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Research Quarterly for Exercise and Sport Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/urqe20
Preparatory Postural Positions and Body Composition Measurement by Bioelectrical Impedance a
a
a
a
Tom R. Thomas , Fred W Kolkhorst , Ben R. Londeree , Michele Melkerson-Granryd , a
Steven T. Linsenbardt & Michael Rutherford a
b
Department of Health and Physical Education , University of Missouri , USA
b
Vista , St. Luke's Hospital , Kansas City , MO , USA Published online: 26 Feb 2013.
To cite this article: Tom R. Thomas , Fred W Kolkhorst , Ben R. Londeree , Michele Melkerson-Granryd , Steven T. Linsenbardt & Michael Rutherford (1990) Preparatory Postural Positions and Body Composition Measurement by Bioelectrical Impedance, Research Quarterly for Exercise and Sport, 61:2, 206-209, DOI: 10.1080/02701367.1990.10608677 To link to this article: http://dx.doi.org/10.1080/02701367.1990.10608677
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
THOMAS. KOLICHORST. LoNDBREB. M!n.xBRSON-GRANRYD. UNSBNBARDT. AND RtrrHERFORD
RESEARCH ~OTB
.RESEARCH QUARTBRLY
FOR,fuamCISB AND SPORT
1990. VOL.61.~o.2.pp.2~209
Preparatory Postural Positions and Body Composition Measurement by Bioelectrical Impedance
Downloaded by [New York University] at 16:02 27 April 2015
TOM R. THOMAS, FRED W. KOLKHORST, BEN R. LONDEREE, MICHELE MELKERSON-GRANRYD, STEVEN T. LINSENBARDT, AND MICHAEL RUTHERFORD University of Missouri
Keywords: reactance,resistance,plasma volume,percentfat, body composition Although theaccuracyof thebioelectricalimpedanceanalysis (BIA) technique has been questioned (Jackson, Pollock, Graves, & Mahar,1988; Segal,Gutin,Presta,Wang, & Itallie, 1985),somerecentpreliminaryreportshaveindicatedthatthe method has potential for success (Jones, Araujo, Thomas, & Aguiar, 1988;VanLoan et al., 1987).Althoughthe validityof the techniquehas been studied,only sparsedata are available on the external factors that may affect the BIA results. Researchers (Jackson et al., 1988; Lukaski, Johnson, Bolonchuk, & Lykken, 1985; Segal et al., 1985) have confirmed the excellent reliability of the BIA technique (r = .957 - .999). However,other preliminaryreports (Runge, Eisenman, & Johnson, 1987; Stump, Houtkooper, Hewitt, Going, & Lohman, 1988)indicated that exercisedehydration affects the resistance measurement. The distributionof body fluids also may affect the resistance measurement At low frequencies, electrical current passes mainly through extracellular fluid (Lukaski, 1987). Tan, Wilmhurst, Gleason, and Soeldner (1973) have demonstratedthat a steady influx of water into the plasma occurs in the first 20 min after moving from the upright to the supine position.It islikelythattheredistributionof bodyfluidswould dilute the extracellular ionic concentration (pitts, 1974) and thus increase the resistance measurement (Nyboer, 1972). Such postural change is typical in preparation for the BIA measurement Therefore, the purpose of this study was to measuretheeffectof preparatorybodypositionandtimein the supine position on BIA measures.
Methods Subjects Subjectswere 10 men and 14 women,ages ranging from 18to 43 years and BIA % fat from 5.3 to 39.8%(see Table 1).
The protocol was approved by the institutionalreview board at the University of Missouri, and all subjects gave informed consent
Preparation Before entering the laboratory for BIA measurement, each subject abstained from liquids for one hr, fasted five hrs, and avoided flatulent-producing foods for 12hrs. Vigorous activity was restricted for the previous 24 hrs, and, if possible, subjects voided the bowel and bladder just before weighing. When coming to the laboratory for testing, each subject walked or bicycled for at least 5 min, but no longer than 10 min. If the subject had properly followed the preparation procedure, he/she was weighed without shoes to the nearest 0.1 kg on a Toledo scale. Syncor Solid State ECG disposable electrodes were then applied to the right side of the body. The subject then placed his/her back to the wall and extended both hands upward. The distance from the point betweenthehandelectrodesto the floor was then measuredto the nearest0.5 em with a steel tape measure.Standingheight also was measured.
