Physically fit people will return to normal breathing and heart rate levels more quickly than unfit people. Why is this? Well it is partly because their bodies have been stressed more often and are more “used to” inducing a quick response to bring the body back into homeostasis. Practice makes perfect, as they say, so someone who exercises a couple times a week has given their body more “practice” in returning the body to homeostasis than someone who sat on the couch watching TV all week.
In order to understand why we breathe more heavily when exercising, you must understand the concept of an oxygen debt. Adenosine Triphosphate (ATP) is what our cells use for energy. As ATP is depleted during exercise, the muscles use increased amounts of oxygen and nutrients to replenish ATP energy. When the blood cannot supply this oxygen and nutrients quickly enough, the muscle cells switch to a method that does not require oxygen. This method, however, also results in the production of lactic acid or Lactate, which we are now understanding to be another form of energy rather than just a waste product but if the muscles do not use it fast enough then the lactate builds up. Oxygen debt is the term we use to refer to the removal of this lactate.
It is commonly believed that lactic acid is the reason you are sore after a workout but this is a myth. Soreness is actually due to muscle damage and the breakdown of connective tissue. After a workout, lactic acid is completely washed out of the muscles within 30 to 60 minutes but over the next 24 hours, damaged muscle becomes swollen and releases chemicals that tend to irritate pain receptors which then causes you to feel sore.
Lactate is now understood to be an important fuel that is used by the muscles during prolonged exercise in order to maintain endurance. Lactate released from the muscle is converted in the liver to glucose, which is then used as an energy source.
But I have gone off on a tangent… back on course…
To understand labored breathing, we will think of oxygen as money and your muscle as a bank account. When you exercise passed a certain point, you “overdraw” your oxygen funds and are in debt. Labored breathing during exercise is the body’s way of trying to reduce the (oxygen) debt incurred by switching to this anaerobic (oxygen-less) source of energy. Labored breathing after exercise works to “repay” the oxygen debt and reduce the lactic acid buildup that was created when the breathing “during” exercise failed to meet the muscle’s needs.
Since muscle is more efficient at oxygenation then fat, a physically fit person will be able to oxygenate their cells more efficiently and pay the oxygen debt faster. The more efficient our muscles are at oxygenating themselves, the less time our breathing needs to be heavier than normal in order to pay the debt. If someone hasn’t exercised their muscles, they will be less efficient at oxygenation and the person will need to breathe heavier for a longer period of time just to get the necessary oxygen to all the muscles.
Exercise also tends to enlarge the ventricles of the heart which allows more blood to be pumped than someone whose ventricles have not been enlarged through exercise. More blood being pumped means that more oxygen will reach the muscles more quickly and they can thus pay the oxygen debt more quickly than someone who pumps less blood per second. Our heart rate will decrease when signals filter back that the debt is being repaid and the demand for oxygen and nutrients has decreased.
Doing different types of exercise can also have different effects on the size and shape of your heart. Endurance exercise tends to increase the size of both the left and the right ventricles of the heart while strength training only tends to enlarge the left ventricles. In addition, the ability of the left ventricle to fully relax between beats (diastolic function) is enhanced in endurance athletes and worsened in strength trainers. It is important to practice both strength training and endurance cardio so that they can balance each other out. Muscle gained during strength training will oxygenate more quickly and larger ventricles from endurance training will allow blood to reach the muscles more quickly.
The entire system revolves around maintaining homeostasis. When we exercise, we throw our bodies out of homeostasis
1. We breathe harder in order to oxygenate the blood faster
2. Our heart rate increases in order to pump blood faster to carry more oxygen and nutrients to the muscles
3. Our body temperature rises due to the increased blood flow and muscle movement
So, it is only natural that, after we stop exercising, our bodies work as quickly as possible to restore homeostasis. A physically fit person will have a body that is more efficient at returning to homeostasis than an unfit person.
– For Educational Purposes Only
– Not meant to diagnose or treat any medical condition
-These statements have not been evaluated by the FDA
– These statements are my opinions and conclusion from the knowledge I have thus far
1. http://articles.mercola.com/sites/articles/archive/2008/05/31/workouts-sculpt-heart-as-well-as-muscles.aspx
Accessed: 03/30/09, Author: Dr. Joseph Mercola
2. Thibodeau & Patton, Structure and Function of the Body, 13th Edition, 2008, p.160
3. http://hyperphysics.phy-astr.gsu.edu/Hbase/biology/atp.html
Accessed: 03/30/09
4. http://www.nytimes.com/2006/05/16/health/nutrition/16run.html
Accessed: 03/30/09, Author: GINA KOLATA
5. http://sportsmedicine.about.com/cs/exercisephysiology/a/aa053101a.htm
Accessed: 03/30/09, Author: Elizabeth Quinn
6. http://www.time-to-run.com/theabc/lactic.htm
Accessed: 03/30/09, Author: Andrew Bosch
7. http://www.time-to-run.com/theabc/postrun.htm
Accessed: 03/30/09, Author: Andrew Bosch
8. http://www.active.com/story.cfm?CHECKSSO=0&STORY_ID=6468
Accessed: 03/30/09, Author: Edmund R. Burke, Ph.D.
Wisdom That Heals 