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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
Comparison of Harpenden and Lange Calipers in Predicting Body Composition a
b
c
c
Joseph J. Gruber , Michael L. Pollock , James E. Graves , Andrea B. Colvin & Randy W. Braith
c
a
Department of Health, Physical Education and Recreation , University of Kentucky , Lexington , KY , 40506 , USA b
Center for Exercise Science , University of Florida , Gainesville , FL , 32601 , USA
c
Center , USA Published online: 26 Feb 2013.
To cite this article: Joseph J. Gruber , Michael L. Pollock , James E. Graves , Andrea B. Colvin & Randy W. Braith (1990) Comparison of Harpenden and Lange Calipers in Predicting Body Composition, Research Quarterly for Exercise and Sport, 61:2, 184-190, DOI: 10.1080/02701367.1990.10608673 To link to this article: http://dx.doi.org/10.1080/02701367.1990.10608673
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
GRUBER, POlLOCK, GRAVBS. CoLVIN, AND
BRAl'I1I
RaSBARCH QuARTERLY
RaSBARCH NOTB
FOR ExBRCISB AND SPORT
1990. VOL. 61, No.2. pp. 184-190
Comparison of Harpenden and Lange Calipers in Predicting Body Composition JOSEPH J. GRUBER University of Kentucky
Downloaded by [Purdue University] at 17:40 12 April 2015
MICHAEL L. POLLOCK, JAMES E. GRAVES, ANDREA B. COLYIN, AND RANDY W. BRArm University of Florida
Key words: skinfold, body composition, body density, skinfold calipers
Field methodsfor predictingbody composition from skinfold equations are becoming increasingly popular in situations where underwater weighing (UWW) is not feasible. Skinfoldmeasuresmustbe free fromanysystematicerrorthat may over- or underpredict body density (OJ and percent fat (%F). Severalinvestigators havealludedtodifferences among skinfoldcalipers as one source of error in predictingDb and %F from a regression equation (Burgert & Anderson, 1979; Lohman & Pollock,1984;Lohman,Pollock,Slaughter, Brandon, & Boileau,1984;Pollock & Jackson, 1984).No systematic differences in skinfold measures were reported by Imbibo, Fidanza, Caputo, and Moro (cited in Womersley & Durnin,1973),whereasSloanand Shapiro(1972)showedthe Harpenden (HRP) producedsmallervaluesat foursites when compared with the Lange (LNG). Meandifferences between threedifferentcaliperswerereportedby Morrow,Fridye,and Monaghen (1986).Other investigators reported that the HRP always produced smaller values when compared with the LNG when these calipers were applied to the same five skinfold sites (Lohman et al., 1984). A majority of these papersfailed to investigatepossibledifferences in Db and %F due to choice of caliper. The purposeof this study was to determineif predictions of Db and %F from the Jackson-Pollock (J-P) generalized equations were significantly related to type of skinfoldcaliper.Asecondary purposewastodevelopcorrectionequations for predicting %F, if needed.
Methods Subjects
Sixty Caucasian college students (n = 31 males; n = 29 females) reportedto the laboratoryfor testingafter signinga RaSBARCIl QuARTERLY Pal.
statementof informedconsent. Height was measured to the nearestO.lemwitha Harpenden stadiometerandweighttothe nearest0.1kg withan AcmeMedicalScale.Themalesranged in age from 19.1to 29.7 yrs (M=23.4±2.5 yrs),heightfrom 163.3to200.7em (M =176.4±7.5cm), and weightfrom 64.7 to 100.7kg (M =80.2 ± 10.7kg). The females ranged in age from18.7to29.9 yrs (M =22.7± 3.4years),heightfrom 154.3 to 173.4cm(M= 165.3±5.5 cm),andweightfrom45.6 to80.6 kg (M =57.4 ± 7.5 kg). Chest,axilla, triceps,subscapula, abdominal, suprailiac, and thigh skinfolds were measured twice in the order presented on the right side of the body with both the LNG and HRPcaliperbyanexperienced investigator. Sitesweremarked on each subject as illustratedin Pollock, Wilmore, and Fox (1984). All data were collected during a single test session usingone set of marks.Each site measurement wasrecorded by an independent scorer.Thus, the tester had no knowledge of the first sevenscoreswhenthesecondsetof measures were taken. If the two measures for a skinfold site did not agree within1mm,a thirdmeasurement wastaken.The meanof the two closest values was the final score for each site. This processwasrepeatedforthesecondcaliper.Caliperorderwas assigned alternately to each subject as he/she appeared for testing. The LNG and HRPcaliperswerecomparedagainsta standard calibration block, and readings between calipers werewithin0.2 mm throughout the range of five blocksizes. After data collection, the tension of both calipers was checkedaccording toproceduresrecommended by thecaliper manufacturers. Harpenden force is that required to begin movement or opening of the caliper jaws. This methodwas also followed in obtainingthe LNG forces. The HRP caliper pressuresrangedfrom8.97to 9.80 g/mm'', withan averageof 9.36g/mm20verseven thicknessesof6, 14,20,24,29, 33,and 37 mm. The LNG caliper pressures were a consistent 9.3 g/mm2 over six readings of 10, 20, 30, 40, 50, and 60 mm. Thus,thecalipersusedin thisstudymettherecommendations that calipers should not vary in pressure by more than 2.0 g/mm2 over a range of 2-40 mm and that the caliperpressure
