Introduction
Every year, new records on different sports are broken by athletes. That is, they set new records on the previous limits of human performance in their respective sports. For example, a previous lap record in a sprint may easily get broken by another individual who can simply run faster and complete the same lap in a significantly shorter length of time. This is, in fact, one of the reasons why most people and experts in the field of sports ask if there is ever a limit to human performance. Some would answer yes and some would answer the opposite.
This also raises the question on the factors that influence, if not directly cause the continuous improvements in human performance not only in sports competitions but in other settings as well. Later on, this gave birth to the notion that genetics play a key role in determining an athlete’s performance in a particular sport. Some would even go as far as saying that athletes are born and not made; that genetics determine, in many ways, an individual’s potential to excel in particular sports, without disregarding the other factors that have also been proven to contribute to the process of honing that potential such as proper training, diet, and discipline. The objective of this paper is to determine whether there is a correlation between genetics and sport performance. The authors of this paper would try to do just that by means of a literature review that would start with a SEED paper and later on to more specific reviews concerning genetics and sports performance.
The SEED article that was published in this case was published in the Journal of Science and Medicine in Sport in 2015. The title of the article was MCT1 A1470T: A Novel Polymorphism for Sprint Performance? Basically, the main objective of the authors was to verify their research hypothesis. Their research hypothesis suggested that the presence of the A1470T polymorphism in the monocarboxylate (lactate/pyruvate) transporter 1 gene MCT1 has a direct influence in athletic performance among general population. That is, individuals who have experienced this particular reaction in their transporter one genes would most likely exhibit increased athletic performance which may later on be interpreted as an increase in that individual’s overall potential in playing a particular sport, thus supporting the notion that genetics indeed have a direct effect on sports performance.
Genetics is the branch of science that talks about the study of genes, genetic variation, and heredity in living organisms, mostly humans and other forms of mammals. In some textbooks, it is considered as a subfield of biology. However, to be safe, most literatures consider it to be an intersection between two or even more branches of life sciences, because after all, genetics deal with living cells of living organisms. Some of the primary principles of genetics that were popularized during the 21st century were the principles of molecular and trait inheritance.
Based on the principles of molecular and trait inheritance, the offspring of two parents who both have broad shoulders, would most likely inherit the molecular and structural qualities that led to the creation of that trait; this means that the offspring would also have broad shoulders. These two were actually the earliest indicators that experts in the field of genetics used to predict the function and general behavior of genes. Of course, contemporary experts in the field worked from those principles and expanded beyond it. Now, the field of genetics does not just focus on the function and behavior of the genes; it now encompasses the study of the different gene structures, functions, variations, and distribution on small and large scale levels.
Whenever a person gets engaged in a high intensity exercise program, large deposits of metabolites such as lactate and protons get accumulated in the different cavities of the contracting muscle or group of muscles. This accumulation comes as a result of glycolysis—one of the different types of metabolism. Physiologically, too much accumulation of lactates and protons within or even near the contracting muscles would lead to cramps, reduced performance and endurance, and other adverse effects that may render the contracting muscles incapable of performing the work.
For the contracting muscle or the effector organ to continue working, it has to continuously remove the accumulated lactates and protons from the cell and into the bloodstream. Naturally, the higher rate of muscle contraction, the faster the accumulation of these substances on the muscle cells would be. This is where the MCT1 and other MCTs job would enter. Basically, MCTs, acronym for monocarboxylate transporters, have the duty of transporting lactates and other unnecessary substances out of the muscle cells so that they may continuously perform their function. MCT1 is just one of the 14 types of MCTs. The higher the rate of removal of the metabolites away from the cells of the muscle that performs an athlete’s muscle for example, the better the performance would be both in terms of power and endurance.
In the SEED article, the authors attempted to verify the existence of a presumed relationship between MCT1 and the spring performance of athletes. 112 endurance athletes were pitted against 100 sprint or power athletes. The control group was composed of 621 sedentary individuals. Their DNA information was extracted prior to the start of the tests. The researchers, Sawczuk, Banting, Cieszczyk, Maciejewska, Zarebska, Duniec, Jastrzebski, Bishop, and Eynon (2015), used Fisher’s exact tests and multinomial logistic regression analyses to objectively determine the association between the MCT1 genotype and the athletic performance of the respondents across the three groups.
