Epigenetics in Athletics Part 2: African dominance explained?
In Part 1 on Epigenetics, we looked at some of the science behind the new field. This we’ll take more of a theoretical look and try and explore some of the possible implications.
As I said in Part 1, the major finding is that these epigenetic changes can potentially impact subsequent generations. Your behavior can essentially be imprinted on your DNA and passed down to subsequent generations.
There seem to be certain windows of time in which transgenerational epigenetic changes occur. For women, there’s a distinct time window while the baby is in the womb that changes are more likely to occur. Similarly, the prepuberty period in men seems to have a significant window. This should make sense if we think of how genetic material is passed on to subsequent generations, but what about other windows? At the present time, we’re unsure, but in theory, Sharp (2009) offered the idea that training could impact these windows. In animal studies, a dramatic stress has been shown to create transgenerational changes outside of the known/accepted windows.
Knowing all of this, several questions arise in regards to performance:
1. Could long term training create small changes in DNA function to adapt future generations for that particular environment (i.e. increase cardiovascular function or EPO or mitochondria)?
2. Could the magnitude of the effects be enhanced if training (cellular stress) was performed during previously found key windows of change?
3. Can the effects be negative to a training stress? For example, it’s been shown that exposure to very high cortisol levels during pregnancy can lead to stress hormone abnormalities due to epigenetic changes in the subsequent generation. Could overtraining during key windows lead to negative epigenetic changes in the next generation?
Finally, how does the body respond to various training effects? The possibilities are seemingly endless. All systems of the body could be potentially impacted, from cardiovascular to muscular.
East African’s and the Epigenome
The consensus being reached by scientists studying the phenomenon is that the East African dominance is not as genetically linked as they previously thought. Perhaps epigenetics provides a partial explanation. Let’s look at the possible mechanisms and theory. It should be noted that this is pure speculation intended to make people think.
In the East African countries of Ethiopia and Kenya, the best distance runners seem to come from a select few tribes in the Rift Valley. In Kenya 80% of the top Kenyan runners come from the Kalenjin tribe which only makes up 10% of the entire Kenyan population. While in Ethiopia, 38% of the top runners come from a tribe that makes up only 5% of the Ethiopian population.
This has led to speculation that perhaps these tribes have a genetic predisposition to running. However, research has demonstrated that for the most part the genetic makeup of the top East African runners is similar to control populations of regular East Africans. See my PowerPoint study for research.
With the genetics theory not providing the substantial difference they expected, speculation on whether the high altitude or environmental factors caused these specific tribes to flourish at running. I’ve covered some of those theories in depth before, but with the new science of epigenetics perhaps the environment plays a larger role on the genetics than we could have previously imagined?
Is it possible that environmental factors that occur in these small tribes have led to epigenetic changes that enhance endurance?
We’ve already established that diet can play a crucial role in manipulating gene expression for several generations. It’s possible that dietary changes could have resulted in a better fueling system. Research has shown that Kenyan runners produced less lactate and had better running economy than their white counterparts. Both of these factors are impacted by fuel usage and utilization. Perhaps diet in previous generations has led to certain adaptations to enhance these processes. It could be their specific diet, which consists of carb intake, or a particular famine which occurred, which both Kenya and Ethiopia have seen their fair share of. Research has shown that famine’s have large epigenetic consequences for subsequent generations. Whether or not a famine would increase fuel processing is unknown. For the former, perhaps a high carbohydrate intake enhances carb utilization?
Activity Level and Training:
The activity level of the East Africans is well known. In International Kenyan runners over 50% of them had to travel greater than 5km to get to school and over 80% of them ran to school. Similarly, the lifestyle in both rural Kenya and Ethiopia requires large amounts of physical activity.
On the former topic, the large amount of activity during the pre-puberty years is of particular interest. In part 1, I discussed how the study on the Swedish village found that one of the epigenetic windows was the prepuberty years for males. If the East African’s spend this time doing informal training, perhaps it is setting them up for endurance excellence as the way certain genes that are beneficial to endurance function change for the better. Since we are more plastic during younger years, this early activity could pave the way for better endurance response during the formidable running years. If the function of such genes responsible for mitochondria biogenesis is switched “on” early in life, this could lead to a greater ease of signaling these genes to activate later in training. Maybe this explains why East Africans seem to have greater trainability and respond quickly to training. Additionally, the lifestyle of the great East African runners’ parents or grandparents could play a role.
An interesting study would be to look at this in America. We have distinct periods of good international running performance and very poor international running performance. Maybe what was going on in the previous generation when they born needs to be looked at?
Another common factor cited for East African running success is altitude. People have speculated that long term living at high altitude might have elicited some favorable adaptation. This has been criticized based on the genetic diversity of the East Africans and the fact that long term adaptations have been seen to take a very long time. Now that we know that environment can create transgenerational changes rather quickly, maybe altitude plays a larger role. There is already an Ethiopian pattern to altitude adjustment (maintenance of hemoglobin and oxygen saturation levels) that differs from Tibetan and Andean. Perhaps the altitude causes epigenetic alterations that enhance endurance performance? We know that several genes, HIF-1a in particular, are impacted by altitude’s effects. It’s possible that endurance activity at altitude has led to various changes in gene function.
Could East African dominance in running be the result of the perfect storm of epigenetic factors that switched on genes that turned out to improve endurance performance?
Lots of questions remain unanswered, but hopefully you can see that this transgenerational adaptation on a rapid scale shows that nature and nurture are intertwined to a much larger degree than we had previously thought. It’s not longer that you’re stuck with the genes you got and what you do won’t impact them. Instead, what you do, what your parents did, and what your grandparents did could be impacting you on the genetic level right now.
Just more reason to keep running and eating right. Your grandkids can thank you in a couple generations!