The Problem with Genetics-Based Training

The pitch is tough to ignore: spit in a tube, send it off to a lab, and two to four weeks later you’ll receive a fitness or nutrition report tailored to your genetics. In the past five years, new companies like FitnessGenes, DNAFit, Genetrainer, and AnabolicGenes have promised just that. Perhaps you have muscles that seem genetically hardwired to recover slowly. Using the information provided by one of these companies’ reports, you may cap your workouts at five a week to prevent overtraining. In theory, you’ll be able to more effectively and efficiently reach your fitness goals because you have more information about your genetics.

The appeal is obvious, but experts say that we may be decades away from truly understanding how genetics affects performance, calling current offerings slick marketing rather than sound services.

All of today’s genetic training companies claim to base their reports at least in part on gene variations, or slight differences in a person’s DNA. Scientists have analyzed a fraction of the body’s nearly 10 million gene variations, which can determine everything from the curl of your hair to how you respond to certain medication. And while they have indeed discovered connections between genes and various traits, that doesn’t mean there’s a straightforward relationship. Genetics are deeply complicated—and that’s the problem.

“Any layperson with no science background can appreciate the fact that our bodies are super complex, and that no one gene can control anything,” says Dr. Mark Sarzynski, an assistant professor of exercise science at the University of South Carolina. “Even if one gene is involved, it’s not likely to be a huge player in the scheme of things, so you can’t make a promise—or structure a fitness plan—based on that one gene.”

For example, Sarzynski says look at studies of obesity. Researchers have found 97 different variants associated with our bodyweight, and each one of those gene variations actually have a very small effect on our overall weight. One’s sex, for instance, will dictate adult bodyweight to a greater degree than any one of the 97 gene variants. “The moral is the science is not there in terms of personal exercise prescriptions,” Sarzynski says.

This isn’t to say that analyzing one's gene variations will never illuminate more efficient and productive ways to exercise. In a paper published last September in the British Journal of Sports Medicine titled “Exercise genomics—a paradigm shift is needed,” Dr. Claude Bouchard, a human genomics professor at Louisiana State University-Pennington's Biomedical Research Center, called for much larger sample sizes, ideally in the thousands; a screen of each participant’s entire genome, instead of a single variant; and more collaborative research and data sharing efforts among all exercise genomics researchers.* He also said it’s important to conduct experimental rather than observational studies—studies that would assign varying exercise programs to random participants, for instance. In the past, most researchers have been financially limited to studying small numbers of people in specific groups—diabetics or collegiate athletes, for example—which makes it tough to tell whether they’ve uncovered an inherent relationship between a gene and a trait, or just something peculiar about that group.

The good news is Bouchard’s research goals are slowly becoming a reality. Sequencing the entire genome of every participant in a study will become easier as the cost continues to fall. In early-2015, the price to sequence a whole human genome was more than $4,000, according to the National Institutes of Health; half a year later, it cost $1,500. And the NIH announced a year ago that it would award a portion of a $170 million grant to researchers studying the relationship between gene variations and physical activity. Part of this program, Sarzynski points out, involves developing a public database of exercise-related research that most any scientist can access.

NIH also seeks to enroll 3,000 people in various physical activity studies to be completed within the next six years. That’ll be a huge step forward, Sarzynski says, but those studies will still only tell us about the genetic response to whatever exercise program is tested. “Ideally we’d do that exact same study for every type of exercise,” says Sarzynski. That is, enroll 3,000 new people in an nearly identical program, but instead have them do HIIT, resistance, or endurance training. Only then would it be possible to make the kinds of personalized recommendations many consumers are looking for.

Sarzynski’s estimate for when that might become a reality? A sobering 20-plus years. “Even that’s probably super optimistic,” he says.

In the meantime, some actionable advice from Stanford School of Medicine sports genetics researcher, Thomas Roos:

Knowing my muscle type from the ACTN3 gene wont change the way I train. If I want to improve my strength I will do the exact same workout: a free weight whole body strength routine. If I want to loose weight I will exercise more and eat healthier, regardless of what my genetics is. If I want to optimize my diet I will use the consensus statement guidelines from nutrition scientists and avoid any fad diets. Most of the actions taken are common sense and really don’t require any genetic insight at this stage, since the genetics is so primitive and explains so little of the variance.

Our genes may harbor shortcuts to achieving our best self. But it looks like our best bet now is simple hard work and intuition.