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Blood

Pressure

in Obese

Adolescents:

Effect

of Weight

Loss

Albert

P. Rocchini,

MD,

Victor

Katch,

EdD,

Judith

Anderson,

PhD,

Judith

Hinderliter,

MS,

Daniel

Becque,

MS,

Monica

Martin,

MD,

and

Charles

Marks,

MS

From the Section of Pediatric Cardiology, Department of Pediatrics, and the Department of Kinesiology, Division of Physical Education, University of Michigan, Ann Arbor, Michigan

ABSTRACT. The BP distribution of a group of 72 obese

adolescents was determined both before and after

weight loss. Weight loss was produced by a program of

caloric restriction and behavior change alone (n = 26)

or with a combination of caloric restriction, behavior

change, and exercise (n

=

25). It was demonstrated that

obese adolescents have a BP distribution that is skewed

1 SD to the right of normal (P < .01), and that with

weight loss this distribution was no longer different

from that of the general population. It was also shown

that a weight loss program that incorporates exercise

and caloric restriction produces the most desirable

ef-fect on BP reduction (ie, greatest decrease in resting systolic BP and greatest decrease in exercise diastolic

and mean BP ).Finally, it was demonstrated that obese

adolescents have structural changes present in the

fore-arm resistance vessels and that these structural

changes are reversed to the greatest extent in the

weight loss program that includes exercise. Pediatrics

1988;82:16-23; blood pressure, exercise, weight loss,

caloric intake restriction, diet, behavior change, adoles-cent obesity.

High BP has been associated with obesity in both children and adults. Lauer et al’ showed that, of those children in the upper decile of body weight, 29% had systolic BPs and 28% had dias-tolic BPs greater than the 90th percentile for age and sex. Similar results have been reported by Webber et al,2 Voors et al,3 and Aristimuno et al.4 Although all of these studies have been focused on evaluating the determinants of BP in the gen-eral population, there have been few studies in

Received for publication June 29, 1987; accepted Sept 9, 1987.

Reprint requests to (APR.) Pediatric Cardiology, Room

FillS, Box 0204, University ofMichigan Medical Center, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0204.

PEDIATRICS (ISSN 0031 4005). Copyright © 1988 by the

American Academy of Pediatrics.

which a direct evaluation of resting and exercise

BP in a group of obese adolescents has been

at-tempted. In addition, there is only limited infor-mation regarding whether weight loss in the

ad-olescent can reduce BP,5’6 and there is no

infor-mation regarding whether the method of

achiev-ing weight loss has any effect on the magnitude

of BP reduction associated with the weight loss. The present study was, therefore, undertaken to

determine the BP distribution of a group of obese

adolescents both before and after weight loss and

to determine whether weight loss produced by a program of caloric restriction, behavior change, and exercise causes a greater reduction in BP

than that which is associated with a weight loss

program composed of caloric restriction and behavior change alone.

MATERIALS

AND

METHODS

A total of 72 obese adolescents (34 boys and 38

girls) with a mean age of 12.6 years (range 10 to

17 years) and ten nonobese adolescents with a

mean age of 12.2 years (range 10 to 14 years) were

studied. All of the ten nonobese adolescents were

previously described by us, whereas only 30 of the

72 obese adolescents were previously described.7

Obesity was defined as weight for height

greater than the 75th percentile for age and sex and triceps and subscapular skin folds greater

than the 80th percentile for age and sex.8

To study the effect of weight loss on BP, the

subjects were randomly assigned to one of three

treatment groups. A group of26 obese adolescents were assigned to and 22 completed a 20-week weight loss program consisting of diet and behav-ior change (diet group). The diet was a

(2)

designed to produce a weight loss of

approxi-mately 2.2 kg (1 lb)/wk. The behavior change

com-ponent ofthe program was composed ofa one-hour

class each week for 20 weeks that consisted of

record keeping, stimulus control, changing eating behavior, and reinforcement of altered behavior.