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GRUBER, POllOCK, GRAVES, COLVIN, AND BRAITH
itself should be between 9 to 20 g/mm" (Edwards, Hammond, Healy, Tanner, & Whitehouse, 1955). The skinfold measures were used in the ,,£7 and "£3 generalized equations (Jackson & Pollock, 1978; Jackson, Pollock, & Ward, 1980) to predict Db' Percent fat was estimated from Db with the Siri (1961) equation. Actual Db was determined by the hydrostatic method with correction for residual volume (RV). Underwater weighing (UWW) was performed in a tank in which a chair was suspended from a 15-kg Chatillon scale. Repeated trials of UWW were performed until three trials agreed within 0.25 g. An average of the three most consistent trials was used as a criterion measure for UWW. Water temperature was recorded for each subject. Body density was calculated from the formula of Goldman and Buskirk (1961) and %F according to Siri (1961). Residual volume was estimated by the open circuit nitrogen washoutprocedure (Wilmore, 1969) using the Medical Graphics Advanced Pulmonary Function System 1070. Repeated trials were performed until two trials were within 50 ml of one another. The mean of these trials served as the RV value. The effectiveness of J-P ,,£7 and "£3 predictions of hydrostatically determined Db and %F were determined with zero-order correlations and standard errors of estimate. Mean differences in UWW, "£7, "£3 estimates of Db' and %F were analyzed with a repeated measures analysis of variance design. These statistical procedures were applied to both the HRP and LNG data sets. A paired r-test explored HRP and LNG differences at each skinfold site. All comparisons were tested for statistical significance at the .05 alpha level.
sources of variation, one the SEE and the other the difference between the true and estimated values. E can therefore be affected not only by the dispersion of individual scores, but also by any systematic error in the differences between true and estimated values (Lohman, 1981; Sinning & Wilson, 1984). The data in Table 1 show thatE exceeds the SEE for the "£7,"£3,and every skinfold site for both males and females. In addition, the mean differences are all negative and exceed the SEE for all but one tabled value. The mean difference for the ,,£7 for the males is -10.70, withE =11.51; the mean difference for the "£7 in the females is -10.25, with E = 11.04. The magnitude of E and the mean differences are similar and exceed SEE, indicating that a systematic error is present, with the HRP systematically producing smaller values at each skinfold site. This results in an underprediction of %F. Results from cross-validation of the J -P ,,£7 and "£3 prediction equations with UWW determined Db and %F are shown in Table 2. The correlations ranged from a r =+.80 to +.85 (p < .05). Standard errors of estimate (SEE) for Db and %F are acceptable and are equal or superior to previously reported data (Bulbulian, 1984; Jackson & Pollock, 1978; Jackson, Pollock, & Ward, 1980; Latin, 1987; Sinning & Wilson, 1984; Thorland, Johnson, Tharp, Fagot, & Hammer, 1984). There is no difference between the LNG or HRP caliper on the magnitude ofrelationships or SEE of Db and %F. These fmdings are consistent for both males and females. One also notes from Table 2 that the J-P "£3equation is just as effective as the ,,£7 equation in predicting Dband %F for this sample. Table 3 presents Db and %F determined by UWW and predicted by the ,,£7 and "£3 generalized equations. When comparing the ,,£7 and the "£3 mean scores for Db and %F in the males and females, one notes that the means are not statistically different (p > .05). Hence, our description of the repeated measures ANOVA results applies to the ,,£7 and "£3 data sets for all groups. There were significant increases in mean Db scores between the UWW, LNG, and HRP procedures, in that order. This translates into a significant decrease in %F predictions when comparing the UWW with the LNG and the LNG with the HRP caliper. In males, the prediction of %F from the LNG was 1.9% less than the UWW estimates. When comparing the LNG and HRP one notes that 1.5% less fat is predicted when using the HRP caliper. The HRP caliper measures predicted 3.4% less fat when compared to the UWW procedure. Somewhat similar values are seen in the data on females where the LNG predicted 1.4% less fat than UWW; the HRP predicted 1.5% less fat than the LNG values and the HRP underpredicted some 2.9%Fwhen compared with UWW estimates of %F. The 1.5% difference in fat between the LNG and HRP calipers is consistentbetween males and females and strongly suggests that application of the HRP caliper introduces a systematic error beyond the random error of the skinfold method (Lohman, 1981), resulting in an underprediction of%F. The 10% systematic error identified in both males and females in this study may be taken into account in future
