1. Bill Coburn

3. Introduction
 Many ways to assess body composition, The BOD
POD® is one
 Valid when controlling body hair, clothing and
temperature
 Sodium bicarbonate and carbonated beverages can
cause bloating and gas in the stomach from carbon
dioxide gas
 No one has researched the effects of extra gas in the
stomach on the BOD POD® measurements

4. Hypothesis
 Therefore, it is reasonable to hypothesize that percent
body fat as estimated by the BOD POD® in subjects
who ingest Sprite© or Alka-Seltzer® will be
overestimated as compared to the percent body fat
estimates of a control group at the p≤.05 level.
Therefore carbonated beverage intake will not be
permitted before BOD POD® testing. The null
hypothesis is that beverage ingestion will have no
effect on percent body fat estimation in the BOD
POD®.

5. Purpose of the Study
 The purpose of the study is to measure the percent
body fat of 10 college students using the BOD POD®
and compare results after ingesting Sprite© or Alka-
Seltzer®.

6. Research Questions
 1. What are the effects of Sprite© ingestion on the
estimation of percent body fat as measured by the
BOD POD®?
 2. What are the effects of Alka-Seltzer® ingestion on
the estimation of percent body fat as measured by the
BOD POD®?
 3. Does stomach gas significantly affect the
estimation of percent body fat by the BOD POD®?
 4. Is the BOD POD® at East Stroudsburg University
reliable?

7. Significance of the Study
 The BOD POD® is a quick, valid way of assessing body
composition. It is a form of appeal for wrestlers
wanting to wrestle at a lower weight than their initial
assessment allows. This study will investigate the
effects of carbonation on the estimation of percent
body fat as measured by the BOD POD®.

8. Assumptions
 1. Isothermal effects have been identified (clothing,
hair, thoracic gas volume, and body surface area
 2. Subjects avoid exercise for 4 hours
 3. Subjects avoid other substances that cause
stomach gas as well as food for 4 hours

9. Limitations
 1. This study will be limited by the population. The
population consists of college students aged 22-32
 2. The body compositions of the population will not
be controlled.
 3. We will use a predicted lung volume instead of
measured

10. Delimitations
 All subjects will wear compression clothing and swim
caps.
 Subjects’ faces will be clean shaven.
 Subjects’ skin will be dry.

11. Definitions
 Air-displacement plethysmography—A method of estimating
body volume by the amount of air displaced.
 Dual energy x-ray absorptiometry (DEXA)—A method of
estimating bone density and the bone mineral, fat, and mineral-
free lean tissue of the body by x-ray attenuation.
 Hydrostatic weighing—A method of estimating body volume by
measurement of weight loss when the body is submerged in
water. It is also called underwater weighing or hydrodensiometry.
 Compartment model—Methods of dividing the body into its
component make up. Two compartments separate the body into
fat mass and fat free mass. Four compartment models divide the
body into fat, mineral, lean tissue, and fluid.
 Adibiatic air—Air that changes temperature from a pressure
change.

13. Background
 Boyle’s law: volume of a confined body of gas varies
inversely as the absolute pressure, provided the
temperature remains unchanged
 Since the BOD POD® is under adibiatic conditions,
Poisson’s law is used
 γ is the ratio of the specific heat of the gas at constant
pressure to that at constant volume

14. Previous Attempts
 Early 19th century Germans used air displacement to
measure body volume
 Siri improved on this with a chamber and helium
dilution but biological and mechanical factors caused
errors
 Fomon followed that attempt with one for infants. He
failed to account for residual lung volume.
 Helium methods failed to measure lung volume
accurately

15. Previous Attempts
 Gnaedinger devised an air displacement method based
on animal research. His chamber was too large for the
subjects
 Taylor devised a 2 chamber system to account for
temperature changes and breathing. Errors came from
movement and air trapped in the gut and lungs

16. The BOD POD ®
 More practical and functional
 Two Chambers with a seat that divides the chambers
 450L front subject chamber and 300L rear reference
chamber
 Diaphragm between chambers acts as volume
perturbation, as one side increases in volume the other
side decreases
 2 point calibration process prepares for human testing
with 50L calibration cylinder

17. Human Measurement
 Air trapped within skin, hair and closing causes
isothermal conditions.
 Isothermal air is more compressible and can cause the
surrounding tissue to show up as negative volume
 Wearing tight compression clothing and a swim cap
controls for this.

