ib biology internal assessment 1.docx

Ahmet Ulusoy College

Biology Higher Level Internal Assessment

The Effect of Body Mass Index on Heart Rate

During Cardiovascular Exercise

Candidate Name: Şevval Beşli

Candidate Number: 006615-006

Şevval Beşli006615-006

Research Question

Do body mass indexes (BMI) of humans affect their heart rate during cardiovascular

exercises?

Objective

Determining whether body mass index of same aged males and females affect the change in

their heart rate during cardiovascular exercises such as stair climbing.

Background Information

Body mass index (BMI), is an index used to measure the body type of individuals. It is

basically used to classify underweight, overweight and obesity in people. (World Health

Organization, 2013). This index is commonly used and is recognized as a legit method of

determining the body shape of humans by the World Health Organization (WHO). Body mass

index is measured via using this formula:

BMI= mass (kg)

(heig h t (m ) )2

Cardiovascular exercises are used to promote improved capacity of the cardiovascular system.

The contraction of major muscle groups must be repeated often enough to elevate the heart

rate to a target level determined during testing (The Free Dictionary by Farlex, 2003). Hearts

of the people that have high BMI, ≥25.00, will have to work harder that those with normal

BMI, between 18.50 and 24.99, to supply energy to the body; hence their heart rate will be

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higher during and after exercise (David E. Mohrman, 2010). Overweight or obese people also

will have a lower recovery heart rate (National Emergency Medicine Association, 2003).

In this experiment, climbing stairs is used as a cardiovascular exercise as this activity allows

each participant to show the same effort, enabling the experimenter to adjust the variables as

intended and thus providing more accurate results.

Graph 1: Body mass index according to body weight and height can also be calculated using

a BMI chart (World Health Organization, 2013).

Hypothesis

Heart rate of participants with higher BMI will show greater difference before and after

cardiovascular exercise than those with normal ranged BMI.

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Design

Variables

Independent Variable

Body mass index of participants; same number of male and female underweight,

normal weight and obese people will be volunteering.

Dependent Variable

Heart rate of participants before and after exercise will vary according to their BMI

values.

Controlled Variables

Body mass index (BMI) of the participants.

Same staircase is used for each trial.

Same stethoscope, timer, scale and measuring tape is used for each trial.

All participants are at the age of seventeen.

Three volunteers with BMI values under, in and over the normal range from both

sexes is going to participate.

Materials

Timer (±1 s) (1)

Measuring tape (±0.5 mm) (1)

Scale (±0.1 g)

Stethoscope (1)

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Ten step staircase (1)

o Three male and three female volunteers with different weights.

Setting up Experiment

1. Make sure that the staircase is clean and dry before the experiment.

2. Clear any obstacles and distracting objects from the staircase.

3. Bring the participants to the location of the staircase.

4. Measure the height and weight of the participants and record the measurements.

5. Remind the participants that they will be required to go up and down the stairs as

quickly as they can for one minute.

Caution: Make sure that the participants are wearing comfortable clothing and have not had a

large meal at least three hours before the experiment to not force their hearts. Participants

should guarantee that they do not have any medical conditions that will restrain them from

cardiovascular exercises. If a participant feels pain, especially in the chest area, stop the

experiment immediately and get medical assistance if necessary.

Procedure

1. Place the stethoscope on the left side of Participant A’s chest and count the heart beats

for twenty seconds. Multiply the result by three to get the number of beats per minute

and record the number in the data table.

2. Tell Participant A to begin climbing the stairs and start the timer. Tally and record the

number of times the participant goes completely up and down the stairs.

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3. After a minute, stop the timer and count the heart beats of Participant A for twenty

seconds using the stethoscope. Multiply the result by three and record the result in the

data table.

4. Count the heart beats of the participant one minute later and record the number. Let

Participant A rest until the second trial begins.

5. Repeat steps 1, 2 and 4 for participants B, C, D, E and F respectively.

6. Repeat steps 1 to 4 five times and record the results.

Pictures

1 and 2: Pictures were taken in the experiment location. Picture 1 shows the Participant A

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Calculations

Classification BMI(kg/m2)

Principal cut-off points Additional cut-off points

Underweight <18.50 <18.50

Severe thinness <16.00 <16.00

Moderate thinness 16.00 - 16.99 16.00 - 16.99

Mild thinness 17.00 - 18.49 17.00 - 18.49

Normal range 18.50 - 24.9918.50 - 22.99

23.00 - 24.99

Overweight ≥25.00 ≥25.00

Pre-obese 25.00 - 29.9925.00 - 27.49

27.50 - 29.99

Obese ≥30.00 ≥30.00

Obese class I 30.00 - 34.9930.00 - 32.49

32.50 - 34.99

Obese class II 35.00 - 39.9935.00 - 37.49

37.50 - 39.99

Obese class III ≥40.00 ≥40.00

Table 1: The International Classification of adult underweight, overweight and obesity

according to BMI (World Health Organization, 2013).

