In contrast, the other gene mentioned previously was simply known as the ACE gene. This gene is responsible for oxygen delivery, blood flow and the regulation of blood flow in the human body. An athlete’s heart is one-third larger than a normal heart.
This means that their Muscle fibres are thicker; the chambers are larger and their walls thicker. This leads to increased cardiac efficiency, meaning the heart is able to pump more blood with each contraction, and thus more efficiently able to deliver oxygen to muscles and carry away waste products. The DD and D1 variants of the ACE gene are the critical variants known to be associated with top athletes in the world and unsurprisingly it seems that the Jamaicans have a high percentage of these particular variants.As shown from the diagram above that 75% of ordinary Jamaicans have this critical variant.
This figure even rises for the athletes. Therefore, what exactly does this mean, surely based on the evidence seen Jamaicans are genetically predisposed to be sprinters. People who have two copies of the 577X version produce absolutely no actinin-3 in their muscle fibres and for the Jamaicans that only represents a very small minority. (Irving, 2010)Compared to the other well-known countries that produce top-level Olympic sprinters, this diagram shows that the Jamaicans are a giant leap ahead. “The desirable variant for a sprinter is known as 577RR (which is a variant of ACTN3).
While only 70% of US international-standard athletes have the desirable variant, 75% of Jamaicans have it whether they are athletes or not. That gives Jamaica another edge.” (Brooks, 2014)We can delve even deeper into the particular variant of the ACTN3 gene that makes the Jamaicans so special and the results are quite alarming… As mentioned before, you are born with what you’ve got. Your parent’s muscle fibres determinate the type of fibres the offspring inherit.
In addition, it has not been scientifically proven that it is possible to change a slow twitch fibre to a fast one or vice versa. Unfortunately, for some, it could affect how successful you are at either developing as a long distance athlete or a sprinter. There are some extremes in terms of the percentage of muscle fibre you have, however, the most common is 50% of both fast and slow titch fibres. On the other hand it could be also said that a sprinter with 90% of fast twitch fibres will have a better chance of winning that someone with only 20% of fast twitch fibres. (Anderson, 2000)Type IIa are known as the fence riders, halfway between both Types I and the Type IIb fibres.
This is the most common amongst humans. Type IIb, on the other hand, are known as the fast twitch fibres, these fibres are responsible for fast, explosive movements. They fire anaerobically, and very quickly.
However they lack the endurance that the Type I offers, meaning they get tired very easily. It is also important to know that ACTN3 is only found in fast twitch fibres. Elite sprinters can often have a makeup of up to 90% of fast twitch fibres, it helps them to be so fast.
Incredibly long-distance competitors can have a make-up of up to 80% of type I (slow twitch fibres). It enables them to conserve energy and allows them to perform at such high intensity for long periods of time without getting tired quickly. Muscle fibresMoreover, Jamaican sprinters such as Usain Bolt and Yohan Blake are known to have an abundance of these fast twitch fibres. The higher prevalence of these fast twitch fibres in the make-up of the sprinters gives them an advantage over other competitors. This is a key factor in the debate that genetics is the biggest factor in the dominance of the Jamaican runners.
ACTN3 is the most research sports gene ever, however, is it the main factor? It is hard to say. There are so many other factors involved and other contributing factors to the nature argument such as the slave trade and superior muscle fibres. In an event such as sprinting where there can be such fine margins, any extra advantage can prove to be the difference between mediocrity and success. It is believed that ACTN3 is mostly found in fast-twitch muscle fibres and it helps them work very efficiently, because of this it means if you are born with lots of these fast twitch fibres, you will have lots of access to the ACTN3.
More ACTN3 results in the increase in the production of the alpha-actinin-3 protein. “Most Africans have alpha-actinin-3, it’s the normal ancestral state. But as you move into European and Asian populations there is a marked increase in the number of people without the protein.” (Emery)ACTN3 is linked with muscle fibres and how they are formatted, it is responsible for the production of alpha-actinin-3, and this is a protein found only in fast twitch fibres. In actuality, ACTN3 can give sprinters a powerful boost because it gives additional energy to muscle cells to produce quick, mighty actions. Everyone has the ACTN3 gene; however, in some cases, a person can have lots of slow twitch fibres (good for endurance) or fast twitch fibres (good for the quick release of speed). Most people normally have a mix of both, which may not beneficial for some depending on the type of athlete they want to be.
It is also important to mention that these slow twitch fibres cannot be turned into fast twitch ones or vice versa. “If you don’t have at least 70 to 80 percent of fast twitch muscle fibres I’d say it’s unlikely you could be among them (the world’s top sprinters)”. (Kellend, 2012)There seems to be a particular gene that keeps appearing more often than most.
The angiotensin-converting enzyme (ACE) and the alpha-actinin-3 (ACTN3) genes are two of the most studied “performance genes” and both have been associated with sprint/power phenotypes and elite performance. ?