exercise phys write up

8/2/2019 Exercise Phys Write Up

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Brooke Gushen Effects on Human Physiology During High-Stress Exercise

Nathan Garvin, Biology 473, Section 3 April 20, 2012

Introduction

When someone begins to exercise, it affects the body in many different ways as it compensates

for increases in ATP demand and oxygen consumption. Exercise increases the work on muscles, therefore

the muscle cells need to produce more ATP. Since oxygen is an electron acceptor necessary in the

production of ATP, the muscles demand more oxygen, leading to an increase in inspiration of the lungs.

The brain responds by increasing heart rate and therefore blood flow to the muscles. The changes in blood

flow lead to increases in blood pressure. The body, however, is able to compensate for these changes and

returns relatively close to the homeostatic blood pressure. As more O2 is channeled to the muscles for the

production of ATP, more CO2 is pumped out of the muscles, increases the concentration in the blood

plasma. The brain communicates with the respiratory system to increase the expiration of CO2. With these

changes in inspiration and expiration, the respiratory rate increases to compensate for these demands of

exercise. As the internal body temperature increases during all this work, the vasodilation of the

circulatory system allows for the heat to be released through sweat, leading to an increased skin

temperature.[1]

It is important to know the physiology behind varying levels of exercise activity to know how the

body responds to these changes. With exercise affecting so many systems, biologists should know exactly

what is going on with each of these systems. Since there are many people with different heart conditions

or even high blood pressure, this stress on the heart and circulatory system may be unsafe for these

people. A better understanding of maximal heart rate could help make exercise safe for these people.

There are also people suffering from respiratory conditions such as asthma, emphysema, and more are

may similarly over exert their lungs during exercise. By understanding the basic physiology of each of

these systems during exercise in healthy patients, doctors and researchers can begin to determine safe

exercise habits for sick patients. Exercise is an important life practice for maintaining a healthy heart,


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weight, and muscle tone, which is why it is so important.

In this experiment, there are four healthy subjects who will be completing a high-stress running

exercise, during which heart rate, carbon dioxide clearance, oxygen consumption, temperature,

hemoglobin saturation, and mean arterial pressure will all be monitored. We expect that when comparing

the resting values to the exercise values, the following will likely occur during the exercise portion. The

heart rate will progressively increase due to the demand for oxygenated blood in the muscles. The oxygen

consumption will increase due to the higher demand for oxygenated blood. The carbon dioxide clearance

will increase due to the increased concentration in the blood plasma from ATP production. The skin

temperature will rise from the heat produced from the work being done on the muscles and coming out in

sweat on the surface of the skin. The hemoglobin saturation will decrease due to the increases transport

and use of oxygen during the activity. The mean arterial pressure should increase initially but eventually

return to a safe homeostatic pressure.

During the recovery period, there are three minutes spent cooling down by walking on the

treadmill and three minutes spent sitting. During the recovery period we expect to see the heart rate

decrease down close to the resting heart rate, and we expect this decrease to occur faster than the increase

during exercise. We expect the oxygen consumption to decrease since there is less demand for ATP from

the muscles. With the reduced ATP production, we expect the carbon dioxide clearance to decrease. The

skin temperature will probably take a while to decrease back to resting, so we may see a slight decrease,

but we do not expect an increase. The hemoglobin saturation is expected to return to almost full

concentration, and the mean arterial pressure should return to very close to the resting mean arterial

pressure.

Method:

Before the exercise experiment began, recorded values of each subjects age, weight, resting heart

rate, smoking habits, and gender were used to calculate each runners Maximal Heart Rate (MHR), which

is the highest heart rate an individual can safely achieve through exercise stress. [2] The Exercise Heart

Rate was calculated at 80% of the MHR, therefore the subject was encouraged to stop the experiment

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once reaching this number to prevent any potential harm to the subject. Also prior to beginning, runners

sat and rested for around fifteen minutes and vitals were taken twice over three minutes, and these values

would act as the control data for the experiment. These vitals included skin temperature, hemoglobin

saturation, blood pressure, exhaled tidal CO2 concentration, exhaled tidal O2 concentration, and

respiratory rate. This resting phase acted as a control for each subject because each individual has slightly

different physiology, and these values acted as each subjects own baseline for the experiment.

