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Generalized equations for predicting body density

Authors:

Abstract

1. Skinfold thickness, body circumferences and body density were measured in samples of 308 and ninety-five adult men ranging in age from 18 to 61 years. 2. Using the sample of 308 men, multiple regression equations were calculated to estimate body density using either the quadratic or log form of the sum of skinfolds, in combination with age, waist and forearm circumference. 3. The multiple correlations for the equations exceeded 0.90 with standard errors of approximately ±0.0073 g/ml. 4. The regression equations were cross validated on the second sample of ninety-five men. The correlations between predicted and laboratory-determined body density exceeded 0.90 with standard errors of approximately 0.0077 g/ml. 5. The regression equations were shown to be valid for adult men varying in age and fatness.
Br.
J.
Nufr.
(19781,
40,
497
497
Generalized equations for predicting body density
of
men
BY
A.
S.
JACKSON*
AND
M.
L.
POLLOCK?
Wake Forest University, Winston-Salem, North Carolina and Institute
of
Aerobics
Research, Dallas, Texas, USA
(Received
3
August
19-77
-
Accepted
28
February
1978)
I.
Skinfold thickness, body circumferences and body density were measured in samples
of
308
and ninety-
five adult men ranging in age from
18
to
61
years.
2.
Using
the sample of
308
men, multiple regression equations were calculated
to
estimate body density
using either the quadratic or log form of the sum of skinfolds, in combination with age, waist and forearm
circumference.
3.
The multiple correlations for the equations exceeded
0.90
with standard errors
of
approximately
+oao73
g/ml.
4.
The regression equations were cross validated on the second sample of ninety-five men. The corre-
lations between predicted and laboratory-determined body density exceeded
0.90
with standard errors of
approximately
0.0077
g/ml.
5.
The regression equations were shown
to
be valid for adult men varying in age and fatness.
Anthropometry is a common field method for measuring body density (Behnke
&
Wilmore,
1974).
BroZek
&
Keys
(1951)
were the first to publish regression equations with functions
of predicting body density with anthropometric variables. Subsequently, numerous investi-
gators have published equations using various combinations of skinfolds and body
circumferences.
The development of generalized equations for predicting body density from anthropo-
metric equations has been found to have certain limitations. First, equations have been
shown to be population specific and different equations were needed for samples of men
varying in age and body fatness. It was shown that with samples of men differing in age,
the slopes
of
the regression lines were homogeneous, but the intercepts were significantly
different (Durnin
&
Womersley,
1974;
Pollock, Hickman, Kendrick, Jackson, Linnerud
&
Dawson,
1976).
It was further shown that the slopes
of
the regression lines of young adult
men and extremely lean world class distance runners were not parallel (Pollock, Jackson,
Ayres, Ward, Linnerud
&
Gettman,
1976).
The differences of either slopes or intercepts
resulted in bias body density estimates. A related problem has been that linear regression
models have been used to derive prediction equations, when research has shown that a curvi-
linear relationship exists between skinfold fat and body density (Allen, Peng, Chen,
Huang, Chang
&
Fang,
1956;
Chen, Peng, Chen, Huang, Chang
&
Fang,
1975;
Durnin
&
Womersley,
1974).
This non-linear relationship may be the reason for the differences in
slopes and intercepts.
Durnin
&
Womersley
(1974)
logarithmically transformed the sum of skinfolds to create
a
linear relationship with body density, but still needed different intercepts to account for
age differences. The purpose of this investigation was to derive generalized regression
equations that would provide unbiased body density estimates for men varying in age and
body composition. Efforts were concentrated
on
the curvilinearity of the relationship and
the function of age
on
body density.
*
Present address: Department of Health and Physical Education, University of Houston, Houston,
Texas,
USA.
t
Present address
:
Cardiovascular Disease Section,
Mount
Sinai Medical Center, University of Wiscon-
sin, School of Medicine, Milwaukee, Wisconsin, USA.
17-2
498
A.
S.
JACKSON
AND
M.
L.
POLLOCK
Table
I.
Physical characteristics
of
the validations and cross-validation samples*
Validation sample Cross-validation sample
(n
308)
(n
95)
,.
7,
.,
Variable Mean
SD
Range Mean
SD
Age (year)
Height
(m)
Weight
(kg)
Body
density (g/ml)
Fat
(%It
Lean weight (kg)
Fat weight (kg)
Sum
7
skinfolds (mm)
Log
7
skinfolds (mm)
Sum
3
skinfolds (mm)$
Log
3
skinfolds (mm)
Waist circumference (m)
Forearm circumference
(m)
32.6 10.8
74.8
11.8
17'7 8.0
1.792
0.065
1.05E6 0.0181
63.9 7.4
14'5 7'9
122.6
52.0
59'4 243
4'70 0.49
3'98 0.49
0.871 0'097
0.288 0.019
I
8-6
I
1.63-2.01
54-
1
23
I
'01
61-1.0996
1-33
48-
100
1-42
3.47-5'61
14-1
18
32-272
2-64-4'78
0.67-1
'25
0'22-0'37
33'3
77.6
18.7
62.4
15.2
124.7
59'2
1.784
1.0564
4'7
I
3'95
0.874
0.287
11.5
0.059
11.7
0.0188
8.3
6.7
7'9
53'1
0.53
25'4
036
0'
I
0'02
I
Range
18-59
1.66-1.91
1.0259-1q98
1-33
47-81
1-31
31-222
3'43-5'40
10-111
2'30-471
0'244,'39
53-102
0.68-1.14
*
For explanation see p.
