You've probably heard stories of superhuman strength, like lifting a car off a trapped child in an emergency. While this is a dramatic example of what the human body can do, physical strength affects nearly every aspect of your everyday life. There’s a lot that can determine how much you can lift, and your DNA is part of it. If you're interested in the genetic influence on your physical strength, AncestryDNA^® + Traits can provide some answers.

What Activities Are Related to Physical Strength?

How much you can lift or carry is heavily influenced by your daily activities. Other physical traits, like athleticism, flexibility, or agility, can also affect your strength. From playing sport to simply getting through your day-to-day routine, you rely on physical strength. Even bringing in the shopping requires a certain degree of strength, especially if you're carrying heavier items like a bag of dog food or garden mulch.

Physical strength is also not a one-size-fits-all ability, as there are several distinct aspects to it.

• Dynamic strength means exerting your muscles repeatedly or continuously.
• Explosive strength, on the other hand, focuses more on using short bursts of muscle force, such as throwing a ball or jumping.
• Static strength is involved when you push, carry, lift, or pull objects.
• Trunk strength is about using your abdominal and lower back muscles to support part of your body continuously over time without your muscles "giving out."

Some occupations depend on a great deal of strength, especially physically demanding trades such as construction and extraction. Firefighters, mechanics, ironworkers, masonry workers, loggers, and oil rig workers also need a high level of physical strength in order to do their jobs.

Genetics and Physical Strength

Certain genetic factors help determine how your muscles work. For example, your genes help determine whether your muscles:

• Perform better for explosive tasks, like weightlifting
• Are suited to endurance activities, like running a marathon
• Experience muscle fatigue quicker than normal
• Are efficient at using oxygen

Ancestry^® scientists sought to get to the bottom of how genetics and physical strength relate by conducting a genome-wide association study (GWAS) to compare the DNA of over 161,000 people and their answers to the question, "How would you rate your natural physical strength?" The scientists found 531 DNA markers that were associated with people’s self-reported physical strength. Those DNA markers, in combination with the participants’ responses, were used to calculate a polygenic risk score—a tool to predict your physical strength based on your genetics.

Importantly, Ancestry scientists found that differences in people’s DNA could only explain a small amount of the variation in their physical strength—about 10%. Which means that non-genetic factors, like your daily activities, diet, and age, influence your physical strength much more than genetics.

What Else Impacts Physical Strength?

It's not just genetics and muscles that determine your strength. Other factors, like how frequently you exercise, also play a role. If you never use your muscles, they'll weaken over time. Conversely, if you use them often, they'll become stronger.

Even temporary factors can impact your physical strength because they can affect your muscles' ability to contract. For example, dehydration can cause muscles to weaken, even if you lose just 2% of your total water weight.

As you age, you'll also see a decline in muscle mass and strength, known as sarcopenia. It's a natural part of the aging process, most commonly beginning sometime in your 30s or 40s. An eight-year study out of Koper, Slovenia, revealed an average of 2.5% decline in muscle strength per year in adults between the ages of 60 and 80. While physical activity can help preserve your physical strength for longer, it's only natural that it will begin to fade over time.

Interesting Facts About Physical Strength

Physical strength isn't fixed. In true emergencies, people have been known to perform extraordinary feats of strength. It's a phenomenon sometimes called "hysterical strength" or "superhuman strength." While scientists can't ethically recreate these life-or-death scenarios to study it, many agree it likely exists.

Adrenaline, the hormone released in response to stress, can increase your strength temporarily. It's part of the body's natural fight-or-flight response and is meant to prime the body to survive life-threatening situations. However, the body can't be trained to perform at these levels normally.

Strength grows steadily, generally reaching its peak levels between the ages of 30 and 35. Even as a newborn, signs of physical strength present themselves. Most babies are born with enough physical strength to support their whole weight with just their hands. Newborns wrap their fingers tightly around something in their hands, a phenomenon known as the palmar grasp reflex. If you were to place your finger in their palm, they would grip strongly enough that you could lift them slightly from their lying position, and they'd dangle by their hands.

Ultimately, your strength is a culmination of genetics and the environment. You can control the environmental factors by adding exercise to your routine, like sports and physical strength training, but you can't change the roughly 10% genetic influence on physical strength. If you're curious to see whether your genetics help or hinder your physical strength, consider taking an AncestryDNA^® + Traits test. If you've already taken one, you can review your trait results with an Ancestry^® membership.

 

References

"60 Physically Demanding Jobs." Indeed. April 18, 2024. https://www.indeed.com/career-advice/finding-a-job/physically-demanding-jobs.

Bennett, Chloe. "How Does Mild Dehydration Affect the Body?" News Medical. July 5, 2019. https://www.news-medical.net/health/How-Does-Mild-Dehydration-Affect-the-Body.aspx.

"Browse by Abilities." National Center for O*NET Development. Accessed May 8, 2024. https://www.onetonline.org/find/descriptor/browse/1.A/1.A.3/1.A.3.b/1.A.3.a.

"How Can Strength Training Build Healthier Bodies As We Age?" National Institute on Aging. June 30, 2022. https://www.nia.nih.gov/news/how-can-strength-training-build-healthier-bodies-we-age.

Lewis, Rhona. "All About Your Baby’s Grasping Reflex." Healthline. November 25, 2020. https://www.healthline.com/health/baby/grasp-reflex.

"Sarcopenia." Cleveland Clinic. Accessed May 8, 2024. https://my.clevelandclinic.org/health/diseases/23167-sarcopenia.

Sissons, Claire. "What Happens When You Get an Adrenaline Rush?" MedicalNewsToday. Accessed May 8, 2024. https://www.medicalnewstoday.com/articles/322490.

"Strength Training: Get Stronger, Leaner, Healthier." Mayo Foundation for Medical Education and Research (MFMER). Accessed May 8, 2024. https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/strength-training/art-20046670.

Teraž, Kaja, Uros Marusic, et al. "Sarcopenia parameters in active older adults – an eight-year longitudinal study." BMC Public Health. May 19, 2023. https://doi.org/10.1186/s12889-023-15734-4.

Vandergriendt, Carly. "How Superhuman Strength Happens." Healthline. Accessed May 8, 2024. https://www.healthline.com/health/hysterical-strength.