More details about muscle explosiveness vis-á-vis endurance

While researching neuromuscular diseases, Australian scientists have focused on the gene ACTN3, which encodes a protein called the α-actinin-3. This gene is present in primitive as well as in highly developed animals (also in humans). Results showed that a number of healthy individuals do not possess an operating form of the gene ACTN3. How is it possible that a gene which is widespread amongst living organisms is defective in such a large number of individuals?

Although many individuals do not possess an operating form of the gene ACTN3, they have no health problems and live quite a normal life. From that scientists have concluded that the gene ACTN3 must play an important role in the functioning of muscle tissue. Because the ACTN3 gene is expressed mostly in fast twitching fibres they assumed it must be important for sprinters who need explosiveness and speed to succeed. They examined more than 400 Australians, all top athletes, many of them representing Australia at the Olympic Games. The researchers divided the athletes into two groups. In the first group there were athletes who need speed and power and in the second group there were those who require endurance. In the first group almost every athlete had the functioning gene version (CC). In the second group athletes mostly had the none-functioning gene version (TT). With this experiment, the hypothesis at the beginning was confirmed. The gene ACTN3 is important for sprinters.

Why some have the inactive gene form

The last research even showed that the sprint results have a negative correlation with the results for jogging 1500 m, which indicates a strong genetic background. Now we can answer the question from the introduction: why do so many individuals have a mutated form of the gene? Obviously selection operated in a balanced way, depending on environmental factors. In some cases, speed was more desired, and in another endurance, that is why both forms of the gene were preserved in the world’s population. They have also discovered that the ACTN3 gene had a greater impact on the female athletes than on the male athletes. The differences regarding the impact on males and females are explained with compensation for the lack of α- actinin-3 in males by a greater expression of androgens during training.

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