Notice how short distance professional swimmers, for example, a 50m freestyle swimmer, breathe only once or twice throughout the whole course. Why is it that it is nearly impossible for normal recreational swimmer to do that? If a person’s lung size cannot increase, how is it possible for professional swimmers to have such large lung capacity thereby able to hold large amount of air? The answer has to do with fitness level and exercise.
Breathing comprises of two actions, inspiration and expiration. Breathing is one of the required bodily functions of human beings. Our lungs deliver oxygen breathed in (inspire) from our surrounding air into the blood inside our body, and contrary exhale (expire) carbon dioxide out of the body. When inspiration occurs, the diaphragm and the intercostal muscles contract and causes the diaphragm to move downwards, increasing the volume of the chest cavity. The intercostals muscles also causes the rib cage to expand, further increasing the volume. Contrary to inspiration, expiration causes the diaphragm and intercostal muscles to relax therefore the thoracic cavity returns to its original volume, increasing the air pressure in the lungs and forcing carbon dioxide to be released from the body. 
Diagram 1.0: The act of Inspiration and Expiration 
We know that our lungs respond to our body’s changing needs for oxygen. We breathe deeper and take faster breaths when our body is associated with vigorous exercise. Our lungs are the organs that perform all our critical breathing functions. As mentioned before, professional athletes attain a larger lung capacity than normal people. Lung vital capacity is the maximum volume of air that can be forcefully exhaled and inhaled in one breath. 
Vital Capacity = IRV (inspiration) + ERV (expiration)
Diagram 1.1: Graph showing the different breathing activities 
There are several factors which affect one’s potential lung capacity. Factors such as:
* Gender – as males have larger lung capacity than females
* Height of person – the taller the person is the tendency that they will have a larger lunch capacity then a shorter height person
* Smoking – smoking damages the lungs and slowly diminishes its functions thus causing the lungs to become weaker
* Exercise – athletes have a larger lung capacity then non-athletes
* Breathing illnesses – eg; asthma can affect one’s breathing activity as the lungs are weak and have difficulty handling rapid changes in physical breathing activity (such as sprinting) 
In this experiment, the fitness level of the participant will be associated with their total vital capacity. It is hypothesised that participants with a high level of fitness will have a large vital lung and those with a low level of fitness will have a small vital lung capacity.
Regular exercise leads to many physiological changes for the human body. One of the benefits and changes to the body is improving cardio-respiratory function.
Improved cardio-respiratory function means that the body is able to exercise much more capably – becomes easier for the body to handle rapid changes in breathing. As a result, it enables the body efficiently and effectively gets oxygen into the blood stream. Regular exercise allows the body to store, transport and utilize oxygen more proficiently.
Although the cardio-respiratory function is improved with exercising and increasing fitness level, it does not change the lung’s ability to expand. The main difference between a person with a high fitness level and a person with a low fitness level is the better ability to extract oxygen from the air in the lungs and also better able to extract oxygen from the blood. Therefore, it allows the person to breathe more easily and able to handle physical vigorous changes. Therefore a person with a high fitness level is able to store large volumes of oxygen in their lungs without any difficulty. 
This experiment will be carried out in school grounds with male students of ages between 15 and 16 will be surveyed about their fitness level and tested for their total vital lung capacity. In addition, male participants must be between the weight of 55 and 65 kilograms and within the height range of 165 and 175 centimetres. All participants in this experiment will not have any breathing illnesses (asthma) and at the time of testing, participants will be at normal health (not sick, coughing etc) and normal physicality (not tired from running etc).
Participants will be asked to take a fitness level survey (refer to ‘Fitness Level survey’ in Appendix) and from the score on the survey (a score out of a possible 32), each participant will be categorised into one of five fitness level groups:
* Extremely low – scores 8 to 18
* Low – scores 19 to 20
* Medium – scores 21 to 22
* High – scores 23 to 24
* Extremely high – scores 25 to 32
The five fitness level groups are the independent variables for this experiment and the respective vital lung capacity is the dependent variable. Each participant’s vital lung capacity will be tested three times.
