Why Do African Runners Dominate Marathons? (#58)

Why do Kenyans and Ethiopians dominate marathon statistics while the rest of the world is trailing? In this article, we take a closer look at what research actually reveals. We move away from simplistic explanations like "magic genes" and explore factors such as running economy, training environment, altitude, diet, early movement, and determination. The emerging picture suggests that the dominance likely doesn’t have a single explanation but results from the interplay of genetics and environment. The practical takeaway is inspiring: there's plenty to learn from, even if you're not born in the Rift Valley.

Why are the top forty plus marathon runners African, particularly Kenyans or Ethiopians? It's only by the 44th position that we see a Moroccan, with Jaouad Gharib finishing with a time of 2:05:27 in 2008. Jaouad Gharib

Quick note: he's the 44th fastest athlete but has "only" the 78th fastest time. Many of these swift runners, including Eliud Kipchoge, have times in the low 2:04 range. The phenomenon of African runners has been studied extensively, and in this article, we explore some of the possible reasons behind their successes.

Mitochondrial DNA (mtDNA) is a genetic marker that researchers use to track the movement of ethnic groups through millennia. One question that has been posed is whether these seemingly isolated ethnic groups have become so skilled due to concentrated genetic development.

But as the researchers state in the study:

This finding does not support the hypothesis that the Ethiopian or indeed Kenyan population, from which the athletes are drawn, has remained genetically isolated in East Africa but shows that it has undergone migration events and subsequent admixture during the development of the species. This opposes the possibility that these elite athletes have maintained and further developed the ancestral endurance phenotype through having remained isolated in the East African highlands.

In short: mtDNA shows blending and migration, not some mysterious isolation that would explain everything.

VO2, or oxygen uptake, is highly associated with performance, but that's not the whole picture. In a comparison between elite runners from Kenya and Germany, the Kenyan runners had an oxygen uptake of 71.5, compared to 70.7 ml/kg for the German runners, indicating a slight difference. Despite this, the personal bests for 10,000 m averaged 28:29 for the Kenyan runners and 30:29 for the German runners – showing a significant performance difference without a corresponding difference in VO2.

Your blood profile is influenced by altitude, and this has been thoroughly studied. In the same study, no difference in hemoglobin concentration or blood volume was observed between the German and Kenyan runners.

For a long time, there's been debate about whether daily running to and from school is a crucial factor. It seems logical and can offer several benefits:

1. It builds a stable foundation and enhances the stability of tendons and ligaments.
2. It sets the stage for mitochondrial biogenesis, the creation of new mitochondria essential for muscle power generation.
3. It promotes early capillarization, the network of blood vessels that deliver oxygen and energy substrates to muscles.

However, there are exceptions. Paul Tergat set a world marathon record in 2003 (2:04:55 in Berlin) but didn't start running seriously until he was 19, peaking at 21. Robert Cheruiyot, whom I (Simon) met at a training camp in Kenya in 2007, also began running only at 20 and went on to win the Boston Marathon three times after posting a time of 2:07:14 the previous year.

Arguments that commute running is detrimental are weak. In fact, 86% of Kenyan runners with international status reported running to and from school as their main means of transport. In Ethiopia, this applies to 68% of international marathon runners (source).

The Kenyan diet is often discussed but never as LCHF (Low Carb High Fat). It can generally be described as 77% carbohydrates, 10% protein, and 13% fat: a high carbohydrate content. Traditional meals often consist of ugali (cornmeal) and sukuma wiki (leafy greens). Carbohydrates are an efficient energy source in terms of oxygen cost and can facilitate intense training at high altitudes without leading to overtraining.

Interestingly, Kenyan runners, despite their high carbohydrate intake, have significantly higher activity of the enzyme HADH (hydroxylacyl-CoA dehydrogenase), which is important for fat oxidation. In Kenyans, 66.8 µmol was measured compared to Scandinavians' 44.7 µmol—about 33% more "fat enzyme" despite a carbohydrate-dominant diet. This efficiency partly explains their ability to maintain high intensity throughout a marathon, but it does not account for performances at 800-5000 m where fat oxidation is secondary.

A small argument for caution in altering the diet to "train" the body to burn fat: you might become fat-adapted primarily through the training you're already doing. If you haven't read our two-part series on train low compete high, you can find it here.

Isolation in mtDNA cannot explain everything, but genetics is an area where much research is ongoing. I believe we will see significant advancements in the next ten years.

The intrigue around the dominance of the East African nations in distance running is heightened by the observation that a large majority of Kenya’s most successful runners hail from a single tribe, the Kalenjin. This tribe, with a population of approximately 3.5 million, has won 75% of all Kenya’s gold medals and a similar percentage of silver medals at major international running competitions. Furthermore, almost half of Kenya’s international runners (44%) come from a subtribe of the Kalenjin known as the Nandi, who comprise only about 3% of the total Kenyan population

The challenge is that many traits are governed by a cluster of DNA variants. Researchers have, for example, identified 21 DNA sequences that can explain how well someone responds to endurance training in terms of VO2max increase. VO2max is just one piece of the puzzle—as we've already seen, runners with similar VO2 can have large variations in performance.

…although attributing Kenyan running success to a genetic explanation seems premature, it is noteworthy that Kenyans present high frequencies of desirable genotypes of certain performance-linked genes. A typical example is ACTN3, which encodes the protein alpha-actinin-3 and is almost exclusively expressed in sarcomeres of fast glycolytic type II fibers responsible for the generation of rapid forceful contractions.10 Two variants in this gene, R and X, have been identified, with the RR variant polymorphism strongly associated with sprint-running performance. In this regard, Yang et al have found that the XX genotype, which is non-desirable for elite sprint-running performance, is almost nonexistent in Kenyans.

Without speculating too much: an increased understanding of the interaction between environment and heredity is likely to provide us with much more knowledge in the future.

It's interesting that many medalists come from ethnic groups living at high altitudes. Even though the connections are not fully established, it's not illogical, as researchers write:

Both the Kenyans and the Ethiopians have lived for millennia at moderate altitude (2000–2500 m) in the highlands of the Great Rift Valley. It is not illogical to assume that this chronic hypoxic exposure has conferred certain as-yet unidentified genetic and phenotypical benefits that allow them to consistently train at altitude at running velocities (vLT and vVO2max) that their non-altitude-based opponents do not seem to be able to achieve without overtraining.

We have briefly written about altitude training here. The ability to train intensely over time at high altitude without breaking down is something both Ethiopian and Kenyan runners have in common (source).

In 2013, nearly half of Kenyans lived below the World Health Organization's poverty line; in Ethiopia, the same figure was 39% (source). Among Kenyan elite runners, 33% reported that economic opportunities were the reason they trained and competed, while only 14% were motivated by Olympic success.

Meanwhile, the big stars testify to a strong inner drive and pride:

We have so much inspiration. We want to be like Bikila, Wolde, Yifter. They gave us a reason to dream and hope. They are our role models. We see in them something that sparks our imagination and encourages us to change our lives for the better” – Haile Gebreselassie

Inner motivation takes over external reward when the former gains significance. Moreover, success breeds success: 22% of the national runners stated they ran because they had “talent.” With so many idols in history, it's easy to think “if they can do it, so can I.”

Personally, I (still Simon) stumbled upon endurance sports by chance – after trying football (without any major success), I got hooked on running. To claim that I had talent is an exaggeration, but the aptitude was greater for running than for football. I look forward to what future years of genetic research will reveal about performance.