Korb, Thomas and Yue

Student abstract

Fall, 2008



Our environment, activities, and bodily positions all affect and influence the way we breathe and the quality of breath. The average pair of human lungs can hold about 6 liters of air, but only a small amount of this capacity is used during normal breathing. Several factors affect lung volumes, larger lung volumes are found principally in males, tall people, non-smokers, athletes, and people living at higher altitudes, while smaller volumes go the opposite of each of those categories. We tested the effects on lung capacity of three bodily positions (sitting, lying down, and standing up) over a timed period. We hypothesized that standing up straight would allow for maximum tidal volume, deeper breaths and a longer ability to hold oneÕs breath.

Using a respirometer, we ran 9 trials for each person in our group (one male, two females), conducting 3 tests sitting down in which we inspired once in small amounts and then on the second inhalation, we took the deepest breath we could and then exhaled, and this was done to measure capacity. Then we took a deep breath and held it as long as we could to see how long we could hold air in under the bodily position we were testing. We repeated this process three times for standing and lying down and recorded the results. Due to maximum spatial extension of the body in the upright position, we predicted that the chest and lungs would expand farther and allow for deeper breathes and longer ability to hold 02 before CO2 levels raised and forced us to breathe again.

Our results showed that while lying down, we had a higher capacity and quality of breathing. We analyze the results by running a t-test to see if there was a significant difference between standing and lying down in the lung capacity; we chose to run the t-test between those two parameters because we thought that the difference between the two activities contrast the most . The results showed an average value of 3.77 L standing and 5.2 L laying down, with a p-value of 0.0003 (p value < .05), which shows that there is significant difference in the lung capacity between standing and laying down.

Our results showed that the lung capacity is affected by the body position. However the higher lung capacity was found while laying down not while standing as we hypothesized. Even though the results showed a significant difference in the lung capacity among the different body positions, there are many variables that could change during this experiment and affect the outcome of the results, like the amount of subject tested, the sex of the subjects, and their health. A study by Lehnigk et al. 1997 published on the Int Arch Occup Environ Health Journal, showed that altitude affected breathing capacities in people of all ages tested under the same positions we did, and we werenÕt able to take that into account, considering all three of us live in the same elevation.