499.
t
Fat
(%)
=
[(4.95/BD)+4.5]
IOO
(Siri,
1961)
Fat
(%).
t:
Sum
of chest, abdomen and thigh skinfolds.
METHODS
A total of
403
adult men between
18
and
61
years of age volunteered as subjects. The
sample represented a wide range of men who varied considerably in body structure, body
composition, and exercise habits. The subjects were tested in one of two laboratories
(Wake Forest University, Winston-Salem, North Carolina and Institute for Aerobics
Research, Dallas, Texas) over a period of
4
years. The total sample was randomly divided
into a validation sample consisting
of
308
men and a cross-validation sample
of
ninety-five
subjects. The validation sample was used to derive generalized regression equations and
were cross-validated with the second sample. This procedure has been recommended by
Lord
&
Novick
(1968).
The physical characteristics of the two samples are presented in
Table
I.
Upon arrival at the laboratory, the subjects were measured for standing height to the
nearest
0.01
m
(0.25
in) and for body-weight to the nearest
10
g. Skinfold fat was measured
at the chest, axilla, triceps, subscapula, abdomen, supra-iliac, and thigh with
a
Lange
skinfold fat caliper, manufactured by Cambridge Scientific Industries, Cambridge, Mary-
land, USA.
Recommendations published by the Committee on Nutritional Anthropometry of the
Food and Nutrition Board of the National Research Council were followed in obtaining
values for skinfold fat (Keys,
1956).
A previous study (Pollock, Hickman
et
al.
1976)
showed
that waist and forearm circumference accounted for body density variance beyond skinfold
fat, and for this reason, were included jn this study. Waist and forearm circumferences
were measured to the nearest
I
mm with a Lufkin steel tape, manufactured by the Lufkin
Rule Company, Apex, North Carolina, USA. The procedures and location of the anthro-
pometric sites measured were shown and described by Behnke
&
Wilmore
(1974).
The hydrostatic method was used to determine body density. Underwater weighing was
conducted in a fibreglass tank in which a chair was suspended from a Chatillon
15
kg scale.
The hydrostatic weighing procedure was repeated six to ten times until three similar read-
ings to the nearest
20
g were obtained (Katch,
1968).
Water temperature was recorded
after each trial. Residual volume was determined by either the nitrogen washout
or
helium
dilution technique. The procedure for determining body density followed the method out-
Generalized body density equations
499
Table
2.
Regression analysis for predicting body density using the
sum
of
seven skinfolds in
adult men aged
18-61
yearst
F, ratio Standard regression
Degrees of Sum
of
Mean for statistical certificate for
Source of variance freedom squares square significance full model
Sum
of
seven skinfolds
Full model
Skinfold fat
Linear
Quadratic
Circumferences
Age
Waist
Forearm
Residual
0.084
I
8
0.07878
(0'07757)
(0'00121)
0'00279
0.00261
-
0.01612
0.01
684
0.03939
0,07757
0'00121
0'00279
0~00261
L
Log transformation of seven skinfolds
Full model
4
0.08425 0~02106 421.20*
-
Log skinfold fat
(I)
0.07706 0.07706 1541.20*
-
0.64
(I)
0.00284 0.00284 56.80*
-0.13
Age
-
-
-
-0.38
-
-
0.23
Residual
303
0.01605
0~00005
-
-
-
Circumferences
(2)
0.00435 0.00435 87~*
Waist
-
Forearm
-
-
*
P
<
0'01.
t
For details, see Table
I.
lined by Goldman
&
Buskirk
(1961).
Body density was calculated from the formula of
Broiek, Grande, Anderson
&
Keys
(1963)
and fat percentage according to Siri
(1961)
(see Table
I).
In
a
factor analysis study,
it
was shown (Jackson
&
Pollock,
1976)
that skinfolds measured
the same factor; therefore, the skinfolds were summed. The sum of several measurements
provides
a
more stable estimate of subcutaneous fat. A second sum consisting of
chest, abdomen and thigh skinfolds was also derived. These three skinfolds were selected
because of their high intercorrelation with the sum of seven and
it
was thought that they
would provide
a
more feasible field test. The sum of skinfolds were also logarithmically
transformed
so
that they could be compared with the work of Durnin
&
Womersley
(1974).
Regression analysis (Kerlinger
8t
Pedhazur,
1973)
was used to derive the generalized
equations. Polynomial models were used to test if the relationship between body-density
and the sum
of
skinfolds was curvilinear. 'Step-down' analysis was used to determine if
age, and then age in combination with the circumference measurements, accounted for
additional body-density variance beyond that attributed
to
the sum of skinfolds. The cross-
validation procedures recommended by Lord
&
Novick
(1968)
were followed to determine
if the equations derived
on
the validation sample accurately predicted the body density of
the cross-validation sample.
RESULTS
Table
I
shows that basic results derived from the validation and cross-validation samples
including natural log transformations of the sum of skinfolds. The standard deviations
and ranges showed that the men differed considerably in both age and body composition.
Tables
z
and
3
show the regression analysis using the sum of seven and sum of three skin-
500
A.
s.
JACKSON
AND
M.
L.
POLLOCK
Table
3.
Regression analysis for predicting body density using the
sum
of
three skinfoldst
Source of variance
Full model
Skinfold fat
Linear
Quadratic
Circumferences
Age
Waist
Forearm
Residual
Full model
Log skinfold fat
Circumferences
Age
Waist
Forearm
Residual
Sum of
squares
F, ratio Standard regression
Mean for statistical certificate for
square significance full model
Sum of three skinfolds
0.01691 338.20*
0~04000 800.00*
0.07943 1588.60*
000055
I
I.OO*
0'00220
44'00*
0.0011~ 23.40.