The average total vital lung capacity for males is 4.6dm3.  Participants’ vital lung capacity will be tested using Pasco GLX and a spirometer. A spirometer is an apparatus used to measure the volume of air inspired and expired by the human lungs. The spirometer is able to record the pressure of air, amount of air and rate of air that is inhaled and exhaled over a period of time. In this experiment the spirometer will be used to measure the amount of air that is breathed in and out at maximum volumes of the participants. The amount or air will be measured in decimetres cubed.
The amount of air breathed (inspired / inhaled) in is given as a negative value on the GLX meter and on the other hand the amount of air breathed out (expired / exhaled) by participants are shown as positive values. This is because when breathing in, participants are taking in all the air from and via the spirometer therefore simply put, the air in the spirometer is a negative value because participants have breathed in all the air. On the contrary, when participants breathe out, air is forced into the spirometer and it can be said that the air is ‘collected’ by the spirometer so therefore the value will be a positive number.
Vital lung capacity = | negative value | + positive value
Diagram 1.2: Pasco Spirometer and mouthpiece 
As human beings are needed for this experiment, there are some ethical issues that need to be discussed prior to testing. Therefore a briefing note is given to all participants before they are being tested. The briefing note outlines the aim of the experiment and the protocol for participants – participants are able to reject the experiment and are allowed to stop testing at any stage of experiment. No participants were forced into performing the experiment (Refer to ‘Briefing’ in Appendix).
Will increasing levels of fitness enable one to have larger vital lung capacity?
It is hypothesised that those with a high level of fitness will have a large vital lung capacity and therefore, those with a low level of fitness will have a small vital lung capacity.
Null Hypothesis (H0)
It is hypothesised that there will be no statistical differences between the lung capacity of a person with higher level of fitness and a person will lower level of fitness.
The fitness level of participant – fitness level is determined by participants’ scores achieved on the fitness survey
– Extremely low
– Extremely high
– The vital lung capacity of participant given in decimetres cubed (dm3) and is measured using a Pasco Xplorer GLX and spirometer
Table 1.0: List of all the variables that will be controlled in this experiment and explanations and method of how the variables will be controlled.
How it will be controlled
All participants tested in this experiment are male students as males are believed to naturally have a larger lung capacity then females.
The male participants must be between the ages of 15 and 16
Weight is important as this can affect one’s vital lung capacity. Therefore for this experiment, all participants must weigh between 55 and 65 kilograms.
Height is big factors that can affect vital lung capacity as the taller you are the bigger your lungs thus enabling you to have a large vital lung capacity. For this experiment, participants must be between 165cm and 175cm tall.
Health of participants
Participants must not be sick at the time of carry out experiment. Participants must not have had any breathing illnesses in the last 5 years. At the time of experiment, participants must be rested and normal body conditions (not tired, sweating or breathing hard). If these issues are not met, the data will become inaccurate as there were hindrances to the results.
Sitting position of participants when doing test
When carryout experiment, participants must be sitting upright with back straight and feet flat on the floor. Ensure that participants are relaxed and not tense. Sitting upright will prevent any blockages of airways, enabling accurate results to be recorded.
Technique of holding spirometer
Spirometer should be placed in the palm (one hand pinching nose, one hand holding the spirometer) of the participant. The mouthpiece of the spirometer should be positioned directly in front of the participant’s mouth.
Method of breathing
Participants must inhale as deeply as they can outside of the spirometer, then exhale forcefully into the spirometer. As soon as the participant has finished exhaling, they must immediately inhale as deeply as they can, still with the spirometer in their mouth.