BfA Procedure Bioelectricalimpedanceanalysismeasurementsconsisted of hand-to-foot resistance and reactance (HF Resist, HF React) and neck-to-footresistance and reactance (NF Resist, NF React). Although HF Resist is the most commonly used impedancevariable,otherBIAvariableswereusedbecauseof their potential for use in multiple regression impedanceformulas. The RJL BIA-I03B Body Composition Analyzer, resolved to 1.0 ohm, was used for all impedance measurements.Onepair ofelectrodeswasplacedon therightfoot.One memberof thepair wasplacedon the footat theanterior-distal metatarsals. The other member was placed on the anterior surface between the medial and lateral malleoli of the ankle. A secondpairof electrodeswasplaced on thebackof theright hand. One member of the pair was placed at the distal
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Table 1 Subject Characteristics
Sex
n
Male
10
M
SE Female
14
M
SE Total
24
M
SE
Age (yrs)
Weight (kg)
Height (em)
24.6 2.0 21.2 2.6 23.5 1.4
76.03 2.72 62.07 1.72 67.89 2.02
181.2 9.3 168.4 6.2 173.8 9.8
HF Height" (em)
208.7 3.4 195.8 2.3 201.2 2.3
Body Fat
,
'.
(%)
14.9 1.4 26.0 2.1 21.4 1.7
Downloaded by [New York University] at 16:02 27 April 2015
"Extended hand-to-floor height
metacarpals, while the other was placed between the distal prominences of the radius and ulna. The third pair of electrodes were placed on the lateral-anteriorside of the neck on the subject's right side above the clavicle. This pair of electrodes was fixed approximately 3 em apart. Duringmeasurements, the subjectremained still, in the supine position, with feet apart and hands at the side, not touching the body. Protocol1consistedof 10minof standingfollowedby 30 min of BIA analysis in the supine position. Protocol 2 consistedof 5 min of standingand then 15minof sittingfollowed by 30 min ofBIA analysisin the supineposition.The orderof protocolswas randomlyassigned,and a 10-minwalk indoors separatedthe two protocolsfor each subject.Electrodeswere kept in place during the walk.The procedurewas designedto simulate two possible position sequences that would be performed in a waitingroom prior to BIA analysis. In addition, the walkprior to each protocolwas used to simulatea walk to a laboratoryor doctor's office. Analyses
Body density was calculated according to Jones et al. (l988), in which HF Resist and NF React are used: Body Density 1 = 1.21537- 0.13721 (p) + 1.05499 X 10-3 (NF React) + 0.01791 (In sex) - 4.34286 X 10-4 (HF Height),
(1)
where: p =(HF Resist x Weight)/HF Height' In sex =natural log of 1 for women and 2 for men For this equation, R = 0.912 and SEE = 0.0070 glml or 3.2% fat, BodyDensity2 andLBMalso werecalculatedaccording to formulasprovided by the manufacturer (RJL, 1985). For men: Body Density 2 =1.1411 - 0.0763 (HF Resist x Weight/HeightZ)
(2)
RBsIlAROI QuARTBRLY POR
For women: LBM =0.3981 (HeightZ)/HF Resist + 0.3066 (Weight) + 0.0953 (Height - 100) + 0.7414. (3) Percent fat was calculated using the Siri equation (Siri, 1961),with the Jones equation designatedas % Fat 1 and the RJL equationas % Fat 2. All data wereexpressedas means± SE. The factors were subjectsx sex x trial x time. The means were compared using a four-way ANOV A with repeated measureson trial and time.SignificantF ratios (p < .05)were followed with a Tukey post-hoc test, Reliability was calculated for each BIA variableusing intraelasscorrelation; time and trialswerepooled in the error term to providea conservative estimate.
Results Males exhibitedsignificantlylower values than females for HF Resist (484 ± 13 vs. 601 ± 23 ohms) (F[l,6] = 15.93, P =.0006), NF Resist (291 ± 9 vs. 334 ± 12 ohms) (F[I,6] = 7.37,p =.0127), % Fat 1 (14.8± 1.3 vs. 26.1 ± 2.0) (F[l,6] = 18.62, P = .0003), and % Fat 2 (19.2 ± 2.0 vs. 26.6 ± 1.6) (F[I,6] = 13.48, p = .(013). Males and females were not significantly different on NFReact (41 ± 2 vs. 40± 2 ohms) orHFReact (6O±2 vs. 66± 3 ohms).The male % Fat 1values were significantly lower than the male % Fat 2 values (t[9] = 2.51,p < .05).The changesfor any variableover timeor as a result of position were not significantly affected by sex. Therefore, the data forbothsexeswerecombinedforanalyses. In addition,trials (afterstandingvs.after sitting)producedno significantdifferencesinany electricalmeasure(see Table2). Therefore, trials were combined for further analyses. HF Resistincreasedprogressivelyover the30-minsupineperiod, F(6,132) = 48.40, P = .0001 (see Table 3). Likewise, NF Resistincreasedoverthe30min (F[6,132] =64.00,p= .0001), but the change was relatively small (12 ohms). HF React (F[6,132] =80.96, p =.0001) and NF React (F[6,132] =42.49, P = .0001) increased progressively over time, but these changes also were small (6 and 3 ohms, respectively) (see Table 3).
