Glucose aids in muscle movement and provides mechanical support, which helps the runner maintain performance over long distances. This chemical is one of the most important energy source of cells in the body. They provide the necessary stimulus to perform several processes in the body. It is usually taken from food that we intake. The food that we ingested then releases this type of simple sugar and converts it into usable energy. Athletes who take regular doses of this use it for athletic performance, in this case during a continuous and prolonged aerobic activity.
It depends on the person, but I know that the average cycle is about 28 days long, and it only occurs once a month, in normal situations. Hope this helps! :) Stay smart, ~Mistermistyeyed.