A recent blog headline caught my attention: Training in Line With Your Genetic Potential Can Boost Your Performance Gains More Than 600%.

So could this be true?

Can you really use your genetics to get massive breakthroughs in fitness?

How Genetic Testing Works

So let’s first take a quick look at how genetic testing works.

Genetic tests are typically performed on a sample of blood, hair, skin, amniotic fluid (the fluid that surrounds a fetus during pregnancy), or saliva. Most modern popular DNA tests for fitness or nutrition, including the one you’ve likely heard of—23andme—use a saliva sample in a method called a “spit test.” Although it isn’t a map of your entire detailed genome, this direct-to-consumer genetic testing, also known as at-home ­genetic testing, allows you to conveniently get a glimpse of important sections of your DNA, including parts that affect your fitness.

Just one mouthful of your saliva contains a huge amount of biological material from which your genetic blueprint can be determined, including hundreds of complex protein molecules called enzymes, along with cells sloughed off from the inside of your cheek. Inside each of these cells is a nucleus, and inside each of these nuclei are chromosomes. Chromosomes are made up of DNA, the double-stranded molecule that affect protein programming in your body, including how you look, how you act, how you process certain types of food, and how your muscles work. 

Genetic Testing for Fitness

Let’s take a look at how different enzymes can affect your fitness. 

One enzyme is called ACE, or “Angiotensin I-converting enzyme.” This is a small enzyme that plays an important role in blood pressure regulation and electrolyte balance. Its activity leads to blood vessel constriction and increased blood pressure, and it is also the most researched gene in relation to exercise performance.

If you have what is called a “DD” copy of this gene, then power-based training is recommended, and you get good muscle growth from weight training and strength sports, along with good muscle recovery. On the flip side, you need to ensure your blood pressure is monitored during high intensity exercise because it can tend to get too high.  

Interestingly, when it comes to nutrition, this same D variation may increase sensitivity to refined carbohydrates and lead to reduced insulin sensitivity, especially in overweight individuals. 

If you have the “ID” version of this gene, then a mixture of power and endurance based training recommended.

The D variation may increase sensitivity to refined carbohydrates and lead to reduced insulin sensitivity, this effect is aggravated in overweight individuals. The negative effects of the D variant on insulin sensitivity may be ameliorated by regular exercise, and if you have the II copy, then endurance sports and high repetition weight training is recommended. This is because carries of the II version have an increased volume of slow twitch muscle fiber and have greater aerobic efficiency and VO2max.

Or take, for example, the IL-6 gene, also known as “Interleukin-6,” which is responsible for expression of a pro- inflammatory cytokine. IL-6 stimulates the immune response to training and is involved in the inflammatory repair process.

If you have the “GG” version, then this is associated with lower levels of inflammation after hard training sessions, and leads to quicker recovery times. This genotype has also been independently associated with performance in power sports. If you have the “GC” version, you may experience moderately increased levels of inflammation after strenuous exercise and a longer rest period between training sessions may be required compared to GG. If you have the “CC” version, you may experience higher levels of inflammation after strenuous exercise, and a longer rest period between training sessions may be required compared to GG.

There are an enormous number of genes that affect everything from power vs. endurance training response, inflammatory response to exercise, recovery from exercise, response to a low carb vs. a high carb diet, and much more.

Here is a full list of different ways genes affect your fitness:

Study on Fitness and Genetics

So what did this most recent study on fitness and genetics find?

The study, conducted by a group of European researchers, is actually the first to demonstrate that “matching the individual’s genotype with the appropriate training modality leads to more effective resistance training.”

Researchers actually performed two studies in groups of male athletes. In both studies, athletes completed an eight week high- or low-intensity resistance training program, which either matched or did not match their genotype for either power training or endurance training. 

In other words, the high-intensity training group was selected from people who expressed a power-responder genotype and the low-intensity training group was selected from people who expressed the endurance genotype, but the researchers also tested what happened when endurance responders trained with power and power responders trained with endurance. 

In a nutshell, what researchers found was that the advantage of training according to your genotype results in a significantly enhanced response to training over not training according to your genotype, and training in discordance with your genotype yielded a less beneficial response to training that ranged from 55% up to 610%!

So what is the takeaway from this study? In an era where genetic testing is affordable, easy-to-interpret based on guides you receive after testing, and now proven to assist with fitness (and nutrition) programming, I’m a big fan of getting genetically tested and paying attention to your results. 

For more details, I’d recommend you listen to an hour long podcast I recorded with DNAFit representative and Olypmic athlete Andrew Steele, entitled “How to Use Genetic Testing to Personalize Your Workout And Diet.” In the show notes for that episode, you can download my own genetic testing results to see what genetic testing for fitness actually looks like. 

Do you have questions, comments, or feedback about how to use genetics to get fit? Join the conversation at Facebook.com/getfitguy.