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THOMAS. KOLICHORST. LoNDBRBB. MBLJCBRSON-GRANRYD. L!NSBNBARDT. AND RUTHERFORD
Discussion
The % Fat 1 values showed only slight deviations over time, and the ANOVA was not significant (O-min M = 21.3 and 30-min M = 21.6, see Figure 1). The % Fat 2 values increased significantly (F[6,13] = 34.31, P = .0001) and progressively over time parallel to the HF Resist (see Table 3, Figure 2). The difference in mean % fat values at 0 and 30 min was relatively small, 22.9 and 24.1 %, respectively. Intraclass reliability for the impedance variables ranged from a low of .985 to a high of .999. Because trials and times were pooled, these are conservative values.
Several reports have indicated that BIA is a very reliable measure under normal conditions. For example, Segal et al. (1985) observed virtually no change in HF Resist readings over five trials, although no time frame or preparation of subjects was reported. Jackson et al. (1988) found that, although the reliability of BIA was high (N =.960), subjectby-day interaction was the greatest source of error, perhaps due to changes in body water over test days. Preliminary reports on exercise dehydration have suggested that changes in hydration levels can affect HF Resist and thus % fat calculations (Runge et al., 1987; Stump et at, 1988). If water is taken to prevent exercise dehydration, then the Resist changes are prevented (Stump et al., 1988). Body fluid changes are known to affect other methods of assessing % fat methods (Thomas, Etheridge, Londeree, & Shannon, 1979). In one of the most systematic BIA reliability experiments, Lukaski et al. (1985) reported that HF Resist differences over a five-day period ranged from 12 to 55 ohms (M = 22± 11 ohms). While these differences were not significantly different, a change in Resist of 20-55 ohms in a given individual would produce a considerable difference in the % fat calculation in those equations that use only HF Resist. The BIA readings in the present study were similar whether the subject was standing or sitting during the preliminary waiting period. These results may indicate the efficacy of the standard preparation (i.e., walk, fast, etc.) in stabilizing the measurements. In addition, pooling all sources of variance in a single residual error term produced very high intraclass correlations. These results support the generalizabil-
Table 2 Postural Position Prior to BIA Measurement
Downloaded by [New York University] at 16:02 27 April 2015
HF Resist
M
SE HF React
M
SE NF Resist
M
SE NF React
M
SE % Fat 1
M
SE % Fat 2
M
SE
After Standing
After Sitting
552 7 63 1 315 3 41 1 21.3 0.6 23.5 0.5
553 7 64 1 316 3 41 1 21.4 0.6 23.5 0.5
Note. Values are means and standard errors for the 30-min lying period. No significant differences between positions, N= 24.
Table 3 Effect of Time In Lying Position on Mean Impedance Variables
M
5
10
Time (min) 15
20
25
30
SE
547· b 13
550 bc 13
552 al 13
555 d• 13
558d• 13
562· 13
553 13
60 1
62 1
63 1
64· 1
65ab 1
65bc 1
66e 1
64 1
310 6
312 6
315· 6
316ab 6
318 b 6
320 c 6
322 c 6
316 6
NF React (ohms) 39· Total 1
40· b 1
40bc 1
41al 1
41 d 1
42d• 1
42· 1
41 1
0 HF Resistance 543· (ohms) 13 HF React (ohms)
NF Resist (ohms)
Note. Values are means ±SEfor total group, N = 24. Each BIA variable increased significantly over time; means with same superscript are not significantly different. RBs!!AR0i
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THOMAS, KOLKHORST, LoNDIlRIlIl, Mm.!cBRsON-GRANRYD, I..!NSBNBARDT, AND RUTHBRFORD
Time (min)
Time (min)
Downloaded by [New York University] at 16:02 27 April 2015
Figure 1. % Fat 1 (Jones et at, 1988) over time In the lying position. Symbols are means and vertical lines are ± SEs. No significant differences over time.
