­ent in a large and com­plex recipe.”

The recipe for ex­cel­lence is com­plex in­deed. “We know genes con­trib­ute to sports per­for­mance, po­ten­tially con­tribut- ing to phys­i­cal traits such as strength, co­or­di­na­tion, en­durance, and men­tal traits such as fo­cus, com­pet­i­tive drive. But these traits are also in­flu­enced by en­vi­ron­men­tal fac­tors (train­ing, coach­ing, equip­ment),” Roth tells dte (see in­ter­view). “So suc­cess­ful elite ath­letes are very likely suc­cess­ful due to both some unique ge­netic con­tri­bu­tions as well as sup­port­ive en­vi­ron­men­tal

con­di­tions.”

Pele also re­mem­bers his fa­ther telling him: “You were born to play foot­ball. You’ve got a gift for it. But if you don’t work at it and prac­tise, then you’ll be just like the rest.”

AFRICAN PHE­NOM­E­NON

Yet to Jon En­tine, the au­thor of Taboo: Why Black Ath­letes Dom­i­nate Sports and Why We’re Afraid to Talk About It, when it comes to run­ning the “en­vi­ron­men­tal ex­pla­na­tion is an or­tho­doxy”. He con­tends that “at the most elite level, the vic­tory is con­tested by those with the best genes”. What prompts him to claim this is the phe­nom­e­nal suc­cess of the peo­ple of African an­ces­try in run­ning—sprint­ers from West Africa and dis­tance run­ners from East Africa. As he points out, among men, ath­letes of African an­ces­try hold ev­ery ma­jor run­ning record, from the 100 m to the marathon. Of the past seven Olympics men’s 100 m races, all 56 fi­nal­ists have been of West African de­scent. African dom­i­nance is vis­i­ble in dis­tance run­ning as well. If you look at it closely they come from dis­tinct re­gions: Kenya, Ethiopia and Ja­maica (Ja­maicans are de­scen­dants of en­slaved West Ari­cans). Even within Kenya the ma­jor­ity of the run­ners come from a small sub­set, the Kalen­jin tribe, and in Ethiopia from the Arsi re­gion. This strength­ens the sus­pi­cion that peo­ple in these pock­ets could have evolved in iso­la­tion to ac­quire some un­beat­able ge­netic ad­van­tage.

But bi­ol­o­gist Yan­nis Pit­si­ladis points out that “these ath­letes, al­though aris­ing from dis­tinct re­gions of east Africa or Ja­maica…do not arise from a lim­ited ge­netic iso­late”. Cur­rently, Pro­fes­sor of Sport and Ex­er­cise Science at the Univer­sity of Brighton, UK, Pit­si­ladis has trav­elled for years in Kenya, Ethiopia and Ja­maica. He has col­lected dna sam­ples of 1,000 Olympic ath­letes. “The only avail­able ge­netic stud­ies of elite Ethiopian and Kenyan dis­tance run­ners and sprint­ers from Ja­maica, Nige­ria, andthe usa do not find these ath­letes pos­sess unique ge­netic pro­files; rather they serve to high­light a high de­gree of ge­netic di­ver­sity among these ath­letes,” he writes in Ge­netic and Molec­u­lar As­pects of Sport Per­for­mance. “Al­though ge­netic con­tri­bu­tions to the phe­nom­e­nal suc­cess of black sprint­ers and east African dis­tance run­ners can­not be ex­cluded, re­sults to date pre­dom­i­nantly im­pli­cate en­vi­ron­men­tal fac­tors.”

Sev­eral stud­ies high­light the Kenyans’ bird-like physique—longer legs, shorter tor­sos and slen­der limbs, es­pe­cially lower legs—which gives them an edge in run­ning. And they are will­ing to train be­cause they have lim­ited ca­reer op­por­tu­ni­ties. Pit­si­ladis thinks it is more likely that these peo­ple have re­alised their ge­netic or bi­o­log­i­cal po­ten­tial.

Talk­ing about the Kalen­jin tribe of Kenya in a pod­cast chat, David Ep­stein, au­thor of The Sports Gene, ob­served: “You get this amaz­ing striv­ing and lack of any fear to at­tempt to train like an Olympian and you pair that with cer­tain phys­i­ol­ogy, you get what I think is the big­gest over­rep­re­sen­ta­tion of the sport­ing prow­ess we have seen in any sport ever any­where.”

3 1 Du­tee Chand, In­dian sprinter 2 Usain Bolt, Ja­maican sprinter 3 Shi Zhiy­ong, Chi­nese weightlifter

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1 2 3 4 1 Michael Phelps, US swim­mer Vikas Kr­is­han Ya­dav, In­dian boxer Ash­wini Akkunji, In­dian sprinter Yo­gesh­war Dutt, In­dian wrestler 2 3 4

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