ABSTRACT
Middle- and long-distance running events are determined by a complex mix of factors. The highest rate of energy production that can be maintained for the race duration and the ability to convert that into movement determine middle- and long-distance performance. Running is one of the most popular global sporting and leisure-time activities. The popularity of running has grown in recent years with the creation of events such as the parkrun, a weekly, free-to-enter 5-km run, which began with 13 runners back in 2004 and now has 5 million registered runners worldwide. The faster the running speed, the greater the rate at which the active muscles must produce force, and by extension the metabolic systems produce the required energy. The ‘currency’ for the generation of force in the muscle is adenosine tri-phosphate which when hydro-lysed releases the energy used in cross-bridge cycling.