Results Zero-order correlations between all of the HRP and LNG skinfold values are presented in Table 1. In males the correlations ranged from + .96 to + .99 (p < .01), while the women's coefficients ranged from + .97 to + .99 (p < .01). Either caliper is equally effective in ranking individuals on the basis of skinfold values. However, the data in Table 1 also show there are mean differences in HRP and LNG skinfold values. In males, the ,,£7 skinfolds for the LNG = 104.5 mm and for the HRP =93.8 mm. In females, the ,,£7 skinfold values for the LNG = 113.5 mm and HRP = 103.7 mm. This is a 10% difference in both groups, with the HRP caliper producing the smaller values. Application of the paired r-test to the skin fold differences in Table 1 shows that significant differences exist in LNG and HRP caliper measures for each of the seven skinfold sites as well as the ,,£7 and "£3 values with the HRP producing the smaller value at each site. The nature of the differences between the LNG and HRP values can be explained by examining the mean differences, standard errors ofestimate (SEE), and total errors (E) for each skinfold site, the ,,£7 and "£3 values. The value E includes two
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GRUBBIl, POUOCIC, GRAVBS, CoLVlN, AND
application of the HRP caliper by utilizing one of the equations in Table4. Theseregressionequationspredict %F from LNG caliper values used in the I.7 or I.3 generalized equations fromskinfoldmeasurestakenwiththeHRPcaliper. The regression coefficients were all extremely high, and the SEE(%F) wereall withinacceptablelimitsrangingfrom+ 1.5 to 1.8%Ffor the I.7 equationsand + 2.3 to 3.3 %Ffor theI.3 generalized equations. The skinfolddata from the HRPand LNG caliperswere also entered into two other prediction equations to see if similardifferences in predicting Dbwouldoccur.In females,
BRAl'l1I
the skinfolddata for thesuprailiac and tricepssiteswereused in theSloan,Burt,andBlyth(1962) equation. For males, data from the abdomen and thigh sites were entered into the Wilmore and Behnke (1969) equation. As expected, the women'spredictedDbfromtheHRPwassignificantly higher (M = 1.0536± 0.0083) when compared with the LNG (M = 1.0511.±0.0085)(t [28] =8.12,p< .01).Themen's predicted Db from theHRPcaliperwassignificantly higher(M =1.0614 ± 0.0086) when compared with the LNG (M = 1.0589 ± 0.0092) (t [30] =-9.98,p < .01).Thus, the significant differencesin predictedDb in bothmalesand females are a function
Table 1 Comparison of Values- Obtained With the Lange and Harpenden Sklnfold Calipers at selected Sites"
Males (n- 31) HRP
LNG
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M
CH AX TR 55 AB 51 TH I,3 e I,7"
10.5 11.8 11.0 14.5 23.4 17.3 15.9 49.8 104.5
SO
M
SO
4.3 5.2 3.8 6.1 9.5 7.6 4.5 16.3 36.3
9.3* 10.5* 9.7* 13.7* 21.5* 15.2* 13.9* 44.7* 93.8*
3.7 4.5 3.3 5.7 8.8 7.3 4.1 14.9 32.8
CH AX TR 55 AB 51 TH I,3 I,7
11.5 11.6 16.4 14.0 19.9 13.4 26.7 56.5 113.5
MDiff.-
5EE'
f:9
.99 .98 .97 .99 .99 .99 .96 .99 .99**
-1.25 -1.33 -1.29 - 0.78 -1.93 - 2.11 - 1.98 - 5.20 -10.70
0.56 0.64 0.88 0.83 1.30 1.06 1.20 2.21 4.88
1.53 1.83 1.66 1.06 2.29 2.35 2.31 5.68 11.51
r
MDiff.-
5EE'
f:9
.97 .99 .97 .99 .98 .99 .98 .99 .99**
- 0.91 -1.15 -1.25 - 0.65 -1.85 -1.94 - 2.33 - 5.40 -10.25
1.02 1.51 0.90 1.02 1.69 1.02 1.13 2.08 5.40
1.35 1.63 1.59 1.19 2.45 2.24 2.63 5.92 11.04
Females (n = 29) HRP
LNG M
r
SO
M
SO
4.2 6.3 3.7 7.3 8.9 7.2 5.7 14.9 39.3
10.6* 10.7* 15.2* 13.5* 18.1* 11.6* 23.9* 50.8* 103.7*
4.1 6.1 3.6 7.1 8.1 7.1 5.7 14.7 37.3
"p « .05 between HRP and LNG calipers. ** All correlations significant (p < .01). -Lange and Harpenden skinfold measures in mm. loCH, chest; AX, axilla; TR, triceps; 55, subscapula; AB, abdominal; 51, suprailiac; TH, thigh. eI,3, sum of 3 skinfolds (Pollock, Wilmore, & Fox, 1984). dI,7, sum of 7 skinfolds (Pollocket aI., 1984).
-Mean difference •
I, (
yHN- yL )
,
where YH. value of the HRP measure and YL • value for the LNG '5EE • standard error of estimate • s ~ where s = mean of pooleddeviationsfor the two calipers.
9E =total error •
JI. (~
V)2
,
where ~ • LNG and v· the HRPvalue.
