Engaging in high-intensity interval training for two weeks may reduce glucose metabolism in all areas of the brain among people suffering from Type 2 diabetes, a study claims. Researchers at University of Turku in Finland studied how high-intensity interval training (HIIT) alters the brain’s glucose metabolism in physically inactive insulin resistant people. The study, published in Journal of Cerebral Blood Flow and Metabolism, showed that HIIT training reduces brain glucose metabolism of people suffering from type 2 diabetes or prediabetes. Previous studies have shown that the brain’s glucose and fatty acid uptake is increased in type 2 diabetes, and that glucose uptake decreases after weight loss. “We wanted to study if a similar effect could be achieved by exercise, without a significant weight loss,” said Sanna Honkala from University of Turku. However, the mechanisms behind the changes in the brain’s metabolism are still speculations, researchers said.
During HIIT training, eg ketones and lactates are being formed which the brain can use as a source of energy. Glucose being supplemented with ketones, could be one of the explanations for the decreased glucose uptake caused by exercise, researchers said. The team studied middle-aged, non-exercising men and women, who had prediabetes or type 2 diabetes. The research subjects were randomised into two different exercise intensity groups, one of which was for HIIT training and the other for traditional, moderate intensity continuous training. The two-week training intervention included six instructed training sessions which were performed by using exercise bicycles.
HIIT training consisted of 30-second training sessions with four-minute recoveries in between, whereas traditional exercise consisted of uninterrupted, moderate intensity cycling. “Both forms of exercise improved the whole body’s insulin sensitivity equally efficiently and most likely, we would have seen a change also in the brain’s metabolism after moderate training if the exercise period would have been longer,” said Jarna Hannukainen from University of Turku. “In order to improve their insulin sensitivity, everyone can choose the form of exercise they are most comfortable with, which also motivates to exercise regularly,” Hannukainen said.