Genetic Advantages in Athletic Performance

How can inherited traits influence athletic performance?

For an athlete to be successful they must have the drive, the ability, and the discipline to train.

But when athletes put in maximal effort, there is a noticeable gap between a good athlete and an elite athlete. Sports genetics examines genetic advantages in athletic performance alongside training and environment.

Genetics are multifaceted and are not simple and straightforward to understand.

Physical traits can affect sporting demands, but body-type labels do not prescribe one compatible sport for every athlete.

Other factors that enhance performance include tendon placement. Tendon placement relative to a joint can affect the speed–force trade-off, as discussed in the cited 2016 strength-and-conditioning textbook. The cited 2020 educational guide describes how muscle fiber types relate to different physical activities.

A 2017 honors thesis discusses genetic influences on athletic performance, rather than proving a single gene guarantees success.

Any of these factors may give an athlete a natural advantage.

This all depends upon the athlete’s genetics and their chosen sport. If their choice for sports suits their genetic makeup, they have a much better opportunity to maximize their potential.

What do body-type labels tell us?

Body shape can be relevant to a sport, but elite athletes do not all fit one fixed type. Ectomorph, endomorph and mesomorph are descriptive body-shape labels.

These labels are not fixed metabolic destinies.

Ectomorphs are tall and lean. The label describes a relatively slender frame; it does not by itself establish metabolism or an inability to build muscle or gain body fat.

By contrast, the endomorph has a stocky build with more muscle and fat in the lower half of their body. The cited body-type article describes the endomorph as having the “…best strength advantage out of the three different body types…”.

This is a claim from a fitness article, not a demonstrated universal ranking or metabolic diagnosis.

The mesomorph is the intermediate of the body types.

Such individuals are both lean and muscular. Building muscle and losing fat vary with training, nutrition and individual circumstances; a label alone does not establish an easier outcome.

How do sporting demands relate to body shape?

When matching sports with specific body types, there are many factors to consider.

Height, weight, and limb length may help the athlete. Sporting demands can favor certain traits without imposing one body shape.

For instance, a 2016 Live Science interview discusses tall, long-limbed basketball players. The trainer interviewed, Mark Jenkins, said, “Their lower back needs to be strong because they’re always crouched over.”

Such an “ideal” player could be a fusion between the ectomorph who is tall and lean, and the mesomorph, able to build muscle.

Swimmers are another example of sport-specific demands.

The interview also discusses swimmers’ body fat, buoyancy, muscle mass and drag.

These examples reflect a trainer’s explanations, not a trial showing that every swimmer gains fat from water exposure or fits a predetermined somatotype. Athletic swimmers still need strength to meet the demands of the water.

What do slow-twitch muscle fibers do?

Skeletal muscles are composed of fibers, or cells, that have physiological characteristics that could be advantageous for certain activities.

According to a 2020 paper, cells can be categorized into two “twitch” types, and three subtypes: Slow twitch (Type I) and fast twitch (Type IIa and Type IIx).

The slow-twitch or

Type I fibers have low force production and high endurance capability.

Such fibers are suited for aerobic exercises and respond well to training.

The slow-twitch fibers focus on both postural control and sustained activity.

Such fibers contain mitochondria that utilize oxygen to produce adenosine triphosphate (ATP) which is used as an energy source for such exercises.

Type I fibers also have a significant number of capillaries, priming the body for oxygen and nutrient distribution to the muscles during sustained low intensity activity.

Thus, slow-twitch muscles have a higher oxygen capacity than fast-twitch muscles.

Slow-twitch muscles have a lower activation threshold and are smaller in size, meaning they are the first to contract during any movement.

However, if the

Type I fibers do not produce enough force to complete or sustain the movement, fast-twitch muscles are recruited.

What do fast-twitch muscle fibers do?

Fast-twitch fibers are divided into two subtypes: Type IIa and Type IIx.

Fast-twitch muscle fibers are best utilized for short, high-intensity bursts of movement.

They contract swiftly, producing a great amount of force.

Type II fibers are useful in more volatile sports that utilize strength, speed, and power in short spurts. Fast-twitch fibers have large glycogen stores used in anaerobic energy production. This supports rapid energy production and produces lactate, which can also be used as fuel or recycled to glucose.

Type II fibers are larger in size and are recruited after their Type I counterparts.

How do Type IIa and IIx fibers differ?