-
-
-
-
-
-
-1.11
-0.12
0.43
-
-0.31
0.19
-
0.01571
0~00005
-
Log
transformation
of
three skinfolds
0.08415 0~02104 420.80*
-
007614
0.07674 1534.80~ -0.62
om~248 0.00248 49'60*
-0.11
0.00493 0.00493 98.60*
-
-0.41
0.23
0.01626
0~00005
-
-
-
- -
-
-
-
*
P
<
0'01
t
For details,
see
Table
I.
folds respectively. The correlation between the sum of three and seven skinfolds was
0.98;
thus, the regression analyses for these variables were nearly identical. The full model
consisted of either the linear and quadratic or the log transformed sum of skinfolds in
combination with age, and body circumferences. The multiple correlations for these full
models were nearly identical, ranging from
0.915
to
0.9
18.
Regression equations for the
full models may be found in Table
4.
Since the full models were significant, the step-down analysis was conducted to determine
if
each variable accounted for
a
significant proportion of body-density variance. The first
analysis within the full model was to determine if the relationship between skinfold fat and
body density was linear or quadratic. This was found to be quadratic which supported the
findings of other investigators (Allen
et al.
1956;
Chen
et
al.
1975;
Durnin
&
Womersley,
1974).
Durnin
&
Womersley
(1974)
used a log transformation to form a linear relationship
between skinfold fat and body density. For this reason, only the linear relationship with
log transformed skinfolds was used.
Age was the next variable entered into the regression model and it accounted for a signifi-
cant proportion of body-density variance beyond the log-transformed
or
quadratic form
of skinfolds. Waist and forearm circumference were the last two variables entered into the
full model and these measures accounted for a significant proportion of body-density
variance beyond age and skinfold fat.
The standardized regression coefficients for the full model are presented in Tables
2
and
3.
The magnitude of these weights represented the relative importance of each variable with
the effects of the other variables held constant. These statistics showed that the linear and
quadratic components accounted for most of the body density variance. The negative
weighting of the sum of skinfolds and positive weighting of the squared sum
of
skinfolds
represent the quadratic relationship between body density and the sum of skinfolds. The
Generalized body density equations
501
Table
4.
Generalized regression equations
for
predicting body density
(BD)
of
adult men
ages
I
8-61
years*
Anthropometric Eauation
variables
S,P,
age
S,Sz,
age,
C
log
S,
age
log
S,
age,
C
S,S1,
age
(5)
Regression equation no. R
Sum of seven skinfolds
BD
=
1.1
IZOOOOO-0.00043499
(X1)+0.00000055
I
0.902
BD
=
1~10100000
-
0.00041
I
50
(X,)
+
0~00000069
(
X,),
z
0916
-0~00028826 (X3)
-0.0002~63I (X3)-0'0059239 (X4)+0.0190632
(X,)
BD
=
1'21394-0'03101 (log X,)-0~00029 (X3) 3 0.893
BD
=
1.17615-0.02394 (log
X,)-OQOOZZ (X,)
4 0'917
-0.0070
(X4)+0'02120
(X,)
Sum of three skinfolds
BD
=
1.1093800-0~0008267 (X,)+0~0000016
(X,)a
5
0'905
-0.0002574
(Xs)
BD
=
1.0990750-0.0008~09 (X2)+0~0000026
(A',),
6
0.918
BD
=
1,18860-0.03049 (log X,)-0~00027
(X,)
7
0.888
-00002017 (X3)-0*005675
(X,)
-t
0.018586
(X,)
BD
=
1.15737-0.02288 (log X,)-000019
(X,)
8
0,915
-0.0075
(xd)+O'OZ23
(XE.)
SE
0.0078
0'0073
0.0082
0.0073
0.0077
om72
0.0083
0.007
3
s,
Sum of skinfolds;
C,
circumference;
X,,
sum of chest, axilla, triceps, subscapula, abdomen, suprailium
and front thigh skinfolds;
X,,
sum of chest, abdomen and thigh skinfolds; X3, age;
X4,
waist circumference;
X,,
forearm circumference.
*
For details, see Table
I.
Table
5.
Cross-validation
of
generalized equations
on
the calibration sample (n
95)
Range of
SE
A
,
\
Variables Equation no.*
ryyf
SET
Age$ Fat§
S,S2,
age
I
0.915 0.0078 0~0064-0~0085 0~0066-0~0092
S,
Sa,
age,
C
2
0.915 00077 00057-0Oog4 00067-0.0084
log
S,
age 3 0.914 0.0078
oao55-0.0085
0.0054-0.oog1
log
S,
age,
C
4 0.913 0.0078 0.0061-0.0098 0~0064~~oog1
S,
S2,
age
5
0.917 0~x177 0~0066-0m83
0~00574~0087
S,
S2,
age,
C
6
0920
0.0076 00066-00092 oa~58-0~0087
Sum
of
seven skinfolds
Sum of three skinfolds
Log
S,
age 7 0.904
0.0085
0.0064-0.0112
0~00474'0102
log
S,
age,
C
8
0.910
0.0082
OfX357-0~0100
OC€&-O~oOg7
s,
sum of skinfolds;
C,
circumference;
ruvt,
correlation between predicted
(y')
and laboratory determined
*
For
details, see Table
4.
t
SE
=
2/[~(J"--Y)a/~1.
2
Age (years) categories
;
<
19.9, ZOe--299, 39'0-39'9, 40'0-49'9,)
50'0.
3
Fat
(%)
categories: <9.9, 10.0-14.9, 15c-19.9, 20.0-249,)
25.0.
b)
body
density.
positive weighting for waist and negative weighting for forearm is consistent with the results
reported by Katch
&
McArdle
(1973).