The results of the authors’ analyses showed that the sprint or power athletes were more likely than controls to possess the minor T allele genotype; and more likely than endurance athletes to have the TT genotype, all of which suggests that the MCT1 TT genotype has a high level of association with elite sprint and power athletes compared to the respondents belonging to the sedentary group.
Review of the Literature (Body)
In one article published in the European Journal of Applied Physiology in 2005, the researchers conducted a study by determining the relationship between the insertion of a variation of the ACE gene (human angiotensin converting enzyme) and the performance of endurance swimmers. They did it by studying the genetics of 35 elite long distance swimmers. The 35 respondents were divided into two groups the first one being the swimmers better at 1 to 10 km distances (n=19) and the second one being the swimmers best at 25 km races (n=16). What the researchers looked for was the presence of the ACEI alleles in the two groups. The results showed that the frequency of the ACE I allege was greater among those who best compete internationally at distances of 25 km.
One of the common metrics used in appraising an athlete’s performance is his susceptibility to injuries. Injuries are common among athletes, especially those who are engaged in high intensity and high impact sports such as basketball, American football, among others. According to a study published in the Medical Sports Science in 2009, one of the contributories to musculoskeletal soft tissue injuries among athletes is a wide range of genetic risk factors. Apart from acute and chronic overuse musculoskeletal injuries, genes allegedly play an important role in determining an athlete’s susceptibility to injury.
Basically, the presence of these gene variants in Achilles tendon injured athletes would indicate that genetic risk factors are real and that they can really worsen or even turn into a musculoskeletal soft tissue injury. The authors concluded that even after using genetic association studies, it is still too early to tell whether there is conclusive evidence that the presence of or the quality of having genetic variants such as the ones that were named as examples above, may indeed lead to a higher risk of developing musculoskeletal soft tissue injuries.
Lastly, in a study published in the Journal of Sports Medicine in 2013, the authors studied the heritability of specific phenotypical traits that may be potentially relevant for physical performance that may be helpful in sports and other competitions. Basically, the authors investigated whether certain DNA traits may indicate that an individual ma have superior physical performance or have a lesser likelihood of developing a disease compared to another individual who does not have that DNA trait.
This was not a quantitative experimental study about the relevance of genetics in the field of sports science. Rather, it was a review that linked genetic studies to functions, the emergence of phenotypical traits and the variation in disease risk. In conclusion, the authors suggested that it is not yet possible at least as of the moment to fully investigate the epigenetic characteristics of endurance or any other physical trait that may be of use in the field of sports medicine in a single study unless further divisions in the phenotypes of the genes that will be observed will be an option. “All in all, newly discovered information about the interactions between genetic and epigenetic factors will force us to adjust our expectations of the extent to which an individual athlete’s physical potential is predetermined”; this in a way, reaffirms the already empirically proven hypotheses of the remaining sources featured in this literature review.
In general, all the studies, except for the fourth one, had the same limitation and that is the use of a relatively small sample size. However, to give credit where it is due, the size of the control group population in was not small at all. However, since it was only a control group, it would not really make that much of an impact on the generalizability of the study. Therefore, we recommend that all future researches that would make use of a similar or at least an almost similar conceptual framework make use of a considerably larger sample population in order to arrive at a more generalizable set of results and findings.
Conclusions
Three of the four academic journals featured in this literature review suggested that genetics indeed play a role in an athlete’s sports performance. The study by (Collins & Raleigh, 2009) was the one that did not show any positive correlation between genetics and sports performance. In that paper, the authors concluded that even after using genetic association studies, it is still too early to tell whether there is conclusive evidence that the presence of or the quality of having genetic variants such as the ones that were named as examples above, may indeed lead to a higher risk of developing musculoskeletal soft tissue injuries. The study by (Ehlert, Simon, & Moser, 2013) also was not as conclusive as the remaining two sources but it seemed that the reason behind it was the fact that the authors were playing safe when they wrote the conclusions of their review and so as a result, the integrity of their paper got affected. However, based on the evidences they presented in their paper, it would certainly appear that their findings affirm the two conclusive studies that suggest that there is indeed a positive correlation between genetics and sports performance.
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