A total of 25 obese adolescents were assigned

to and 23 completed a 20-week weight loss pro-gram composed of diet, behavior change, and

ex-ercise (exercise group). The diet and behavior

change were as previously described. The exercise program consisted ofthree 1-hour exercise classes per week for 20 weeks. Each class included warm-up exercise and aerobic activity. The warm-up

ex-ercises consisted of progressive stretching

tech-niques and muscle strengthening for ten minutes

at the beginning of each exercise class. Aerobic

activities were used for total body activities

de-signed to maintain heart rate for at least 40

mm-utes at greater than 70% to 75% of maximal

ex-ercise heart rate. The duration ofexercise was

mi-tially 15 minutes and was progressively increased

to 40 minutes. Specific activities included

walk-ing,jogging, swimming, aerobic dance, soccer, and

other recreational activities. To ensure adequate supervision and motivation, there were two to four adolescents per exercise leader.

A total of 22 obese adolescents were assigned

to the control group and 18 completed the 20-week

study and received no weight loss program for 20

weeks. There were no significant differences be-tween the three treatment groups with respect to age or gender. The 72 obese adolescents were

tested before and 63 were tested after the three

20-week programs. The ten nonobese adolescents were only tested once.

Experimental

Protocol

All subjects were admitted overnight to the

clinical research center at the University of

Mich-igan Hospitals. All adolescents fasted after 10 PM

the evening preceding the study and were main-tamed in a supine position after 4 AM the morning of the study. A heparin lock was inserted at 7:30

AM while the adolescents were supine. The heart

rate and arterial pressure during the 30-minute

rest period were the values recorded. Mean

ar-terial pressure also was calculated as diastolic

pressure plus one-third pulse pressure.

All adolescents also performed a multistaged

discontinuous exercise test in the sitting position

using an electronically braked bicycle ergometer.

The first two stages were done at 15 and 30 W.

Subsequent work stages were increased by 30-W

increments until the adolescent could no longer

turn the pedals at 60 rpm. Each work rate was

performed for five minutes and there was a

three-minute rest period between every other work

stage. The following measurements were taken

during each stage ofexercise: BP, heart rate, tidal

volume, oxygen uptake, and carbon dioxide pro-duction. Gas exchange was continuously moni-tored by an online measurement of ventilation rate (pneumotachometer), percentage of carbon dioxide (Beckman carbon dioxide analyzer), and percentage of oxygen (Applied Electrochemistry oxygen analyzer). Following the exercise test, all

adolescents were given lunch and then had body

composition (percentage of fat) measured by

hy-drostatic weighing as described by Katch et al.9 Finally, forearm blood flow was measured in the

right arm using a mercury in Silastic strain gauge

plethysmography and venous occlusion.’0 During

measurements of forearm blood flow, circulation

to the hand was arrested by inflating a cuff around the wrist to the point of suprasystolic pressure.

Initially, four blood flows were recorded every 10

seconds and an average value was calculated

while BP was measured in the left arm with a

Critikon monitor. Forearm vascular resistance

was calculated by dividing mean arterial pressure

by forearm blood flow (milliliters per minute per

100 mL of forearm volume). Minimum forearm vascular resistance was assessed by inflating the cuff on the upper arm to above systolic pressure

for ten minutes to occlude arterial flow while

hay-ing the adolescent squeeze a ball ten times. After

release of the arterial occlusion, forearm blood flow was measured after 5 seconds and every 10

seconds thereafter for three minutes. BPs were

measured at approximately 30-second intervals

after release of the arterial occluding cuff. The peak blood flow recorded after release of arterial occlusion was used to calculate the minimal fore-arm vascular resistance.

Laboratory

Procedures

Weight was measured in kilograms using a beam balance scale and height was measured to the nearest 0. 1 cm using a stabilometer.

Statistical Analysis

Statistical analysis was performed using an

analysis of variance to compare differences

be-tween the nonobese and obese adolescents. To compare differences among the three obese groups at the end of the randomized 20-week treatment,

a one-way analysis ofyariance with a Scheff#{233}pro-cedure for multiple comparisons on the pretest

minus posttest values was used. Systolic and

dias-tolic BP values were adjusted for age and sex by

(3)

