Athletic Performance in Relation to Fast-Twitch and Slow-Twitch Muscle Fibers

Rowan Wiley

What genes help to determine athletic performance?

The ACE and ACTN3 genes help determine what type of fibers an individual’s muscles are made up of, and whether they have more fast-twitch muscle fibers or slow-twitch muscle fibers. (2)

Fast-twitch muscle fibers can generate more power and contract more quickly and forcefully. Slow-twitch muscle fibers use oxygen more efficiently and tire more slowly. As a result, athletes who compete in strength/speed events (short-distance running) usually have more fast-twitch muscle fibers, while athletes who compete in endurance events (distance running) usually have more slow-twitch muscle fibers.

Usain Bolt competes in an event that tends to favor athletes with more fast-twitch fibers

Eliud Kipchoge competes in an event that tends to favor athletes with more slow-twitch fibers

ACE

ACE instructs cells to create angiotensin-converting enzyme, a protein that converts the angiotensin hormone from angiotensin I to angiotensin II. (2)

If an individual has a variant of ACE known as ACE I/D Polymorphism, then that individual may have a higher level of angiotensin-converting enzyme. Individuals can have one of three patterns: the II pattern, the ID pattern, and the DD pattern. Individuals with the DD pattern have the highest frequency of angiotensin-converting enzymes in their muscles. These individuals tend to have more fast-twitch muscle fibers. (2)

ACTN3

ACTN3 instructs cells to create alpha-actinin-3, a protein frequently found in fast-twitch muscle fibers. (2)

If an individual has a variant of ACTN3 known as R577X, then their alpha-actinin-3 is quickly broken down, resulting in less fast-twitch muscle fibers. If an individual is homozygous for that trait (R577XX), then they have no alpha-actinin-3 whatsoever in their muscle fibers. This leads to an individual having far more slow-twitch muscle fibers than fast-twitch muscle fibers. (6)

How Prevalent are These Traits?

Frequency of ACE D allele:

66% of Asians, 59% of Nigerians, 70% of African Americans, 46-58% of Caucasians, 33-35% of Japanese, 29% of Chinese, 15% of Yanomami Indians, and 9% of Samoans have one or more ACE D alleles. (1)

Frequency of R577X allele:

>25% of Asians, <1% of Bantu Africans, ~18% of Europeans have one or more R577X alleles.

Sprint athletes: 6% XX, 50% RR, 45% RX. Control group: 18% XX, 30% RR, 52% RX. Endurance athletes: 24% XX. (9)

Gene Functions

ACE functions mainly in regulating blood pressure. It is most commonly produced by cells in the lungs, blood vessels and kidneys. (7)

It is not yet understood how variations in ACE affect athletic performance. However, there is definitely a link between blood pressure and athletic performance, so it is not surprising that ACE has an impact on athletes.

ACTN3 functions mainly in muscle fibers. It is most found in skeletal muscle. (2)

It makes sense that variations in the length of alpha-actinin-3 proteins affect athletic performance because the shorter proteins are more easily broken down, leading to a lower proportion of fast-twitch muscles.

Why get tested?

A test may be useful in order to determine what sort of muscle fibers make up an individual’s skeletal muscle and therefore what sort of athletic events they have more potential for success in.

What sort of test would be best?

A Single Gene DNA Sequencing Test that looks at either the ACE gene of the ACTN3 gene is the best option. Many tests are available that select a few key genes and examine them.

Potential options:

Atlas Sports Genetics, a company based in Colorado offers a test for $149 to determine the level of alpha-actinin-3 in an individual’s muscles. (4)

Related image — The Atlas Sports Genetics Test on amazon.com

American International offers a $200 test that looks for variations in seven genes including ACTN3 that supposedly affect an individuals’ strength and endurance. (8)

How good is the evidence?

There is little evidence linking those with the ACE DD genotype to successful speed/power athletes, and the connection between the two groups is not yet understood completely. (2)

There is strong evidence showing that high-level speed/power athletes are more likely to have the R577RR genotype while high-level endurance athletes are more likely to have the R577XX genotype. However, there are plenty of examples of successful athletes in either group who do not have those genotypes, so many more factors influence strong athletic performance. (9)

Are individuals with the trait at risk?

If an individual has the ACE DD genotype then they are at risk of developing hypertension or left ventricular hypertrophy. (7)

The ACTN3 gene does not have any major risks associated with it.

Thoughts before being tested

One should consider the multitude of factors that influence someone’s athletic potential. There are so many things that affect how one performs on a physical level, much less an emotional level. As a result, one should be aware that even if the test recommends an individual for endurance sports, it doesn’t mean that that individual with necessarily be able to succeed in those events. (3)

Reasons not to get tested

Someone should not take the test if they are planning on making decisions about whether or not to compete in a certain sport, because the test in no way indicates whether or not someone will be successful, it just points out whether one has the potential to succeed.