Table
4
lists selected raw score equations and the equation's multiple correlation and
standard error. The high multiple correlations are due partially to the heterogeneous sample
studied. However, the standard errors are low and well within the values reported by other
502
A.
s.
JACKSON
AND
M.
L.
POLLOCK
1.100
1.095
1.090
1.085
1.080
1.075
1.070
1.065
2
1,060
.-
1.055
1.050
1.045
8
1.040
1.035
1,030
1.025
1.020
1.015
1.010
.
0
-
+
-
'
+*
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
investigators (Katch
&
McArdle,
1973;
Pascale, Grossman, Sloane
&
Frankel,
1956;
Pollock, Hickman
et
af.
1976;
Sloan,
1967;
Wilmore
&
Behnke,
1969;
Wright
&
Wilmore,
1974)
who used more homogeneous samples.
The 'raw score' equations were applied to the anthropometric results
of
the cross-
validation sample. The cross-validation analysis is presented in Table
5.
The product
moment correlation between laboratory determined and estimated body density were all
higher than
0.90,
and the standard errors were within the range found with tte validation
sample results.
The cross-validation sample was then reduced first, to five age categories, and next,
to
levels
of
body fat content by five fat
(%)
categories. The ranges
of
standard errors for these
different categories are also presented
in
Table
5.
With the exception
of
the
log
equations,
none
of
the standard
errors
exceeded
O.OIOO
g/ml. Since these standard error estimates
were based on sample sizes that varied from ten to thirty-three cases, more variability was
expected. These analyses showed that the regression equations accurately predicted body
density for samples differing in age and fatness.
DISCUSSION
The findings
of
several studies (Durnin
&
Womersley,
1974;
Pollock, Hickman
ct
d.
1976)
showed that regression equations were population specific. The application
of
regres-
sion equations derived
on
one sample, but applied
to
other samples that differed in age and
fatness, produced biassed body density estimates. The findings of this study showed that
some of this bias may be attributed to the use
of
linear regression models because the
Generalized body density equations
503
relationship between skinfold fat and body density was quadratic. This is shown by the
‘scattergram’ between the sum of seven skinfolds and body density which is presented as
Fig.
I.
Both linear and quadratic regression lines are provided. The differences between the
two regression lines showed where the largest bias prediction errors would occur. This was
at the ends
of
the bivariate distribution. For example, the fat
(yo)
differences between the
linear and quadratic sum of seven skinfold equations for
250
and
40
mm of skinfold fat
were
2.9
and
1.3
fat
(yo)
respectively, while the difference was only
0.5
fat
(yo)
for
150
mm.
In
a previous study (Pollock, Jackson
et
al.
1976),
it was found that the slopes of the
regression lines of lean world-class distance runners and young adult men were not parallel.
The prediction of the body-density of the lean runner with linear equations derived on
a
sample of young adult men systematically underestimated the body density of these lean
subjects. This source of systematic error is documented by the differences between the linear
and quadratic regression lines shown in Fig.
I
and confirms the need for quadratic equations.
Jt has been shown that the intercepts of the regression lines of young adult men and older
(+
35
years) and fatter men were different (Pollock, Hickman
et
al.
1976).
Since the relation-
ship between body-density and skinfold fat was quadratic, the differences in intercepts
could be partly due to the use of linear regression equations. The results reported by
Durnin
&
Womersley
(1974)
showed, however, that age was also responsible for the inter-
cept differences. Durnin
&
Womersley
(1974)
used
a
logarithmic transformation of the
sum of four skinfolds. This transformation changed the quadratic relationship between
body density and the sum of skinfolds, in the ‘raw score’ form, into
a
linear relationship.
With male subjects who ranged from
16
to
59
years of age, they reported that the slopes for
samples divided by
10
year intervals were parallel, but had different intercepts. This would
result in biassed estimates due to age differences, thus Durnin
&
Womersley
(1974)
pro-
vided five different equations which had the same slope, but different intercepts.
The finding of this study, that age accounted for
a
significant proportion of body-density
variation beyond that attributed to quadratic or logarithmic sum of skinfolds agreed with
the findings reported by Durnin
&
Womersley
(1974).
They suggested that this age-
relationship may be due to
a
higher proportion of total body fat being situated internally
and a decrease in the density of fat-free mass. The decrease in fat-free mass was primarily
attributed to skeletal changes (Durnin
&
Womersley,
1974).
In the present study, the use
of age as an independent variable accounted for intercept difference, and eliminated the
need for several different age-adjusted equations. The cross-validation results documented
the accuracy
of
a
generalized equation for samples differing in age and fatness. The standard
errors found in these analyses are within the range reported by Durnin
&
Womersley
(1974).
Using
209
men who varied in age from
16
to
72,
Durnin
&
Womersley
(1974)
reported standard errors that ranged from
0.0059
to
0.0
I
17
g/ml for prediction equations
derived for similar age groups.
The multiple correlations for the generalized equations derived with the logarithmic
or
quadratic sum of skinfolds were nearly identical. The results of the cross-validation analysis
suggested that the quadratic equations were more accurate. The standard errors tended to
be lower for the total sample and less variable for the total sample and for the different
age and fat
(Oh)
categories. This was expecially true for the sum of three skinfolds.
The generalized equations provided valid and accurate body-density estimates with adult
men varying in age and fatness. The cross-validation of equations is important because one
is not certain that equations developed with one sample will predict body density with the
same accuracy when applied to the data of a different sample. The best evidence
is
pro-
vided by the standard error when the equation is cross-validated on the second sample. The
standard errors for the cross-validation analysis were low and nearly identical to the
standard errors found with the validation sample. This provided the strongest evidence
504
A.
s.
