Physical Growth and Somatotype of Sasak Schoolchildren at Different Altitude in Lombok Island

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PHYSICAL GROWTH AND SOMATOTYPE OF SASAK

SCHOOLCHILDREN AT DIFFERENT ALTITUDES IN

LOMBOK ISLAND

NOVITA TRI ARTININGRUM

GRADUATE SCHOOL

BOGOR AGRICULTURAL UNIVERSITY BOGOR

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STATEMENT LETTER

I hereby declare that thesis entitled Physical Growth and Somatotype of Sasak Schoolchildren at Different Altitude in Lombok Island is original result of my own research supervised under advisory committee and has never been submitted in any form at any institution before. All information from other authors cited here are mentioned in the text and listed in the reference at the end part of the thesis.

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SUMMARY

NOVITA TRI ARTININGRUM. Physical Growth and Somatotype of Sasak Schoolchildren at Different Altitude in Lombok Island. Supervised by BAMBANG SURYOBROTO and TETRI WIDIYANI.

The human life cycle can be staged into neonatal, infancy, childhood, juvenile, puberty, adolescence, adulthood, and senescence. During this cycle, the body changes significantly in size, structure, proportions, and composition. The physical growth and somatotype of schoolchildren are one of the important phases in human life cycle. The puberty stage within this age range are indicated by the growth spurt of stature (BH) and weight (BW) and followed by change in somatotype.

The focus of this research is to evaluate the age-related body size and shape variations at different altitude in Sasak children. A cross sectional growth study was conducted during July to December 2012. The samples are students of

kindergarten to senior high schools aged 3 to 19 years. All of subjects are rural children who lives in low (16 to 28 m asl), medium (525 to 628 m asl), and high altitude (1130 to 1213 m asl). Ten anthropometric measurements are used to determined the growth of body size and shape.

The result showed the children in low altitude were higher and heavier than medium and high altitudes. Until puberty, the children in medium have same stature and weight with those reside in high altitude but shorter and lighter thereafter. The difference of height and weight are statistically different in girls and indifferent in boys.

In growth of body shape, the Sasak children have a common pattern of somatotype composition. It is an increased in endomorphy, a decreased in mesomorphy, and an increased in ectomorphy during growth. The girl in medium altitude show delayed and slowly increasing of endomorphy and slowly decreasing of mesomorphy. Socioeconomic factors such as family income and parental education gave more influence to the differentiation than the altitude factor.

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RINGKASAN

NOVITA TRI ARTININGRUM. Pertumbuhan Fisik dan Somatotype Anak Sekolah Suku Sasak pada Ketinggian Berbeda di Pulau Lombok. Dibimbing oleh BAMBANG SURYOBROTO dan TETRI WIDIYANI.

Kehidupan manusia dibagi dalam beberapa tahap yaitu bayi, batita, anak-anak, prepubertas, pubertas, remaja, dewasa, dan tua. Setiap tahap mengalami perubahan ukuran, struktur, proporsi dan komposisi tubuh yang signifikan. Pertumbuhan fisik dan somatotipe anak-anak sekolah adalah salah satu fase yang penting. Pada fase ini terjadi pubertas yang ditandai dengan percepatan pertumbuhan tinggi dan berat badan yang diikuti dengan perubahan somatotipe.

Fokus dari penelitian ini untuk mengevaluasi variasi ukuran dan bentuk tubuh yang berkorelasi dengan umur anak-anak Suku Sasak pada ketinggian berbeda. Studi cross sectional telah dilakukan selama Juli sampai Desember 2012. Sampel adalah anak-anak sekolah umur 3 – 19 tahun dari PAUD sampai SMA. Semua subjek adalah anak-anak desa yang tinggal di dataran rendah (ketinggian 16-28 m dpl), menengah (525-628 m dpl) dan dataran tinggi (1130-1213 m dpl). Sepuluh pengukuran tubuh digunakan untuk mendeterminasi pertumbuhan dan bentuk tubuh anak-anak Suku Sasak.

Penelitian ini menunjukkan anak-anak dataran rendah, lebih tinggi dan lebih gemuk dibandingakan anak-anak dataran menegah dan dataran tinggi. Sampai fase pubertas, anak-anak dataran menengah memiliki tinggi dan berat badan yang sama dengan anak-anak dataran tinggi tetapi lebih pendek dan lebih kurus setelah pubertas. Perbedaan tinggi dan berat badan berbeda secara statistik pada anak-anak perempuan dan tidak berbeda pada anak-anak laki-laki.

Berdasarkan perubahan bentuk tubuh, anak-anak Suku Sasak memiliki pola komposisi somatotipe yang umum selama pertumbuhan yaitu peningkatan

endomorphy, penurunan mesomorphy, dan peningkatan ectomorphy. Anak perempuan di dataran menegah menunjukkan penundaan dan peningkatan

endomorphy yang rendah, dan penurunan mesomorphy yang rendah. Status sosioekonomi seperti penghasilan keluarga dan pendidikan orangtua memberikan pengaruh yang lebih besar terhadap pertumbuhan anak daripada perbedaan ketinggian.

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Copyright © 2013 by Bogor Agricultural University

All Rights Reserved

It is prohibited to cite all or a part of this thesis without referring to and mentioning the source. Citation is permitted for the purposes of education, research, scientific paper, report, or critism writing only; and it does not defame the name and honour of Bogor Agricultural University.

