The respiratory system is responsible for taking oxygen into the body and moving carbon dioxide out. When we exercise, muscles, tissues and other bodily processes require more oxygen to function properly. The respiratory system, along with the circulatory system, responds to this need by pumping more oxygen-carrying blood into the body.
Basics
The respiratory system is a complex system that is regulated by the brain and consists of the lungs, trachea, larynx and bronchial tree in the lower respiratory tract, and the nose, sinuses, nasal cavity and pharynx in the upper respiratory tract. When we breathe normally, the muscle below the chest cavity, the diaphragm, expands and contracts along with the muscles of the chest to let air into and out of the lungs.
When air is moved into the lungs, oxygen and carbon dioxide are exchanged through the blood vessels in the lungs. Red blood cells carry oxygen molecules into the body, and carbon dioxide is expelled out of the body. During a normal breath cycle, the total volume of air exchanged is about 500 ml -- about 1 pint -- of air, according to "Hole's Anatomy and Physiology."
Exercise
When exercising, the body needs more oxygen to produce energy for cells and muscles. The respiratory system responds by increasing the rate of breath, expanding the chest to take in more air and by expanding the capillaries of the lungs to let more oxygen through. The body also produces acid waste products that it needs to get rid of, which increases the level of carbon dioxide. The carbon dioxide needs to be released from the body before it gets too excessive, and the response of the respiratory system facilitates this.
Benefits
Exercise, particularly cardiovascular exercise, increases the efficacy of the respiratory system when performed consistently over a period of time. Although the lungs don't actually get larger and aren't able to take in more air, they can distribute oxygen to the blood quicker, thus increasing the length of time before waste products are created. Muscles and cells are nurtured with more speed, and carbon dioxide gets released at a more rapid pace. When endurance is built, it takes less effort for the lungs to achieve the same effect; meaning the lungs, and heart, don't have to work as hard to keep up with the demands of the body when exercising.
Considerations
If you haven't exercised for a long time or if you have a chronic health condition, such as asthma or bronchitis, get a doctor's approval before beginning exercise. Start any exercise program slowly, and work your way up to more intense levels. A good rule of thumb is if you can talk while exercising, you are at the proper intensity for your fitness level.
References
- "Hole's Human Anatomy and Physiology, 11th Edition"; David Shier, et. al.; 2007
- MayoClinic.com: Aerobic exercise -- Top 10 reasons to get physical
- Weber University: "Benefits of Aerobic Conditioning"; Dr. Michael Olpin; Nov. 2010
