Saturday, 11 February 2012

The Effects Of Exercise On Breathing Rate |

The Effects of Exercise on Breathing Rate Photo Credit jogging image by Emmanuelle Combaud from

During exercise, the increased activity of the muscles increases oxygen consumption and production of carbon dioxide. The respiratory system, in conjunction with the cardiovascular system, must adjust to meet these demands. These additional requirements on the respiratory system are met largely by increases in respiratory rate, or the number of breaths per minute, and by deeper breaths.

Immediate Response

The onset of exercise results in an immediate increase in respiratory rate. This response occurs before any changes in the concentrations of oxygen and carbon dioxide in the blood. Part of this increase is believed to be a "learned" response to exercise. Neural or brain pathways receive information from receptors in muscles and tendons. These receptors send signals to the brain about the activity in the muscles and the impending increase in metabolic demands.

Moderate Exercise

Increased respiratory rate during moderate exercise appears to rely on oscillations in the blood levels of oxygen and carbon dioxide. Blood gas levels do not change greatly during moderate exercise; however, small fluctuations can be detected by chemical sensors called chemoreceptors. The carotid bodies, which are small areas of tissue with many capillaries near the branching of the carotid artery in the neck, are the primary peripheral chemoreceptors that detect changes in the blood. The signal from the oscillations in blood levels of oxygen and carbon dioxide is relayed from the carotid bodies and contributes to the changes in respiratory rate.

Intense Exercise

Changes in respiratory rate during intense exercise are caused mostly by the buildup of metabolic byproducts. The exercising muscles produce an increase in the levels of carbon dioxide and hydrogen ions in the blood. The increased activity also decreases oxygen levels in the blood. These changes are detected by peripheral chemoreceptors such as the carotid bodies as well as central chemoreceptors that detect changes in the cerebral spinal fluid. Greater changes are required to activate central chemoreceptors. Their activation signals the need for a further increase in respiratory rate.

Resting Breathing Rate

Training increases the ability to perform physical activity. Most of these changes, however, are due to improved cardiovascular function and increased oxygen uptake or extraction by the muscles. While regular exercise produces a decrease in resting heart rate, it has little or no impact on resting breathing rate at rest. Exercise can, however, increase the strength of respiratory muscles and decrease the fatigue associated with prolonged increases in breathing rate.


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