Researchers Hunt for Genetic Link Between Exercise and Fitness

Written by: CEHD Communications Staff
Post date: December 14, 2010

In the famous training sequence from the classic movie Rocky, Rocky Balboa works relentlessly to hone his body and prove himself against his opponent. What if, at the end of that sequence, Rocky didn’t become stronger, faster and fitter? What if he didn’t see any improvement after his training? This scenario is actually not all that far-fetched. Research suggests that people's responses to exercise training vary greatly, to the point where some individuals experience little difference after training and others see dramatic results.

This variation in response has a genetic component, says Michael Massett, assistant professor of exercise physiology. Massett is principal investigator of a five-year National Institutes for Health project charged with finding that specific genetic component. He and his research team are trying to identify genes that influence how people respond to exercise training. "Cardio and respiratory fitness is a good predictor of morbidity, mortality and chronic disease.

The more fit you are, the lower your risk for these types of diseases," Massett says. "Our main goal is to find the genes that link cardio and respiratory fitness with the beneficial effects of exercise." To identify the genes, researchers use mice, which can reproduce in a matter of weeks and provide the large number of subjects needed for a human genetic study. The mice complete four weeks of exercise training on a treadmill and are tested both before and after the training to track their response. Researchers look for strains that have a large response to the exercise training and those that have a small one. "We can compare two strains for any kind of phenotype—or physical characteristic—weight, body fat composition, their ability to exercise on a treadmill or their response to exercise. If there is any difference between the two strains, we know that some component of this is due to genetics. We can use these differences to identify the genes that are responsible for that difference," Massett says.

If successful, researchers will be able to identify several candidate genes. These genes then can be explored in humans to see if they are related to training response. Eventually, the research could lead to identifying therapeutic agents that may help individuals who suffer from diseases related to lower fitness levels, such as diabetes, heart disease or cancer. "If someone has a version of a gene that is not up to par, and if we know where to find that gene, we might be able to design therapeutic agents to turn that gene on, off or up a little," Massett says. "It could be a drug or medication, or it could be changes in diet and exercise."