Increased blood sugar levels likely to decrease benefits of aerobic exercise

Aerobic exercises are well known for its many benefits for overall health. However, a team of scientists, from Joslin Diabetes Center now have discovered that some benefits of aerobic exercise may be dampened by higher-than-normal blood sugar levels, a condition is known as hyperglycemia. These diminished gains are seen in mouse models and humans with chronic hyperglycemia that is in the "prediabetes" range, said Sarah Lessard, PhD, a  Joslin assistant investigator in the section of Clinical, Behavioral and Outcomes Research and senior author on a paper in Nature Metabolism that presents the work. The study also showed that this maladaptive trait is independent of obesity and insulin levels in the blood. Clinical studies have demonstrated that people with diabetes or chronically high levels of blood sugar struggle to improve their aerobic exercise capacity compared to people with normal blood sugar levels. The study also aimed to uncover the mechanisms that may lead to low fitness levels in people with hyperglycemia. Muscle tissue can remodel itself, which is one reason why exercise becomes easier when we do it regularly, Lessard says. Over time, aerobic exercise such as running or swimming can alter muscle fibres to become more efficient at using oxygen during exercise.