The quest to understand what makes an athlete excel lies at the heart of every competitive endeavor. Genetics, commonly thought of as the “blueprint of life”, holds the secret to unlocking the mysteries of human performance. The role that genetics play in our lives remains one of the most complicated and intriguing aspects of biological science. In this article we will delve into the role genetics plays in influencing athletic performance and exercise-induced muscle damage/injury, the intricate interplay between our complex genetic code and the physical expertise that defines athletic ability
What Makes a World-Class Athlete?
In the early days of sport, the link between genetics and athletic success simply played out anecdotally. Families boasting multiple generations of Olympic champions or world-record holders hinted at a hereditary component to athletic prowess. What began as mere folklore planted the seed for a deeper scientific inquiry.
As much as we would like to believe that anyone can achieve Olympian status simply by training hard and eating properly, much more goes into the “making” of a champion than we realize; and more than a little of it occurs on a cellular/molecular level. As we know, muscular performance relies heavily on an athlete’s lean muscle mass and its dynamic response to appropriately challenging training. Yet recent research studies have considered the possible genetic factors that influence the physiques and performances of top world-class athletes.
Technically speaking, the inheritance of approximately 20,000 genes defines each of us as human entities. However, within this dazzling array, the endless possibilities of variation exist between every individual’s genetic make-up. Multitudes of human phenotypes or characteristics — muscle strength, bone structure, tendon elasticity, and the sizes of hearts and lungs size – hold the potential to influence sports performance, each one the result of a complex interaction between anatomical, biochemical and physiological systems. Genetic factors may actually account for as much as 50-80% of the individual variations observed in lean body mass, which in turn impacts its growth rate.
Infrequent Genetic Combinations
While many of the desirable genotypes do not commonly appear in the average person, their combination in ideal ratios proves even rarer. In theory, the chances of an individual having a perfectly stellar athletic-performance-related genotype lie much lower than 1 in 20 million. In addition, as the number of genetic variants increases, the odds of them turning up together in one individual decrease correspondingly.
Understanding the Science of Inheritance
As the field of athletic-related genetics continues to evolve, scientists have culled a deeper understanding of the role that genes play in shaping an individual’s physical/physiological traits. The discovery of specific gene variants associated with athletic ability marked a turning point in sports science, with researchers now able to look at the delicate interplay between genetics and such things as muscle strength, oxygen utilization, and metabolic efficiency.
The term allele refers to one of two or more versions of DNA sequence (a single base or a segment of bases) at a particular place on the genetic thread. During conception, every individual inherits two alleles, one from each parent, for any given genomic location where such variations exist. If two identical alleles appear, we consider the individual “homozygous” for that allele. If the alleles differ, we term the individual “heterozygous”.
Gene Sequencing Reveals Answers
The genetic blueprint that each individual inherits from his parents plays a pivotal role in shaping his athletic abilities. As we touched upon briefly above, this genotype reveals a complex superhighway of information that influences a wide array of physical/physiological traits. To truly understand how genetics can impact sports performance, we must delve into the science behind genotypes and their relationship to athletic prowess.
- Muscle Strength and/or Endurance: Genetic variations can influence muscle fiber composition, predisposing some individuals to have a higher proportion of slow-twitch or fast-twitch fibers. Slow-twitch fibers work with efficiently for endurance activities such as long-distance running, while fast-twitch fibers prove advantageous for short bursts of speed or strength. The distribution of these fibers gets influenced by multiple genes, each with its own set of alleles that contribute to the overall muscle phenotype.
- Recovery: The body’s ability to recover from physical exertion, another key aspect of athletic performance, owes its presence to a genetically determined pattern. Certain genes, such as those involved in the production of antioxidants, can affect how quickly an athlete bounces back from intense training sessions or competitions. Those with a genetic predisposition for efficient recovery may find themselves able to train harder and more frequently than their gym buddies, providing them with a distinct competitive edge in their specific sport.
With the introduction of genetic sequencing techniques, scientists can now pinpoint polymorphisms—variations in DNA sequences—that can significantly influence an athlete’s potential. As mentioned above, alleles, the different forms of a gene, can affect everything from the type of muscle fibers which predominate to the efficiency of the cardiovascular system.
We can consider as an example the ACTN3 gene, often referred to as the “gene for speed”. It possesses a common polymorphism that affects the production of alpha-actinin-3, a protein found in fast-twitch muscle fibers, crucial for powering explosive movements in sports like sprinting and weightlifting. Variants of ACTN3can predispose individuals to excel in these high-velocity activities, highlighting the genetic lottery that underlies athletic specialization.
Specific Genes and Their Impact on Sports Performance
Beyond ACTN3, numerous other genes have undergone rigorous study for their potential impact on athletic performance. Variants of the ACE gene, associated with endurance and cardiovascular efficiency, boast the ability to influence activity of the angiotensin-converting enzyme, which plays a role in blood vessel constriction and therefor blood flow regulation. Athletes with certain ACE gene variants may possess enhanced endurance capabilities, making them well-suited for sports that require sustained effort.
