The announcer yells, "Michael Johnson breaks the 200m world record with a time of 19.83 seconds!" and the crowd goes wild, fans cheering . . . Do you recall the Summer Olympics in 1996 in which many top athletes (especially Michael Johnson!) achieved outstanding and unheard-of standards of physical excellence? A lot of folks were thinking, "How did he do this? Could I do that, too?" Was it through careful and consistent training, or was it just natural? If so, what did that training change about his body to make him the "fastest human being" ever?

There are many factors that contribute to Michael's continued high performance. Today's lab will look at one of the factors that helped him as well as many other athletes along the way to achieve greatness. This factor is lung capacity, or the volume of air that our lungs can hold. Lung capacity can be used as an indicator of physical fitness? or an indicator of the lifestyle or living environment. This is because when the body needs more oxygen, which happens when you are at higher elevations or are exercising regularly, the lungs are able to adapt in order to utilize the body's oxygen intake more efficiently.

The reason for the efficiency of this mechanism is that, as living organisms, we are required to breath regularly in order to obtain oxygen for our bodies to use in all of their processes. This breathing process provides oxygen for our cells to do their jobs and allows us to get rid of carbon dioxide. As the heart pumps oxygen through our bodies via the blood stream, it is taken up and used by our cells, which then give off carbon dioxide. This gas is then released to the air as we breath out.

Most of the time, people do not utilize all of the space that is available in their lungs for holding oxygen-rich air. Full use of our lungs is dependent on good health and the size of the diaphragm, the muscle below our lungs. There are many reasons for having a larger relative lung capacity, as well as reasons for having smaller capacity. What do you think some of those reasons are?

In the world of running, as mentioned above, the lung capacity of an athlete has a profound effect on the level of their athletic performance. This is because their heightened level of athletic prowess demands more oxygen in a shorter period of time than the normal daily actions of life require. Our bodies need more oxygen per breath (i.e. greater lung capacity) on a long distance run than they do watching television! In this lab, we will be performing a test to find out the volume of air that our lungs can hold.

As an introduction, have the students generate some ideas about lung capacity. One suggestion could be to have the students predict their own lung capacity in liters. Have them blow all of the air out of their lungs, and then take in a big "lungful" of air. Some questions to ask could be: How much air do you think you took in? Was the air you expelled the same as the air you breathed in? What kinds of factors would increase or decrease lung capacity? Is there a difference between male and female lung capacity, or between athletes and non-athletes? Give the students an opportunity to design their own experiment to test out one of these questions, or one they generate, complete with controls and a general hypothesis.

lungs

lung capacity

oxygen

carbon dioxide

Separate the students into cooperative groups of two or three. They can then:

1. Fill the dishpan or bucket approximately halfway with water.
2. Fill the jug or jar ALL THE WAY with water.
3. Cap the jug, leaving no air bubbles at the top. If you don't have a cap, it works fine to cover the opening with your hand, and invert it quickly into the water.
4. Invert the jug in the water and remove the cap from the jug, making sure that no air gets into the jug, and that no water leaks out.
5. Keep the open end of the jug submerged in the water, and put one end of the tube through the opening into the jug, keeping the other end out of the water bucket. Be careful not to let any air into the jug.
6. Have one person hold the jug carefully, still submerged in the water. and have the other person exhale air in one forced breath from your lungs through the tube into the jug. QUICKLY cover the end of the tube with your finger, to keep any more air from entering the jug.
7. Mark on the outside of the jug with the marker (or a small piece of tape) where the water level is.
8. Now empty the water out of the jug and put the jug on the table in an upright position.
9. Fill the jug up to the mark with water, and use the measuring cup to measure this volume of water in liters. This is your lung capacity!
10. Record this volume of water in ml on a chart for each person in the class.

Students should each hand in a lab report including the questions the students were addressing, their original hypothesis, and analyses of the classroom data in tabular form.

Discuss the ways that lung capacity is determined, including genetic history, environment (elevation level), exercise level, childhood activity level, pollution levels, and posture.

This works well as part of a unit on the respiratory system (see the lab "Don't Take My Breath Away"), and can be incorporated into coaching, as well as the classroom!

Lung capacity is one of the most interesting adaptations that humans have evolved. This adaptation has been most clear in the running performances of athletes from some of the African nations that are at high elevations. People who have grown up in the mountains at high elevation often have increased lung capacity due to the decrease in oxygen. Their bodies need to take in more air per breath, because there is less oxygen in the air. This is an advantage for runners, because when they come down in elevation to compete, their bodies are able to take in more oxygen, which prevents their muscles from building up lactic acid as quickly. Students should be able to come up with other examples in which the human body has adapted to respond to the environment.

SCIENCE CONTENT STANDARD 1: NATURE OF SCIENCE

This experiment satisfies Benchmark 3 for grades 5-8: "collect and summarize data from an experiment and interpret the results in terms of the data."

• SCIENCE CONTENT STANDARD 4: HUMAN ORGANISM
• This experiment satisfies Benchmark 1 for grades 5-8: "illustrate how human beings, like other animals, have body systems for obtaining and providing energy."

This experiment also satisfies Benchmark 4 for grades 5-8: " demonstrate how or~ans and organ systems work together (e.g., lungs and circulatory system work together to distribute oxygen).',

Besides being a really fun, relevant activity, this lab goes great in a unit on the respiratory system. It also incorporates some math skills such as measuring volume.