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Are You Fit? Testing Lung CapacityFeatured science projectScience project video


Do you think you're in good shape? Being healthy and fit is very important. One way to find out how fit you are is to test your lung capacity. This is a measurement of just how much air your lungs hold. The more air your lungs can hold, the more oxygen your lungs can distribute to your body during exercise. With a few simple materials, a 2 liter bottle, plastic tubing, masking tape and water, you can determine the volume of someone's lungs by displacing the water in the bottle with the air in the lungs.


If someone has a higher volume of water displacement, then his lung capacity is greater than someone with less volume displacement.


In this fun and easy science fair project, you will use water displacement to determine lung capacity and compare this amongst various volunteers of different fitness levels.

Scientific Terms

water displacement method, lung capacity, volume, cardio-respiratory, oxygen, VO2 max


The maximum amount of air one can force out of his or her lungs with one exhale determines lung capacity. To measure this, a technique called water displacement method is used. This method is quite simple: the air takes the place of the water in the bottle. To use the water displacement method, take a big, deep breath then blow fully into a tube connected to a container filled with water. The resulting volume (amount) of water that is pushed out is equal to the volume of air the lungs can hold. But how does this determine someone's fitness level?

The more air capacity in the lungs, the more efficiently the body can distribute oxygen to the muscles during exercise. Oxygen is vital for muscles to work properly. That is because working muscles use oxygen to create the energy necessary to function. With regular exercise, one's cardio-respiratory function improves (cardio, referring to the heart, and respiratory referring to lungs). If one exercises regularly, their body becomes more efficient at bringing in, transporting, and using oxygen. Increasing the intensity of regular workout results in even greater the benefits to cardio-respiratory function and lung capacity. This improves the VO2 max, which is the maximum oxygen consumption during exercise. VO2 max comes from V for volume, O2 for oxygen, and max for maximum. Therefore, regular and intense exercise results in larger lung capacity. This is one measurement of someone being fit.

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