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Table 2 Cross-Validation Correlation Coefficients" for Estimating Hydrostatically Determined Body Density (OJ and %F from the "i"f> and "i3c Sklnfoldsb Using Two Different Sklnfold Calipers Females (n = 29)
Males (n= 31)
Caliper 'yt
SEEb(%F)
SEE(OJ
'yt
SEE(%F)
SEE(OJ
.84 .84
3.0 2.9
0.0067 0.0065
.85 .84
2.5 2.5
0.0055 0.0057
"i7 LNGd HRp·
.85 .84
2.6 2.4
0.0059 0.0057 "i3
.82 .80
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LNG HRP
2.7 2.6
0.0062 0.0061
·AII zero-order correlations significantly (p < .001) greater than zero. bOb calculated from the "i7 skinfolds using the following equations: males (Jackson & Pollock, 1978); females (Jackson et aI., 1980). cOb calculated from the "i3 skinfolds using the following equations: males and females (Jackson et aI., 1980). dLNG; Lange skinfold caliper. ·HRP; Harpenden skinfold caliper. 'SEE .. S ..J 1 Y
_,2 . yt
of caliper choice and are not unique to one particular prediction equation.Thisisdueto thefactthatoncesignificant caliper differences are shown to exist, the beta weights or constantsin any other equationwill not eliminate the differencesin thesamedataproducedby theHRPandLNGcaliper. Sites measured and/or constants in anyone equation will modifyslightly both the value of the HRP and LNG predictionsof Dbcomparedwithanotherequation,but note that the differences in predictions are still thereand are a function of caliper choice.
Discussion One is tempted to claim the differences in skinfold measures obtained with the LNG and HRP calipers in this studyare uniqueto thecalipersusedin our laboratory. This is not the case since the HRP caliper produced smaller values whencomparedwith theLNGin twoearlierstudies(Lohman etal., 1984;Sloan & Shapiro,1972).Thecalipersusedinthese three different laboratories were manufactured and used in differenttime periods. The averagepressuresof the calipers used in this study were 9.3 for LNG and 9.36 g/mm" for the HRP. Edwards et al, (1955) have indicated that pressure differences exertedat the facesof the caliperof only 1g/mm2 shouldnotaffectthereadingsby morethan0.2 mm.Thiswas not a problemin this studysince the pressuresexertedby the HRP and LNG calipers were the same. Explanation of the 10% difference between caliper measures may well lie in the design of the caliper and the nature of the soft tissue to which it is applied. Pressure is equal to force dividedby surfacearea. It followsthat as area is increased for the same amount of force, pressure will
decrease. Conversely, as surface area increases, force must increase to maintain an equal pressure. The surface area of each side of the LNG jaw opening is 30 mrn-, and the HRP surfacearea is 90 mm", Hence,an absoluteforceof 280 g for the LNG and 842 g for the HRP was requiredto developthe reportedpressures. Pressure is applied equally per unit of surface area to a liquid or gas enclosed in a cylinder. There may well be an unequal distribution of forces on skinfolds with the forces beinggreateror lesserat edgesof the calipersurfaceareadue to the nature of soft tissue. Applying a larger force is more like!ytodistortorcompressanobject,suchassofttissue,more than a smallerforce. The HRP required3.2 timesmoreforce to open its caliperjaws whencomparedwith the LNG in this study.Onecanalsoperceivethroughsensoryfeedback mechanismsin the hand that moreforceis requiredto open thejaws of the HRP caliper. In addition, when both calipers were appliedto the same skinfold, we noted it tookabouta second longer for the HRP dial pointer to stop moving, perhaps reflectinga greater force applied to the skinfold. Predictions of Db and %FfromtheJ-P generalized L7 and L3 equations in this study were more than adequate as evidenced by the high correlations withUWWestimates and the lowSEEof Dband %Ffor both maleand female samples. These cross validation findings are in agreementwith previous work on diverse samples (Bulbulian, 1984; Jackson & Pollock, 1978; Jackson et al., 1980; Latin, 1987; Pollock, Schmidt, & Jackson, 1980; Sinning & Wilson, 1984; and Thorlandet al., 1984).However, one notesfromTable 3 that significant differences existedin Dbmeans between theUWW estimatesandthe L7and L3 predictions. Themeandifference between UWW and LNG predictions was only 1.9%. Although statistically significant, this difference is relatively
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Table 3 Body Density (Db) and Percent Fat (%F) Values Determined by Underwater Weighing (UWW), Lange Sklnfold Calipers (LNG), and Harpenden Sklnfold Calipers (HRP) For Males and Females" Underwater Weighing Males (n .. 31)
Variable
M
1.0619 0.0104
SO %F
M
UWW
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M
SO LNG%F
M
SO
Variable
M
SO HRP%F
M
SO
1.0457 0.0114
16.1 4.6
SO
Variable
Females (n .. 29)
23.4 5.2
'£7 Skinfold Calculations
'£3 Skinfold Calculations
Males (n-31)
Females (n .. 29)
Males (n .. 31)
Females (n = 29)
1.0665 0.0111
1.0488 0.Q124
1.0665 0.0108
1.0481 0.Q104
14.2 4.9
14.2 4.7
22.0 5.6
22.4 4.7
,£7 Skinfold Calculations
'£3 Skinfold Calculations
Males (n .. 31)
Females (n .. 29)
Males (n .. 31)
Females (n .. 29)
1.0698 0.0105
1.0521 0.0121
1.0699 0.Q101
1.0523 0.0105
12.7 4.5
20.5 5.5
12.7 4.4
20.4 4.7
"Mean values for Db: UWW < LNG < HRP (p < .05); and for %F UWW > LNG> HRP (p
Research Quarterly for Exercise and Sport Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/urqe20
Comparison of Harpenden and Lange Calipers in Predicting Body Composition a
b
c
c
Joseph J. Gruber , Michael L. Pollock , James E. Graves , Andrea B. Colvin & Randy W. Braith
c
a
Department of Health, Physical Education and Recreation , University of Kentucky , Lexington , KY , 40506 , USA b
Center for Exercise Science , University of Florida , Gainesville , FL , 32601 , USA
c
Center , USA Published online: 26 Feb 2013.