– Participants who matches the requirements
– 25 Fitness level survey * Refer to Appendix
– Fully charged Pasco Xplorer GLX
– Pasco Xplorer Spirometer
– 25 Sterilized Disposable mouth pieces
– 1 Stopwatch
– 2 Pen
– Results table to record data
– Pair of gloves
– 2 Plastic bag
Health and Safety
– Always wear gloves when handling the spirometer, disposable mouth pieces and alcohol
– Experimenter should dress appropriate when carrying out experiment – this includes closed in shoes and hair tied back
– Always use sterilized spirometer during experimenting – when carrying out multiple trials on the same participant, the same spirometer can be reused on the same participant
– Use a new mouth piece for each participant and immediately dispose the mouth piece into a ‘USED’ plastic bag after trials are completed
Table for recording result
Age; Weight; Height
Date; Location; Time
Score on survey
Vital lung capacity
Cleaning and preparing equipments
1. Wear gloves on
2. Using sufficient amount of cotton balls, soak it in alcohol then drain it until it is moderately dry
3. Use the cotton balls to thoroughly clean the disposable mouthpieces and places on the spirometer that will be in contact with the participant’s mouth
4. Allow around 1 minute for equipments to dry
5. After equipments are dry, secure the mouthpiece on the spirometer
6. Ensure that there is no damage to the mouthpiece. If the mouthpiece is damaged, dispose it into the ‘DAMAGED’ plastic bag and use a new mouthpiece for the experiment
Participants completing survey and results * Refer to Appendix for survey
7. Ensure participant satisfies the requirements of the experiment – age, weight height and current physical conditions
8. Briefly explain to participant about the experiment and ask participant to read the ‘Briefing’ section of the survey
9. If agreed, ask participant to sign name
10. Record data including, name, age, weight and height of the participant, the date, time and location of when and where the experiment is being carried out
11. Ask participant to complete the fitness survey
12. Calculate participant’s fitness score and determine which fitness level category the participant fits in
Testing the participant
1. Sit participant down
2. Ensure participant is sitting upright, his back is straight and feet flat on ground
3. Explain to participant that they must inhale as deeply as they can outside of the spirometer, then exhale forcefully into the spirometer. As soon as the participant has finished exhaling, they must immediately inhale as deeply as they can, still with the spirometer in their mouth.
4. Ask participant to pinch their nose and hold the spirometer on the other hand. The mouthpiece of the spirometer should be positioned directly in front of the participant’s mouth.
5. Turn on the Pasco GLX and connect the spirometer.
6. Read the value of vital lung capacity on the GLX. On the homepage, select ‘DIGITS’.
7. Press the ‘PLAY’ button, wait for the green light and then begin the experiment
8. On the Pasco GLX screen, it will show two sets of values, only record the second number which is located on the bottom half of the screen
9. When the number on the screen is stable and not changing anymore (the stableness of the number will only be short due to the rapid breathing changes of the participant – inhaling after exhaling and vice versa), record the number that is shown on the screen
10. Allow the participant to rest for 2 minutes before carrying another trial. Use a stopwatch to time the rest
11. For the same participant, the mouthpiece may be reused for additional trials
12. Repeat steps 4 to 11 until three data values have been recorded
13. Dispose the mouthpiece into the ‘USED’ plastic bag after completing all three trials
Calculating the participant’s mean vital lung capacity
Using the Pasco GLX and Spirometer 
DATA COLLECTION AND PROCESSING
Recording Raw Data
Table 2.0: This table shows the number participants’ number, their score that they received on the fitness level survey out of 32 and their respective fitness level (extremely low / low / medium / high / extremely high); the participants’ age, weight (kg) and height (cm); the date in year 2009, location and time that the experiment was carried out. The table also shows three repeat sets of data of each participant – each set having two values of (a negative and positive value), the positive added to the negative value is the vital lung capacity of the participant (Refer to Background Information). All values of vital lung capacity is given in dm3.