30

PRE WEIGHT LOSS PROGRAM

N- 72

25

20

POST WEIGHT LOSS PROGRAM N=63

1J=diet z-1.O9 1.1

r-

exercise z-1.O6 .70

EJcontroi z-1.03 .98

EJ=z-.451.1

= 2 =0.02 .72

L::J- =1.21 1.1

15

10

5

-2 -1 0 1 2 3 -2 -1 0 1 2 3

z SCORE z SCORE

Fig 1. Distribution of systolic BP in obese adolescents compared with those rates in

the Second National Health and Nutrition Examination Survey before and after

20-week weight loss program. All values presented are means ± SD. Diet, diet and

be-havior change group; exercise, diet, exercise, and behavior change group; control, obese

control group.

z

0

I-4 -J

0 I’-0

according to the formula z

=

x - i/SD, where x

=

measured BP,

=

mean ofthe expected BP for age and sex (the second National Health and Nu-trition Examination Survey data),8 and SD

=

standard deviation of the expected BP for age and sex. Linear regression analyses were performed prior to the weight loss program using z score

sys-tolic and diastolic BP values as dependent van-ables with total body weight, percentage of fat, heart rate, and forearm blood flow and resistance

as the independent variables. Where appropriate,

nonparametnic for pairwise comparisons (the Wil-coxon, signed-rank test, and the Friedman two-way analysis of variance) were performed.

RESULTS

We observed that, when compared with the ten

nonobese adolescents, the 72 obese adolescents had significantly higher systolic, diastolic, and mean arterial pressures. Because BP is affected in childhood by both age and sex, to compare our group of obese adolescents with the adolescent population in general, a z score BP distribution was calculated for obese adolescents using data from the second National Health and Nutrition Examination Survey.8 We observed that the obese adolescents had both a systolic and diastolic BP distribution that was significantly skewed to the right (P < .01, Figs 1 and 2). Both the systolic and

diastolic BP distributions for the obese

adoles-TABLE 1. Anthropo morphic and Resting Hemodynamic Data*

Variables Adolescents

Nonobese (n = 10) Obese (n = 72)

Age (yr) 12.1 ± 3 12.6 ± 3

Wt (kg) 42.2 ± 13 75.4 ± 161

Height (cm) 148.2 ± 10.4 156 ± lit

%Fat 20±7 44± 71:

BP (mm Hg)

Systolic 104 ± 6 132 ± 131:

Diastolic 60 ± 7 78 ± 121:

Mean 74±8 97± 101:

z

score

Systolic (mm Hg) 0.20 ± 0.54 1.06 ± 0.931:

Diatolic (mm Hg) 0.59 ± 0.78 0.94 ± 1.2

Heart rate (beats/ 77 ± 6 88 ± 121:

mm)

* Results are given as means ± SD.

tP < .05.

1:P < .01.

cents were skewed greater than 1 SD to the right

of the children in the second National Health and

Nutrition Examination Survey8 (systolic BP 1.06

±

0.93 and diastolic BP 0.94 ± 1.2). We also

ob-served a significant linear correlation between

the z score BP values and totaly body weight (r

=

.49 systolic; r

=

.62 diastolic, P < .01) and fat

weight (r

=

.62 systolic; r

=

.77 diastolic, P <

.01). No significant relationship was observed be-tween lean body weight and the z score BP (r

=

(4)

addi-25

J-diet z-.971.2

20

=exercise z=.941.O

D=control z=931.1

D-z-.41.2

D-z-.15.7

D-z= .931.2

-2 -1

15

10

5

z SCORE z SCORE

Fig 2. Distribution of diastolic BP in obese adolescents compared with those rates in

the Second National Health and Nutrition Examination Survey before and after a

20-week weight loss program. All values presented are means ± SD. Diet, diet and change

group; exercise, diet, exercise, and behavior change group; control, obese control group.

3

TABLE 2. Anthropomorphic and Hemodynamic Data Before and After 20-Week Weight Loss Program (n = 63)*

Variables Obese Control Group

(n = 18) Preprogram Postprogram

Obese Diet Group

(n = 22)

Preprogram Postprogram

Obese Exercise Group (n = 23)

Preprogram Postprogram

Wt (kg) 73 ± 14 77 ± 16 73 ± 14 70.5 ± 15t1: 72 ± 12 69.6 ± lltt Height (cm) 159 ± 12 162 ± i2t 157 ± 8 161 ± 8t 159 ± 10 163 ± 8t

%Fat 41±6 42±8 43±8 39±8t1: 41±6 35±4t1:

Right forearm 26.3 ± 2.9 26.6 ± 2.9 26.9 ± 2.2 26.6 ± 2.3 26.1 ± 1.1 25.7 ± 1.3

circumference (cm)

BP

126 ± 13 130 ± 14 127 ± 14 117 ± 8tt 129 ± 9 113 ± 6t1:

78±10 77±15 80±11 68±9t1: 79±11 66±7t1:

90±11 93±12 95±9 82±8tt 95±10 83±7t1:

84±14 85±10 88±12 79±11 88±13 72±iltt

30 PRE WEIGHT LOSS PROGRAM N#{149}72

POST WEIGHT LOSS PROGRAM N:63

z

0 4 -J

0.

0

0. U.

0

Systolic (mm Hg)

Diastolic (mm Hg)

Mean (mm Hg)

Heart rate (beats/mm)

* Results are given as means ± SD.

t P < .05, pre- v postprogram.

1:P < .05, Control group v obese diet or exercise group.

§P < .05, diet group v exercise group.

tion to having an elevated BP, the obese children

also had tachycardia when compared with our

nonobese group (P < .01, Table 1). There also was a significant positive correlation between resting

heart rate and z score systolic and diastolic BP

values (r = .39, P < .05 systolic; r = .48, P < .01 diastolic).

The effect of weight loss on BP and heart rate was evaluated by comparing the changes that oc-curred after 20 weeks of weight loss induced by either diet and behavior change alone or in

com-bination with exercise v that which occurred after

a 20-week control period. Of the 72 obese

adoles-cents who started in the program and were

mi-tially tested, there were 63 adolescents who

com-pleted both weight loss or control periods and had a posttest performed (Table 2). No significant

dif-ferences were noted between the three groups of

obese adolescents prior to the weight loss pro-gram. When compared with the obese control group, the two 20-week weight loss groups expe-nienced a modest but significant decrease in body

weight (P < .01, Table 2). The modest decrease in

body weight observed in the two weight loss groups was associated with a significant change

in body composition (P < .01, Table 2). Although

the exercise group tended to have a greater

de-crease in percentage of fat (measured by

hydro-static weighing), there were no significant

(5)

TABLE 3. Submaxim al and Maximal Bicycle Exerc ise Data Before and After 20- Week Weight Loss Program*

Exercise Obese Control Group Obese Exercise Group Obese Diet Group

(n = 18) (n = 22) (n = 23)

Preprogram Postprogram Preprogram Postprogram Preprogram Postprogram

Submaximal

Heart rate (beats/ 144 ± 19.7 148 ± 14 147 ± 21 128 ± l8t1: 144 ± 21 140 ± 21

mm)

Systolic BP (mm 135 ± 25 138 ± 20 138 ± 13 125 ± lit 140 ± 15 130 ± 14

Hg)

Diastolic BP (mm 80 ± 15 79 ± 16 81 ± ii 60 ± i3t1: 82 ± 13 69 ± lit

Hg)

Mean BP (mm Hg) 98 ± 17 98 ± 18 100 ± 12 81 ± i2t1: 101 ± 14 89 ± 12t

02 consumption (mid 1,225 ± 222 1,277 ± 252 1,349 ± 302 1,109 ± 2i6t1: 1,226 ± 189 1,200 ± 156 mm)

Maximal

Heart rate (beats/ 188 ± 15 188 ± 12 189 ± 14 182 ± 12 185 ± 14 184 ± ii

mm)

Systolic BP (mm 156 ± 18 160 ± 17 159 ± 20 148 ± 16 163 ± 22 154 ± 17

Hg)

Diastolic BP (mm 84 ± 16 85 ± 17 83 ± 16 70 ± i4t1: 81 ± 16 78 ± lit

Hg)

Mean BP (mm Hg) 108 ± 17 110 ± 17 108 ± 18 95 ± l5t1: 108 ± 19 103 ± 15

02 consumption (mL/ 2,019 ± 544 2,014 ± 538 2,236 ± 520 2,283 ± 557 2,188 ± 505 2,003 ± 719 mm)

Total time (mm) 22.2 ±5.5 22 ± 4.7 23 ± 4.8 25 ± 4.3 23.3 ± 4.8 22.9 ± 4.5

*Results are given as means ± SD.

t P < .05, preprogram v postprogram.