ity of the BIA technique under the present set of conditions. However, these data may not be generalizable to more prolongedperiodsof standingor sittingprior to BIA assessment. The present data suggestthat the timingofBIA mayplay a role in the reliability of the technique. In the newly developedregressionequation (% Fat I), the increasein HF Resist and NF React offset each other mathematically. However,in most BIA equations, the % fat reading is directly dependent only on HF Resist, and in such equations % fat measurement increases over time. When using these equations, Resist readings should be taken at a standardized time after lying down, perhaps between 5-10 min, when the change in HF Resistmeasureis minimal(seeTable 3,Figure2). In addition, it isnotnecessarytocontrolthepreparatoryposition(standing or sitting) of the subject immediately prior to measurement.
References Jackson, AS., Pollock,M. L., Graves, J. E., & Mahar, M. T. (1988). Reliability and validity of bioelectrical impedance in detennining body composition. JournalofAppliedPhysiology, 64, 529534. Jones, T. E., Araujo, 1., Thomas, T. R., & Aguiar, C. A. (1988). Predicting body density by electrical impedance. Medicineand Science in Sports and Exercise, 20, S41. (Abstract No. 246) Lukaski, H. C. (1987). Methods for the assessment of human body composition: Traditional and new. AmericanJournalof C linical Nutrition, 46,537-556. Lukaski, H. C., Johnson, P. E., Bolonchuk, W. W., & Lykken, G. I. (1985). Assessment of fat-free mass using bioelectrical impedance measurements of the human body. AmericanJournal of ClinicalNutrition, 41,810-817. Nyboer, 1. (1972). Workable volume and flow concepts of biosegments by electrical impedance plethysmography. Tl.T. Journal ofLife Science, 2,1-13. Pitts, R. F. (1974) Physiology ofthekidneyand bodyfluids. Chicago: Year Book Medical Publishers. RJL Systems (1985). BIA-103 body composition users manual. Detroit: RJL Systems. Runge, P. 1., Eisenman, P. A, & Johnson, S. C. (1987). Effects of exercise induced dehydration on bioelectrical impedance ana-
Figure 2. % Fat 2 (RJL Systems, 1985) over time In the lying position. Symbols are means and vertical lines are ±SEs. Significant changes over time for male, female, and combined groups (p < .05). For the combined group, time periods after 5 min are significantly different from all other time periods except no adjacent periods are different. lyzation to determine body composition. Medicine andScience in Sports and Exercise, 19, S38. (Abstract No. 227) 'Segal, K. R., Gutin, B., Presta, E., Wang, 1., & Itallie, T. B. (1985). Estimation of human body composition by electrical impedance methods: A comparative study. J ournalofAppliedPhysiology, 58, 1565-1571. Siri, W. E. (1961) Body composition from fluid spaces: Analysis of methods. In J. Brozek and A Henschel (Eds.), Techniques for measuringbodycomposition (pp. 223-244). Washington, DC: , National Academy of Science-National Research Council. Stump, C. S., Houtkooper, L. B., Hewitt, M. J., Going, S. B., & Lohman, T. G. (1988). Bioelectric impedance variability with dehydration and exercise. Medicineand Sciencein Sportsand Exercise, 20 S82. (Abstract No. 491) Tan, M. H., Wilmhurst, E. G., Gleason, R. E., & Soeldner, J. S. (1973). Effect ofposture on serum lipids.New EnglandJournal ofMedicine, 289, 416-419. Thomas, T. T., Etheridge, G. L., Londeree, B. L., & Shannon, W. (1979). Prolonged exercise and changes in percent fat detenninations by hydrostatic weighing and scintillation counting.
ResearchQuarterly, 50,709-714. VanLoan, M. D., Mayclin, P. L., Lohman,T, G., Going, S., Carswell, C., Slaughter, M. H., Stillman, R. J., & Kanaley, 1. A. (1987). Interlaboratory comparison of resistive impedance for the prediction of fat-free body and % fat. Medicine and Science in Sports and Exercise, 19, S-39. (Abstract No. 232)
Submitted: July 15. 1988 Accepted:May 15.1989 TomR. Thomas is a professor; Ben R. Londereeis an associateprofessor; and Fred W. Kolkhorst, Michele M. Granryd, and Steven T. Linsenbardt are graduate students in the Department of Health and Physical Education. University of Missouri. Michael Rutherfordis director of Lifewise at the Vista. St. Luke's Hospital, KansasCity. MO. Addresscorrespondence to TomR. Thomas. Ph.D.•RothwellGym. Department of Health and PhysicalEducation. University of Missouri.Columbia. MO 65211.
