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What Should I Know About Lung Capacity?

M.R. Anglin
M.R. Anglin

Total lung capacity refers to the maximum amount of air a person’s lungs can hold, about four to six liters (4000 to 6000 cm3) for the average human. Only a third of this capacity is used during normal activity, but this fraction increases during strenuous activity when the body requires more oxygen. On average, males have a 20-25% higher capacity than females, and tall individuals have a greater capacity than short people.

The human lungs enable respiration. When air is inhaled, the lungs extract oxygen and transfer it to the blood where the oxygen is then carried to cells. The blood supplies cells with oxygen and collects carbon dioxide, a waste resulting from cell functions. The carbon dioxide is then carried back to the lungs where it is exhaled.

The human respiratory system, showing the trachea, bronchioles, and lungs.
The human respiratory system, showing the trachea, bronchioles, and lungs.

Those who live in higher altitudes also have a higher lung capacity than those who live at sea level. This is because air is less dense at high altitudes, and thus the concentration of oxygen is lower. Lungs, therefore, have to inhale a greater volume of air to extract the same amount of oxygen than they would have to at sea level.

Total lung capacity (TLC) is measured by adding together Inspiratory Reserve Volume (IRV), Tidal Volume (Vt), Expiratory Reserve Volume (ERV), and Residual Volume (RV) to come up with the formula, TLC=IRV + Vt + ERV + RV. Tidal Volume is the amount of air normally inhaled or exhaled. Inspiratory Reserve Volume is the amount of additional air that could be inhaled in order to completely fill up the lungs. Expiratory Reserve Volume is the amount of additional air that can be expelled after a normal exhale. These values are measured with a spirometer. There is a certain amount of air that cannot be exhaled under any circumstances. This is the Residual Volume and is measured by other pulmonary function tests.

A human respiratory system.
A human respiratory system.

It is important to keep the lungs healthy because all cells need oxygen to function. Cigarette smoke reduces lung capacity by causing lung disease. One of these diseases is emphysema which destroys the alveoli--the air sacs within the lungs where the exchange of oxygen and carbon dioxide takes place. As a result, the lungs lose elasticity and are unable to stretch properly, thus reducing the amount of air that is able to be inhaled. Asthma, a disease that causes inflammation of the lungs, and chronic obstructive pulmonary disease (COPD), the combination of chronic bronchitis and emphysema, also decrease total lung capacity.

Discussion Comments

parmnparsley

@ Babalaas- Deep breathing exercises can also improve lung capacity. Exercises like Yoga, Qi Gong, and Tai Chi are very beneficial to respiratory health as well as having numerous other benefits. All these exercises focus on deep rhythmic breathing. Many deep breathing exercises are adapted from Tai Chi, Yoga, and Qi Gong to help with respiratory related ailments.

Paying attention to your posture can also help improve lung capacity. Your lungs do not have room to expand when you slouch.

Whether or not you have the time to exercise there are many little tricks to expanding your lung capacity.

Babalaas

There are things that people can do to improve their lung capacity. Aerobic exercises condition the lungs, and have the added benefits of strengthening the heart and improving the circulatory system. Any exercise that requires rhythmic breathing and works the long muscles of the body is an aerobic exercise.

Good aerobic exercises for increasing lung capacity are biking, hiking, swimming, dancing, and rowing. There are many others, so everyone can improve their lung capacity regardless of their ability.

Alchemy

The section in the article about lung function at higher elevation gave me a better understanding of why exercise at higher elevations makes me winded.

I live in Phoenix, which sits at about 900 feet above sea level. I like to go north to Sedona or Flagstaff to mountain bike, but I notice that I cannot bike as long or as hard as I do in the city. Now I know my loss of stamina relates to the density of the air, and the relationship between air density and lung capacity.

I wonder if people who live at higher elevations have larger lungs, or if they are simply able to compress what they inhale. This is something I would like to know a little more about.

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    • The human respiratory system, showing the trachea, bronchioles, and lungs.
      By: Alexandr Mitiuc
      The human respiratory system, showing the trachea, bronchioles, and lungs.
    • A human respiratory system.
      By: pixelcaos
      A human respiratory system.
    • Asthma patients tend to have decreased lung capacity.
      By: perfectmatch
      Asthma patients tend to have decreased lung capacity.
    • Cigarette smoke reduces lung capacity.
      By: Николай Григорьев
      Cigarette smoke reduces lung capacity.
    • Spirometers measure total lung capacity.
      By: Lisa F. Young
      Spirometers measure total lung capacity.