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 Beşli 006615-006
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 a ffect 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=
( )
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 t he 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) 4
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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 restrai n 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 s tart 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 lat er 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 and Participant C can be seen in Picture 2.
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Calculations BMI(kg/m2)
Classification
Principal cut-off points
Additional cut-off points
<18.50
<18.50
<16.00
<16.00
Moderate thinness
16.00 - 16.99
16.00 - 16.99
Mild thinness
17.00 - 18.49
17.00 - 18.49
Underweight
Severe thinness
Normal range Overweight
18.50 - 22.99
18.50 - 24.99
23.00 - 24.99
≥25.00
Pre-obese
≥25.00
25.00 - 27.49
25.00 - 29.99
Obese
27.50 - 29.99
≥30.00
≥30.00
Obese class I
30.00 - 34.99
Obese class II
35.00 - 39.99
Obese class III
≥40.00
30.00 - 32.49 32.50 - 34.99 35.00 - 37.49 37.50 - 39.99 ≥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
Participant A:
formula: ( ) Participant B:
mass= 42.3 kg
mass= 55.6 kg
height= 158 cm
height= 165 cm
BMI=
= 16.94
BMI=
Participant A’s BMI shows that she is
= 20.42
BMI of Participant B shows that she is in
moderately thin according to the data in
the normal range.
Table 1.
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Participant C:
Participant E: mass= 98.0 kg
mass= 66.2 kg
height= 169 cm
height= 180 cm
BMI=
= 34.31
BMI=
= 20.43
BMI of Participant C shows that she is in
BMI of Participant A shows that he is in
obese class I.
the normal range.
Participant D:
Participant F: mass= 54.5 kg
mass= 101.5 kg
height= 176 cm
height= 182 cm
BMI=
= 17.59
BMI=
= 30.64
BMI of Participant D shows that he is
BMI of Participant A shows that he is in
mildly thin.
obese class I.
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Data Collection Results for female participants:
Trial
Heart Rate Before
Heart Rate After
Flights of Steps
Difference
Trial (
Trial (
(
(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
Heart Rate Before
Heart Rate After
Flights of Steps
Difference
Trial (
Trial (
(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
Heart Rate Before
Heart Rate After
Flights of Steps
Difference
Trial (
Trial (
(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
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). 9
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Results for male participants:
Trial
Heart Rate Before
Heart Rate After
Flights of Steps
Difference
Trial (
Trial (
(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
Heart Rate Before
Heart Rate After
Flights of Steps
Difference
Trial (
Trial (
(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
Heart Rate Before
Heart Rate After
Flights of Steps
Difference
Trial (
Trial (
(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
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).
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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.
Heart Rate Comparison Between Underweight Participants A and D 160 140 ) 120 m p b100 4 ± ( e 80 t a R t 60 r a e H 40
Before Trial (A) Before Trial (D) After Trial (A) After Trial (D)
20 0 1
2
3
4
5
Trials
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 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 11
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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 ver y 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.
Heart Rate Comparison Between Normal Weight Participants B and E 160 140
) m120 p b 4 100 ± ( e t 80 a R 60 t r a e 40 H
Before Trial (B) Before Trial (E) After Trial (B) After Trial (E)
20 0 1
2
3
4
5
Trials
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
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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.
Heart Rate Comparison Between Obese Participants C and F 180 160 ) 140 m p 120 b 4 ± 100 ( e t a 80 R t r 60 a e H
Before Trial (C) Before Trial (F) After Trial (C) After Trial (F)
40 20 0
1
2
3
4
5
Trials
Graph 4: Comparison of heart rate change values between obese Participants C and F.
BMI values of Participants C and F showed the biggest differ ence among all participants, being 34.31 and 30.64 respectively. However, they are both still considered to be in obese 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 percenta ge change between the heart rate measurements in each trial is fairly low with and exception of the data recor ded 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 13
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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 t o show the relationship between BMI and heart rate change:
The Relation Between BMI and Heart Rate Difference ) 70 m p b 460 ± ( e50 c n e r40 e f f i D30 e t a20 R t r10 a e H 0 . v A
BMI and Av. Heart Rate Difference of Participants A, D, B, E, F and C Respectively
16.94
17.59
20.42
20.43
30.64
34.31
BMI Values of Participants
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 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 part icipants during cardiovascular exercises. 14
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Relation Between BMI Values and Flights of Steps Climbed ) s 10 t h g i l f 9.5 2 . 0 ± 9 ( d e b8.5 m i l C 8 s p e t S7.5 f o s 7 t h g i l F
Flights of Steps Climbed by Participants A, D, B, E, F and C Respectively
16.94
17.59
20.42
20.43
30.64
34.31
BMI Values of Participants
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 ran ge 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 the heart (Javis, 2013). Thus, it can be said that keeping BMI in normal range is essential to live healthy.
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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 incr eases, 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 Even though the data obtained from the experiment were generally accurate and parall el 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 va riation is caused by genetic determinants of
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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 s tairs climbed by Participant D. He had managed to climb nearly as many steps as nor mal 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 st eps 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 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
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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-obesityspectrum. National Emergency Medicine Association. (2003). Heart Rate or Pulse. Retrieved October 08, 2013, from http://www.nemahealth.org/programs/healthcare/heart_rate_pulse.htm. 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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