BMI of each participant should be calculated via using mass (kg)

(heig h t (m ) )2 formula:

Participant A:

mass= 42.3 kg

height= 158 cm

BMI= 42.3

(1.58)2 = 16.94

Participant A’s BMI shows that she is

moderately thin according to the data in

Table 1.

Participant B:

mass= 55.6 kg

height= 165 cm

BMI= 55.6

(1.65)2 = 20.42

BMI of Participant B shows that she is in

the normal range.

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Participant C:

mass= 98.0 kg

height= 169 cm

BMI= 98.0

(1.69)2 = 34.31

BMI of Participant C shows that she is in

obese class I.

Participant D:

mass= 54.5 kg

height= 176 cm

BMI= 54.5

(1.76)2 = 17.59

BMI of Participant D shows that he is

mildly thin.

Participant E:

mass= 66.2 kg

height= 180 cm

BMI= 66.2

(1.80)2 = 20.43

BMI of Participant A shows that he is in

the normal range.

Participant F:

mass= 101.5 kg

height= 182 cm

BMI= 101.5

(1.82)2 = 30.64

BMI of Participant A shows that he is in

obese class I.

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Data Collection

Results for female participants:

Trial Heart Rate Before

Trial (± 4 bpm¿

Heart Rate After

Trial (± 4 bpm¿

Flights of Steps

(± 0.2 flig hts ¿

Difference

(After-Before)

1 78 126 9.0 48

2 81 123 9.5 42

3 81 126 8.4 45

4 90 129 8.0 39

5 84 126 7.8 42

Average 82.8 126 8.54 43.2

Table 2: Experiment results for underweight Participant A (BMI 16.94).


Trial (± 4 bpm¿

Heart Rate After

Trial (± 4 bpm¿

Flights of Steps

(± 0.2 flig hts)

Difference

(After-Before)

1 81 135 9.8 54

2 78 129 9.6 51

3 84 132 10.0 48

4 87 144 8.7 57

5 75 129 9.0 54

Average 81 133.8 9.42 52.8

Table 3: Experiment results for normal weight Participant B (BMI 20.42).


Trial (± 4 bpm¿

Heart Rate After

Trial (± 4 bpm¿

Flights of Steps

(± 0.2 flig hts)

Difference

(After-Before)

1 81 138 8.8 57

2 84 144 8.1 60

3 81 144 7.5 63

4 93 147 7.4 54

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5 78 129 8.0 51

Average 83.4 140.4 7.96 57

Table 4: Experiment results for obese Participant C (BMI 34.31).

Results for male participants:


Trial (± 4 bpm¿

Heart Rate After

Trial (± 4 bpm¿

Flights of Steps

(± 0.2 flig hts)

Difference

(After-Before)

1 90 141 11.0 51

2 87 135 9.4 48

3 81 132 9.3 51

4 90 144 8.8 54

5 81 129 8.5 48

Average 85.8 136.2 9.4 50.4

Table 5: Experiment results for underweight Participant D (BMI 17.59).


Trial (± 4 bpm¿

Heart Rate After

Trial (± 4 bpm¿

Flights of Steps

(± 0.2 flig hts)

Difference

(After-Before)

1 84 141 10.0 57

2 87 135 10.3 48

3 78 138 9.7 60

4 84 138 8.5 54

5 93 144 9.0 51

Average 85.2 139.2 9.5 54

Table 6: Experiment results for normal weight Participant E (BMI 20.43).


Trial (± 4 bpm¿

Heart Rate After

Trial (± 4 bpm¿

Flights of Steps

(± 0.2 flig hts)

Difference

(After-Before)

1 78 132 9.0 54

2 93 144 8.6 51

3 87 144 7.8 57

4 90 150 8.0 60

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5 96 162 7.5 66

Average 88.8 146.4 8.18 57.6

Table 7: Experiment results for obese Participant F (BMI 30.64).

Processed Data

Data obtained from experiments can be used to compare the effect of independent variable,

BMI, on the dependent variable, heart rate. Firstly, the heart rate measurements of

underweight participants (A and D) are compared in order to derive a conclusion.

1 2 3 4 50

20

40

60

80

100

120

140

160

Heart Rate Comparison Between Underweight Participants A and D

Before Trial (A)

Before Trial (D)

After Trial (A)

After Trial (D)

Trials

Hea

rt R

ate

(±4

bpm

)

Graph 2: Comparison of heart rate change values between underweight Participants A and

D.

