Chemistry and Sport - Athletics: The 400m Event

The 400 m is considered to be one of the toughest athletics events athletes compete in. The energy system employed by the athletes to produce the energy fast enough to sprint, for the 45 s or so the race takes, produces lactic acid as a by-product. The module uses this link to sport to explore acids and bases.

The 400 m race, an athletics event that is recognised as being one of the toughest speed endurance races it is possible to compete in, dates back to the Ancient Olympics of 724 BC (the 14th Ancient Olympic Games). Here the Diaulos Race was introduced, consisting of a single lap of the stadium approximately 400 m long.

The event was repeated at all subsequent Ancient Olympic Games and every Modern Olympic Games since their reintroduction in 1896. The 400 m race is considered to be so tough because a sprint is required over a distance which is too long to be a sprint, due to the nature of the energy system athletes employ for sprinting. For a 400 m race, the most predominant energy system used by elite athletes is anaerobic glycolysis. This energy system can last from 30 to 40 s when trained, almost long enough to complete the entire race which takes the very best athletes between 44 to 50 s to complete. 

Anaerobic means produced without oxygen. As a by-product of the manufacturing of energy through anaerobic glycolysis, lactate is produced from the breakdown of glucose without oxygen. Over the initial few 100 m’s the concentration of lactate builds up in the muscle cells of the athletes. This build up can give a sensation of pain, known as a stitch, to the runner. Lactate is sometimes, although incorrectly, interchanged with the term lactic acid, however this does simplify the concept and therefore lactate can be considered to be lactic acid for the purpose of this module.

Acids and alkalis are very important in chemistry and through the examination of lactic acid, produced by the runners of a 400 m race, acid and pH (a measurement of acidity) will be explored. 

A simple description of lactic acid is that it is a waste product from creating energy for exercise when insufficient amounts of oxygen are available. Effectively, the body has a small store of energy for exercise (known as its ATP store). Once this store has dissipated, there needs to be a way of re-synthesizing it so the body can carry on exercising.  There are three ways that the body can replenish its ATP stores.

These are through ATP PC, anaerobic glycolysis and aerobic glycolysis. The body can reproduce ATP which is the fuel for exercise at varying rates for varying amounts of time depending on intensity of exercise.  Briefly: ATP PC can create ATP very quickly but only for a short space of time (6-10 s). Anaerobic glycolysis produces more ATP per molecule of glucose but more slowly than ATP PC and it can be produced for a longer period of time (30 – 40 s).

An unfortunate byproduct is lactic acid but this can be removed after it has been produced by providing oxygen to the areas affected. A cool down exercise helps to increase oxygenated blood flow to the area. Finally aerobically, ATP is produced most efficiently, for the longest period of time and is produced using oxygen.