Anaerobic Exercise: Updated
Published: August 09, 2013
Anaerobic means in the absence of oxygen. When exercise is described as anaerobic it means that the energy you require is produced through energy pathways which do not require oxygen. Glycolysis is the metabolic pathway that breaks down glucose: one of the two major energy nutrients you use for fuel.
The end result of glycolysis is pyruvate a 3-carbon compound that has a key role in energy metabolism. Pyruvate can enter another energy pathway,TCA (tricarboxylic acid cycle or Kreb's cycle where, in the pressence of oxygen, pyruvate yields more energy in the form of ATP (adenosine triphosphate) an energy molecule.
However, when there is insufficient oxygen pyruvate is converted to lactic acid. This results in a build up of lactate in your muscles which results in muscle pain, along with fatigue and increasing breathlessness. The increase in lactic acid which accumulates in your muscle tissue decreases the pH in your muscle tissue which results in a burning sensation.
Pyruvate can also be converted to a few specific amino acids which may be converted to glucose in the process of gluconeogenesis. Lactic acid may be transported to your liver where a metabolic process called the Cori cycle converts lactic acid to glucose. Muscle cells lack a specific enzyme necessary for this process and cannot convert lactic acid to glucose.
Fats and amino acids in your body are also a source of energy, but require oxygen for the metabolic processes which release energy. With insufficient oxygen to fully breakdown glucose, fats, and amino acids, your body has to rely on its reserves of ATP and ATP from glycolysis.
A small amount of ATP is always present in all body tissues for immediate energy needs. CP (Creatine Phosphate) in muscles helps replenish ATP stores, but these stores only provides sufficient energy for short spurts of activity such as sprints.
Glycolysis does not require oxygen for the catabolism of glucose, thus, glucose in you muscles and that which is available in you blood, is the main source of ATP during anaerobic exercise.
The anaerobic pathway provides you with energy very quickly, but cannot be sustained for very long.
Typically, anaerobic exercises and activities are those which involve short intense intervals of activity followed by intervals of rest or very low intensity to allow your body to replace your ATP stores by allowing energy pathways which require oxygen to function efficiently.
Your energy pathways work dynamically together, but when your exercise is very intense the oxygen burning energy pathways are unable to cope with your demand for energy.
Anaerobic activities include:
- sprint swimming
- interval training
- intense strength training
Anaerobic exercise can build anaerobic capacity (the ability to perform short bursts of high intensity exercise) and can also build cardiovascular fitness to some degree, although aerobic exercise is usually the prefered method for building cardiovascular fitness.
If you are beginning a physical activity and exercise program it is best to start with low to moderate intensity acitivites and gradually develop your cardiovascular fitness. Intense anaerobic execise may over stress your body and may result in negative health consequences.
If you participate in weekend sports which require anaerobic fitness, anaerobic and aerobic training will enhance your performance.
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Corbin, C.B. & Lindsey, R. (1994). Concepts of Physical Fitness. Dubuque, IA: Wm. C. Brown Communications Inc.