Variables Effecting Vital Capacities Among Undergraduate Biology Students

Abstract

Vital capacity’s importance is to determine an individual’s lung function, or how what volume of air can be expelled from a person’s lungs. In this study, we investigated the relationships between vital capacity and heart rate, chest circumference, height, gender, and stature in undergraduate Biology students. This was measured via a spirometer. We found that the average vital capacity in males while standing was 4.25 L while females was 3.22 L. Comparing stature, the average standing vital capacity for all students was 3.53 L and seated was 3.40 L, showing that there is no discernible difference in the two. Heart rate held no correlation to vital capacity. On the other hand, chest circumference and height had a positive correlation with vital capacity. In summary, the majority of these variables produced anticipated data, while heart rate did not.

Introduction

Vital capacity (VC) is defined as the maximum volume of air that an individual can exhale after a maximum inhalation (Hoffman, et al. 2018). This is important to study to understand one’s respiratory health. We know that having healthy lungs can minimize respiratory problems because it enables us to consume the necessary amount of oxygen for daily metabolic functions. A healthy individual will have a vital capacity between 2 and 5 liters. Keeping our lungs well inflated will maintain our oxygen levels to ensure we are getting enough in our bodies where it is needed. The normal breathing we do on a day to day basis is called tidal volume (TV). Inhaling beyond the normal tidal volume is considered the inspiratory reserve volume (IRV), and the opposite, breathing outward is called expiratory reserve volume (ERV). The sum of inspiratory reserve volume, expiratory reserve volume, and tidal volume equals vital capacity. A spirometer is a tool used to measure vital capacity, which was invented in 1842 by Dr. John Hutchinson (Geddes, 2016). His studies, conducted by a calibrated bell inverted in water, concluded that vital capacity was directly related to height and inversely related to a person’s age (Petty, 2002). Many studies have shown that vital capacity can be affected by other numerous factors.

Some factors have a positive correlation with vital capacity, gender being one of them.

A spirometry test was done between triathletes from Malaysia to test the forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). After taking body composition measurements, the results showed that the male’s vital capacity was more statistically significant than the female triathletes (Johari, 2017). Another factor that has shown a positive effect on vital capacity is chest circumference and height. A study conducted by measuring the height and chest circumference of 1276 men weighing between 100 lbs and 200 lbs showed that the taller men and the individuals with larger chest circumference exhibited greater total exhalation (Hutchinson, 1846).

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This knowledge led to other researchers testing new variables, some of which have a negative effect on vital capacity. Expiratory volumes of a person in the seated position, when compared to standing, was found to have a statistically significant value of p=0.001 in a study conducted with 90 middle-aged male subjects alternating between the two positions (Townsend, 1983). Little research has been studied on whether heart rate plays a role in vital capacity. Although there is not a lot of research on the effects of pulse, exploration in the relationship between the heart rates of moderate to severe COPD patients and lung function were shown to hold a negative correlation in lung function, specifically FEV (forced expiratory volume) (Mazzuco, 2015). Smoking, which serves as a key player in inhibiting the lungs has shown to also have a negative effect on the respiratory system. Vital capacity and other lung functions were tested in 34 smokers and 34 nonsmokers between the ages of 15 and 18. There was a significant decrease in VC in the group who smoked compared to the youth who did not (Tantisuwat, 2014). Lung disease also appears to show a negative effect on vital capacity. A study done between normal and asthmatic children revealed that children with asthma indicted lower vital capacities when compared to children without it (Kattan, et al. 1978).

In this study, the relationships were investigated between vital capacity and variables of height, chest circumference, resting pulse rate, gender, and stature. Based on previous research, we expect to see the male students to have a larger vital capacity than females. We also believe that the subjects in standing position will exhibit a larger vital capacity compared to the sitting trials. It is anticipated that there will be a negative relationship between heart rate, but a positive correlation with height and chest circumference and vital capacity.

Materials and Methods

In this study, a variety of factors were measured that affect vital capacity. It was conducted by a group of 67 (20 male and 47 female) undergraduate Slippery Rock University Principles of Biology students. Height was measured in centimeters. Chest circumferences were measured by wrapping a tape measure (cm) around the individual’s chest, just below the sternum, or under the bra level. Resting pulse (bpm) was recorded by placing two fingers on the radial artery and counting the number of pulses in a 15-second interval and multiplying that number by 4. This was done in three trials to get an average reading of resting heart rate. A spirometer was used to measure vital capacity (L). Each student measured their vital capacity by inhaling maximally, placed their mouth on the tube and exhaled maximally. All experiments were measured in triplicate, as was for the seated and standing positions. Along with recording the number of males and females, lifestyle factors were also noted, such as if the student was an athlete, has been diagnosed with asthma, or was considered a smoker.

Results

Upon completion of the experiment, spirometry data for the 67 Principles of Biology students showed an average standing vital capacity of 3.53 L, while the seated vital capacity was 3.40 L (Table 1). This suggests that there is no difference between the two statures. For the 20 males, the average standing vital capacity was 4.25 L and seated was 3.23 L. For the 47 females, the average standing VC was 3.22 L, while the seated VC was 3.04 L (Table 1). This shows males had a higher vital capacity than females. Height and vital capacity exhibited a positive correlation in our study (Figure 1). This advocates as the height of the individual increased so did vital capacity. The results showed a positive correlation found between chest circumference and standing vital capacity (Figure 2). This evidence suggests that larger chest circumference and/or height, the more oxygen one can respire. On the other hand, there was no correlation found between pulse and vital capacity in our study (Figure 3).

Discussion:

The collected data found was mainly as expected, apart from heart rate. As discussed, we believed to see positive correlations between height/chest circumference and vital capacity, and a negative correlation with pulse. Out of these trends, the data supported the claims of chest circumference and height. This was exhibited similarly in the study showing the men who are taller/larger chest circumferences produced a higher average vital capacity (Hutchinson, 1846). Although our results were not conclusive with having a negative correlation between heart rate and vital capacity in a previous study, other research found that heart rate variability (HRV) correlated moderately, but not significantly (Biachim, et al. 2017). This research supports the results found in this study since there was no correlation in pulse and VC. We also expected to see a higher standing vital capacity than seated, which was not supported by our results. In a study done in brass players, researchers asked the participants to produce a note of maximum duration while seated and while they stood. There was a significant reduction in vital capacity in the seated positions compared to the standing position (Price, et al. 2014). Since there were no discernable differences in this study, our findings did not support this research. We did not conduct this study in musicians who are trained to produce a maximal musical note, therefore this might explain the differences in our results. Looking at the differences between males and females, in both variables of seated or standing, the average vital capacity in males was higher than those of females. In additional research, the volume of adult female lungs is typically 10-12% smaller than male lungs even if they are the same height and age (Bellemare, et al. 2003). Having a smaller lung volume capacity would not allow you inhale or exhale as much oxygen compared to someone with larger lungs. This research and the results of our study support our expectancies that males have a greater vital capacity on average than females. In summary, we anticipated the results of chest circumference, height and gender on VC. Additional research helped explain why our results showed no correlation/significance in heart rate and stature on VC.

References

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Table 1: Average Vital Capacities between males and females while sitting and standing

Figure 1: The relationship between height and vital capacity in undergraduate students while standing, as measured using a spirometer. There is a positive correlation in the data.

Figure 2: The relationship between chest circumference and vital capacity in undergraduate students while standing, as measured using a spirometer. A positive correlation was found in the data.

Figure 3: The relationship between pulse and vital capacity in undergraduate students while standing, as measured using a spirometer. No correlation was found in the data.