REsEARCH QuARTIlRLY FOR ExERCISB AND
209
SPORT,
VOL.
61, No.2
Research Quarterly for Exercise and Sport Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/urqe20
Preparatory Postural Positions and Body Composition Measurement by Bioelectrical Impedance a
a
a
a
Tom R. Thomas , Fred W Kolkhorst , Ben R. Londeree , Michele Melkerson-Granryd , a
Steven T. Linsenbardt & Michael Rutherford a
b
Department of Health and Physical Education , University of Missouri , USA
b
Vista , St. Luke's Hospital , Kansas City , MO , USA Published online: 26 Feb 2013.
To cite this article: Tom R. Thomas , Fred W Kolkhorst , Ben R. Londeree , Michele Melkerson-Granryd , Steven T. Linsenbardt & Michael Rutherford (1990) Preparatory Postural Positions and Body Composition Measurement by Bioelectrical Impedance, Research Quarterly for Exercise and Sport, 61:2, 206-209, DOI: 10.1080/02701367.1990.10608677 To link to this article: http://dx.doi.org/10.1080/02701367.1990.10608677
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
THOMAS. KOLICHORST. LoNDBREB. M!n.xBRSON-GRANRYD. UNSBNBARDT. AND RtrrHERFORD
RESEARCH ~OTB
.RESEARCH QUARTBRLY
FOR,fuamCISB AND SPORT
1990. VOL.61.~o.2.pp.2~209
Preparatory Postural Positions and Body Composition Measurement by Bioelectrical Impedance
Downloaded by [New York University] at 16:02 27 April 2015
TOM R. THOMAS, FRED W. KOLKHORST, BEN R. LONDEREE, MICHELE MELKERSON-GRANRYD, STEVEN T. LINSENBARDT, AND MICHAEL RUTHERFORD University of Missouri
Keywords: reactance,resistance,plasma volume,percentfat, body composition Although theaccuracyof thebioelectricalimpedanceanalysis (BIA) technique has been questioned (Jackson, Pollock, Graves, & Mahar,1988; Segal,Gutin,Presta,Wang, & Itallie, 1985),somerecentpreliminaryreportshaveindicatedthatthe method has potential for success (Jones, Araujo, Thomas, & Aguiar, 1988;VanLoan et al., 1987).Althoughthe validityof the techniquehas been studied,only sparsedata are available on the external factors that may affect the BIA results. Researchers (Jackson et al., 1988; Lukaski, Johnson, Bolonchuk, & Lykken, 1985; Segal et al., 1985) have confirmed the excellent reliability of the BIA technique (r = .957 - .999). However,other preliminaryreports (Runge, Eisenman, & Johnson, 1987; Stump, Houtkooper, Hewitt, Going, & Lohman, 1988)indicated that exercisedehydration affects the resistance measurement. The distributionof body fluids also may affect the resistance measurement At low frequencies, electrical current passes mainly through extracellular fluid (Lukaski, 1987). Tan, Wilmhurst, Gleason, and Soeldner (1973) have demonstratedthat a steady influx of water into the plasma occurs in the first 20 min after moving from the upright to the supine position.It islikelythattheredistributionof bodyfluidswould dilute the extracellular ionic concentration (pitts, 1974) and thus increase the resistance measurement (Nyboer, 1972). Such postural change is typical in preparation for the BIA measurement Therefore, the purpose of this study was to measuretheeffectof preparatorybodypositionandtimein the supine position on BIA measures.
Methods Subjects Subjectswere 10 men and 14 women,ages ranging from 18to 43 years and BIA % fat from 5.3 to 39.8%(see Table 1).
The protocol was approved by the institutionalreview board at the University of Missouri, and all subjects gave informed consent
Preparation Before entering the laboratory for BIA measurement, each subject abstained from liquids for one hr, fasted five hrs, and avoided flatulent-producing foods for 12hrs. Vigorous activity was restricted for the previous 24 hrs, and, if possible, subjects voided the bowel and bladder just before weighing. When coming to the laboratory for testing, each subject walked or bicycled for at least 5 min, but no longer than 10 min. If the subject had properly followed the preparation procedure, he/she was weighed without shoes to the nearest 0.1 kg on a Toledo scale. Syncor Solid State ECG disposable electrodes were then applied to the right side of the body. The subject then placed his/her back to the wall and extended both hands upward. The distance from the point betweenthehandelectrodesto the floor was then measuredto the nearest0.5 em with a steel tape measure.Standingheight also was measured.