To cite this article: Joseph J. Gruber , Michael L. Pollock , James E. Graves , Andrea B. Colvin & Randy W. Braith (1990) Comparison of Harpenden and Lange Calipers in Predicting Body Composition, Research Quarterly for Exercise and Sport, 61:2, 184-190, DOI: 10.1080/02701367.1990.10608673 To link to this article: http://dx.doi.org/10.1080/02701367.1990.10608673
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
GRUBER, POlLOCK, GRAVBS. CoLVIN, AND
BRAl'I1I
RaSBARCH QuARTERLY
RaSBARCH NOTB
FOR ExBRCISB AND SPORT
1990. VOL. 61, No.2. pp. 184-190
Comparison of Harpenden and Lange Calipers in Predicting Body Composition JOSEPH J. GRUBER University of Kentucky
Downloaded by [Purdue University] at 17:40 12 April 2015
MICHAEL L. POLLOCK, JAMES E. GRAVES, ANDREA B. COLYIN, AND RANDY W. BRArm University of Florida
Key words: skinfold, body composition, body density, skinfold calipers
Field methodsfor predictingbody composition from skinfold equations are becoming increasingly popular in situations where underwater weighing (UWW) is not feasible. Skinfoldmeasuresmustbe free fromanysystematicerrorthat may over- or underpredict body density (OJ and percent fat (%F). Severalinvestigators havealludedtodifferences among skinfoldcalipers as one source of error in predictingDb and %F from a regression equation (Burgert & Anderson, 1979; Lohman & Pollock,1984;Lohman,Pollock,Slaughter, Brandon, & Boileau,1984;Pollock & Jackson, 1984).No systematic differences in skinfold measures were reported by Imbibo, Fidanza, Caputo, and Moro (cited in Womersley & Durnin,1973),whereasSloanand Shapiro(1972)showedthe Harpenden (HRP) producedsmallervaluesat foursites when compared with the Lange (LNG). Meandifferences between threedifferentcaliperswerereportedby Morrow,Fridye,and Monaghen (1986).Other investigators reported that the HRP always produced smaller values when compared with the LNG when these calipers were applied to the same five skinfold sites (Lohman et al., 1984). A majority of these papersfailed to investigatepossibledifferences in Db and %F due to choice of caliper. The purposeof this study was to determineif predictions of Db and %F from the Jackson-Pollock (J-P) generalized equations were significantly related to type of skinfoldcaliper.Asecondary purposewastodevelopcorrectionequations for predicting %F, if needed.
Methods Subjects
Sixty Caucasian college students (n = 31 males; n = 29 females) reportedto the laboratoryfor testingafter signinga RaSBARCIl QuARTERLY Pal.
statementof informedconsent. Height was measured to the nearestO.lemwitha Harpenden stadiometerandweighttothe nearest0.1kg withan AcmeMedicalScale.Themalesranged in age from 19.1to 29.7 yrs (M=23.4±2.5 yrs),heightfrom 163.3to200.7em (M =176.4±7.5cm), and weightfrom 64.7 to 100.7kg (M =80.2 ± 10.7kg). The females ranged in age from18.7to29.9 yrs (M =22.7± 3.4years),heightfrom 154.3 to 173.4cm(M= 165.3±5.5 cm),andweightfrom45.6 to80.6 kg (M =57.4 ± 7.5 kg). Chest,axilla, triceps,subscapula, abdominal, suprailiac, and thigh skinfolds were measured twice in the order presented on the right side of the body with both the LNG and HRPcaliperbyanexperienced investigator. Sitesweremarked on each subject as illustratedin Pollock, Wilmore, and Fox (1984). All data were collected during a single test session usingone set of marks.Each site measurement wasrecorded by an independent scorer.Thus, the tester had no knowledge of the first sevenscoreswhenthesecondsetof measures were taken. If the two measures for a skinfold site did not agree within1mm,a thirdmeasurement wastaken.The meanof the two closest values was the final score for each site. This processwasrepeatedforthesecondcaliper.Caliperorderwas assigned alternately to each subject as he/she appeared for testing. The LNG and HRPcaliperswerecomparedagainsta standard calibration block, and readings between calipers werewithin0.2 mm throughout the range of five blocksizes. After data collection, the tension of both calipers was checkedaccording toproceduresrecommended by thecaliper manufacturers. Harpenden force is that required to begin movement or opening of the caliper jaws. This methodwas also followed in obtainingthe LNG forces. The HRP caliper pressuresrangedfrom8.97to 9.80 g/mm'', withan averageof 9.36g/mm20verseven thicknessesof6, 14,20,24,29, 33,and 37 mm. The LNG caliper pressures were a consistent 9.3 g/mm2 over six readings of 10, 20, 30, 40, 50, and 60 mm. Thus,thecalipersusedin thisstudymettherecommendations that calipers should not vary in pressure by more than 2.0 g/mm2 over a range of 2-40 mm and that the caliperpressure