JACKSON
AND
M.
L.
POLLOCK
that the generalized equations were accurate and valid
for
use with adult men varying in
age and body density.
REFERENCES
Allen,
T.
H., Peng,
M.
T.,
Chen, K. P., Huang,
T.
F.,
Chang, C.
&
Fang, H.
S.
(1956).
Metabolism
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... The standard error of estimation (SEE) of body fat from the SF method is about 2-3% of body weight [22] or a total error (biological plus technical) for the prediction of body fat content of about 3.3% [13]. Under standardized conditions, however, the SF method has been frequently used for determining body composition with a relatively high validity compared to the UWW method [13,[22][23][24]. ...
... For determining body fat, the UWW methods have a standard error of estimation of about 2-3% of body weight [22] or a total error (biological and technical error) of 3-4% [13]. For the past 20-30 years, the UWW method was the widely accepted reference method for determining body composition [6,[22][23][24]. ...
... When the two measurements taken at each site were greater than 1 mm, a third or fourth measurement was repeated. The nearest two values within 1 mm were averaged and used for calculating body density (Db) using the generalized equation of Jackson and Pollock for males [23] and females [24]. The %BF was then calculated according to Brozék et al. [6]. ...
Article
Full-text available
The purpose of the study is to examine the effect of exercise-induced dehydration on body composition using three indirect methods: bioelectrical impedance analysis (BIA), skinfold thickness (SF), and underwater weighing (UWW).Method: Thirty healthy, physically active subjects with normal weight (22 males) participated as study subjects. After baseline body composition measurements using the above three methods were obtained, the subjects began to dehydrate by exercise until an average of 1.5% body weight loss was accomplished. Within 10 minutes post-exercise, the subjects’ body composition measurements using the same measurement methods were repeated. Results: There was a significant (p<0.05) difference between the three methods for determining fat free mass (FFM), fat mass (FM), and percent body fat (%BF). The %BF and FM measurements using the BIA method were significantly (p<0.05) affected by exercise-induced dehydration, but not the UWW or the SF method. Compared to the UWW method before dehydration, the SF method significantly (p<0.05) under-estimated FM, %BF, and over-estimated FFM, whereas the BIA method significantly (p<0.05) over-estimated FM and % BF, and under-estimated FFM. These observations also occur after exercise-induced dehydration. Comparing genders, the BIA method produced higher %BF and FM values in the female subjects than in the male subjects both before and after dehydration. Conclusion: We concluded that exercise-induced dehydration of 1.5% weight loss significantly (p<0.05) limits the usefulness of the BIA method for determining human body composition in physically active and normal weight adults, whereas dehydration induced an insignificant effect on the SF or UWW method.
... Deri kıvrımları, derinin iki katmanının kalınlığını ve alt kısmında bulunan deri altı yağını ölçer. Deri kıvrımında ölçülen kısımlar vücut yağı yüzdesini çeşitli kısımların ölçümünü yaparak tahmin edilebilir (30). Örneğin önceki modellerde yedi farklı bölgeden alınmış deri kıvrım kalınlıkları kullanılırken Jackson ve Pollock (1985) vücut yağının tahmini için üç deri kıvrımı (göğüs, karın ve uyluk) toplamından oluşan bir denklem geliştirmişlerdir (31). ...
... Lower-thigh girth circumference was measured 5cm from the top of the patella, and calf girth circunference was measured with legs slightly apart with body mass equally distributed on both legs. All circumferences assessed were as follow: (1) [26], additionally, the BF% was calculated by using the Siri [27] formula. The thickness of the nine skinfolds (triceps, subscapular, biceps, supra iliac, abdominal, pectoral, medium axillar, front-thigh, and media calf) was measured using a Harpenden skinfold calliper (British Indicators, Burgess Hill, UK) and calculated according to Durnin and Womersley [28]. ...
Article
Full-text available
Rink hockey is a highly specialized and physiological demanding sport with sparse research regarding the game and athletes' characteristics. A cross-sectional study was developed to characterize the body composition and grip strength of elite male rink hockey players and to establish the relationship between ethnicity on body composition and grip strength. A sample of 100 elite rink-hockey athletes aged 26.59 ± 6.02 participated in the study, comprised of 69 Caucasian male adults aged 27.58 ± 6.44 years and 31 Black African male adults aged 24.39 ± 4.27. Body composition was assessed by anthropometric measurements. Static grip strength was assessed with an adjustable dynamometer. Multiple regression analysis was applied to understand which variables constraints body fat percentage (BF) and grip strength. Body mass showed an average of 76.36 ± 9.18 kg for 175.80 ± 5.87 cm of height and BF% of 10.82 ± 5.07%. Maximal right grip strength was 50.91 ± 6.26 kg and 50.27 ± 6.23 kg for left grip strength. Four predictors accounted for 70.01% of the variance of BF%: abdominal circumference (p < 0.001), right thigh circumference (p < 0.001), right calf circumference (p = 0.001) and ethnicity (p = 0.016). Three predictors accounted for 13.1% of the variance of right grip strength: ethnicity (p = 0.013), chronological age (p = 0.024) and right distal thigh circumference (p = 0.014). Results suggest that elite rink hockey athletes have a specific anthropometric identity, which at the elite level may lead to reduced body fat and greater handgrip strength. Ethnicity seems to predict body fat and grip strength in elite rink hockey athletes.
