A recent study in the Journal of Applied Physiology finds that not only does interval heart rate training lead to dramatic cardiovascular performance, but also improves the body’s ability to burn fat. The conclusion of the study supported an increase in fat burning by 36% and improved cardiovascular fitness by 13%.
One advantage to interval training appears to be that it allows the body to spend more time doing high-intensity activity than it could in a single sustained effort. To run hard, the body must use new muscle fibers. Once these fibers are trained, they are available to burn fuel even during low-intensity exercise. That’s great news! Exercise that recruits new muscle fibers can enhance the body’s ability to metabolize carbohydrates and fat. Interval training also stimulates change in mitochondria, where fuel is converted to energy, causing them to burn fat first, again, even at low and moderate intensity levels.
Interval training should never be performed on consecutive days, and is best incorporated into your weekly regimen as a once a week workout—twice a week at most for advanced runners.