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GRUBER, POllOCK, GRAVES, COLVIN, AND BRAITH
itself should be between 9 to 20 g/mm" (Edwards, Hammond, Healy, Tanner, & Whitehouse, 1955). The skinfold measures were used in the ,,£7 and "£3 generalized equations (Jackson & Pollock, 1978; Jackson, Pollock, & Ward, 1980) to predict Db' Percent fat was estimated from Db with the Siri (1961) equation. Actual Db was determined by the hydrostatic method with correction for residual volume (RV). Underwater weighing (UWW) was performed in a tank in which a chair was suspended from a 15-kg Chatillon scale. Repeated trials of UWW were performed until three trials agreed within 0.25 g. An average of the three most consistent trials was used as a criterion measure for UWW. Water temperature was recorded for each subject. Body density was calculated from the formula of Goldman and Buskirk (1961) and %F according to Siri (1961). Residual volume was estimated by the open circuit nitrogen washoutprocedure (Wilmore, 1969) using the Medical Graphics Advanced Pulmonary Function System 1070. Repeated trials were performed until two trials were within 50 ml of one another. The mean of these trials served as the RV value. The effectiveness of J-P ,,£7 and "£3 predictions of hydrostatically determined Db and %F were determined with zero-order correlations and standard errors of estimate. Mean differences in UWW, "£7, "£3 estimates of Db' and %F were analyzed with a repeated measures analysis of variance design. These statistical procedures were applied to both the HRP and LNG data sets. A paired r-test explored HRP and LNG differences at each skinfold site. All comparisons were tested for statistical significance at the .05 alpha level.
sources of variation, one the SEE and the other the difference between the true and estimated values. E can therefore be affected not only by the dispersion of individual scores, but also by any systematic error in the differences between true and estimated values (Lohman, 1981; Sinning & Wilson, 1984). The data in Table 1 show thatE exceeds the SEE for the "£7,"£3,and every skinfold site for both males and females. In addition, the mean differences are all negative and exceed the SEE for all but one tabled value. The mean difference for the ,,£7 for the males is -10.70, withE =11.51; the mean difference for the "£7 in the females is -10.25, with E = 11.04. The magnitude of E and the mean differences are similar and exceed SEE, indicating that a systematic error is present, with the HRP systematically producing smaller values at each skinfold site. This results in an underprediction of %F. Results from cross-validation of the J -P ,,£7 and "£3 prediction equations with UWW determined Db and %F are shown in Table 2. The correlations ranged from a r =+.80 to +.85 (p < .05). Standard errors of estimate (SEE) for Db and %F are acceptable and are equal or superior to previously reported data (Bulbulian, 1984; Jackson & Pollock, 1978; Jackson, Pollock, & Ward, 1980; Latin, 1987; Sinning & Wilson, 1984; Thorland, Johnson, Tharp, Fagot, & Hammer, 1984). There is no difference between the LNG or HRP caliper on the magnitude ofrelationships or SEE of Db and %F. These fmdings are consistent for both males and females. One also notes from Table 2 that the J-P "£3equation is just as effective as the ,,£7 equation in predicting Dband %F for this sample. Table 3 presents Db and %F determined by UWW and predicted by the ,,£7 and "£3 generalized equations. When comparing the ,,£7 and the "£3 mean scores for Db and %F in the males and females, one notes that the means are not statistically different (p > .05). Hence, our description of the repeated measures ANOVA results applies to the ,,£7 and "£3 data sets for all groups. There were significant increases in mean Db scores between the UWW, LNG, and HRP procedures, in that order. This translates into a significant decrease in %F predictions when comparing the UWW with the LNG and the LNG with the HRP caliper. In males, the prediction of %F from the LNG was 1.9% less than the UWW estimates. When comparing the LNG and HRP one notes that 1.5% less fat is predicted when using the HRP caliper. The HRP caliper measures predicted 3.4% less fat when compared to the UWW procedure. Somewhat similar values are seen in the data on females where the LNG predicted 1.4% less fat than UWW; the HRP predicted 1.5% less fat than the LNG values and the HRP underpredicted some 2.9%Fwhen compared with UWW estimates of %F. The 1.5% difference in fat between the LNG and HRP calipers is consistentbetween males and females and strongly suggests that application of the HRP caliper introduces a systematic error beyond the random error of the skinfold method (Lohman, 1981), resulting in an underprediction of%F. The 10% systematic error identified in both males and females in this study may be taken into account in future