BfA Procedure Bioelectricalimpedanceanalysismeasurementsconsisted of hand-to-foot resistance and reactance (HF Resist, HF React) and neck-to-footresistance and reactance (NF Resist, NF React). Although HF Resist is the most commonly used impedancevariable,otherBIAvariableswereusedbecauseof their potential for use in multiple regression impedanceformulas. The RJL BIA-I03B Body Composition Analyzer, resolved to 1.0 ohm, was used for all impedance measurements.Onepair ofelectrodeswasplacedon therightfoot.One memberof thepair wasplacedon the footat theanterior-distal metatarsals. The other member was placed on the anterior surface between the medial and lateral malleoli of the ankle. A secondpairof electrodeswasplaced on thebackof theright hand. One member of the pair was placed at the distal
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THOMAS, KOLKHORST, LoNDBRBB, Mm.KBRSON-GRANRYD, LINSBNBARDT, AND RIlTHI!RFORD
Table 1 Subject Characteristics
Sex
n
Male
10
M
SE Female
14
M
SE Total
24
M
SE
Age (yrs)
Weight (kg)
Height (em)
24.6 2.0 21.2 2.6 23.5 1.4
76.03 2.72 62.07 1.72 67.89 2.02
181.2 9.3 168.4 6.2 173.8 9.8
HF Height" (em)
208.7 3.4 195.8 2.3 201.2 2.3
Body Fat
,
'.
(%)
14.9 1.4 26.0 2.1 21.4 1.7
Downloaded by [New York University] at 16:02 27 April 2015
"Extended hand-to-floor height
metacarpals, while the other was placed between the distal prominences of the radius and ulna. The third pair of electrodes were placed on the lateral-anteriorside of the neck on the subject's right side above the clavicle. This pair of electrodes was fixed approximately 3 em apart. Duringmeasurements, the subjectremained still, in the supine position, with feet apart and hands at the side, not touching the body. Protocol1consistedof 10minof standingfollowedby 30 min of BIA analysis in the supine position. Protocol 2 consistedof 5 min of standingand then 15minof sittingfollowed by 30 min ofBIA analysisin the supineposition.The orderof protocolswas randomlyassigned,and a 10-minwalk indoors separatedthe two protocolsfor each subject.Electrodeswere kept in place during the walk.The procedurewas designedto simulate two possible position sequences that would be performed in a waitingroom prior to BIA analysis. In addition, the walkprior to each protocolwas used to simulatea walk to a laboratoryor doctor's office. Analyses
Body density was calculated according to Jones et al. (l988), in which HF Resist and NF React are used: Body Density 1 = 1.21537- 0.13721 (p) + 1.05499 X 10-3 (NF React) + 0.01791 (In sex) - 4.34286 X 10-4 (HF Height),
(1)
where: p =(HF Resist x Weight)/HF Height' In sex =natural log of 1 for women and 2 for men For this equation, R = 0.912 and SEE = 0.0070 glml or 3.2% fat, BodyDensity2 andLBMalso werecalculatedaccording to formulasprovided by the manufacturer (RJL, 1985). For men: Body Density 2 =1.1411 - 0.0763 (HF Resist x Weight/HeightZ)
(2)
RBsIlAROI QuARTBRLY POR
For women: LBM =0.3981 (HeightZ)/HF Resist + 0.3066 (Weight) + 0.0953 (Height - 100) + 0.7414. (3) Percent fat was calculated using the Siri equation (Siri, 1961),with the Jones equation designatedas % Fat 1 and the RJL equationas % Fat 2. All data wereexpressedas means± SE. The factors were subjectsx sex x trial x time. The means were compared using a four-way ANOV A with repeated measureson trial and time.SignificantF ratios (p < .05)were followed with a Tukey post-hoc test, Reliability was calculated for each BIA variableusing intraelasscorrelation; time and trialswerepooled in the error term to providea conservative estimate.
