A metabolic system for generating energy. There are three main systems, an aerobic system, an anaerobic ATP-PCr energy system (sometimes called the phosphagen system), and the anaerobic lactate (glycolytic) system or lactic acid system. The aerobic system is the predominant energy system used for endurance activities and provides what is sometimes called the endurance pathway; the ATP-PCr system is used for short bursts of high intensity activity lasting less than 4 s and provides the power pathway; and the lactic acid system is used for more sustained high intensity activities, typically lasting 4–60 s, and thus provides the speed pathway. See also energy continuum.
Subjects: Sports and Exercise Medicine.