1:P < .05, obese exercise group v obese diet group and obese control group.

with respect to any of the anthropometnic van-ables measured.

The changes in cardiovascular fitness following the weight loss programs are summarized in Table 3. Prior to weight loss, the heart rate and oxygen consumption response to bicycle exercise were similar in all three groups of obese adoles-cents. After the 20-week program, both weight loss groups of children experienced a significant decrease in resting heart rate; however, this de-crease in heart rate was significantly greater in the weight loss group that exercised (P < .01). In addition, only the group ofchildren in the exercise group experienced a decrease in both heart rate and oxygen consumption at the 60-W submaximal exercise stage (P < .01). The exercise group also tended to have the largest increase in maximal oxygen consumption and endurance (Table 3). When compared with the obese control group, the two weight loss groups experienced significant decreases in systolic and diastolic mean and z

score BP values (Figs 1 and 2, Table 2). After the

20-week weight loss program, both weight loss

groups experienced a decrease in BP; however, when we performed an analysis of covaniance (with the change in body weight as the

concomi-tant variable), we observed that there was a

sig-nificantly greater decrease in resting systolic BP

in the exercise group than was observed in the diet group. In addition, differences between the two weight loss groups in their response to bicycle

exercise were also noted. As can be seen in Table 3, the increase in diastolic and mean BP that

oc-curs during both submaximal and maximal

ex-ercise were significantly less in the exercise group

following the 20-week weight loss program (P <

.01).

Finally, vascular reactivity was evaluated by measuring forearm blood flow and resistance at rest and following ten minutes of arterial

occlu-sion (Table 4). When compared with the nonobese

control subjects, the obese adolescents had

in-creased resting forearm blood flow and postis-chemic forearm vascular resistances and de-creased forearm vascular resistance and postis-chemic vascular blood flow (P < .01). In addition,

prior to weight loss, we observed in the obese group a significant correlation between z score

systolic and diastolic BP and the postischemic

vas-cular resistance (r = .36, P < .05 systolic, r =

.47, P < .01 diastolic). Following the 20-week

weight loss program, we observed that only the exercise group experienced a significant decrease

in resting forearm blood flow and a significant

(6)

TABLE 4. Resting and Postischemic Forearm Vascular Resistance and Blood Flow in Obese and Nonobese Ad-olescents

Group At Rest Postischemia

Forearm Blood Flow Forearm Vascular Resistance Forearm Blood Flow Forearm Vascular Resistance

Preprogram1 Postprogram Preprogram Postprogram Preprogramt Postprogram Preprogram Postprogram

Obese

Control 13.7 ± 7 13.1 ± 9 6.7 ± 4.5 7.1 ± 1.9 43.6 ± 15 44 ± 14 2.6 ± 1.0 2.6 ± 1.4

Diet 13.4 ± 8 11.2 ± 15 79 ± 2.0 7.8 ± 3.5 40.3 ± 19 42 ± 16 3.0 ± 1.7 2.2 ± 1.31:

Exercise 12.9 ± 8 9.2 ± 101:1 7.3 ± 2.4 9.1 ± 2.31:* 41.2 ± 16 54.2 ± 161: 2.9 ± 1.5 1.5 ± 0.61:i

Nonobese 5.6 ± 1.9 14.1 ± 3.6 65.2 ± 19 1.2 ± 0.5

Results are given as means ± SD. Forearm blood flow is given in mLIminIlOO mL offorearm volume; forearm vascular resistance

is given in mm Hg/mL/minIiOO mL of forearm volume. t P < .05, nonobese group v control, diet, or exercise group.

1:P < .05, preprogram v postprogram.

§P < .05, exercise group v diet group.

DISCUSSION

An association between obesity and

hyperten-sion has previously been reported in both

adults’1’3 and children.’6 In the present study,

we confirmed this association by demonstrating

that obese adolescents have a BP distribution that

is skewed 1 SD to the right of normal and that,

following weight loss, this distribution is no

longer different from that of the general

popula-tion (Figs 1 and 2). We also showed that the

method by which weight loss is accomplished is

important in determining the degree of BP

re-duction. Although both of our weight loss groups experienced a significant decrease in resting

sys-tolic and diastolic BP and heart rate, the weight

loss group that combined caloric restriction and

exercise experienced the greatest decrease in

rest-ing systolic BP and heart rate. Differences

be-tween the two weight loss groups in their BP

re-sponse to bicycle exercise were also observed.

