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Using InBody Testing to Measure the Accuracy of Bioelectrical Impedance When Affected by Different Hydration Levels Jack Streibich and Lindsay Wendt Mr. Spangler- Whitefish High School- Advanced Chemistry

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Research Question and Hypothesis Does BIA (Bioelectrical Impedance) accuracy vary as level of hydration fluctuates? If the subject is dehydrated then BIA will be less accurate(give a higher body fat estimate).

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What is the In-Body Test? Uses bioelectrical impedance to measure total body water o Sends electronic pulses through the body to measure total amount of water inside the body Total body water can be used to determine BMI, BFP, FAT, and SMM.

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Basic Principles of BIA Electrical currents travel faster through water than other solid materials o Muscles are primarily made up of water o Fat has a much lower water content Creates body fat estimate by measuring the time taken for different frequencies to reach electrodes o The slower the time, the more fat there is

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Possible Inaccuracies with Inbody Hydration Levels o Overhydration- Decreases bodys electrical resistance because the extracellular water amount increases, allowing the current to travel quicker o Dehydration- Increases bodys electrical resistance because the extracellular water amount decreases, causing the current to travel slower Consuming food before testing affects hydration

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Procedure 20 Whitefish High School student volunteers o Two groups of ten Each group went through a cycle of being hydrated and over hydrated o Being InBody tested during each phase of the cycle Other factors such as amount of water consumed, whether or not they ate breakfast, and exercise were also monitored

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Procedure Continued Sample of testing procedure

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Hydration Standards 100 oz - considered hydrated for girls 125 oz - considered hydrated for boys Anything significantly less was considered dehydrated

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Results Groups: o 1- Overhydrated the first day, normal on second o 2- Normally hydrated the first day, over on second PBF: o Percent of Body that is Fat Change in PBF: o PBF Dehydrated- PBF Normally hydrated Hypothesis: o Change in PBF will be negative because lower hydration levels should resist impedance.

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SubjectGroupHydrated PBFDehydrated PBFChange in PBF 1222.321.21.1 2210.7 0 3211.210.5.7 427.67.5.1 518.110.2-2.1 6120.320.00 7121.923-1.1 8218.414.93.5 92108.11.9 1018.19.6-1.5 11219.317.81.5 12115.817.5-1.7 13224.724.6.1 14127.527.4.1 15115.115.6-.5

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Tests Conditions: Data is matched(not independent) Individuals are independent Normal population o Distribution clearly normal Both unimodal and symmetric

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Testing Methods Various Students T tests were used to determine whether factors such as hydration and eating before testing affected the consistency of the InBody test.

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Test 1 Subjects include those who: o Drank recommended amount of water Ho: There is no difference between PBF when hydrated and PBF when dehydrated. Ha: There is a difference between PBF when hydrated and PBF when dehydrated. t=.367 p=.719 95% int(-.678,.958) P value of.719 is above a.05 alpha level, so we fail to reject the null hypothesis. There is no evidence of a difference between PBF when hydrated and dehydrated

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Test 2 Subjects include those who: o Drank recommended amount of water o Ate breakfast before both tests Ho: There is no difference between PBF when hydrated and ate breakfast and PBF when dehydrated and ate breakfast. Ha: There is a difference between PBF when hydrated and ate breakfast and PBF when dehydrated and ate breakfast. t=1.55 p=.152 95% int(-.27,1.5) P value of.152 is higher than.05 alpha level so we failed to reject our null hypothesis. There is no evidence that eating breakfast affects PBF.

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Test 3 Subjects include those who: o Drank recommended amount of water o Did not eat breakfast before either test Ho: There is no difference between PBF when hydrated and didnt eat breakfast and PBF when dehydrated and didnt eat breakfast. Ha: There is a difference between PBF when hydrated and didnt eat breakfast and PBF when dehydrated and didnt eat breakfast. t=-2.5 p=.0875 95%int(-2.76,.326) P value of.0875 is higher than.05 alpha level but not much higher. Still we fail to reject the hypothesis. There is little evidence that not eating affects PBF.

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Conclusion All three tests failed to show evidence of variables changing PBF levels. It is likely that BIA is relatively consistent, and may be more accurate than we expected.

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Improvements Specific group of individuals must be targeted and tested both ways with less variables.

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References Jansen, Ian, Steven B. Hymsfield, Richard N. Baumgaurtner, and Robert Ross. "Estimation of Skeletal Muscle Mass By Bioelectrial Impedance Analysis." Journal of Applied Physiology 89 (2000): 465-71. Web. 5 Oct. 2014. Lukaski, H. C., P. E. Johnson, W. W. Bolonchuck, and G. I. Lykken. "Assessment of Fat-free Mass Using Bioelectrial Impedence Measurements of the Human Body." The American Journal of Clinical Nutrition 41 (1985): 810-17. Web. 19 Nov. 2014. Mackenzie, Brian. "Bioelectrical Impedance Analysis (BIA)." Bioelectrical Impedance Analysis (BIA). N.p., 10 May 2014. Web. 11 Jan. 2015.