... Lower-thigh girth circumference was measured 5cm from the top of the patella, and calf girth circunference was measured with legs slightly apart with body mass equally distributed on both legs. All circumferences assessed were as follow: (1) [26], additionally, the BF% was calculated by using the Siri [27] formula. The thickness of the nine skinfolds (triceps, subscapular, biceps, supra iliac, abdominal, pectoral, medium axillar, front-thigh, and media calf) was measured using a Harpenden skinfold calliper (British Indicators, Burgess Hill, UK) and calculated according to Durnin and Womersley [28]. ...
Article
Full-text available
Rink hockey is a highly specialized and physiological demanding sport with sparse research regarding the game and athletes' characteristics. A cross-sectional study was developed to characterize the body composition and grip strength of elite male rink hockey players and to establish the relationship between ethnicity on body composition and grip strength. A sample of 100 elite rink-hockey athletes aged 26.59 ± 6.02 participated in the study, comprised of 69 Caucasian male adults aged 27.58 ± 6.44 years and 31 Black African male adults aged 24.39 ± 4.27. Body composition was assessed by anthropometric measurements. Static grip strength was assessed with an adjustable dynamometer. Multiple regression analysis was applied to understand which variables constraints body fat percentage (BF) and grip strength. Body mass showed an average of 76.36 ± 9.18 kg for 175.80 ± 5.87 cm of height and BF% of 10.82 ± 5.07%. Maximal right grip strength was 50.91 ± 6.26 kg and 50.27 ± 6.23 kg for left grip strength. Four predictors accounted for 70.01% of the variance of BF%: abdominal circumference (p < 0.001), right thigh circumference (p < 0.001), right calf circumference (p = 0.001) and ethnicity (p = 0.016). Three predictors accounted for 13.1% of the variance of right grip strength: ethnicity (p = 0.013), chronological age (p = 0.024) and right distal thigh circumference (p = 0.014). Results suggest that elite rink hockey athletes have a specific anthropometric identity, which at the elite level may lead to reduced body fat and greater handgrip strength. Ethnicity seems to predict body fat and grip strength in elite rink hockey athletes.
... The inclusion criteria were athletes aged between 14 and 18 years, visiting the outpatient clinic for a voluntary performance review. Each study participant underwent a clinical examination for the suitability of a physical load (12-lead ECG), determination of the resting heart rate (Assy Cam 14®, GE Healthcare, Chicago, Illinois, USA), resting blood pressure (oscillatory, Boso Medi-cus®, BOSCH+SOHN, Jungingen, Germany), physical examination, an estimation of the total body fat (Caliper, John Bull, British Indicators Ltd., St Albans, UK) (Jackson and Pollock, 1978), and a history of the accomplished training. Athletes were excluded from the study in case of incomplete study parameters. ...
Article
The maximal oxygen uptake (VO2max) and maximal power output (Pmax) are commonly used parameters to evaluate the endurance fitness status. A connection between exercise and the kynurenine pathway (KP), which describes the metabolism of unused tryptophan, has already been reported. However, a potential association of the KP with endurance fitness levels remains unknown. In this study, adolescent competitive athletes performed an exhaustive incremental exercise test. Blood samples were taken before, directly after, and 30 minutes after the end of exercise. Tryptophan (Trp), kynurenine (Kyn) and kynurenic acid (KA) serum levels were determined by high-performance liquid chromatography (HPLC). Forty-four male and 27 female athletes (median age: 16 years) were recruited. During exhaustive exercise tests, Trp initially declined and then increased 30 minutes after discontinuing exercise. Similar findings were observed for Kyn, whereas KA levels behaved inversely. After incremental exhaustive exercise the relative increase of Trp concentrations, termed the tryptophan-recovery-index (TRI), showed a highly significant positive correlation with VO2max and Pmax (r=0.468 and 0.491, p-values <0.001). There was a significant gender-difference with higher levels of all metabolites at all measured time points in male participants. In the present study, a highly significant correlation was found between the TRI and the maximal oxygen uptake in well-trained athletes. The implementation of TRI can therefore be suggested as a biomarker for physical fitness.
... Baseline testing consisted of measurements of stature, body mass, body fat percentage, and VO 2 max. Body density was estimated using three-site (chest, abdomen, thigh) skinfold measurements (Lange, Beta Technology, Santa Cruz, CA) (Jackson and Pollock 1978), and then converted to body fat percentage using a standardized equation (Brožek et al. 1963). Participants performed a graded exercise test on a motorized treadmill (Precor, TRM885, Woodinville, WA) to determine their VO 2 max. ...
Article
Full-text available
Purpose The purpose of this study was to determine the effect of prolonged high-intensity interval (INT) and moderate-intensity continuous (CONT) treadmill exercise in the heat on markers of enterocyte injury and bacterial endotoxin translocation. Methods Nine males completed 2 h of work-matched exercise in the heat (40 °C and 15% RH) as either INT (2 min at 80% VO2max and 3 min at 30% VO2max) or CONT (~ 50% of VO2max). Blood samples collected pre- and post-exercise were assayed for intestinal fatty acid-binding protein (I-FABP), claudin-3 (CLDN-3), and lipopolysaccharide-binding protein (LBP). Results I-FABP was significantly increased from pre- to post-exercise in CONT (913.96 ± 625.13 to 1477.26 ± 760.99 pg•mL⁻¹; p = 0.014, d = 0.766) and INT (714.59 ± 470.27 to 1547.93 ± 760.99 pg•mL⁻¹; p = 0.001, d = 1.160). Pre- to post-exercise changes in I-FABP were not different between CONT and INT (p = 0.088, d = 0.414). LBP was significantly increased from pre- to post-exercise in INT (15.94 ± 2.90 to 17.35 ± 3.26 μg•mL⁻¹; p = 0.028, d = 0.459) but not CONT (18.11 ± 5.35 to 16.93 ± 5.39 μg•mL⁻¹; p = 0.070, d = 0.226), and pre- to post-exercise changes in LBP were higher in the INT compared to CONT (p < 0.001, d = 1.160). No significant changes were detected from pre- to post-exercise for CLDN-3 in CONT (14.90 ± 2.21 to 15.30 ± 3.07 μg•mL⁻¹) or INT (15.55 ± 1.63 to 16.41 ± 2.11 μg•mL⁻¹) (p > 0.05). Conclusions We conclude that prolonged exercise in the heat induces enterocyte injury, but interval (or intermittent) exercise may cause greater bacterial endotoxin translocation which may increase the risk for local and systemic inflammation.