The MCT1 gene encodes for a protein involved in the transport of lactate across cell membranes. A byproduct of anaerobic metabolism, a body needs efficient lactate removal from its muscles in order to maintain performance during high-intensity exercise. Genetic variations in the MCT1 gene, which encodes for a protein involved in transporting lactate across cell membranes, can affect an athlete’s tolerance to lactic acid buildup, influencing his ability to perform at peak levels during intense physical activity.
Second-Stage Exercise-Induced Muscle Damage
Although athletes expect some measure of muscle damage with rigorous training, a critical necessity in order for adaptation to occur, excessive damage or inadequate recovery from said muscle damage definitely can lead to an uptick of injury risk. We see this heightened in the case of older individuals, who experience more damage than their younger athletic counterparts and require longer to recover as well.
Geneticists now know that individual variation exists in a person’s response to exercise-induced muscle damage, and that genetic variability most likely plays a key role. Even with this scientific field still in its early stages, certain gene variations, or polymorphisms, have aligned directly with exercise-induced muscle damage and recovery time following strenuous exercise.
The process of exercise-induced damage occurs in two distinct stages. In the initial phase, mechanical damage occurs: a pulled hamstring, an overstressed muscle, etc. The second phase, a consequence of the first, consists of the body’s inflammatory response. In this stage, certain genetic variants may determine which athletes will end up having to endure more or less post-exercise muscle damage.
The products originating from the damaged muscle tissue attract immune cells in a process known as chemotaxis. This in turn will initiate the inflammatory process itself. The body simultaneously experiences the release of certain molecules, known as cytokines (mainly IL1B, IL6 and TNF), that enhance this inflammatory process. It seems that even this comes under the control of genetic variants.
Genetics May Affect Injury Resistance, Susceptibility and Recovery
Following closely on the heels of research performed on exercise-induced muscle damage, scientists have identified several genes that may affect an athlete’s susceptibility to injuries. These genes can influence various physiological traits known to play crucial roles in injury resistance:
- Ligament Strength: Genes such as COL1A1 and COL5A1 code for collagen production, essential for ligament strength. Variants of these genes have aligned with an increased risk of anterior cruciate ligament (ACL) injuries.
- Bone Density: Genes like ESR1 and VDR can affect bone mineral density, a critical factor in preventing fractures and stress injuries. Athletes with certain genetic variants may live with a higher risk of bone-related injuries.
Genetics and Physical Performance Among the Elderly
Experts continuously learn more and more about how genetics influences athletic-related traits, even those which do not figure prominently in elite sports. Almost 200 genetic polymorphisms exist within the vitamin D receptor (VDR) gene. An individual’s VDR genotype reflects the differences in strength observed in premenopausal women, as its expression tends to diminish with age.
High levels of inflammatory mediators can lead to the reduced physical capabilities and muscle function seen in many elderly individuals. Here again, polymorphisms may affect the expression/synthesis of these molecules, thereby influencing the intensity of the inflammatory response. Physical exercise can often help mitigate age-related chronic inflammation and improve physical performance.
In one study, elderly female subjects with a combination of genotypes uniquely associated with an anti-inflammatory profile (low TNF-α and IL-6 production, high IL-10 production) showed better physical capabilities, proving the interactive influence of genetic/environmental factors on boosting physical performance in elderly women.
Genetics, Training and Environs
We can begin to see how genetic variations can predispose individuals to excel in specific sports or physical activities. However, genetics does not tell the whole story, as it remains just one piece of the puzzle. Environmental factors, training, nutrition, and psychological traits also play significant roles in an athlete’s development and success.
While genetics may set the stage, the environment in which an athlete lives and trains often dictates the script. Apparently athletic success does not simply boil down to a lucky genetic “rolling of the dice”; it takes more than just one or two dominant genes to propel one to athletic prowess. A list of factors that contribute to the nurturing aspect of athletic development includes:
- Training Regimen: Tailored exercise protocols designed to challenge an athlete’s innate strengths and address weaknesses
- Nutrition: A diet that aligns with an athlete’s metabolic needs and training/competition goals
- Psychological Conditioning: Honing mental fortitude, focus, and the ability to handle pressure
- Support Systems: Coaches, trainers, and a close-knit community of like-minded individuals who offer the guidance and motivation necessary for success
We have acknowledged how genetic variations can predispose individuals to excel in specific sports or physical activities. However, genetics does not tell the whole story, as it remains just one piece of the puzzle.
Final Reflections
As our knowledge of genetics continues to expand, we can expect to see more personalized approaches to athletic development, where genetic insights get integrated into training regimens and injury prevention strategies. Knowing how a client most likely will respond to a particular type of exercise could help coaches and personal trainers individualize their clients’ training protocols, thereby maximizing recovery and adaptation while reducing overload-associated injury risk.
This personalized approach holds the promise of optimizing athletic performance while minimizing the risk of injury, ultimately leading to a more efficient and effective path to athletic excellence.
References:
https://pmc.ncbi.nlm.nih.gov/articles/PMC4983298/
https://pubmed.ncbi.nlm.nih.gov/23430759/
https://pubmed.ncbi.nlm.nih.gov/21923202/
https://pubmed.ncbi.nlm.nih.gov/20308700/
https://pubmed.ncbi.nlm.nih.gov/27294501/
https://pubmed.ncbi.nlm.nih.gov/17289909/