Underweight female (A) and male (D) participants showed similar changes in the heart rate

throughout the experiment. Even though the visual data shows the relationship between the

heart rate change of Participants A and B as reasonably analogue; the variation between the

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average differences of heart rate change before and after experiment shows that the

underweight male participant experienced more alteration in the heart rate. The average

difference before and after exercise for the number of heart beats of Participant A is 43.2, the

lowest result among all participants while the difference for Participant D is 50.4. Percentage

change shown in the graph is fairly low for all data points, except for the line showing

Participant D's heart rate after trial. This may be caused by additional factors such as emotions

and effort of the participant and will be further evaluated at the end of this report.

The BMI values of Participants A and D are very close, being 19.94 and 17.59 respectively.

Thus the variation between the average differences of heart rates should be caused by a

different reason such as the difference between the metabolic and consequently heart rates of

males and females. Males are considered to have a higher metabolic and heart rate than

females, however this still does not clearly explain the fairly large difference between the

heart rate values of underweight participants. Further investigation for this problem is given in

the evaluation part of this report. A conclusion can be achieved after investigating the

differences between normal weight and obese participants.

1 2 3 4 50

20

40

60

80

100

120

140

160

Heart Rate Comparison Between Normal Weight Participants B and E

Before Trial (B)Before Trial (E)After Trial (B)After Trial (E)

Trials

Hea

rt R

ate

(±4

bpm

)

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Graph 3: Comparison of heart rate change values between normal weight Participants B

and E.

Heart rate measurements of normal weight participants (B and E) showed an even more

similar pattern than those of participants A and D. BMI values of Participants B and E are

nearly the same, being 20.42 and 20.43 respectively. As expected, results for the average

differences in the heart rate of normal weight participants are very close, being 52.8 for

Participant B and 54 for Participant E, indicating a direct relationship between the body mass

index and the increase in the heart rate during cardiovascular exercises. The percentage

change between the measured heart rates in each trial is fairly low, as seen in the graph. Thus,

it can be concluded that the results obtained for Participants B and E are more accurate than

those for Participants A and D.

1 2 3 4 50

20

40

60

80

100

120

140

160

180

Heart Rate Comparison Between Obese Participants C and F

Before Trial (C) Before Trial (F)After Trial (C)After Trial (F)

Trials

Hear

t Rat

e (±

4 bp

m)

Graph 4: Comparison of heart rate change values between obese Participants C and F.

BMI values of Participants C and F showed the biggest difference among all participants,

being 34.31 and 30.64 respectively. However, they are both still considered to be in obese

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class I according to the values determined by WHO in Table 1 and the records for their heart

rate showed resemblance as expected. Again, the percentage change between the heart rate

measurements in each trial is fairly low with and exception of the data recorded for the heart

rate of Participant F after exercise. Comparing the differences between the heart rates

measured before and after exercise shows that the variation between the average difference is

the smallest for Participants C and F. Hence, the values suggest that there is a direct

relationship between BMI and heart rate increase during aerobic exercise. Taking this

argument into account, collected data can be used to show the relationship between BMI and

heart rate change:

16.94 17.59 20.42 20.43 30.64 34.310

10

20

30

40

50

60

70

The Relation Between BMI and Heart Rate Difference

BMI and Av. Heart Rate Dif-ference of Participants A, D, B, E, F and C Respectively

BMI Values of Participants

Av.

Hea

rt R

ate

Dif

fere

nce

(±4

bpm

)

Graph 5: The relation between BMI and heart rate difference of each participant.

As seen in Graph 5, the average heart rate difference before and after cardiovascular exercises

generally rise as body mass index value increases. This could be called a gradual increase but

the difference recorded for Participant C with BMI of 34.31 the slightly lower than the heart

rate difference recorded for Participant F. This situation is most likely caused by the

difference in the metabolic activity rate of the male and female participant and is not enough

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to overrule the hypothesis given in this assessment. Visual and calculated data clearly

suggests that people with higher BMI values experience a bigger heart rate change during

cardiovascular exercises.

Average flights of steps climbed can be used to show the fitness level of each participant and

the effect of BMI on the general endurance of participants during cardiovascular exercises.

16.94 17.59 20.42 20.43 30.64 34.317

7.5

8

8.5

9

9.5

10

Relation Between BMI Values and Flights of Steps Climbed

Flights of Steps Climbed by Participants A, D, B, E, F and C Respectively

BMI Values of Participants

Fli

ghts

of S

teps

Cli

mbe

d (±

0.2

flig

hts)

Graph 6: The relation between BMI values and flight of steps climbed by each participant.

Graph 6 shows that the participants with BMI values in normal range were able to climb most

number of steps in one minute. Underweight Participant D has nearly reached the average

steps climbed by participants with normal weight. Obese participants, on the other hand, have

managed to climb least number of steps among other participants. This observation suggests

that people with BMI in the normal range have higher endurance in cardiovascular exercises

that the ones under or over the normal range. Higher BMI values than normal range mean that

the heart needs to work harder to pump blood to whole body; and lower values indicate the

existence of malnutrition which leads to irregular heart rhythms and mounting more force to

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the heart (Javis, 2013). Thus, it can be said that keeping BMI in normal range is essential to

live healthy.