... composition via 3-site skinfolds (21,22), and a maximal graded exercise test on a cycle ergometer at 440 Torr in a hypobaric chamber. The maximal graded exercise test was a 20 watt•minute -1 ramp protocol which began at 40 watts. ...
Article
Purpose: The purpose of this study was to evaluate the effects of acute ibuprofen consumption (2 x 600 mg doses) on markers of enterocyte injury, intestinal barrier dysfunction, inflammation, and symptoms of gastrointestinal (GI) distress at rest and following exercise in hypobaric hypoxia. Methods: Using a randomized double-blind placebo-controlled crossover design, nine males (age: 28 ± 3 years, weight: 75.4 ± 10.5 kg, height: 175 ± 7 cm, body fat: 12.9 ± 5 %, VO2peak at 440 Torr: 3.11 ± 0.65 L•min-1) completed a total of three visits including baseline testing and two experimental trials (placebo and ibuprofen) in a hypobaric chamber simulating an altitude of 4300 m. Pre- and post-exercise blood samples were assayed for intestinal fatty acid binding protein (I-FABP), ileal bile acid binding protein (I-BABP), soluble cluster of differentiation 14 (sCD14), lipopolysaccharide binding protein (LBP), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-10. Intestinal permeability was assessed using a dual sugar absorption test (L/R ratio). Results: Resting I-FABP (906 ± 395 vs 1168 ± 581 pg•mL-1; p = 0.008) and sCD14 (1512 ± 297 vs 1642 ± 313 ng•mL-1; p = 0.014) were elevated in the ibuprofen trial. Likewise, the L/R ratio (0.217 vs 0.295; p = 0.047) and the pre- to post-exercise change in I-FABP (277 ± 308 vs 498 ± 479 pg•mL-1; p = 0.021) were greater in the ibuprofen trial. Participants also reported greater upper GI symptoms in the ibuprofen trial (p = 0.031). However, MCP-1 (p = 0.007) and TNF-α (p = 0.047) were lower throughout the ibuprofen trial compared to placebo (main effect of condition). Conclusions: These data demonstrate that acute ibuprofen ingestion aggravates markers of enterocyte injury and intestinal barrier dysfunction at rest and following exercise in hypoxia. However, ibuprofen appears to suppress circulating markers of inflammation.
... Body mass index (BMI) was calculated from the participant's height and weight as follows: BMI = Body mass/Stature height 2 (kg/m 2 ). Body composition was evaluated according to the skinfold thickness method at the chest, triceps, biceps, abdominal, subscapular, iliac crest, axilla, thigh, and calf using gender-specific equation development by Jackson and Pollock [25,26] to determine body density, body fat, and lean body mass. The intraclass correlation coefficients (ICCs) from our laboratory are 0.93 (95% confidence interval [CI] 0.89-0.97) ...
Article
Full-text available
Purpose The Covid-19 restriction exposed most athletes to insufficient training stimuli leading to detraining. This study investigated whether a home-based exercise training program could preserve body composition and exercise performance in young high-level kayak athletes during Covid-19 restriction. Methods Seventeen healthy young high-level kayak athletes (10 males and 7 females), aged 14.7 ± 1 yrs, participated in this study. A 7-week home-based training program was followed during Covid-19 restriction. Baseline measurements were assessed 4 weeks before Covid-19 pandemic and ended on 4 May 2020. Body composition, flexibility, isometric muscle trunk strength (Biodex), anaerobic power (30-s all-out trial), and aerobic capacity (4-min maximal test) were evaluated. Personal daily loads and wellness details were collected with AthleteMonitoring.com software. Results Home-based exercise training program was effective to improve flexibility (9.20 ± 2.85%) and lean body mass (3.96 ± 0.89%), to maintain muscle strength, anaerobic power, body mass, and body fat percentage but insufficient to maintain aerobic capacity (− 8.96 ± 2.49%). Conclusion The findings of the present study potentially highlight the importance of the implementation of such a program to minimize the detraining effect on young athletes during periods of movement restriction caused by pandemics.
Article
Purpose: This study compared physiological and perceptual variables between short and long durations of rowing-based high intensity interval exercise (HIIE). Methods: Fourteen active adults (age = 26.4 ± 7.2 yr) performed incremental rowing exercise to fatigue to measure maximal oxygen uptake (VO2max) and peak power output (PPO). The subsequent 20 min sessions required HIIE (eight 60 s efforts at 85%PPO with 90 s of active recovery at 20%PPO or 24 20 s efforts at 85%PPO with 30 s of active recovery at 20%PPO) or moderate intensity continuous exercise (MICE) at 40%PPO. During exercise, VO2, heart rate (HR), blood lactate concentration (BLa), rating of perceived exertion (RPE), and affective valence were measured. Results: Data show significantly (p < 0.001) higher peak VO2 (84 ± 7 vs. 76 ± 5%VO2peak, d = 0.99), peak HR (94 ± 4%HRpeak vs. 90 ± 4%HRpeak, d = 1.12), BLa (7.0 ± 2.5 mM vs. 4.1 ± 1.0 mM, d = 1.22), end-exercise RPE (12.8 ± 2.0 vs. 11.0 ± 1.7, d = 1.29), and lower affective valence (2.1 ± 1.6 vs. 2.9 ± 1.2, d = 0.61) with long versus short HIIE. Time spent above 85%HRpeak was significantly higher (p < 0.001) in short versus long HIIE (606 ± 259 vs. 448 ± 26 s, d = 0.91). Conclusion: Longer rowing-based intervals elicit greater cardiometabolic and perceptual strain versus shorter efforts, making the latter preferable to optimize perceptual responses to HIIE.
