Portal de Periódicos da CAPES

Top Marathon Performance

2015; Lippincott Williams & Wilkins; Volume: 14; Issue: 1 Linguagem: Inglês

10.1249/jsr.0000000000000115

1537-8918

E. Randy Eichner,

Genetics and Physical Performance

Introduction The New York City Marathon in November 2014 was another show of Kenyan dominance in distance running. Wilson Kipsang of Kenya won the men’s race, and Mary Keitany of Kenya won the women’s race. Kipsang also set a world record, winning the 2013 Berlin Marathon in 2 h, 3 min, 23 s. Another Kenyan, Dennis Kimetto, set a new world record in Berlin in 2014, winning the marathon in just under 2 h, 3 min. In fact, East Africans have dominated the marathon since 1999. In a story about the possibility of a 2-h marathon, Runner’s World magazine analyzed top-20 marathon times worldwide over a 30-yr span, from 1984 through 2013. Of the 100 fastest marathoners in history, 59 are Kenyan and 31 are Ethiopian. Runner’s World predicts that the first man to run the marathon in 2 h will 1) have a stellar maximal oxygen uptake (V˙O2max) and running economy, 2) be 5 ft 6 inches tall, weigh 120 lb, and have long legs and slender calves, 3) be in his early 20s, with towering self-confidence and very fast friends, and 4) have access to things we cannot imagine (4). Runner’s World seems to have in mind an elite runner from the Kalenjin tribe in Kenya. An earlier analysis by esteemed exercise physiologists reached similar conclusions and was followed by 15 pages of letters from other experts with other ideas (1,6). More on this “long running” debate is discussed as follows, along with troubling trends as to “…things we cannot imagine.” What Makes East African Runners So Good? Why do Kenyans and Ethiopians excel at distance running? This question has spurred many studies and articles. One noted article — on “genes and cultures” — is long on anecdotes but short on scholarship. It draws from sketchy sources, misunderstands the adaptations to altitude, and quotes from a chapter on Kenyan runners in Malcolm Gladwell’s book, Outliers (3). That book has no such chapter. A commendable recent review explores eight proposed contributors to East African dominance in distance running, as follows: 1) genetic predisposition, 2) high V˙O2max from lifelong running, 3) high hematocrit (Hct), 4) top running economy, 5) favorable muscle fiber and enzyme profile, 6) high-carbohydrate diet, 7) living and training at altitude, and 8) desire for economic success (9). Genetic studies do not explain why about 75% of Kenya’s best runners come from just one of Kenya’s 40 tribes, the Kalenjin, on the western rim of the Great Rift Valley. Kenyan runners have a high V˙O2max, yet they run faster than German counterparts with a high V˙O2max. Kenyans have a high Hct and top running economy. Their muscle profile and diet are not all that unique. They are born and bred at altitude (2,000 to 2,500 m) and can train hard — even at race pace — at that altitude. Finally they are inspired as runners by a heritage of excellence and by knowing that winning will bestow great economic and social success to them and their family. Thin Air and Thick Blood One might assume that living in thin air, as Kenyan and Ethiopian runners do, would lead to “thick blood,” a higher Hct. This is the rationale for doping with erythropoietin (Epo) in competitive cycling: raising Hct without unduly raising the blood viscosity can enhance aerobic performance by boosting oxygen delivery to muscles (2). Elite Kenyan runners do tend to have a relatively high Hct. In a study of 41 Kenyan runners cited in the previously mentioned review (9), mean Hct was 49% and one-fourth of the runners had a Hct >50%. In a study of 10 Kenyan runners versus 11 German runners, although no clear difference was found between groups in total hemoglobin mass (as measured by an “optimized carbon monoxide rebreathing method”), the Kenyans had a higher mean hemoglobin level (16.1 vs 15.5 g·dL−1) and a significantly higher (49% vs 45%) mean Hct (8). A study presented at an international sports medicine meeting in 2013 shows that, even in Kenyans, Epo can drive Hct higher and speed running performance. Studied were 15 Kenyan and 19 Scottish runners. The Kenyans started with significantly higher mean Hct (46% vs 42%) and V˙O2max, along with much faster 3K run times (9 min, 20 s vs 11 min, 8 s). After 4 wk of Epo administration, Hct rose to 50% in the Kenyans and 49% in the Scots, and both groups ran about 5% faster in the 3K trial (10). Alas studies like this are noticed by coaches and athletes. One might ask, “What is the point of a study like this?” Yes, knowledge beats ignorance, but in light of all we already know about Epo and athletes, does the high-profile presentation of this Epo study do more good than harm? See Troubling Trends in the following section. Troubling Trends Kenyan Rita Jeptoo, 33, of the Kalenjin tribe, is one of the best marathoners in the world. She has won the Boston Marathon three times. In September 2014, she tested positive for Epo in an out-of-competition urine test in Kenya, just 2.5 wk before she won the Chicago Marathon for the second straight year. Jeptoo was to receive a $500,000 prize for marathoning excellence, but that award is on hold, as her “B” sample is tested and events play out. Jeptoo denies taking any banned drug. Unlike in the early days of Epo testing, however, the “B” sample now usually confirms the “A” sample. Troubling trends have followed big money into marathoning. Kenyans are wonderful runners — they have been for decades — and no one would imagine they would cheat or would need to cheat. That was in the old days. Times have changed. Testing for doping has been lax in Kenya, and in 2012, a German television report alleged drug use by some top Kenyan runners. Under international pressure, a Kenyan antidoping task force reported a spike in doping cases, as follows: 18 Kenyan runners failed doping tests in 2012 and 2013, compared with only 18 Kenyan doping cases in the 19 years before 2012. One article names 17 of those caught doping; 15 were marathoners, and most were subelite runners trying to become elite runners; five classes of drugs were found, including nine runners on anabolic steroids and three on Epo. One, Matthews Kisorio, who ran the third fastest half-marathon ever, was caught for an anabolic steroid but tacitly admitted to taking Epo also (5). Now that hundreds of marathons are offering millions of dollars in prize money and hundreds of Kenyan runners are competing to lift themselves and their families out of poverty with just one triumph, human nature tells us that the incentive to cut corners is strong. Some who know distance running well are skeptical of the Kenyan program. For example, Frank Shorter, the American who won the Olympic Marathon in 1972, recently told the New York Times that his first indication that some Kenyan runners might be doping came in the 1980s when they began to use Italian doctors as agents (7). Yet in some ways, who can blame the Kenyans? After all, the rest of the world has their share of athletes who cheat to win. And when it comes to cheating in a broader sense, who will throw the first stone? I will leave it to the ethicists to defend “the spirit of sport.” My concern is “dying to win.” I fear that for an athlete on Epo, there can be a thin line between winning and dying. Doping with Epo has killed up to 25 or 30 European competitive cyclists (2). Let us not see that tragedy replayed among the magnificent Kenyan runners. The author declares no conflicts of interest and does not have any financial disclosures.