Ethics

Taking a test to determine what variations one has of the ACE and ACTN3 genes may emotionally impact an individual if it leads that individual to believe that they either stand no chance at succeeding in a sport or stand no chance at failing in a sport. This may lead to emotional trauma. It also may lead to parents treating their children differently as a result of a child’s genotype.

Children should not be placed in different sports just due to their genotypes

Privacy concerns?

The consumer doesn’t really have to worry about companies selling their information because it doesn’t benefit the company or harm the consumer in any way. However, they may want to consider coaches treating athletes differently due to the outcome of the test, whether that is giving them more or less playing time/attention, or even a scholarship. In addition, parents may also treat their children differently or force them to play different sports. (5)

Potential downsides

Individuals may become either apathetic or overconfident as a result of test results, and may even give up on an activity due to their genetic variations.

How do people respond to the test?

There are not any studies done on how people respond to the knowledge because it isn’t generally in the interest of the companies to see how parents react to the results.

Pre-Test Considerations

Runs in the family?

The vast majority of the tests that are currently offered look at the level of alpha-actinin-3 in an individual rather than the individual’s genotype, and variation in the ACTN3 gene only accounts for a small percentage of variation in muscle composition, so one family member’s will not necessarily predict the results of another family member’s test. (3)

How to respond to the test

An individual shouldn’t decide what sports they or their children play based on the results of the test, but it may be worth trying new things that the test claims one might be good at.

Tell a doctor?

There is no reason to tell your doctor about your results if you take a test based on the ACTN3 gene because variations in the gene don’t lead to any risks. However, one should tell a doctor if a test reveals that you are ACE DD because of the heightened risks of hypertension and left ventricular hypertrophy.

Further actions

No screenings are necessary because the test does not reveal any health conditions and should not lead one to drastically alter their lifestyle unless one has the ACE DD variation in which case one should have their blood pressure monitored.

Sources

Al-Hinai et al. “Genotypes and Allele Frequency of Angiotensin-Converting Enzyme (ACE) Insertion/Deletion Polymorphism among Omanis.” U.S. National Library of Medicine – National Center for Biotechnology Information, Apr. 2002, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3174717/
“Is Athletic Performance Determined by Genetics?” U.S. National Library of Medicine – Genetics Home Reference, https://ghr.nlm.nih.gov/primer/traits/athleticperformance
MacArthur, Daniel. “The ACTN3 Sports Gene Test: What Can It Really Tell You?” Wired, 30 Nov. 2008, https://www.wired.com/2008/11/the-actn3-sports-gene-test-what-can-it-really-tell-you/
Macur, Juliet. “Born to Run? Little Ones Get Test for Sports Gene.” The New York Times, 29 Nov. 2008, https://www.nytimes.com/2008/11/30/sports/30genetics.html
Mannino, Barbara. “Testing Kids for a Sports Gene: Would You Do It?” FOX Business, 29 Jun. 2011, https://www.foxbusiness.com/features/testing-kids-for-a-sports-gene-would-you-do-it
Pickering, Craig, and Kiely, John. “ACTN3: More Than Just a Gene for Speed.” U.S. National Library of Medicine – National Center for Biotechnology Information, 18 Dec. 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5741991/
Rana et “al. “Association of DD Genotype of Angiotensin-Converting Enzyme Gene (I/D) Polymorphism with Hypertension among a North Indian Population.” U.S. National Library of Medicine – National Center for Biotechnology Information, 2 Aug. 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5752652/
Stein, Rob. “Genetic Testing for Sports Genes Courts Controversy.” The Washington Post, 18 May. 2011, https://www.washingtonpost.com/national/genetic-testing-for-sports-genes-courts-controversy/2011/05/09/AFkTuV6G_story.html
Yang et al. “ACTN3 Genotype is Associated with Human Elite Athletic Performance.” U.S. National Library of Medicine – National Center for Biotechnology Information, 3 Jul. 2003, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1180686/

Images

https://media.gq.com/photos/56420ddb6ff00fb522b06ccb/3:2/w_4047,h_2698,c_limit/usain-bolt.jpg

https://hips.hearstapps.com/hmg-prod.s3.amazonaws.com/images/kipchoge-eliudfh1d-london19-jpg-1556468114.jpg?crop=0.893xw:1.00xh;0.0545xw,0&resize=640:*

https://ghr.nlm.nih.gov/gene/ACE

https://ghr.nlm.nih.gov/gene/ACTN3#

https://www.amazon.co.uk/Atlas-Biomed-DNA-Test-Nutrition/dp/B0797SSPKS

https://i0.wp.com/images-prod.healthline.com/hlcmsresource/images/News/childrens-health/082616_childsports_THUMB_LARGE.jpg?w=1155

Final Project Reflection – Rowan Wiley

I attended the Rivers Alive waterway cleanup on 10/5 from 9 am until 11:30 am, and worked all morning at the Derby and Branch site removing trash from the creek and bagging it so that it could be disposed of. There were all kinds of things left there including a giant rug, two animal skulls, and a crossbow bolt, but bottles seemed to be the most common.