The development of chemical analytic techniques during the early nineteenth century was followed closely by their application to biological materials. During the past century a number of fetal, and a few adult, carcasses have been chemically analyzed; until very recently, the results of these analyses formed the basis of our knowledge concerning body composition in man. The past 2 decades have witnessed an increasing interest in body composition, an interest fostered by the development of techniques suitable for use in living subjects. Early in 1959, at a conference held under the sponsorship of the Quartermaster Research and Engineering Command, these newer techniques were reviewed and discussed. The present volume represents the proceedings of this conference and includes some 19 presentations in all. The discussion centers about the chemical "dissection" of the body into 4 major components: water, fat, mineral, and nonosseous solids. Some of the techniques, such as measurement of
Article
1. Pigs growing from 20 to 60 kg live weight were given diets based on barley, weatings and fish meal, or starch, sucrose and groundnut meal or starch, sucrose and casein. Seventeen pigs were fitted with single re-entrant cannulas in the duodenum (posterior to entry of bile and pancreatic ducts), jejunum or terminal ileum and twenty-four non-cannulated pigs were used in a conventional digestibility trial. 2. The amounts of calcium, phosphorus, magnesium, sodium and potassium passing through the reentrant cannulas and amounts excreted in the faeces were measured. These values were used to calculate the direction and extent of net movements of the five elements through the walls of the four parts of the digestive tract anterior to the collection sites. 3. The small intestine was the principal site of Ca and P absorption but there were differences between the diets in the relative importance of the regions anterior and posterior to the mid-jejunum. 4. Secretion of small amounts of Mg occurred in the anterior small intestine; the ileum and large intestine were the principal sites of net absorption. 5. There was a large net secretion of Na anterior to the duodenal cannulas and further secretion into the anterior small intestine with each diet. There were marked differences between diets in the amounts secreted but the ileal Na concentration was the same in each instance. Absorption occurred in the ileum and large intestine. 6. Secretion of small amounts of K was evident anterior to the duodenal cannulas and net absorption occurred in both parts of the small intestine with each diet.
Article
1. An experiment has been described in which pigs were fed rations containing four different levels of cellulose, each ration being fed successively at three different levels of water intake. The cellulose levels were superimposed on a highly digestible basal ration. 2. It appears that altering the level of water intake, while keeping the ration constant, has only a very limited effect on the level of faecal dry-matter percentage, and on the pattern of variation therein. 3. Further evidence is cited in support of the theories, advanced in a previous paper, relating to the influence of fibrous cellulose on water relationships in the digesta and faeces.
Article
1. Two experiments have been described in which pigs were fed different levels of fibrous cellulose superimposed on a highly digestible purified basal ration. These experiments involved 24 hr. faecal collections and ultimate slaughter of the animals, together with analysis of faecal material and gut contents. 2. The results of these experiments, together with those from experiments described in the previous paper in this series, have provided the basis for a discussion of the effects of adding bran and cellulose to pig rations, and of the influence of the progress of the residues of feeds through the digestive tract, on the pattern of excretion and the dry matter content of the faeces.
Article
1. Six pigs, four with caecal cannulae, were given diets containing 8% or 26% cellulose. Cannulation did not affect the digestibility of dry matter or cellulose. 2. Digestibility of cellulose, though variable, was higher for the 8%-cellulose diet. 3. Pigs on the 26%-cellulose diet had larger amounts of digesta in the caecum, and lower caecal retention times, than pigs on the 8%-cellulose diet. 4. Measurements of production rates of volatile fatty acids in the caecum indicated that only 2·7% and 1·9% of the apparent digestible energy of the 26%- and 8%-cellulose diets respectively came from the acids, and it was concluded that the caecum played only a small role in the breakdown of feed substances.
Article
1. Twelve blocks of six enzootic-pneumonia-free Large White litter-mate pigs were individually fed, wet, from 20 to 92 kg live weight on six different levels of feed intake. Four groups were fed according to scales based on live weight and two were fed on a ‘semi-ad libitum ’ system. One of the scales used was based on the ARC (1967) recommendations. 2. Pigs on ‘semi-ad libitum ’ feeding grew significantly faster than those on scale feeding although the feed: gain ratios were similar. Differences in performance between the four scale-fed groups were relatively small. 3. Although treatment differences in carcass measurements were in the main small, the commercial grading results favoured the carcasses from the scale-fed pigs. The firmness of backfat assessed by thumb pressure was reduced as the level of feeding was increased. 4. The results were compared with those obtained in a similar trial carried out at Shinfield in 1957 using pigs of a completely different genetic background. The general conclusions reached were similar in the two trials, that to obtain the most satisfactory overall results some form of controlled scale-feeding was necessary.
Article
The design and manufacture of plastic cannulae are described and the chief hazards associated with cannulated re-entrant fistulae in sheep are discussed.(Received April 17 1962)(Online publication October 1962)