Not everyone responds the same to exercise. Some people see visible results faster than others. Not surprisingly, genetics play a role in how much and how quickly a person can develop lean body mass. People who have more of an ectomorphic body type have to work harder and take in more calories to build muscle. On the other hand, mesomorphs gain muscle definition quickly. What about endurance exercise? Just as there are differences in how quickly people can build lean body mass, there are variations in individual responses to cardiovascular exercise.
Low Responders versus High Responders: Is It in Your Genes?
A study called the Heritage study identified 30 genetic variations that affect how people respond to endurance training. This study showed that some people can improve their V02 max significantly through endurance training while others are “low responders,” meaning they get little or no improvement in V02 max after starting a training program.
V02 max is a measure of maximal aerobic capacity. It’s an indicator of how effectively your body can send oxygen to your muscles during exercise and how readily your muscles can use that oxygen. V02 max reflects how well your lungs extract oxygen from the air, your heart’s ability to pump that oxygen and the ability of your muscles to take it up and use it. A person with a high V02 max can deliver more oxygen to their hard-working muscles, giving them more endurance than someone with a lower V02 max.
Two sedentary people may have different baseline V02 max values due to differences in genetic make-up before they begin an exercise program. As it turns out, people also have differing abilities to increase their V02 max or aerobic capacity. One person might start a cardiovascular training program and experience significant improvements in their V02 max, while another individual may have little change despite doing the same training. Researchers refer to people who experience little change in V02 max with endurance training as “low responders.”
A New Test Can Tell You How You’ll Respond to Endurance Training
Researchers have just developed a test that can tell you whether you’re likely to be a “low responder” or “high responder” to aerobic training even before you get off the couch to train. A British company called XRGenomics can send you a swab to rub inside your cheek and return to them for genetic testing. Based on that sample, they can tell you whether you’re likely to be a high responder to exercise or not respond as readily. As they point out, genes only determine about 23% of your response. If you’re a low responder, you may have to train harder to see significant improvement in aerobic capacity compared to someone who’s a high responder.
Is There Any Benefit to Knowing You’re a Low Responder?
There could be disadvantages to making this test available. Some people may become discouraged when they find they’re genetically programmed to be a low responder to exercise. On the other hand, it could also tell them they’ll need to train a little harder to boost their V02 max. Plus, this test only looks at one exercise benefit – improved aerobic capacity. It doesn’t measure other benefits of exercise – reduced blood pressure, improved insulin sensitivity, weight control, stress relief, etc. It also doesn’t take into account how a person will respond to resistance training.
The bottom line? Even if you were a non-responder in terms of aerobic capacity, you’d still get substantial health benefits from working out. Besides, genetics are only a small part of a person’s ability to excel at fitness or anything else.
References:
J Appl Physiol, Vol. 87, No. 3. (1 September 1999), pp. 1003-1008.
J Appl Physiol 90:1770-1776, 2001.
New York Times blog. “Are You Likely to Respond to Exercise?”
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