Your DNA Results Can Ruin Your Workout
It is clear that a certain physical form is genetic : everyone who does the same workout cannot be expected to have the same results. It’s tempting to get tested to see if you personally have the same genes as elite sprinters or weightlifters. But DNA tests can’t tell you much about your fitness , and it turns out that knowing your results can actually change your well-being and performance.
A recent study (paid but well summarized here ) tested 116 people for changes in the CREB1 gene , which is associated with aerobic fitness. They then randomized the test results: half of the participants were told they had a “high-risk” version of the gene, and half were told they had a “protective” version. But they deliberately gave some people the wrong results, just to see what came of it.
The researchers then asked the participants to take a treadmill test and guess who had the worst results? Not people who had “bad” genes, but people who were told they had bad genes. This is the opposite of the placebo effect: sometimes, if you think you are sucking on something, you end up doing it.
This effect, sometimes called “nocebo”, is actually quite common. People who expect to feel pain are more likely to actually feel it; people who are told about test results in an alarming manner may end up feeling more anxious. The same researchers who conducted the treadmill trial also made a version in which they told people that they have a gene that makes them feel more or less full. (This gene was a good friend of ours, the FTO, which you may remember from this story about DNA tests for weight loss .) The results were similar: people responded in a measurable, physiological way to genes they thought they had.
The nocebo effect, like the placebo effect, does not change your body at the level of nuts and bolts. But when we talk about feelings like pain, satiety, or fatigue, your brain filters information from your body. If you lie and tell a cyclist that he is going slower than usual, he usually finds the strength to accelerate and break his own record.
It turns out that what you think about yourself can actually affect your performance in the gym. So if you did a genetic test out of curiosity, don’t get too hung up on it. After all, there are many more factors in fitness than just a few DNA bases in a test report. Try to tell yourself that you are great and see what results it brings.