Results Zero-order correlations between all of the HRP and LNG skinfold values are presented in Table 1. In males the correlations ranged from + .96 to + .99 (p < .01), while the women's coefficients ranged from + .97 to + .99 (p < .01). Either caliper is equally effective in ranking individuals on the basis of skinfold values. However, the data in Table 1 also show there are mean differences in HRP and LNG skinfold values. In males, the ,,£7 skinfolds for the LNG = 104.5 mm and for the HRP =93.8 mm. In females, the ,,£7 skinfold values for the LNG = 113.5 mm and HRP = 103.7 mm. This is a 10% difference in both groups, with the HRP caliper producing the smaller values. Application of the paired r-test to the skin fold differences in Table 1 shows that significant differences exist in LNG and HRP caliper measures for each of the seven skinfold sites as well as the ,,£7 and "£3 values with the HRP producing the smaller value at each site. The nature of the differences between the LNG and HRP values can be explained by examining the mean differences, standard errors ofestimate (SEE), and total errors (E) for each skinfold site, the ,,£7 and "£3 values. The value E includes two
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GRUBBIl, POUOCIC, GRAVBS, CoLVlN, AND
application of the HRP caliper by utilizing one of the equations in Table4. Theseregressionequationspredict %F from LNG caliper values used in the I.7 or I.3 generalized equations fromskinfoldmeasurestakenwiththeHRPcaliper. The regression coefficients were all extremely high, and the SEE(%F) wereall withinacceptablelimitsrangingfrom+ 1.5 to 1.8%Ffor the I.7 equationsand + 2.3 to 3.3 %Ffor theI.3 generalized equations. The skinfolddata from the HRPand LNG caliperswere also entered into two other prediction equations to see if similardifferences in predicting Dbwouldoccur.In females,
BRAl'l1I
the skinfolddata for thesuprailiac and tricepssiteswereused in theSloan,Burt,andBlyth(1962) equation. For males, data from the abdomen and thigh sites were entered into the Wilmore and Behnke (1969) equation. As expected, the women'spredictedDbfromtheHRPwassignificantly higher (M = 1.0536± 0.0083) when compared with the LNG (M = 1.0511.±0.0085)(t [28] =8.12,p< .01).Themen's predicted Db from theHRPcaliperwassignificantly higher(M =1.0614 ± 0.0086) when compared with the LNG (M = 1.0589 ± 0.0092) (t [30] =-9.98,p < .01).Thus, the significant differencesin predictedDb in bothmalesand females are a function
Table 1 Comparison of Values- Obtained With the Lange and Harpenden Sklnfold Calipers at selected Sites"
Males (n- 31) HRP
LNG
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M
CH AX TR 55 AB 51 TH I,3 e I,7"
10.5 11.8 11.0 14.5 23.4 17.3 15.9 49.8 104.5
SO
M
SO
4.3 5.2 3.8 6.1 9.5 7.6 4.5 16.3 36.3
9.3* 10.5* 9.7* 13.7* 21.5* 15.2* 13.9* 44.7* 93.8*
3.7 4.5 3.3 5.7 8.8 7.3 4.1 14.9 32.8
CH AX TR 55 AB 51 TH I,3 I,7
11.5 11.6 16.4 14.0 19.9 13.4 26.7 56.5 113.5
MDiff.-
5EE'
f:9
.99 .98 .97 .99 .99 .99 .96 .99 .99**
-1.25 -1.33 -1.29 - 0.78 -1.93 - 2.11 - 1.98 - 5.20 -10.70
0.56 0.64 0.88 0.83 1.30 1.06 1.20 2.21 4.88
1.53 1.83 1.66 1.06 2.29 2.35 2.31 5.68 11.51
r
MDiff.-
5EE'
f:9
.97 .99 .97 .99 .98 .99 .98 .99 .99**
- 0.91 -1.15 -1.25 - 0.65 -1.85 -1.94 - 2.33 - 5.40 -10.25
1.02 1.51 0.90 1.02 1.69 1.02 1.13 2.08 5.40
1.35 1.63 1.59 1.19 2.45 2.24 2.63 5.92 11.04
Females (n = 29) HRP
LNG M
r
SO
M
SO
4.2 6.3 3.7 7.3 8.9 7.2 5.7 14.9 39.3
10.6* 10.7* 15.2* 13.5* 18.1* 11.6* 23.9* 50.8* 103.7*
4.1 6.1 3.6 7.1 8.1 7.1 5.7 14.7 37.3
"p « .05 between HRP and LNG calipers. ** All correlations significant (p < .01). -Lange and Harpenden skinfold measures in mm. loCH, chest; AX, axilla; TR, triceps; 55, subscapula; AB, abdominal; 51, suprailiac; TH, thigh. eI,3, sum of 3 skinfolds (Pollock, Wilmore, & Fox, 1984). dI,7, sum of 7 skinfolds (Pollocket aI., 1984).
-Mean difference •
I, (
yHN- yL )
,
where YH. value of the HRP measure and YL • value for the LNG '5EE • standard error of estimate • s ~ where s = mean of pooleddeviationsfor the two calipers.
9E =total error •
JI. (~
V)2
,
where ~ • LNG and v· the HRPvalue.
