Can a DNA analysis help improve your fitness?

By Melanie Radzicki McManus, CNN

(CNN) — Millions of people around the globe are spitting into vials in the hopes of learning more about their genes. But they’re not just looking for information about their ancestry.

Increasingly, people are interested in pursuing how their genes may be affecting their health, nutrition, fitness potential and risk of injury.

The global market for these direct-to-consumer genetic tests is projected to soar in the next several years, skyrocketing from $1.9 billion in 2023 to $8.8 billion by 2030, according to a market analysis report by Grand View Research. North Americans are leading the way, with 60.5% of the market share, although Europe is projected to become the fastest-growing market over the next six years, the analysis shows.

In 2013, some 20 companies were offering direct-to-consumer genetic tests aimed at sports performance and injury risk — a number that rose to about 70 by 2019, according to one study review. In addition, a 2020 study published in the Indian Journal of Orthopaedics reported Uzbekistan and China are using genetic testing in their Olympic-talent identification programs, while Australia’s National Rugby League players are using DNA tests to tailor their workouts for sprinting or explosive power lifting.

Despite all this buzz, many researchers said there’s too much hype and too little solid science behind these tests. One such skeptic is Dr. Timothy Caulfield, a professor in the law faculty and school of public health at the University of Alberta in Edmonton.

“I’ve been following this field since the late 1990s, and the progress hasn’t been substantial,” Caulfield said.

Excitement at first

There was a lot of excitement about genetic testing when scientists discovered the BRCA1 and BRCA2 genes in 1994 and 1995, respectively. Women with mutations in either of these genes were found to have a 60% to 80% lifetime risk of breast cancer. In addition, a mutation in BRCA1 meant a 40% to 50% lifetime risk of ovarian cancer, while a mutation in BRCA2 carried a 10% to 20% lifetime risk.

“There was hope that we’d find a lot of genes like these that would be highly predictive, and where you could take steps to make a difference in your health,” Caulfield said. “But it really hasn’t panned out that way.”

Instead, he said, scientists have discovered how our genes work is a complex topic, especially regarding fitness and sports. Caulfield took a genetic test, for example, which showed he was unlikely to excel in sprinting. Yet he was talented at the sport, competing through childhood and college.

“There’s no doubt that genes matter, but the question is how much?” Caulfield said. “Even when you look at Olympic-level long jumpers, who need highly explosive movements, not all of them have the sprinting gene. If it really mattered, they all would have to have it.”

Indeed, scientists say there are so many additional factors when it comes to sporting talent and success, such as diet, sleep, training, motivation, socioeconomic background and even in utero experiences. Similarly, there are innumerable variables when it comes to your risk of injury.

Another concern among researchers is the scientific validity behind these tests. While the accuracy in terms of the actual genetic testing is likely good, the science behind how the companies are interpreting the results can be problematic, said Dr. Dylan MacKay, assistant professor of nutrition and chronic disease at the University of Manitoba in Winnipeg, Canada.

“A lot of times these tests are based on associations, not randomized, controlled trials looking for causal effect,” MacKay said. “For example, watermelon consumption is associated with drowning — because more people swim in the same season as they eat watermelons. But that’s just an association.”

The advice companies give based on your test results is often vague or standard, too. Caulfield’s results indicated he was at risk for certain cardiovascular problems and cancers.

“What was my personalized advice to stay healthy? Eat well, exercise regularly, don’t smoke, drink in moderation,” Caulfield said.

Still, some are intrigued

Despite these issues, many remain intrigued by DNA fitness tests. One such person is Devin Maier, co-owner of Balance Gym in Washington, DC. Balance Gym recently partnered with FitnessGenes, a UK-based company that sells genetic tests, to help its clients achieve better results from their workouts.

While the tests don’t spit out precise instructions for getting fitter, Maier said he believes they can be helpful. One of his clients was attempting to put on muscle by lifting heavier weights, but with fewer reps. His test results showed his muscle type would do better with higher-volume training, so Maier had him switch to lifting lighter weights with more reps. Within a month or two, the client was seeing the desired muscle gains.

These tests also can help you discern your strengths and weaknesses, Maier said, so you can address them.

“You might not have the genes to be a good endurance athlete,” he said, “but if you want to run a marathon, we can help you train better so you can do so.”

Maier said he thinks there’s a lot of potential in the field, too.

“Our DNA isn’t changing, but the science and information is, and it will continue to do so,” Maier said.

Time, and further scientific advances, may shed more light on whether DNA fitness tests are, or can be, useful. But MacKay remains doubtful.

“I’ve been in this field for a long time, and while genetic testing is getting better and better, there are no new findings that are groundbreaking,” he said.

Caulfield said he hopes parents won’t use these tests to force their child into — or away from — a specific sport or activity.

“Genes aren’t determinative as to whether you’re going to like a sport or be good at it,” he said. “You should do what you love, and don’t let these genetic tests make it more complicated than it needs to be.”

Melanie Radzicki McManus is a freelance writer who specializes in hiking, travel and fitness.

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