In the fitness industry, professionals often use the terms aerobic and anaerobic training to describe different components of fitness. Essentially, aerobic and anaerobic exercise are terms referencing the three basic energy systems used to fuel your workouts. In aerobic exercise, oxygen is required to create energy to fuel the activity, whereas, it is not required in anaerobic exercise.
ATP-PCr System
The Adenosine Triphosphate-Phosphocreatine System or ATP-PCr is the simplest of energy systems used for high-energy activity lasting only a few seconds. This energy system does not require oxygen, therefore, considered anaerobic. Activities that rely on this system include sprinting, jumping and powerlifting. ATP-PCr stores are very limited and used up quickly, resulting in exhaustion within three to 15 seconds of an all-out intensity activity, note Jack H. Wilmore and David L. Costill authors of "Physiology of Sport and Exercise."
Glycolytic System
The glycolytic system, like ATP-PCr, is anaerobic but differs because it breaks down glucose in the bloodstream to create energy. The glucose comes from carbohydrates you eat and turned into glycogen that is stored in the muscles or liver to be used for energy. The glycogen is then converted to pyruvic acid through a process called glycolysis. Ultimately, the pyruvic acid converts to lactic acid. The accumulation of lactic acid in the muscles limits the duration of the anaerobic glycolysis system to one to two minutes before fatigue is reached. This system is primarily used for strength training and short-duration activities.
Oxidative System
The oxidative system requires the use of oxygen to continue to produce energy for the body, and, therefore, is the aerobic system. Oxygen is needed to mobilize and breakdown fat in the body to be used as energy. This is a more complex process than the other two systems but results in long-duration exercise lasting greater than 30 minutes such as walking, cycling, swimming and low-impact aerobics. Protein in the muscles can also be used for energy but usually as a last resort when carbohydrates and fat stores are used up, and makes up no more than 5 percent of the energy used, notes Phil Davies of Sports Fitness Advisor.
Energy System Interaction
In general, all three of the energy systems work together to fuel your workouts. Although, one of them is usually dominant, they do overlap one another. During the first few seconds of a high-intensity activity, the ATP-PCr system is dominant, but the other two systems are providing some energy. The oxidative system relies on the other two systems to provide energy, as well. For the most part, when a person is referring to aerobic exercise, it is long-duration exercise; whereas, anaerobic exercise refers to sprinting or weightlifting forms of exercise.
References
- "Physiology of Sport and Exercise"; Jack H. Wilmore and David L. Costill; 2004
- Sports Fitness Advisor; Energy Systems in Sport & Exercise; Phil Davies
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