I was shocked by how much trash there was, I had no idea that people threw that much into waterways. It didn’t look too bad from the road, but once we got into the woods and the creek there were hundreds of pieces of trash scattered everywhere. Some of the stuff had obviously been there a long time, but other pieces of trash were relatively new. This proves that this is an ongoing problem that started many years ago. Luckily, we had a lot of people working with us, and we were able to get the majority of the trash cleaned up and taken care of.

Keeping our waterways clean and trash free should be a relatively easy task, it doesn’t take much effort at all to hold on to a piece of trash and place it in the proper receptacle rather than chuck it into a stream. Also, if people just picked up trash that they found instead of ignoring it, the problem wouldn’t reach the scale that it is at today. Otherwise you end up with a huge buildup of trash and waste products which profoundly affect the environment. Plants and animals are harmed by litter and water quality can suffer as a result of unsafe trash.

I felt like we accomplished a lot at the event, but that if we don’t come back frequently the problem will just reappear. I think an important step to take in order to address this problem is to increase awareness and try to educate people on the harm that they do when they throw trash into a waterway. I am willing to continue to work to pick up trash that others leave behind, but I think that it would be a lot more efficient if I instead helped show them why it isn’t ok for them to litter.

Climate Simulation – Rowan Wiley

Acting as an important executive for the United States made me feel powerful and important and like I could make a major difference. However, after actually trying to negotiate with other world powers and address climate change, I felt confused and disappointed. I realized that the impact of my decisions was actually not as significant as I had hoped it would be.

I felt pretty confident about our ability to address climate change at the start of the exercise. I knew that the US contributed a great deal to global CO₂ emissions and that we also have tremendous global power when it comes to negotiations, so I thought for sure that we could address the problem with a little effort. However, actually attempting to reduce emissions proved a lot harder than I expected, especially when other countries were unwilling to cooperate.

My group didn’t really change our ideas very much over the course of the exercise. We kept our deforestation and afforestation rates consistent throughout the entire exercise and we only added to our fund contribution in an effort to appease China. We did move our peak and reduction years forward, but once again that was in conjunction with China and India.

The most significant factor that led us to change our initial policies was the limited impact that our reductions had on climate change. In addition, the willingness of China and India to cooperate with us made things easier. We had a lot more trouble reaching agreements with the Other Developing Countries and Other Developed Countries.

I do think that emissions can be cut, but not by a significant enough margin to eliminate the effects of climate change. Based on the results of the exercise I think it is borderline impossible to truly minimize climate change before it is too late. Even with almost unanimous support and cooperation we were unable to reach the target of 2 ̊C.

Economic concerns and global competition seemed to be the biggest barriers to me. Reducing emissions and funding afforestation programs while reducing deforestation is an extremely expensive endeavor that will severely damage the economy, and most countries are unwilling to jeopardize their economic welfare. This doesn’t even take into account the money that other countries asked for in order to address climate change. Other groups were quick to jump on China and the US for not offering to donate very much money, but I don’t think they really understand how much it will cost to implement domestic changes that are significant enough to make a difference.

We can catalyze change in the US by ensuring that more people are educated about climate change and know how to address it. Doing little things personally isn’t going to make any difference whatsoever, massive industrial companies are the ones driving the emissions, so instead we should focus on bringing the problem to the attention of the government and high ranking officials in major companies. Only then can we hope to mitigate the damages of climate change.

Watershed Photo Reflection

Rowan Wiley

I consider this picture a point of pride.

In this picture, I see a simple sewer grate set into the side of the road with a label in front of it that says “NO DUMPING! DRAINS TO RIVER.”

What I notice in this picture is how clear the warning label. It is written in capital letters on a white background, is surprisingly large, and even has illustrations of water and a fish to emphasize the point.

This picture makes me think about rivers and streams and how they are constantly impacted by our bad choices. We are always dumping trash and other toxins into the waterways around us and think little of it.

When I look at this picture, I feel proud but also sad. I’m proud of the community for putting up a sign like this in an effort to remind us of the consequences of our actions. However, I also feel sad because I realize that we shouldn’t need a label there and that the only reason it is there is because we messed up in the past.

I think this picture is about us learning from our past mistakes and trying to do the right thing as we move forward.

Rowan Wiley

I took biology my freshman year of high school, chemistry my sophomore and junior year, and physics my senior year. I enjoyed biology and chemistry and hated physics.

I want to learn more about biology because I enjoyed it freshman year but haven’t tried to pursue it at all since. I hope to get a greater understanding and appreciation of biology.

I am interested in learning how to help keep trash and other debris out of waterways so as to preserve the natural beauty. I have participated in a number of trash pick-ups at various creeks. I think my fellow students also want to prevent littering and enjoy trash-free water.

I hope I can learn how to help make the environment around me a better, cleaner, and safer place. I also look forward to learning how to reduce the negative impact I have on the environment.

I am interested in exploring biology in more depth than I have in the past. I want to learn more about the natural world around me.