Results Males exhibitedsignificantlylower values than females for HF Resist (484 ± 13 vs. 601 ± 23 ohms) (F[l,6] = 15.93, P =.0006), NF Resist (291 ± 9 vs. 334 ± 12 ohms) (F[I,6] = 7.37,p =.0127), % Fat 1 (14.8± 1.3 vs. 26.1 ± 2.0) (F[l,6] = 18.62, P = .0003), and % Fat 2 (19.2 ± 2.0 vs. 26.6 ± 1.6) (F[I,6] = 13.48, p = .(013). Males and females were not significantly different on NFReact (41 ± 2 vs. 40± 2 ohms) orHFReact (6O±2 vs. 66± 3 ohms).The male % Fat 1values were significantly lower than the male % Fat 2 values (t[9] = 2.51,p < .05).The changesfor any variableover timeor as a result of position were not significantly affected by sex. Therefore, the data forbothsexeswerecombinedforanalyses. In addition,trials (afterstandingvs.after sitting)producedno significantdifferencesinany electricalmeasure(see Table2). Therefore, trials were combined for further analyses. HF Resistincreasedprogressivelyover the30-minsupineperiod, F(6,132) = 48.40, P = .0001 (see Table 3). Likewise, NF Resistincreasedoverthe30min (F[6,132] =64.00,p= .0001), but the change was relatively small (12 ohms). HF React (F[6,132] =80.96, p =.0001) and NF React (F[6,132] =42.49, P = .0001) increased progressively over time, but these changes also were small (6 and 3 ohms, respectively) (see Table 3).
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Discussion
The % Fat 1 values showed only slight deviations over time, and the ANOVA was not significant (O-min M = 21.3 and 30-min M = 21.6, see Figure 1). The % Fat 2 values increased significantly (F[6,13] = 34.31, P = .0001) and progressively over time parallel to the HF Resist (see Table 3, Figure 2). The difference in mean % fat values at 0 and 30 min was relatively small, 22.9 and 24.1 %, respectively. Intraclass reliability for the impedance variables ranged from a low of .985 to a high of .999. Because trials and times were pooled, these are conservative values.
Several reports have indicated that BIA is a very reliable measure under normal conditions. For example, Segal et al. (1985) observed virtually no change in HF Resist readings over five trials, although no time frame or preparation of subjects was reported. Jackson et al. (1988) found that, although the reliability of BIA was high (N =.960), subjectby-day interaction was the greatest source of error, perhaps due to changes in body water over test days. Preliminary reports on exercise dehydration have suggested that changes in hydration levels can affect HF Resist and thus % fat calculations (Runge et al., 1987; Stump et at, 1988). If water is taken to prevent exercise dehydration, then the Resist changes are prevented (Stump et al., 1988). Body fluid changes are known to affect other methods of assessing % fat methods (Thomas, Etheridge, Londeree, & Shannon, 1979). In one of the most systematic BIA reliability experiments, Lukaski et al. (1985) reported that HF Resist differences over a five-day period ranged from 12 to 55 ohms (M = 22± 11 ohms). While these differences were not significantly different, a change in Resist of 20-55 ohms in a given individual would produce a considerable difference in the % fat calculation in those equations that use only HF Resist. The BIA readings in the present study were similar whether the subject was standing or sitting during the preliminary waiting period. These results may indicate the efficacy of the standard preparation (i.e., walk, fast, etc.) in stabilizing the measurements. In addition, pooling all sources of variance in a single residual error term produced very high intraclass correlations. These results support the generalizabil-
Table 2 Postural Position Prior to BIA Measurement
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HF Resist
M
SE HF React
M
SE NF Resist
M
SE NF React
M
SE % Fat 1
M
SE % Fat 2
M
SE
After Standing
After Sitting
552 7 63 1 315 3 41 1 21.3 0.6 23.5 0.5
553 7 64 1 316 3 41 1 21.4 0.6 23.5 0.5
Note. Values are means and standard errors for the 30-min lying period. No significant differences between positions, N= 24.
Table 3 Effect of Time In Lying Position on Mean Impedance Variables
M
5
10
Time (min) 15
20
25
30
SE
547· b 13
550 bc 13
552 al 13
555 d• 13
558d• 13
562· 13
553 13
60 1
62 1
63 1
64· 1
65ab 1
65bc 1
66e 1
64 1
310 6
312 6
315· 6
316ab 6
318 b 6
320 c 6
322 c 6
316 6
NF React (ohms) 39· Total 1
40· b 1
40bc 1
41al 1
41 d 1
42d• 1
42· 1
41 1
0 HF Resistance 543· (ohms) 13 HF React (ohms)
NF Resist (ohms)
Note. Values are means ±SEfor total group, N = 24. Each BIA variable increased significantly over time; means with same superscript are not significantly different. RBs!!AR0i
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Time (min)
Time (min)
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Figure 1. % Fat 1 (Jones et at, 1988) over time In the lying position. Symbols are means and vertical lines are ± SEs. No significant differences over time.
ity of the BIA technique under the present set of conditions. However, these data may not be generalizable to more prolongedperiodsof standingor sittingprior to BIA assessment. The present data suggestthat the timingofBIA mayplay a role in the reliability of the technique. In the newly developedregressionequation (% Fat I), the increasein HF Resist and NF React offset each other mathematically. However,in most BIA equations, the % fat reading is directly dependent only on HF Resist, and in such equations % fat measurement increases over time. When using these equations, Resist readings should be taken at a standardized time after lying down, perhaps between 5-10 min, when the change in HF Resistmeasureis minimal(seeTable 3,Figure2). In addition, it isnotnecessarytocontrolthepreparatoryposition(standing or sitting) of the subject immediately prior to measurement.