Ab-solute systolic, diastolic, and mean BPs during

maximal and submaximal exercise were

signifi-cantly reduced in both weight loss groups.

How-ever, following the 20-week weight loss program,

only the exercise group experienced a

signifi-cantly smaller increase in diastolic and mean BP

during both submaximal and maximal exercise

testing. These differences in resting and exercise

BP and heart rate in the exercise group probably

reflect changes in the autonomic nervous system that occur after physical conditioning. Other have previously demonstrated that after physical

training sympathetic nervous system activity

de-creases, whereas parasympathetic nervous

sys-tem activity increases.’4”5

The present study also may provide some

in-sight into why there is a strong association

be-tween BP and body weight in obese adolescents.

Numerous studies involving obese adults have

demonstrated that obesity is associated with an

increased cardiac output and stroke volume and

a decreased systemic vascular resistance. 1619

Neither cardiac output nor total systemic

vascu-lan resistance were directly measured in our

study; however, because we observed that obese

adolescents had an elevated resting forearm blood

flow and a reduced nesting forearm vascular

re-sistance, our results are compatible with these

obese adolescents having an elevated cardiac

out-put and a reduced systemic vascular resistance.2#{176}

Our data also suggest that, although vascular

ne-sistance may be reduced, it is not reduced enough

to result in a normal BP.

Results of studies in children2’ and adults2023

have suggested that structural changes in the

ne-sistance vessels may occur in the presence of

hy-pertension. Structural changes in resistance

yes-sels can be assessed physiologically by measuring

vascular resistance during ischemia-induced maximal vasodilation. Several studies have doc-umented the fact that the minimal vascular

re-sistance measured at peak reactive hypenemia

can be used as an index of the structural

compo-nent of vascular nesistance.2024 As can be seen

in Table 3, at peak reactive hyperemia, forearm

vascular resistance was significantly greaten in

the obese adolescents as compared with the

non-obese control group. Thus, the elevated minimum

forearm vascular resistance suggests that

struc-tural changes were present in the forearm

resis-tance vessels of the obese adolescents. The exact

nature of these vascular changes are unknown

but might involve vascular smooth muscle hy-pertrophy with increased wall to lumen ratio, water logging, a decreased number of resistance

vessels, or decreased size of the vessels without

vascular hypertrophy. Egan and Julius24

dem-onstnated in children with essential hypertension

that minimal forearm vascular resistance

come-lates with increased sympathetic drive as

(7)

suggested that chronic sympathetic stimulation

may have produced vascular smooth muscle hy-pertrophy. For the following two reasons, our data also suggested that chronic increased sympathetic drive activity may also be responsible for the structural changes in the forearm resistance

yes-sels observed in obese adolescents.

First, unlike the previous reports concerning obese adults,’6”7 our results demonstrated that obese adolescents have an increased heart rate when compared with nonobese children. We also observed that, with weight loss, heart rate

sig-nificantly decreased. Others have also

demon-strated in obese adults that weight loss is asso-ciated with a reduction in heart rate.’8”9 Al-though we do not know why our obese adolescents have an elevated nesting heart rate, we believe that the increased heart rate probably reflects in-creased sympathetic nervous system activity. In many but not all studies of obese adults, it has been suggested that, based on plasma and/or

un-nary norepinephnine levels, increased

sympa-thetic activity may contribute to the increased BP observed in these patients.2527 Conversely, most

studies have also demonstrated that weight

re-duction during caloric restriction results in a

progressive decrease in circulating

catechola-mines.’8”9

Second, we observed that, with weight loss, minimum forearm vascular resistance decreased to the greatest extent in the exercise group. Al-though we do not have direct proof, we believe that the significant decrease in minimum forearm vascular resistance in the exercise group may be due to reversal of structural changes in the resis-tance vessels as a result of chronic attenuation of

sympathetic nervous constrictor influences on the

local resistance vessels of the forearm (either due to decreased sympathetic nervous system activity or decreased sensitivity of the peripheral affector

tissue to sympathetic nervous system

activ-ity).28’29

In summary, we have demonstrated that, like obese adults, obese adolescents have an elevated

BP that is reduced with weight loss. We have also

shown that a weight loss program that

inconpo-mates exercise with caloric restriction produces the most desirable effects in BP reduction. Finally, we have demonstrated that obese adolescents appear to have these structural changes present in the forearm resistance vessels and that these struc-tunal changes are reversible.

