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How Exercising Saves You From Diseases and Cellular Malfunction.

Have you ever wondered what working out actually helps you? We've conducted this lab to showcase the influence of exercise frequency on your maintenance of cellular respiration. Our team has analyzed homeostasis (specifically in cellular respiration) comprehensively and essentially ascertained the results. We have tested 7 people with different amount of weekly exercise hours and tested their change of concentration in carbon dioxide exhalation.

More exercise hours help people balance cellular respiration during workouts

Ray Cheng

American School of Kuwait

Honors Biology SLC



We are conducting this experiment to discover how a person’s athletic ability, measured by their weekly exercise hours, affects the pH of their carbon dioxide (concentration) after 5 minutes of running. Homeostasis is one of the main focuses in this experiment; it’s the maintenance of stability of organs and systems within any organism. When we exercise, our bodies require more oxygen to produce sufficient energy which turns our bloodstream slightly acidic, subsequently the carbon dioxide we exhale also concentrates, leading to a slight acidity. We conducted this experiment by putting 50ml of tap water into each of 7 beakers and distributed them to the 7 experimenters. They exhaled into the beakers before and after 5 minutes of running and we measured the difference. We figured out that people with more weekly exercise hours tend to have a milder change in their carbon dioxide concentration, suggesting they might have better stamina. This information allowed us to showcase the importance of exercising on homeostasis. We’ll use this data to encourage more people to workout. As reflected in this lab, more exercise hours allow us to maintain a range of carbon dioxide concentration during workouts, which further bolsters homeostasis; if homeostasis does not function properly, severe consequences such as disease and cellular malfunction may be caused.

Keywords: Weekly workout hours, cellular respiration, homeostasis, pH, carbon dioxide, concentration, cellular malfunction, disease


Homeostasis is inherently crucial inside our body and all organisms. We are setting this experiment to ascertain how a person’s athletic ability, determined by their weekly exercise hours, affects their carbon dioxide concentration during exercise. With the involvement of homeostasis, more specifically the adaption of the respiratory system during the performance of cellular respiration, we’ll be revealing how a person’s athletic ability (weekly exercise hours) affects their respiratory system by analyzing their rate of change in carbon dioxide pH level change after 5 minutes of running.

Homeostasis is one of the main focuses in this experiment. According to livescience, homeostasis is defined as the stability, balance, or equilibrium within the body; how a human body or any organism passively adapts to different conditions that influences their body. 

For instance, our body temperature is a great example of homeostasis. When you’re playing in the snow during winter or lying down under the summer sun, our body’s temperature only changes by a degree or two; you shiver when you’re cold, and you sweat under the sun, that’s an example of how homeostasis is maintained. In this case, our body tends to require more oxygen for cellular respiration to provide energy during exercise.

Without homeostasis, our bodies wouldn’t function properly. According to ck12.org, many homeostasis mechanisms keep the internal environment within certain limits (e.g. body temperature between 36.5 degrees to 37.5 degrees), when your cells don’t function properly, the homeostasis balance is disrupted, leading to disease and cellular malfunction. 

Cellular Respiration is a set of metabolic chemical reaction that occurs in your body to create energy, specifically forming nutrients into ATPs; when you are exercising your body’s energy demand increases; cellular respiration requires oxygen (O2) and created carbon dioxide (CO2).

Cellular Respiration: C6H12O6 +6O2 →6H2O+6CO2 +36ATP

According to BBC Bitesize, the pH of our blood is usually 7.35 - 7.45. During exercise, the concentration of carbon dioxide in the blood and respiring tissue increases, which would lower the pH (making the blood more acidic). Carbon dioxide itself is not an acid, however carbon dioxide reacts with water and forms carbonic acid; this will make our water in the experiment more acidic and act as an indicator to the concentration of carbon dioxide. This phenomenon occurs as your muscles work harder when you’re under intense workout, therefore your body more oxygen and produces more carbon dioxide. The more oxygen you inhale, the more CO2 you will exhale which increases the concentration of your carbon dioxide. 

To alleviate this phenomenon, we can increase the rate and depth of breathing speed which speeds up the rate carbon dioxide is removed from the bloodstream. The rate and depth of breathing is often balances better for someone who frequently exercises, this is also a reason why athletes have better stamina than others. 

When we exercise regularly, your strength of muscles will increase and your muscles will be more efficient; they will require less oxygen to move and they will produce less carbon dioxide.

As such, if we test the change in carbon dioxide concentration throughout exercise on 7 people with different exercise frequencies, then the person who exercises the most will have the least change in his/her carbon dioxide levels as people with better athletic ability tend to possess a milder change in carbon dioxide concentration due to their balance of breathing rate in cellular respiration.