The subtypes Type IIa and Type IIx are slightly different from the general Type II description. The cited 2020 educational guide describes Type IIa fibers as having both oxidative and glycolytic capacities.

Also referred to as fast oxidative muscle fibers, Type IIa fibers primarily utilize aerobic energy production while still contracting quickly.

They also have the capability of switching to anaerobic glycolysis when necessary to produce large amounts of energy in little time.

“This also means that they produce more tension than slow fibers but also fatigue faster”.

Type IIx, by contrast, have a high force production but a low endurance capability.

Also known as fast glycolytic muscle fibers, they primarily utilize anaerobic glycolysis energy production and respond well to training.

These fibers can produce the greatest force capability, but this comes at the expense of endurance capability.

What do ACTN3 and ACE variants mean?

Genes are made up of DNA. The cited 2021 MedlinePlus page describes the Human Genome Project’s historical estimate that “…humans have between 20,000 and 25,000 genes”.

However, research has suggested that less than 1% of genes vary between individuals.

Alleles are forms of the same gene with small DNA-sequence differences that can contribute to individual characteristics. Beyond body shape, tendon mechanics and muscle fibers, many genetic variants may contribute small effects to athletic performance.

ACTN3, also known as the “sprinter’s gene,” causes the production of alpha-actinin-3, a type of protein that favors Type II muscle fibers which contract intensely at high speeds. The cited 2019 source is a genomics-company blog, not a new trial. ACTN3 variants have been associated with aspects of sprint and power performance, rather than the simple presence or absence of the gene. The 2017 thesis states, “The majority of the elite sprinters in the world have at least one copy of this gene, giving them the advantage”.

Here the relevant distinction is a variant of

ACTN3, not whether a person has the gene. ACTN3 and ACE are not genes found only in particular kinds of athletes.

ACE variants have been studied in relation to endurance and power, but the enzyme does not simply assign every muscle fiber or instruct ACTN3 to guarantee performance. Associations with variants do not predict one athlete’s sporting success.

“An insertion allele (one of two alternative forms of a gene) along with a decrease level of circulating angiotensin II, reduces the vascular resistance and facilitates cardiac output during exercise”.

How do genetics and effort fit together?

Elite athletes make sure their bodies are attuned to the demands of the sport. Body shape, tendon mechanics, muscle fibers and inherited variation can matter, alongside training and environment. There is no universal genetic template for sporting success.

Genetics can provide a boost to the athlete’s career, but success also involves effort.

To be the best, you need the talent, motivation, and willingness to struggle toward victory.

This is the way of the elite athlete.

References

Angona. (2019, September 20). Sport Genomics – athletics. Mapmygenome.in. https://mapmygenome.in/blog/sports-genomics-athletics/.

Haff, G. G., & Triplett, T. N. (2016). Chapter 2: Biomechanics of resistance exercise. In Essentials of strength training and conditioning (4th ed., pp 23-25). (4th Ed.). Illinois, IL: National Strength and Conditioning Association.

Hay, J. (2017). A gene ahead of the game: A look at sports (Honors thesis). Eastern Kentucky

University, Richmond, KY.

Kiikka, D. (2020, April 11). Complete guide to muscle fiber types. The Sports EDU.

https://thesportsedu.com/muscle-fiber-types/.

MedlinePlus. (2021). What is a gene? https://medlineplus.gov/genetics/understanding/basics/gene/

Trinh, M. (n.d.). The three different body types and how they affect your training. Jefit.

https://www.jefit.com/exercise-tips/three-different-body-types.

Weisberger, M. (2016, August 09). Olympic form: How sports influence body shape. Lifescience. https://www.livescience.com/55702-olympic-athletes-body-types.html.

Wood, R. (2010). Endurance sports. Topendsports. https://www.topendsports.com/fitness/sports-endurance.htm

MedlinePlus Genetics. Is athletic performance determined by genetics? https://medlineplus.gov/genetics/understanding/traits/athleticperformance/

Brooks, G. A. (2018). The science and translation of lactate shuttle theory. Cell Metabolism, 27(4), 757–785. https://doi.org/10.1016/j.cmet.2018.03.008

“A 2017 honors thesis discusses genetic influences on athletic performance, rather than proving a single gene guarantees success.”

“However, research has suggested that less than 1% of genes vary between individuals.”

“Elite athletes make sure their bodies are attuned to the demands of the sport.”