How Genes Affect Your Fitness, Health, and Athletic Ability

Practice makes perfect, or is it genetics? Studies show athletic performance is influenced by both your environment and genetics. Evidence of genes like ACTN3 and ACE are linked to improved athletic performance. Whereas genes like APOE may increase your chances of developing Alzheimer’s.

Either way, genes play an important role in your overall health, fitness, and athletic ability.

Sports Genes

There are several genes most closely associated with athletic performance. These genes influence the type of fibers that compose the muscles and have been linked to power and endurance.

ACTN3, the speed gene, instructs the body to make a protein called alpha (a)-actinin-3; the same protein predominantly found in fast-twitch muscles. The ACTN3 gene is often found in natural born sprinters. 

There are different variants of ACTN3. Research shows if you have the R variant of ACTN3, you are more likely to have fast-twitch muscles and the ability to run faster. If you have the X variant, you are very unlikely to be a sprinter, but could fare well in an endurance sport.

ACE, the endurance gene, instructs production of a protein called angiotensin (converting enzyme). The gene enables the body to convert the angiotensin hormone into other hormones that help control blood pressure and skeletal muscle function.

Gene testing is as simple as a cheek swab and can be conducted very early on. Some parents are even testing children as early as infancy to determine their ability to become successful athletes!

Training Matters

Researchers say early gene testing may produce premature results of athletic ability as athleticism is also strongly influenced by environment.

A supportive environment from family, coaches, economics, and other circumstances that allow pursuit of an activity play a role in athletic excellence. For example, epigenetic factors or being an offspring of famous athletes can improve the chances of having athletic ability.

In fact, the inheritance of certain genes may predispose your response to specific types of exercise. Even your mindset can have an effect.

A recent study reported in the New York Times claims mindsets or mental expectations seem to play an equal or even greater role than DNA in shaping some of our bodies’ reactions to diet and exercise.

Muscle Composition

Physical traits like strength of muscles and the composition of their fibers directly influence a person’s athletic capabilities. The two types of skeletal muscle fibers, slow-twitch (type I) and fast-twitch (type II) support athletes in various activities. Slow-twitch muscles support endurance activities, i.e. distance running, while fast-twitch muscles support powerful bursts, i.e. sprinting.

Fast-twitch muscles can also be broken down into two categories: moderate (type lla) and fast-twitch (type llb or llx). Moderate fast-twitch muscles are thicker, quicker to contract, and tend to wear out more rapidly than slow-twitch muscles. On the other hand, fast-twitch muscles offer the most power, and only used when the body meets maximum exertion.

Exercising both sets of muscles is important. Training fast-twitch muscles with fast movements will help improve strength and increase muscle mass. Best exercises for fast-twitch muscles include explosive movements like box jumps, jump squats, and kettlebell swings.

Whereas training slow-twitch muscles through aerobic exercise can help increase stamina and oxygen capacity. Generating less power than fast-twitch muscles, but important since they fatigue at a slower rate. Best exercises to train slow-twitch muscles include jogging, biking, and other endurance activities.

Other Genes

According to the International Journal of Molecular Sciences, recent advances in genomics studies shed light on the genetic basis of obesity and body fat distribution. If you have any of these gene variants, you’ll want to carefully monitor your fat intake:  

APOA2 can increase weight gain and obesity when saturated fat intake is high, as well as insulin resistance and atherosclerosis.

APOA5 is associated with greater weight gain and less weight loss when eating a high-saturated fat diet.

APOE is the genetic variant that predicts Alzheimer’s and Cardiovascular Disease. You can develop dementia and Alzheimer’s without this genetic variant, but many people diagnosed with Alzheimer’s also have this gene.

APOe4 can increase your risk for Alzheimer’s and Cardiovascular Disease. A low-fat diet is recommended for this genotype, which means no saturated fats from animals and little or none of the healthier fats from plants.

FABP2 is the fatty-acid-binding protein 2, strongly influences fat absorption in the small intestine. With the A variant, you will absorb more fat in your small intestine, increasing the likeliness of gaining weight.  

FABP2 gene A variant is associated with insulin resistance and higher triglycerides when fat is eaten.

FTO is associated with a higher risk for a larger waist circumference and obesity if you have the A variant and eat saturated fat. As a result, you would need to carefully manage your total fat intake.

Gene composition doesn’t conclusively indicate athletic ability, but the presence of certain genes promotes a best-case scenario for success.


Molecular Genetics and Genomics.  International Journal of Molecular Sciences.  

Moon, Jeenah.  Mind May Trump DNA in Exercise and Eating Habits.  New York Times.  1-9-19 

Is Athletic Performance Determined by Genetics?  U.S. National Library of Medicine 

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