18. Test Procedure
 Subject is weighed
 Calibration with cylinder follows
 Subject is introduced and breathes ambient air
 Door is opened and closed for second trial. If those
vary too much a third trial is performed
 Volume measurements must be within 150mL of each
other
 Thoracic gas volume can be measured or estimated

19. Validity to DEXA
 Dual-energy x-ray absorptiometry
 DEXA higher for children
 BOD POD higher in adult men
 Equal in Mexican elderly
 More closely related to each other than hydrostatic
weighing

20. Validity to Hydrostatic Weighing
 BOD POD has tendency to overestimate
 Subjects prefer the BOD POD
 Disagreement among athletic populations. Valid for
some invalid for others
 Disagreement on person to person basis

21. Factors Affecting Validity
 Hospital gowns cause 5.5% underestimation in women and
9% in both sexes
 T-shirt underestimates 4.1% in men and 2.9% in women
 A t-shirt and track-suit pants causes an underestimation of
percent body fat by 11.8% in men and 10.2% in women
 Males in cotton shorts underestimates by 3%
 Scalp hair led to a 2.3% underestimation while facial hair
led to a 1% underestimation
 Excess heat and moisture will also lead to a small but
significant underestimation of percent body fat by 1.8%

22. Reliability
 Intra-device reliability is high
 Inter-device reliability is variable depending on
location
 Different units in the same lab are high
 Units in different locations have low reliability

23. Predicted vs Measured Thoracic
Gas Volume
 McRory found no difference but recommended
measured for research
 Predicted method caused overestimation in some
populations

24. Carbonated Beverage and Sodium
Bicarbonate Intake
 Ingestion of Sprite© can cause bloating and belching
after ingestion of 300mL. This ingestion did not affect
the physiological functions
 Ingestion of sodium bicarbonate will also cause carbon
dioxide gas production. The full expected amount
would take over three hours after ingestion of 1.8g of
baking soda

26. Participants
 10 ESU graduate and undergraduate students were
used
 Age 23-32
 All in good health
 Randomized into which treatment they received at the
first testing session

27. Instrumentation
 BOD POD Gold Standard model BOD POD 2007A
used for collection of data
 Quality control measures performed before each
session

28. Procedures
 Quality control measures
 Subjects randomized into which treatment they received on the first
test
 Each session began with a baseline test. We used estimated thoracic
gas volume because the breathing tube was not available
 Subjects ingested beverage as fast as possible after the baseline test
 12 ounce can of Sprite or 4 ounces of water with 2 Alka-Seltzer tablets
dissolved in solution
 Subjects were not to expel any gas
 BOD POD measurements repeated 10 and 30 minutes after ingestion
 Second testing session occurred between 24 and 96 hours after the first
testing session

29. Beverage Ingestion

30. BOD POD Testing

32. Statistical Analysis
 SPSS
 Two-way ANOVA
 T-Test
 Pearson correlation

33. Descriptive Statistics
Descriptive Statistics
Group Mean
Standard
Deviation N
Sprite Baseline 27.05 4.59934 10
Sprite 10 Minutes 27.55 4.62703 10
Sprite 30 minutes 27.52 4.27988 10
Alka Seltzer Baseline 27.8 4.88467 10
Alka Seltzer 10 minutes 28.09 4.58365 10
Alka Seltzer 30 minutes 28.02 4.6346 10
Table 1. Descriptive statistics of the groups

34. ANOVA results
Type3SumofSquares df MeanSquareF Sig.
Beverage 5.34 1 5.34 2.296 0.164
Time 1.85 2 0.925 2.857 0.084
Beverage*Time 0.18 2 0.09 0.102 0.903
Table2.TestsofWithinSubjectEffects
TestsofWithinSubjectEffects
 None of the results were
significant
 Failed to reject the Null
Hypothesis
 Beverage Ingestion does
not affect percent body
fat measurements in the
BOD POD

35. Reliability Results
 T-Test result was 0.370043. This is not significant
 Pearson Correlation Coefficient was 0.8611935. This is a
strong correlation
 The East Stroudsburg University BOD POD is reliable

37. Purpose of Study
 Measure effect of stomach gas on body fat percentage
estimation
 No effect
 Test reliability of the BOD POD at East Stroudsburg
University
 It is reliable

38. Reliability
 We demonstrated strong reliability from day to day in
contrast to the Anderson study. Previously only within
day was reliable

39. Estimated Thoracic Gas Volume
 Biggest limitation
 Not available, probably lost
 Overestimation may be seen with measured thoracic
gas volume
 We were attempting to artificially inflate the gas
volume
 BOD POD correction equations may counteract the
attempted inflation

40. Non-compliance with delimitations
 One subject had facial hair which can cause 1%
underestimation, but the facial hair was the same for
both testing sessions
 Male subjects did not shave body hair which can cause
3% underestimation. The body hair level was the same
for both sessions
 One subject had decorations on her bathing suit which
could have trapped air. The same bathing suit was
worn for both sessions

41. Summation
 Future testing should look at using the measured
thoracic gas volume.
 Varied results on reliability and validity of the system

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