Differences In Anaerobic & Aerobic Exercise In Athletes

An athlete training for long-distance swimming might engage in a training regimen focused on extended periods of exercise sustained below the maximum heart rate, as suggested by the American Sports Medicine Institute. By contrast, an American football player might alternate bouts of exercise 30 seconds or less with longer intervals of rest. Such activity-specific training, as well as innate differences in muscle-fiber energy release, influences performance in the very different sports of marathon swimming (an aerobic activity) and football (primarily anaerobic). It all has to do with the means by which the body makes its fuel available.

Adenosine Triphosphate

Humans, like other animals, rely on adenosine trisphophate, or ATP, as an energy source for physiological effort like muscle contraction. ATP is manufactured from food material through a series of biochemical reactions. The route taken depends primarily on the availability of oxygen. Aerobic respiration creates ATP from glucose through the use of oxygen; anaerobic respiration without it. Humans may rely on anaerobic respiration when engaging in brief, intense bouts of activity. While the main byproducts of aerobic respiration, carbon dioxide and water, are easily removed from the body, anaerobic respiration produces lactic acid. Because lactic acid still has much energy the body can use, it must be metabolized rather than excreted--but if it builds up in muscle tissue too quickly, it can impair its function.

Anaerobic Exercise

While not as fruitful a source of ATP as aerobic respiration, anaerobic respiration can produce ATP very quickly--its rate of production can be substantial. This partly explains its value in supplying short bursts of energy. A classic example of anaerobic exercise is the 100-meter dash. The rapid rate of ATP production through anaerobic pathways allows the sprinter to run at a very high speed. (See Reference 3, p. 164.) The same is true of the baseball player rounding the bases or the sprint-swimmer muscling through a lap or two.

Aerobic Exercise

Compare the sprinter to the marathon runner. Racing on an extended course at the sprinter's speed would result in a buildup of lactic acid, which can acidify cells and internal fluids and negatively affect muscular function. The sprinter in the 100-meter dash needs time to recover so that the lactic acid can be metabolized by the body, a process that takes a bit of time. The marathon runner, therefore, competes at a slower rate of speed than the sprinter, relying primarily on aerobic respiration to create the ATP necessary for the exercise.

In Sports

In addition to sprinters and baseball players, many athletes competing through impressive spurts of high-energy activity--as in American football or weight-lifting--are fueled mainly by anaerobic respiration. The cross-country skier or singles tennis player relies heavily on aerobic pathways for energy production. Lactic acid buildup will induce fatigue in anaerobic exercise; declining glucose supplies over extended exertion will bring it on for aerobic athletes.