You can achieve sustainable exercise because your muscle cells can convert food sources into energy. When you have this reaction, there is a need for an increased amount of oxygen. A product of increased metabolism is the production of carbon dioxide. While the heart delivers the oxygenated blood to working cells, your lungs take in oxygen and clear carbon dioxide from the bloodstream.
The Anatomy of Breath
Your lungs are inside your rib cage. The muscles of your chest, between your ribs and your diaphragm, contract and relax in order to change the pressure inside your lungs. This allows you to breathe air in and out. During exercise, other muscles -- termed accessory inspiratory muscles -- assist in the increased demand for air and work to lift out the ribs and collarbone. These muscles include the sternoclediomastoid, scalenes and trapezius, according to the book "Exercise Physiology."
Breathing Rate
When you exercise, your breathing rate increases. Your frequency of breaths is measured in breaths per minute. At rest, the average person breathes at a frequency of 12 breaths per minute. During maximal exercise, your breath can increase to 48 breaths per minute, "Exercise Physiology" says.
Volume of Breath
The amount of air you breathe in with each breath is called tidal volume. It also increases during exercise. At rest, the average healthy person takes in 0.5 liters of air per breath. At a maximum amount of exercise, this can increase to 4 liters of air per minute, the book says.
Adaptations to Exercise
When you become more aerobically fit, your respiratory system enhances in order to provide working muscles with more oxygen. Regular exercise trains the inspiratory and accessory muscles to become more effective in breathing. In addition, residual volume, or the amount of air that's left inside the lungs and is not used, also decreases. If residual volume decreases, that means tidal volume increases and more of the breath you take in is getting used, increasing the exchange of carbon dioxide for oxygen, according to the book "Fitness and Health."
References
- "Exercise Physiology"; George A. Brooks, Thomas D. Fahey, Kenneth M. Baldwin; 2005
- "Fitness and Health"; Brian J. Sharkey and Steven E. Gaskill; 2007