References Jackson, AS., Pollock,M. L., Graves, J. E., & Mahar, M. T. (1988). Reliability and validity of bioelectrical impedance in detennining body composition. JournalofAppliedPhysiology, 64, 529534. Jones, T. E., Araujo, 1., Thomas, T. R., & Aguiar, C. A. (1988). Predicting body density by electrical impedance. Medicineand Science in Sports and Exercise, 20, S41. (Abstract No. 246) Lukaski, H. C. (1987). Methods for the assessment of human body composition: Traditional and new. AmericanJournalof C linical Nutrition, 46,537-556. Lukaski, H. C., Johnson, P. E., Bolonchuk, W. W., & Lykken, G. I. (1985). Assessment of fat-free mass using bioelectrical impedance measurements of the human body. AmericanJournal of ClinicalNutrition, 41,810-817. Nyboer, 1. (1972). Workable volume and flow concepts of biosegments by electrical impedance plethysmography. Tl.T. Journal ofLife Science, 2,1-13. Pitts, R. F. (1974) Physiology ofthekidneyand bodyfluids. Chicago: Year Book Medical Publishers. RJL Systems (1985). BIA-103 body composition users manual. Detroit: RJL Systems. Runge, P. 1., Eisenman, P. A, & Johnson, S. C. (1987). Effects of exercise induced dehydration on bioelectrical impedance ana-
Figure 2. % Fat 2 (RJL Systems, 1985) over time In the lying position. Symbols are means and vertical lines are ±SEs. Significant changes over time for male, female, and combined groups (p < .05). For the combined group, time periods after 5 min are significantly different from all other time periods except no adjacent periods are different. lyzation to determine body composition. Medicine andScience in Sports and Exercise, 19, S38. (Abstract No. 227) 'Segal, K. R., Gutin, B., Presta, E., Wang, 1., & Itallie, T. B. (1985). Estimation of human body composition by electrical impedance methods: A comparative study. J ournalofAppliedPhysiology, 58, 1565-1571. Siri, W. E. (1961) Body composition from fluid spaces: Analysis of methods. In J. Brozek and A Henschel (Eds.), Techniques for measuringbodycomposition (pp. 223-244). Washington, DC: , National Academy of Science-National Research Council. Stump, C. S., Houtkooper, L. B., Hewitt, M. J., Going, S. B., & Lohman, T. G. (1988). Bioelectric impedance variability with dehydration and exercise. Medicineand Sciencein Sportsand Exercise, 20 S82. (Abstract No. 491) Tan, M. H., Wilmhurst, E. G., Gleason, R. E., & Soeldner, J. S. (1973). Effect ofposture on serum lipids.New EnglandJournal ofMedicine, 289, 416-419. Thomas, T. T., Etheridge, G. L., Londeree, B. L., & Shannon, W. (1979). Prolonged exercise and changes in percent fat detenninations by hydrostatic weighing and scintillation counting.
ResearchQuarterly, 50,709-714. VanLoan, M. D., Mayclin, P. L., Lohman,T, G., Going, S., Carswell, C., Slaughter, M. H., Stillman, R. J., & Kanaley, 1. A. (1987). Interlaboratory comparison of resistive impedance for the prediction of fat-free body and % fat. Medicine and Science in Sports and Exercise, 19, S-39. (Abstract No. 232)
Submitted: July 15. 1988 Accepted:May 15.1989 TomR. Thomas is a professor; Ben R. Londereeis an associateprofessor; and Fred W. Kolkhorst, Michele M. Granryd, and Steven T. Linsenbardt are graduate students in the Department of Health and Physical Education. University of Missouri. Michael Rutherfordis director of Lifewise at the Vista. St. Luke's Hospital, KansasCity. MO. Addresscorrespondence to TomR. Thomas. Ph.D.•RothwellGym. Department of Health and PhysicalEducation. University of Missouri.Columbia. MO 65211.
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