Figures in Table 2.4 illustrates that between most of the fitness level groups, there were statistical differences between the total vital lung capacities of the male students. The only groups of independent variables that statistically were the same and therefore accepting the Null Hypothesis were the comparisons between the fitness level group ‘Extremely Low’ and ‘Low’ and the comparisons between the groups ‘Low’ and ‘Medium’. This therefore means that the following comparisons of groups rejected the Null Hypothesis and the mean total vital lung capacity of these groups is statistically different:
* Extremely Low versus Medium/High/Extremely High
* Low versus High/Extremely High
* Medium versus High/Extremely High
* High versus Extremely High
Figures presented in Table 2.3 emphasises the scope of differences in values of the five fitness level groups. The mean vital lung capacity for the group ‘Extremely Low’ is 2.78dm3 and for the ‘Low’ group it is 3.07. This means there is only a 0.29 dm3 between the two groups. As a result, when the standard deviation and t-value are calculated and processed, it shows that the mean values of these two groups are statistically the same. This is also the case for the groups ‘Low’ and ‘Medium’ fitness level as between their two mean values, there is only a 0.2dm3 difference. Again, these values emphasises why statistically, these groups are the same and not different.
The Null Hypothesis was concluded as ‘rejected’ or ‘accepted’ for the comparisons between the five independent variables of this experiment from using values of standard deviation and t-test.
When all data was processed, the degrees of freedom was calculated to be 8. The critical value for this experiment was 0.05 or 5%. The probability value of these two numbers (8 and 0.05) was 2.31.
The t-values calculated in this experiment are as follows
* Ex Low versus Low 1.91 < 2.31
* Ex Low versus Medium 2.63 > 2.31
* Ex Low versus High 7.02 > 2.31
* Ex Low versus Extremely High 25.7 > 2.31
* Low versus Medium 1.33 < 2.31
* Low versus High 6.16 > 2.31
* Low versus Ex High 22.0 > 2.31
* Medium versus High 4.93 > 2.31
* Medium versus Ex High 13.9 > 2.31
* High versus Ex High 2.58 > 2.31
In Graph 2.0 the mean vital lung capacity differences between the different fitness level groups are clearly presented. The graph illustrates the minor differences in value between the groups ‘Extremely Low’, ‘Low’ and ‘Medium’, and on the other hand the groups of ‘High’ and ‘Extremely High’ have large mean values of vital lung capacity. The biggest difference in values is between groups of ‘Medium and High’. A reason for this is that participants with extremely low, low and medium fitness level are those that do not do regular exercise but participants with high and extremely high fitness level are those who do regular exercise. Therefore the biggest deviation is between medium and high fitness level as it shifting from participants who do not exercise regularly to participants who do exercise on a regular basis. There is an immense different in values between the medium and high group. Referring back to Table 2.3, the difference between the mean vital lung capacity of the ‘Medium’ fitness level group and the ‘High’ group is 1.59dm3.
Graph 2.0 also presents error bars. The error bars shows how much the data is spread out. The bigger the value for error bars the more the data is spread out. From Graph 2.0 it is seen that the ‘High’ fitness level group has the biggest error bar, therefore having the largest spread of data.
Literature value indicates that the average vital lung capacity for adult males is 4.6dm3.  The group that is closest to this value is the ‘High’ fitness level group. A reason for this is that participants in this experiment are between the ages of 15 and 16 and are not fully grown adults yet. Therefore where the ‘Medium’ group is meant to be near the literature value, in this experiment it is not due to the age. As people grow, they are able to build onto their fitness level. One is not born with a definite fitness level but one has to build and train their body to become fit.
In Table 2.1, observations of the participants were qualitatively recorded. The observations in Table 2.1 show that participants with a larger vital lung capacity can sustain their breath for a longer period of time. This confirms the idea that participants who are unfit have short breaths and take more breaths in a certain period of time than a fit person. This is because the body of people who regularly exercise are able to proficiently exchange oxygen and carbon dioxide. In addition they can efficiently store, transport and utilise their oxygen, allowing their body to feel at ease and for example, not gasping for air at vigorous stages of exercising. 