The rate of change in pH is highly related to one’s stamina, when your blood pH decrease reaches a certain point, feedback occurs, sends a fatigue signal to your brain which you will feel tired.

Homeostasis in cellular respiration is truly appealing; as people always say: “Exercise is important to sustain healthy.” But never indicates how it can specifically bolster your organs and systems. This experiment will allow us to know if a person who frequently exercises would show a clearer maintenance on homeostasis in their cellular respiration process compared to someone who barely works out; which further shows how exercise is important for your health. 

Materials and Method

First of all, we put 50ml of tap water into each of 7 beakers and distributed them to the 7 experimenters. Then, we measured the initial pH of tap water with pH meter. Afterwards, the 7 experimenters blew into each of their beakers for 30 seconds. We recorded each of their liquid’s pH, and they started running for 5 minutes. While they were running, we poured all the beakers and replenished it with 50ml of tap water, to assure the pH is the same as the initial pH before blown. After the 7 experimenters ran for 5 minutes, they blew into their beakers for 30 seconds again, and we recorded the final pH with the pH meter. Finally, we compared their pH difference between the first blow and the second blow.


Table 1. pH change of exhaled carbon dioxide before and after exercise.

Figure 1: Percent change in pH contrasted with weekly workout hours.

We have arranged the table’s data from the people with the most weekly exercise hours to the least. Anas, who exercises for 20 hours per week, had an overall decrease in his carbon dioxide pH of 0.54%. Following him was George C, who works out for 16 hours per week, had a pH decrease of 0.93%. After George is Dany, who works out for 15 hours weekly and had a pH decrease of 1.60%. Then it’s Hashem who works out for 14 hours weekly and pH decreased for -1.60% as well. Afterwards, it’s Dalal and Sarah who workout for 12 and 11 hours weekly with a pH decrease of 3.33% and 3.60%. Lastly, George A, who works out for 5 hours per week had a pH decrease of 4.35%. The data was further shown by the line graph to indicate the connection between exercise amount and carbon dioxide concentration change.


After conducting all the data, there’s a trend which suggests that people with more weekly exercise hours (suggests that they have better athletic abilities) have a milder change in the pH of their carbon dioxide concentration after 5 minutes of running. As shown in the table and the graph, George A, who had the least weekly workout hours in the experiment, had the most significant change in his carbon dioxide concentration, the pH his CO2 dropped from 7.58 to 7.25, with a 4.35% decrease. In contrast, Anas, with the most weekly workout hours, had the mildest change in his carbon dioxide concentration. 

These results are extremely important as it suggests that exercising more regularly and quantitatively will bolster our body’s maintenance in homeostasis, as the more we exercise the more efficient our muscles will become which will require less oxygen and prevent an overwhelm of carbon dioxide concentration. Homeostasis in cellular respiration provide our bodies the proper function for cells, and essentially keeping us healthy. With these results, we can encourage more people to exercise and keep themselves healthy.

Our hypothesis foresaw that the more weekly exercise hours we have, the milder our carbon dioxide concentration will change. As seen in the data, there is a clear trend that runners with more exercise hours had a milder change which firmly conforms our hypothesis. 

Next time, we might make test this experiment on more people and identify the pattern more precisely. Beyond that, we’ve spotted that the two girls in this experiment seem to have a significant change even though their weekly exercise time wasn’t too much behind; as shown in Dalal’s results, she had only two weekly exercise hours less than Hashem but her CO2 concentration change was 1.73% higher than Hashem. This phenomenon makes us wonder if girls tend to have a more significant increase in their carbon dioxide concentration during workouts than boys even though their athletic ability isn’t too much behind. Do girls have an innate disadvantage than boys in carbon dioxide concentration balancing? Or even in homeostasis? How does this relate to female athletes, do they have to work harder than male athletes to reach a specific athletic ability? As such, we might carry out an experiment specifically for testing the difference between male and female on CO2 concentration balancing, or specifically the homeostasis of cellular respiration. 

As gender may be a factor to this, we might also test the difference of balancing carbon dioxide concentration between teenagers and adults. We might take several adults and teenagers with the same weekly exercise hours and evaluate their change in CO2 concentration.

As this experiment is relatively vague, more questions emerge. Such as, how might different sports affect people’s maintenance in carbon dioxide concentration? Would a soccer player have a more significant increase than a basketball player because of indoor and outdoor? Would a soccer player have a more significant change in their pH than a swimmer as soccer players often require more stamina while swimmers need the acceleration?


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Wilkin, Douglas, and Niamh Gray-Wilson. “Homeostasis Imbalance.” CK, CK-12 Foundation, 17 June 2017, www.ck12.org/biology/homeostasis-imbalance/lesson/Disruption-of-Homeostasis-Advanced-BIO-ADV/

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