Conclusion

After the investigation and evaluation of the data obtained from experimental observations, an

answer to the research question can be given. Body mass index directly affects the heart rate

change during cardiovascular exercises. As body mass index value increases, the heart rate

difference before and after exercise proportionately increases. Body mass index is also related

to the endurance of people during exercises. Underweight and obese people are shows less

durability than normal-weight people during cardiovascular activity. Obese participants'

resting (measured before trial) heart rates were observed to be higher that the heart rates of

normal weight participants, indicating that the obese people's hearts need to work harder than

normal to keep pumping blood to whole body. Even though the rate of heart and metabolic

activity differ between males and females in the same BMI range, they show similar heart rate

increases during aerobic exercise. As regular aerobic exercises increase endurance, improve

circulation and help body to use oxygen better, strengthen heart and cardiovascular system

and help reduce body fat (WebMD Medical Reference, 2013), they should be implemented

into daily routine to stay healthy and fit.

Evaluation

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Even though the data obtained from the experiment were generally accurate and parallel to the

hypothesis, there were some deviations from the expected results. The average difference

between the heart rate before and after the experiment for Participant A was lower than the

expected results. It is improbable to determine the actual reason behind this deviation, but

considering that the age of all participants were the same, 17, and Participant D’s BMI value

was close to A’s; it could be assumed that this variation is caused by genetic determinants of

heart rate. Neither the participant nor a close family member of her has suffered from a heart

disease, yet an extensive medical exam would be needed to prove that. Thus, to be able to

research the effect of BMI on heart rate change, the clinical and genetic background of the

participants should be investigated more in depth.

A similar problem occurred with the number of flights of stairs climbed by Participant D. He

had managed to climb nearly as many steps as normal weight participants, which was

unexpected. However, this is most probably a consequence of general fitness level of

Participant D; even though he is underweight, he has been playing basketball regularly for

two years which certainly caused him to improve his endurance. As this is an experiment

where humans' heart rates are dependent variables, most of the deviations from the expected

results will be caused by physiology and even psychology of participants attended and also,

the amount of effort that they put into the physical activity. If they get unmotivated and do not

climb the stairs as fast as they can, the flights of steps they climb will change, thus affecting

the heart rate change before and after the experiment.

Improvements

This experiment can be improved by further investigating the genetic and medical history of

the participants. All coronary diseases in the family history of the participants should be taken

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into consideration. Otherwise, large variations from the expected results can be encountered

like the change in the heart rate of the Participant C.

Participants needs to be calm and well-rested before the experiment. In this experiment,

participants were only told to not eat large meals three hours prior to the beginning of the

experiment and to wear comfortable clothes. But their emotional states, excitement and

exhaustion are also factors that may affect their heart rate and should have been taken into

consideration. The experiment could be repeated in a quiet environment in order to enable

participants to rest and the experimenter to get more accurate heart rate measurements.

Limitations of the number of participants volunteered in the experiment are another factor that

needs to be evaluated. There were only six participants in the experiment, all Caucasian, three

males and three females. Even though accurate experimental results could have been

achieved, the universality of the deductions needs to be discussed. This experiment could be

repeated with a large number of participants from different ages and races, so that a more

general and accurate conclusion can be achieved.

References

David E. Mohrman, Lois Jane. (2010). Cardiovascular Physiology, Seventh Edition. USA: The McGraw-Hill Companies, Inc.

Iowa State University. (2000, February 08). Material Safety Data Sheet-Lead Nitrate Reagent ACS. Retrieved October 06, 2013, from http://avogadro.chem.iastate.edu/MSDS/Pb(NO3)2.htm.

Javis, D. S. (2013, March 27). Patient.co.uk. Retrieved October 09, 2013, from www.patient.co.uk/blogs/sarah-says/2013/03/underweight-issues---the-other-end-of-the-obesity-spectrum.

National Emergency Medicine Association. (2003). Heart Rate or Pulse. Retrieved October 08, 2013, from http://www.nemahealth.org/programs/healthcare/heart_rate_pulse.htm.

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The Free Dictionary by Farlex. (2003). Medical Dictionary- Cardiovascular Exercise. Retrieved October 08, 2013, from http://medical-dictionary.thefreedictionary.com/cardiovascular+exercise.

WebMD Medical Reference. (2013). Exercise for a Healthy Heart. Retrieved October 09, 2013, from http://www.webmd.com/fitness-exercise/guide/exercise-healthy-heart.

World Health Organization. (2013, October 07). Global Database on Body Mass Index. Retrieved October 08, 2013, from http://apps.who.int/bmi/index.jsp?introPage=intro_3.html.

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