ACKNOWLEDGMENT

This work was supported, in part, by grants NIH

ROl-AM309-89, NIH MOi-RP00042-2i, and NIH 2ROi-HL-35743 from the Natiopal Institutes of Health.

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23. Takeshita A, Mark A: Decreased vasodilator capacity of forearm resistance vessels in borderline hypertension.

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24. Egan B, Julius 5: Vascular hypertrophy in borderline hy-pertension: Relationship to blood pressure and sympa-thetic drive. Clin Exp Theory Pract 1985;A7:243-255 25. Sowers JR, Nyby M, Stern N, et al: Blood pressure and

hormone changes associated with weight reduction in the

obese. Hypertension 1982;4:686-691

26. Sowers JR, Whitefield LA, Catania RA, et al: Roles of

sym-pathetic nervous system in blood pressure maintenance in

obesity. J Clin Endocrinol Metab 1982;54:ll8l-1l86

27. Tuck ML, Sowers JR, Dornfeld L, et al: Reduction in

plasma catecholamines and blood pressure during weight

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REFERENCES

DAVID

HUME,

THE SCOTTISH

PHILOSOPHER,

ON HOW A CHILD

LEARNS

NOT TO TOUCH

A BURNING

CANDLE

(1749)

David Hume (1711-1776), a Scottish philosopher, was one ofBritain’s lead-ing advocates of the philosophical doctrine of empiricism. This doctrine held

that all knowledge is derived from experience. This position is opposed to

rationalism in that it denies the existence of innate ideas.

Hume’s empiricism is evident in this description of how a child learns not to put his hand near a burning candle.’

It is certain that the most ignorant and stupid peasants-nay infants, nay even

brute beasts-improve by experience, and learn the qualities of natural objects, by

observing the effects which result from them. When a child has felt the sensation of

pain from touching the flame of a candle, he will be careful not to put his hand near

any candle; but will expect a similar effect from a cause which is similar in its sensible

qualities and appearance. Ifyou assert, therefore, that the understanding ofthe child

is led to this conclusion by any process of argument or ratiocination, I may justly

require you to produce that argument; nor have you any pretense to refuse so equitable

a demand. You cannot say that the argument is abstruse, and may possibly escape

your inquiry; since you confess that it is obvious to the capacity of a mere infant. If

you hesitate, therefore, a moment on if, after reflection, you produce any intricate or

profound argument, you, in a manner, give up the question, and confess that it is not

reasoning which engages us to suppose the past resembling the future, and to expect

similar effects from causes which are, to appearance, similar. . . . If I be right, I

pre-tend not to have made any mighty discovery. And if I be wrong, I must acknowledge

myselfto be indeed a very backward scholar; since I cannot now discover an argument

which, it seems, was perfectly familiar to me long before I was out of the cradle.

Noted by T.E.C., Jr, MD

1. Hume D: An Enquiry Concerning Human Understanding. Garden City, NY, Anchor Books,

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1988;82;16

Pediatrics

Monica Martin and Charles Marks

Albert P. Rocchini, Victor Katch, Judith Anderson, Judith Hinderliter, Daniel Becque,

Blood Pressure in Obese Adolescents: Effect of Weight Loss

Services

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including high resolution figures, can be found at:

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(10)

1988;82;16

Pediatrics

Monica Martin and Charles Marks

Albert P. Rocchini, Victor Katch, Judith Anderson, Judith Hinderliter, Daniel Becque,

Blood Pressure in Obese Adolescents: Effect of Weight Loss

http://pediatrics.aappublications.org/content/82/1/16

the World Wide Web at:

The online version of this article, along with updated information and services, is located on

American Academy of Pediatrics. All rights reserved. Print ISSN: 1073-0397.

References

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