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Table 2 Cross-Validation Correlation Coefficients" for Estimating Hydrostatically Determined Body Density (OJ and %F from the "i"f> and "i3c Sklnfoldsb Using Two Different Sklnfold Calipers Females (n = 29)
Males (n= 31)
Caliper 'yt
SEEb(%F)
SEE(OJ
'yt
SEE(%F)
SEE(OJ
.84 .84
3.0 2.9
0.0067 0.0065
.85 .84
2.5 2.5
0.0055 0.0057
"i7 LNGd HRp·
.85 .84
2.6 2.4
0.0059 0.0057 "i3
.82 .80
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LNG HRP
2.7 2.6
0.0062 0.0061
·AII zero-order correlations significantly (p < .001) greater than zero. bOb calculated from the "i7 skinfolds using the following equations: males (Jackson & Pollock, 1978); females (Jackson et aI., 1980). cOb calculated from the "i3 skinfolds using the following equations: males and females (Jackson et aI., 1980). dLNG; Lange skinfold caliper. ·HRP; Harpenden skinfold caliper. 'SEE .. S ..J 1 Y
_,2 . yt
of caliper choice and are not unique to one particular prediction equation.Thisisdueto thefactthatoncesignificant caliper differences are shown to exist, the beta weights or constantsin any other equationwill not eliminate the differencesin thesamedataproducedby theHRPandLNGcaliper. Sites measured and/or constants in anyone equation will modifyslightly both the value of the HRP and LNG predictionsof Dbcomparedwithanotherequation,but note that the differences in predictions are still thereand are a function of caliper choice.
Discussion One is tempted to claim the differences in skinfold measures obtained with the LNG and HRP calipers in this studyare uniqueto thecalipersusedin our laboratory. This is not the case since the HRP caliper produced smaller values whencomparedwith theLNGin twoearlierstudies(Lohman etal., 1984;Sloan & Shapiro,1972).Thecalipersusedinthese three different laboratories were manufactured and used in differenttime periods. The averagepressuresof the calipers used in this study were 9.3 for LNG and 9.36 g/mm" for the HRP. Edwards et al, (1955) have indicated that pressure differences exertedat the facesof the caliperof only 1g/mm2 shouldnotaffectthereadingsby morethan0.2 mm.Thiswas not a problemin this studysince the pressuresexertedby the HRP and LNG calipers were the same. Explanation of the 10% difference between caliper measures may well lie in the design of the caliper and the nature of the soft tissue to which it is applied. Pressure is equal to force dividedby surfacearea. It followsthat as area is increased for the same amount of force, pressure will
decrease. Conversely, as surface area increases, force must increase to maintain an equal pressure. The surface area of each side of the LNG jaw opening is 30 mrn-, and the HRP surfacearea is 90 mm", Hence,an absoluteforceof 280 g for the LNG and 842 g for the HRP was requiredto developthe reportedpressures. Pressure is applied equally per unit of surface area to a liquid or gas enclosed in a cylinder. There may well be an unequal distribution of forces on skinfolds with the forces beinggreateror lesserat edgesof the calipersurfaceareadue to the nature of soft tissue. Applying a larger force is more like!ytodistortorcompressanobject,suchassofttissue,more than a smallerforce. The HRP required3.2 timesmoreforce to open its caliperjaws whencomparedwith the LNG in this study.Onecanalsoperceivethroughsensoryfeedback mechanismsin the hand that moreforceis requiredto open thejaws of the HRP caliper. In addition, when both calipers were appliedto the same skinfold, we noted it tookabouta second longer for the HRP dial pointer to stop moving, perhaps reflectinga greater force applied to the skinfold. Predictions of Db and %FfromtheJ-P generalized L7 and L3 equations in this study were more than adequate as evidenced by the high correlations withUWWestimates and the lowSEEof Dband %Ffor both maleand female samples. These cross validation findings are in agreementwith previous work on diverse samples (Bulbulian, 1984; Jackson & Pollock, 1978; Jackson et al., 1980; Latin, 1987; Pollock, Schmidt, & Jackson, 1980; Sinning & Wilson, 1984; and Thorlandet al., 1984).However, one notesfromTable 3 that significant differences existedin Dbmeans between theUWW estimatesandthe L7and L3 predictions. Themeandifference between UWW and LNG predictions was only 1.9%. Although statistically significant, this difference is relatively
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GRUBER, POlLOCK, GRAVBS. CoLVIN, AND BRAl1lI
Table 3 Body Density (Db) and Percent Fat (%F) Values Determined by Underwater Weighing (UWW), Lange Sklnfold Calipers (LNG), and Harpenden Sklnfold Calipers (HRP) For Males and Females" Underwater Weighing Males (n .. 31)
Variable
M
1.0619 0.0104
SO %F
M
UWW
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M
SO LNG%F
M
SO
Variable
M
SO HRP%F
M
SO
1.0457 0.0114
16.1 4.6
SO
Variable
Females (n .. 29)
23.4 5.2
'£7 Skinfold Calculations
'£3 Skinfold Calculations
Males (n-31)
Females (n .. 29)
Males (n .. 31)
Females (n = 29)
1.0665 0.0111
1.0488 0.Q124
1.0665 0.0108
1.0481 0.Q104
14.2 4.9
14.2 4.7
22.0 5.6
22.4 4.7
,£7 Skinfold Calculations
'£3 Skinfold Calculations
Males (n .. 31)
Females (n .. 29)
Males (n .. 31)
Females (n .. 29)
1.0698 0.0105
1.0521 0.0121
1.0699 0.Q101
1.0523 0.0105
12.7 4.5
20.5 5.5
12.7 4.4
20.4 4.7
"Mean values for Db: UWW < LNG < HRP (p < .05); and for %F UWW > LNG> HRP (p
