It has been obvious while watching the Olympics that the Caribbean countries particularly Jamaica dominates the sprints and East African countries such as Kenya and Ethiopia long distance running. The usual factors apply; genetics, environment and opportunity.
Fast /slow twitch muscles fibres:
There are two types of fibres in muscle. Slow twitch which contract slowly but keep going for a long time and use oxygen efficiently. They are the most useful for the long distance runner.Fast twitch fibres contract quickly but do not use oxygen as efficiently and get tired more rapidly. The concentration of theses are important for sprinters. Olympic sprinters have been shown to have 80% fast twitch whereas Olympic long distance runner have been shown to have 80% slow twitch.Fibre type is known to be genetically determined but it is still uncertain whether training can actually change fibre type.
The 3 countries which dominate long distance running are the three adjacent countries of Kenya, Ethiopia and Somalia and many tribes are genetically related.
Jamaicans, Caribbean countries and black people from America tend to dominate sprinting. They all have similar origins having been selected for their strength during the slave trade from the west coast of Africa. The infamous crossing ensured that only the very strongest survived [survival of the fittest]
Erythropoietin (EPO) is a hormone naturally produced in the kidneys which stimulates red blood cell production. With more red blood cells you can carry and deliver more oxygen to your muscles.
At high altitude, the air is ‘thinner’ therefore there are fewer oxygen molecules in the lungs making fewer molecules available for red blood cells to bind to. When this happens, more erythropoietin is produced to counteract this. Now there will be more red blood cells and therefore more oxygen can be carried. Athletes sometimes train at high altitude in order to gain more red blood cells in this manner before returning to normal altitude. When they return, they will keep high levels of red blood cells for a while thus allowing better performance. Somalia, Kenya and Ethiopia are high altitude countries and runners are used to running in thin air.
EPO can be made artificially. It is illegal for athletes to take erythropoietin to improve performance and the act of doing so is termed ‘blood doping.’ Another form of blood doping is when an athlete transfuses blood previously taken from themselves to increase the amount of red blood cells. Until recently blood doping was impossible to detect however recent advances have meant that the ratio of young immature red blood cells to mature red blood cells may be able to tell if it occurred. EPO also leads to a similar result .
Oxygen dissociation curve:
The oxygen dissociation curve is important for understanding how our body carries and releases oxygen. This is what it looks like:
Its sigmoid shape enables oxygen to be transferred from red cells to oxygen deprived tissues efficiently. At high altitude, we produce more of a compound called DPG. This shifts the curve to the right which enables oxygen release from haemoglobin to muscles to occur even more efficiently (at even higher P02 partial pressures).
Running is cheap. It is one sport in which relatively poor countries can excel. You don’t need boats, swimming pools, horses or skiing equipment. In rich countries you may actually have less opportunity to run. When I visited Kenya on Safari our driver picked up a boy to give him a lift to school. I learnt that he would jog 5 miles 4 times a day as he would come home for lunch. I asked in all seriousness if he had thought about taking a packed lunch as I thought he probably burnt off as many calories as he would eat by travelling home in the middle of the day. My comment produced much laughter at the time but in reality in communities such as those, running was a natural everyday occurrence. Everybody did it, those who were particularly good would stand out and of course as with everything the more you do the better you get. Our population is generally untested, how many 8 year olds have a hidden talent for long distance running, at that age very few will have tried to run 6 miles or more? One Olympic coach said in answer to the question ‘How do you beat the Kenyans at long distance running?’ –‘Buy them school buses!’