The following instruments were used to record various physiological values of the subjects:

Heart rate monitor - recorded the heart rate (beats/minute)

Spirometer measured tidal volume (L/breath)

Capnometer (CO2 & O2 analyzers) measured exhaled tidal CO2 concentration (mmHg), exhaled

tidal O2 concentration (%), and respiratory rate (breaths/min)

Thermometer headband measures skin temperature (C) Pulse Oximeter measures blood hemoglobin saturation (%)

Sphygmomanometer measures systolic and diastolic blood pressure (mmHg)

When the exercise portion of the experiment began, heart rate was continuously monitored. Every

three minutes, the exhaled tidal CO2 concentration, exhaled tidal O2 concentration, and respiratory rate

were recorded over forty seconds, and the tidal volume was recorded over three breaths. Skin

temperature, hemoglobin saturation, and blood pressure were not recorded during exercise do to the

movement. As the time intervals progressed, the speed and incline of the treadmill increased. After the

subject reached his/her own Exercise Heart Rate, the exercise stopped after that time interval or the next

depending on the state of the subject (around 12-15 minutes). Immediately after the exercise stopped, the

subject walked for three minutes and sat for three more, and the skin temperature, hemoglobin saturation,

and blood pressure were recorded in addition to the three-minute recordings as the recovery data points.

After the exercise, carbon dioxide clearance, oxygen consumption, and mean arterial pressure

were calculated from the values recorded during exercise. The following equations were used:

CO2 Clearance (L CO2/min) = % CO2 of Exhaled Air x Tidal Volume (L/breath) x Respiratory

Rate (breaths/min)

% CO2 of Exhaled Air was calculated from exhaled tidal CO2 concentration (mmHg).

O2 Consumption (L CO2/min) = % CO2 of Exhaled Air x Tidal Volume (L/breath) x Respiratory

Rate (breaths/min)

Mean Arterial Pressure (mmHg) = 2/3 Diastolic Pressure (mmHg) x 1/3 Systolic Pressure

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The protocol presented in the lab manual was followed exactly. [1]

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Results:

Figure 1: Changes in Heart Rate Over Time During Exercise

Results are based on measurements taken using a heart rate monitor over an exercise period of 12 minutes (Subjects 2

and 3) or 15 minutes (Subjects 1 and 4) and a recovery time of 6 minutes. The heart rate taken at time = 0 min is theresting heart rate of each subject. All subjects showed an overall increase in heart rate over time and a decrease during

the recovery time.

Figure 2: Changes in Carbon Dioxide Clearance Over Time During Exercise

Results are based on measurements taken using a spirometer (measuring tidal volume) and capnometer (measuringexhaled tidal CO2 concentration and respiratory rate) over an exercise period of 12 minutes (Subjects 2 and 3) or 15minutes (Subjects 1 and 4) and a recovery time of 6 minutes. The CO2 clearance was calculated from the values fromthe instruments using the CO2 clearance equation. The CO2 clearance calculated at time = 0 min is based on the resting


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values of each subject. All subjects showed an overall increase in CO2 clearance over time and a decrease during therecovery time.

Figure 3: Changes in Oxygen Consumption Over Time During Exercise

Results are based on measurements taken using an oxygen analyzer (measuring exhaled tidal O2 concentration),spirometer (measuring tidal volume), and capnometer (measuring respiratory rate) over an exercise period of 12

minutes (Subjects 2 and 3) or 15 minutes (Subjects 1 and 4) and a recovery time of 6 minutes. The O2 clearance wascalculated from the values from the instruments using the O2 consumption equation. The O2 consumption calculated attime = 0 min is based on the resting values of each subject. All subjects showed an overall increase in O2 consumptionover time and a decrease during the recovery time.

Figure 4: Skin Temperature Immediately After Exercise

Results are based on measurements recorded using a thermometer headband immediately after an exercise period of 12

minutes (Subjects 2 and 3) or 15 minutes (Subjects 1 and 4). Resting and recovery temperatures were as followed:

Subject 1 (35C, 36C), Subject 2 (33C, 35C), Subject 3 (33C, 35C), Subject 4 (31C, 34C), respectively. An

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increase in skin temperature was seen in all subjects.

Figure 5: Hemoglobin Saturation Immediately After Exercise

Results are based on measurements recorded using a pulse oximeter immediately after an exercise period of 12 minutes(Subjects 2 and 3) or 15 minutes (Subjects 1 and 4). Resting and recovery hemoglobin saturations were as followed:Subject 1 (97%, 95%), Subject 2 (98%, 95%), Subject 3 (97%, 96%), Subject 4 (99%, 96%), respectively. A decreasein hemoglobin saturation was seen in all subjects.

Figure 6: Mean Arterial Pressure Immediately After Exercise

Results are based on measurements recorded using a sphygmomanometer (measuring systolic and diastolic blood

pressure) immediately after an exercise period of 12 minutes (Subjects 2 and 3) or 15 minutes (Subjects 1 and 4). Themean arterial pressure (MAP) equation was used to calculate the value from the given blood pressures. Resting andrecovery MAPs were as followed: Subject 1 (97 mmHg, 90 mmHg), Subject 2 (102 mmHg, 95 mmHg), Subject 3(80mmHg, 77 mmHg), Subject 4 (95mmHg, 93mmHg), respectively. Very slight increases in mean arterial pressure

was seen in all subjects, with the exception of Subject 1, who showed a larger increase in MAP.

