Why don’t people with diabetes respond as well to exercise?

We know exercise is important in preventing and treating chronic disease.

It improves lung function and helps protect against heart disease, the leading cause of death worldwide. It lowers the risk of cognitive decline in older adults and, for those with diabetes or prediabetes, helps make cells more sensitive to insulin.

“There are no chronic diseases or organs that aren’t positively affected by exercise,” said Sarah Lessard, who joined Virginia Tech’s Fralin Biomedical Research Institute at VTC as an associate professor in July.

But while all exercise is beneficial, its benefits aren’t uniformly so. 

“We tend to think that if everyone does the same amount of exercise, we'll all get the same benefit. But some people are almost resistant to health benefits of exercise, similar to how some people don't respond to drugs in the same way,” Lessard said. “If we expose 100 people to the same exercise training program, there would be about 20 who are resistant to improvements in exercise capacity. Clinically, there are also 20 who would have huge improvements, and then the rest of us are right in the middle.”

That imbalance is an important, unanswered question. As the newest member of the institute’s Center for Exercise Medicine Research, Lessard is building a research program focused on uncovering the reasons people respond differently, improving exercise capacity for those with diabetes and prediabetes, and understanding muscle wasting that is common in aging and chronic disease.

Lessard’s interest in nutrition and exercise began early. She grew up hiking, biking and camping in Elliot Lake, a city in Northern Ontario, where she enjoyed downhill skiing and ran cross country on her school’s track team. “I rode my bike everywhere, because I didn’t have a car until I was 30 years old,” Lessard said.

As an undergraduate and master’s degree student at the University of Guelph in Canada, she studied biomedical science, human biology, and nutrition. Her early research was on high performers. “One of the first studies I did was looking at elite athletes, cyclists and triathletes, to see if we could help their performance using special diets,” said Lessard, who also hold an appointment in the Department of Human Nutrition, Foods, and Exercise in Virginia Tech’s College of Agriculture and Life Sciences.  

She was teaching French in Elliot Lake when she learned of an international scholarship to study diabetes and exercise at the Royal Melbourne Institute of Technology in Australia. Lessard packed up and headed to the Southern hemisphere, where she earned her doctoral degree.

Lessard grew more interested in emerging exercise research showing considerable differences in health response.

People with high blood sugar had lower exercise capacity. “Lower exercise capacity means your body isn’t using oxygen as efficiently,” Lessard said. That doesn’t mean exercise isn’t beneficial, but it does mean that the exercise doesn’t come as easily. “When we train regularly, we find our fitness levels improve and exercise gets a little easier. We find that process might be slower in people with diabetes.”

In 2015, Lessard started her own lab as an assistant professor of medicine at Harvard Medical School’s Joslin Diabetes Center. Several years after stating her own research program, she published a study in Nature Metabolism, in which she found that shifts in dietary and metabolic health associated with high blood sugar could blunt the benefits of training, including muscle adaptations and aerobic capacity.

“What we’re trying to do is figure out strategies to optimize their response so they can get the most out of their exercise,” she said. “And that might be by combining other diabetes treatments with the exercise.”

Lessard will continue her research with studies involving tissue culture, laboratory animal models, and human participants, with a focus on practical application. She is excited by potential for collaboration with heart, cancer, and neuroscience researchers at the Fralin Biomedical Research Institute, Virginia Tech, and beyond.

“We are thrilled to have Dr. Lessard, a leader in the research of the mechanisms underlying poor exercise response in diabetes,” said Zhen Yan, professor and founding director of the Fralin Biomedical Research Institute’s Center for Exercise Medicine Research. “Her work sheds light on humoral factor and muscle interactions converging on a fundamentally important signaling pathway. I hope that the Center for Exercise Medicine Research is home to her for many earth-shaking findings in the near future.”

Institute Executive Director Michael Friedlander, who is also Virginia Tech’s vice president for health sciences and technology, said, “Dr. Lessard’s innovative research is strategically positioned to provide important new insights at the intersections of exercise science, metabolism molecular biology and cardiovascular health — areas of major focus at the Fralin Biomedical Research Institute and at the national health level. We are excited to have her join the research institute family.”

Her research is funded by the National Institute of Diabetes, Digestive, and Kidney Diseases, part of the National Institutes of Health.