Although the apparent observations and values were recorded during this experiment and the data illustrates that with higher fitness level, one has a larger vital lung capacity, several significant factors may have affected the data in this experiment. Factors that may have affected the recorded results are:
* Some participants estimated their weight and height and did not know the exact number. As outlined in this report, height affects lung capacity and the taller the person is the larger their lung capacity usually is. Although, some participants did estimate their height and weight, their stature was very alike the other participants – so therefore it could be recognised if their weight and height is alike the other participants, if yes, then they most probably fit with the requirements of this experiment. Consequently there should not be immense outliers of weight and height in this experiment as all participants’ statue was very similar.
* Participants who performed the experiment in the sun and humidity may have struggled to inhale and exhale maximum breaths due to the uncomfortable weather. During the summertime, when this experiment was carried out, it was very humid and hot and this could have tampered the breathing activity of participants who had to take the test outdoors. The weather may have weakened the breathing ability of the participants. However, the weather should not hugely affect results as participants were asked to fully breathe in and out, forcing their bodies to overcome the norm.
* The fitness level survey was the only evidence of participants’ fitness level and participants may have been bias when answering the questions. Some participants may have not answered truthfully therefore being categorised in a different fitness level group. Even thought this may have occurred, for most participants their total vital lung capacity was suitable for what fitness level group they were categorised in.
Even thought, there are factors which may have potentially affected the results, it is still apparent that fitness does affect one’s vital lung capacity. This is illustrated throughout the report where statistically there is a difference between most groups of fitness level. Participants who were fit and did regular exercise were able to take larger breaths and hence exhale much more carbon dioxide then those who did not do any or not much exercise. 
Aspect 2 and Aspect 3
Evaluating Procedure and Improving the Investigation
Limitations / Weaknesses
Significance of it
Although the fitness level survey was a good indicator of how fit the participants were, it did not give extensive evidence of their fitness level. Participants may have been bias on their survey and not answering truthfully.
As the fitness level survey was the only indicator and evidence of the participants’ fitness level, it did not give immense accuracy of participants’ fitness level. In addition, some participants may have been bias on their survey and not answering truthfully consequently putting them into the wrong fitness level group. This will affect the relationship between their fitness level and lung capacity results in this experiment.
In addition to taking the survey, participants must do the “Beep Test” and the score they receive on their beep test will be categorised into a fitness level group.
Extremely low: 1 – 3
Low: 4 – 6
Medium: 7 – 9
High: 10 – 11
Extremely high: 11 – 12
Although the experiment was carried out at school ground in summertime, it was carried out both outdoors and indoors. The heat from the sun and the humidity (very uncomfortable weather) may have affected the participants who were tested outdoors.
The heat and humidity outdoors during the summertime may have affected the participants’ ability to forcefully breathe in an out to their maximum. With increasing humidity, human beings tend to feel that it becomes harder to breathe, therefore participants may have not breathed in and out to their potential maximum level.
Carry out all experiments indoors and temperature must be at 25 degrees Celsius.
Some participants did not know their exact height and weight and therefore gave an estimate number.
Taller people have larger lung capacity then shorter people. Weight also affects lung capacity. This may have affected the validity of the participants’ total vital lung capacity.
Use a tape height measurer to measurer each participant’s height making sure that it is from the sole of the participant’s foot to their tallest part of their head not hair.
Use a weight body scale to measure each participant, making sure participants are wearing their uniform (shirt, short, skirt, sock, tie) not shoes. Use the same scale and tape measure throughout the whole experiment.
The aim of this practical is to investigate the human lung function and its relation with one’s fitness level.
The results gained from this practical will enable calculations of one’s fitness level and their lung capacity.
* If you currently have or had any lung conditions or illnesses that affected your breathing in the last 5 years, please do not participate in this practical
* Major variations in results may occur and this is nothing to be concerned about
* There will be no long-term effects from participating in this practical
* As information gathered from this practical will only purely be used for scientific analysis, please answer survey questions honestly and carry out tests with all effort