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

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).

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.

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

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

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

Procedure Continued Sample of testing procedure

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

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.

SubjectGroupHydrated PBFDehydrated PBFChange in PBF

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

Testing Methods Various Student’s T tests were used to determine whether factors such as hydration and eating before testing affected the consistency of the InBody test.

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= % 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

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= % 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.

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 didn’t eat breakfast and PBF when dehydrated and didn’t eat breakfast. ●Ha: There is a difference between PBF when hydrated and didn’t eat breakfast and PBF when dehydrated and didn’t eat breakfast. ●t=-2.5 p= %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.

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.

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

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): Web. 5 Oct 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): Web. 19 Nov Mackenzie, Brian. "Bioelectrical Impedance Analysis (BIA)." Bioelectrical Impedance Analysis (BIA). N.p., 10 May Web. 11 Jan