The Genetics of Strength Gains: Does Exercise Turn on a Gene That Makes You Stronger?

Exercise has a myriad of health benefits. It improves cardiovascular health and boost endurance. Plus, strength training increases muscle strength and size. And there are other perks. Regular physical activity lowers the risk of a range of chronic health problems including obesity, type 2 diabetes, and cardiovascular disease.

To get these benefits, you need to exercise consistently. During a workout, there’s a lot going on behind the scenes. In response to strenuous exercise, your body releases a host of hormones and signaling molecules including cortisol, norepinephrine, epinephrine, brain-derived neurotrophic factor (BDNF), and testosterone to help your body produce energy, regulate blood glucose, and your muscles repair afterward. BDNF is involved in the growth, maintenance, and survival of nerve cells in the brain and plays a role in learning and memory. It’s responsible for some of the brain health benefits of a workout.

The Role of Genes in Building Muscle Strength

Now scientists have discovered a gene called the C18ORF25 gene that is called into action during exercise. When you launch into a workout, C18ORF25 produces proteins that help your muscles build strength and size.  Mice specially bred to not have this gene have smaller muscles and muscles that don’t contract as forcefully. They also have reduced exercise capacity. Scientists describe this gene as a “regulator of muscle function.”

Although knowledge about the C18ORF25 gene is in its infancy, all types of exercise seem to activate it, not just strength training. Scientists point out that harnessing the power of this gene could be helpful for reducing strength and muscle loss related to aging.

Muscle Strength and Genetics

Muscle strength is determined by how your muscle fibers are arranged and the composition of those fibers. People who are stronger have a higher ratio of fast-twitch muscle fibers relative to slow-twitch ones. The primary difference between the two is that slow-twitch fibers have a greater capacity for endurance, while fast-twitch fibers are optimized for strength and speed.

Muscle size also plays a role in how strong you are. A muscle with a larger cross-sectional area can generate more force than a smaller or thinner muscle. Plus, input from your brain plays a role in force generation. Your brain and muscles work together to lift something heavy.

These factors are also influenced by genetics. It’s clear that genetics play a role in muscle strength, including genes other than C18ORF25. According to the American College of Sports Medicine’s Health and Fitness Journal, genetics and inheritance is responsible for 30 to 95% of strength potential in humans.

Other Genetic Contributors to Strength

One example of a gene that affects muscle growth is myostatin, a protein responsible for limiting muscle growth. Myostatin works by signaling cells in the body that help grow muscle tissue to stop dividing and growing. The purpose of myostatin is to keep your muscles from getting unmanageably big.

There are cases of individuals with a mutation in the myostatin gene. These people can’t produce as much myostatin and are muscle-bound. They have large muscles because they can’t restrict muscle growth, so their muscles can make big gains in muscle size. As you might imagine, people with less myostatin can develop larger muscles than those who have a lot of myostatin.

Genes that code for other proteins, including insulin-like growth factor 1 (IGF-1) and insulin-like growth factor 2 (IGF-2) also affect muscle growth. One gene codes for a protein called ACTN-3 in type 2 muscle fibers. The ACTN3 gene produces the protein alpha-actinin-3, which is found in fast-twitch muscle fibers. A single nucleotide polymorphism (SNP) of this gene, known as R577X, has been associated with elite athletic performance and sprinting ability. However, scientists are looking at other genetic candidates that may affect muscle strength and muscle strength gains.

How You Train Matters Too

Although you can’t change factors like your genetic make-up, you can control how you train, and, ultimately, that’s more important for strength gains and getting the health benefits that exercise offers. Genes may determine the limit of your strength gains, but most people never train hard enough or consistently enough to reach their genetic potential.

Another person may have greater genetic potential to build strength and muscle size than you, but if they train improperly or don’t train at all, you’ll be the one with the strong, well-defined physique.

The key to building strength and maximizing your genetic potential is to use progressive overload. Your body adapts to the stressors placed on it during exercise. When you do an activity, such as lifting weights, your body responds by making changes that allow it to better handle the stresses placed on it next time.

The idea behind progressive overload is simple: If you want to get stronger,  gradually increase the amount of weight you lift or the number of reps you perform. If you lift more weight next week than last week, your body will make further adaptations to handle this new stressor. If you don’t progressively overload your muscles, they won’t make these adaptations and you’ll stop making gains in strength and size.

Progressive Overload Increases the Challenge Over Time

The best way to use progressive overload is by following a structured training plan that gradually increases the challenge on your muscles over time. This will ensure your build muscle and become stronger.

A common myth is that progressive overload means you must lift heavier and heavier weights. While it’s true that you must increase the load on your muscles to recruit more muscle fibers, you can also do so through other means.

For example, you can perform the same exercise with less rest between sets (known as “supersets”) or with shorter breaks between exercises (“circuit training”). You can combine these training approaches with traditional weight training, making them an ideal way to achieve progressive overload with a lower risk of injury.

The Bottom Line

Genetics are a factor in how strong you can become. It sets your upper limit, but it’s proper and consistent training that helps you meet your full genetic potential. Take advantage of what you can control.

References:

  • Ronnie Blazev, Christian S. Carl, Yaan-Kit Ng, Jeffrey Molendijk, Christian T. Voldstedlund, Yuanyuan Zhao, Di Xiao, Andrew J. Kueh, Paula M. Miotto, Vanessa R. Haynes, Justin P. Hardee, Jin D. Chung, James W. McNamara, Hongwei Qian, Paul Gregorevic, Jonathan S. Oakhill, Marco J. Herold, Thomas E. Jensen, Leszek Lisowski, Gordon S. Lynch, Garron T. Dodd, Matthew J. Watt, Pengyi Yang, Bente Kiens, Erik A. Richter, Benjamin L. Parker. Phosphoproteomics of three exercise modalities identifies canonical signaling and C18ORF25 as an AMPK substrate regulating skeletal muscle function. Cell Metabolism, 2022; DOI: 10.1016/j.cmet.2022.07.003.
  • Kostek, Matthew M.S.; Hubal, Monica J. Ph.D.; Pescatello, Linda S. Ph.D., FACSM. Genetic Roles in Muscle Strength. ACSM’s Health & Fitness Journal: March 2007 – Volume 11 – Issue 2 – p 18-23, doi: 10.1249/01.FIT.0000262475.20949.bc.

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