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In Figure 1, the changes of heart rate over time can be seen. All four subjects show an increase in

heart rate during their exercise period. Subjects 1 and 4 exercised for 15 minutes, while Subjects 2 and 3

exercised for 12 minutes, therefore they show their recovery period data starting at the 15-minute interval.

The heart rate typically increased quickly at first and slowed for the remainder of the exercise period. All

subjects showed a decrease in heart rate during the recovery period, however, Subject 1 showed an

increase in heart rate after his final three minutes of recovery.

In Figure 2, the changes in CO2 clearance over time show a very linearly increase in clearance

during the exercise period and a very rapid drop in clearance during the recovery period. In Figure 3, a

similar relationship was seen as in Figure 2 with a linear increase in oxygen consumption ad a quick drop

during the recovery period of each runner.

Figure 4 shows the skin temperature taken right after exercise. Subjects 1 and 2 showed an

increase in skin temperature from resting the exercise and a decrease in skin temperature during recovery.

Subjects 3 and 4 also showed an increase in skin temperature from resting to exercise, however, Subject 3

shows a continued increase in skin temperature, while Subject 4 showed no change in skin temperature.

In Figure 5, the hemoglobin saturation during exercise was measured. All subjects showed a high

saturation initially during resting, but dropped during exercise. All then increased back to a higher level

after recovery. Subject 4 showed a larger decrease and increase during the experiment than the other

subjects. In Figure 6, mean arterial pressure (MAP) after exercise is shown. Subject 1 showed a large

increase and even greater decrease in MAP during the experiment. Subjects 2, 3, and 4 showed very slight

increases and slight decreases in MAP.

Discussion:

The results in Figure 1 show an increase in heart rate during exercise and a decrease in heart rate

during recovery. The increase however was more drastic in the first three minutes compared to the rest of

the exercise period. This may be due to the quick redirection of blood flow to the muscles in the

periphery. Once the volume is in a consistent location of the body, the heart rate can begin to level off.


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The reduction in heart rate was fell faster than it rose during exercise but did not return to the resting heart

rate. This shows that it takes the body more time to recover from that intensity of exercise.

Figures 2 and 3 shows linear increases in CO2 clearance and O2 consumption as expected during

the exercise. This similarity can be attributed to their relationship due to the production of ATP. As

oxygen is being used up to produce ATP, carbon dioxide is being given off by the same mechanism as a

byproduct.

The results found in Figure 4 show an increase in skin temperature during exercise as expected.

The decrease in temperature during recovery seen with Subjects 1 and 2 was expected. Subject 3,

however, continued to increase after recovery, and Subject 4 did not change at all. This may be due to the

subjects different exercise habits. It is possible that subjects that exercise less often may take longer to

recover.

All subjects showed a decrease in hemoglobin saturation during exercise and an increase during

recovery in Figure 5. The greater range of Subject 4s hemoglobin saturation may be related to the

exercise period length. Since this subject exercised for 15 minutes, it is possible that the blood reduces

more and more during extended exercise activity.

Lastly, in Figure 6 the results from Subjects 2, 3, and 4 were as expected, showing very slight

increases and decreases in MAP. However, Subject 1 showed a larger increase after exercise, and after

recovery his MAP dropped even lower than his resting value. Since exercise requires changes in body

position, this may have affected his blood pressure more as he sat during recovery. It is unclear why this

result was only found in the first subject.

One source of error that may have occurred was improved recording methods of vitals. This

means that as the researchers using the equipment practice more during the four trials, they may improve

their methods. This may be why we saw the unusual MAP reading for Subject 1 in Figure 6, since he was

the first subject to participate in the exercise portion. To minimize error, I would have practiced this

experiment a few times to let the researchers get more comfortable with the equipment and procedures.

Also, there were some devices and equipment that malfunctioned or were not very accurate. I would try to

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find a more accurate device for taking temperature, and it would be helpful to perhaps have numerous

devices recording heart rate to compare and backup the results in case the device stops working or is

inconsistent.

I felt that this lab went very well. It was a great culmination of several systems in the human body

that we had studied throughout the semester. It was also interesting seeing how the equipment could all be

used together in a real human experiment setting. I felt I learned a lot from this laboratory experiment.

From the results found in this procedure, we may be able to find a point in time in the exercise period that

the intensity is safe. By doing this experiment we were able to monitor at what point the heart took large

jumps in heart rate that could be harmful to those with heart conditions or the tidal volume increased to a

point that may not be safe for asthmatic patients. If these transition periods can be looked at in more

detail, it may be possible to calculate a safety threshold for these people.

References:

[1] Biol. 473 Exercise Physiology.Department of Biology, The Pennsylvania State University 2012.

[2] Maximum heart rate. .

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