Those who have tried to run once the 42 kilometers of a marathon know that there is a phenomenon similar to the "? pájara" of cycling that is called "the wall". It affects practically half of the runners, and usually appears shortly after kilometer thirty, when the muscles have run out of glycogen.
Benjamin Rapoport, a researcher at Harvard University, has studied how the body uses energy during long-term physical exercise. And he has obtained a mathematical formula that helps not to falter during a marathon, published in the latest issue of the magazine PLoS Computational Biology.
During a strenuous exercise like running, the human body consumes most of the energy it needs in the form of carbohydrates, instead of using the reserves of fat.
Fundamentally, the glycogen stored in the liver and leg muscles, and only a small part of the hydrates consumed come from the glucose that circulates in the blood. When the available "sugar" is exhausted, the body goes into a kind of agony, and is forced to burn fat. By burning fats in the absence of carbohydrates, some byproducts are released, ketones, that cause Fatigue.
To avoid this, Rapoport has created a mathematical model that estimates how much time and how fast the runners can go to "hold out until the end". It uses two parameters: the aerobic capacity (VO2 max), which measures when oxygen can transport the body to the muscles during aerobic exercise - oxygen is needed to "break" the glucose -; and the storage capacity of carbohydrates (glycogen) in the muscles of the legs.
The model helps athletes calculate how many carbohydrates they should consume in the days before the race so that the reserves last 42 kilometers. And it is available to any broker through this on-line calculator: http://endurancecalculator.com/