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Thesis

As partial fulfillment of the requirements for Master Degree in Animal Biosciences

PHYSICAL GROWTH AND SOMATOTYPE OF SASAK

SCHOOLCHILDREN AT DIFFERENT ALTITUDES IN

LOMBOK ISLAND

GRADUATE SCHOOL

BOGOR AGRICULTURAL UNIVERSITY BOGOR

2013

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Title : Physical Growth and Somatotype of Sasak Schoolchildren at Different Altitude in Lombok Island

Name : Novita Tri Artiningrum

NRP : G352110161

Certified by Advisory committee

Dr Bambang Suryobroto Chairman

Dr Tetri Widiyani, SSi, MSi Member

Acknowledged by

Coordinator

Major of Animal Biosciences

Dr Ir RR Dyah Perwitasari, MSc

Dean of Graduate School

Dr Ir Dahrul Syah, MScAgr

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FOREWORD

On the blessing of God I am able to finish my thesis. This paper is made to fulfill the requirement for master degree at Bogor Agricultural University. The

title of my paper is “Physical Growth and Somatotype of Sasak Schoolchildren at Different Altitude in Lombok Island”.

I would like to thank my advisor committee Dr. Bambang Suryobroto and Dr. Tetri Widiyani, SSi, MSi. I am indebted to Bakrie Center Foundation for the Bakrie fellowship. I express my gratitude to the Governments of West Lombok, Central Lombok, and East Lombok Regency for the permission of this study. We would also like to express our gratitude to the school principals, teachers and all the subjects for all their support throughout the study. My special thank to Yuliadi Zamroni (my husband), Annisa Hishnul Izza (my daughter), and all of my friends at Major of Animal Biosciences for their support.

Bogor, August 2013

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LIST OF TABLE

1 Site Sampling of Sasak Children 3

LIST OF FIGURE

1 Height-for-Age Percentiles of Sasak Boys and Girls Aged 3 to 19 Years

Live at Different Altitude 6

2 Growth Pattern of Body Height of Sasak Children 7 3 Annual Velocities of Body Height of Sasak Children 8 4 Weight-for-Age Percentiles of Sasak Boys and Girls Aged 3 to 19

Years Live at Different Altitude 9

5 Growth Pattern of Body Weight of Sasak Children 9 6 Annual Velocities of Body Weight of Sasak Children 10 7 The 50th Percentile Values of Somatotype Components Score in Sasak

Children 12

8 Somatoplot of The 50th Percentile Somatotype Score of Sasak Children

in Low Altitude 13

in Medium Altitude 14

in High Altitude 14

11 Comparison of Body Height and Body Weight of Several Populations

in Indonesia 16

LIST OF APPENDIX

1 Parents Occupation of Sasak Children Included The Study 21 2 Parents Education of Sasak Children Included The Study 22 3 Family Size of Sasak Children Included The Study 23 4 Somatotype Score and Somatotype Categories, by Age, Sex, and

Altitude 24

5 One-way ANOVA results of body height and body weight in Sasak

children 25

6 Tukey HSD test of body height and body weight of Sasak girls in each

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LIST OF ABBREVIATIONS

ANOVA analysis of variance Asl above sea level

BH body height

BPS Badan Pusat Statistik (Statistics Indonesia)

BW body weight

HSD honest significant difference HWR height weight ratio

IDR Indonesian Rupiah

NHANES National Health and Nutrition Examination NTB Nusa Tenggara Barat

MA Madrasah Aliyah (Senior High School level)

PAUD Pendidikan Anak Usia Dini (Kindergarten School level) SD Sekolah Dasar (Elementary School level)

SES socioeconomic statuses

SMA Sekolah Menengah Atas (Senior High School level) SMK Sekolah Menengah Kejuruan (Senior High School level) SMP Sekolah Menengah Pertama (Junior High School level) TKI Tenaga Kerja Indonesia (migrant worker)

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1 INTRODUCTION

The human life cycle can be staged into neonatal (birth to 28 days), infancy (2 to 36 months), childhood (3 to 7 years), juvenile (7 to 12 y), puberty (transition between juvenile to adolescence/ days or few weeks), adolescence (5 to 8 years after the onset of puberty), adulthood (20 years to end of child-bearing years), and senescence (end of child-bearing years to death). During this cycle, the body changes significantly in size, structure, proportions, and composition (Bogin 1999). The age of schooling is one of the important phases in human life cycle. The puberty stage within this age range is indicated by the growth spurt of stature and weight.

Both of genetic and environmental factors contribute to body shape and size variations during development. For instance, children who live in high altitude face numerous environmental stresses. The stresses are hypoxia, cold climate, ultraviolet radiation, and rough and difficult terrain. This condition needs more physical and physiological activities than the children who live in low altitude (Hastuti 2005; Malhotra et al. 2006; Singh et al. 2007). Several studies showed reduced birth weight and reduced childhood growth in the high altitude (Yip et al. 1988; Jensen and Moore 1997; Lestari 2006). The other studies found

little or no difference in growth between children living at low and high altitude (Freyre and Ortiz 1988; Hastuti 2005).

Independent of body size, a somatotype is a convenient shorthand descriptor of overall physique in terms of body shape and composition (Carter 1996). It measurements expressed in a three-number somatotype reflecting body composition; they are endomorphy, mesomorphy, and ectomorphy. Endomorphy is the relative fatness, mesomorphy is the relative musculoskeletal robustness, and ectomorphy is the relative linearity or slenderness of a physique (Carter and Heath 1990). Somatotype is useful for description and comparison of population for monitoring growth change. A large variety somatotype studies have yielded much information about human physique (Bhasin and Jain 2007).

Physical activity is one of factor influenced somatotype variation. Rahmawati et al. (2007) studied the differences of somatotype between athlete

and non athlete. Fett et al. (2006) evaluated the somatotype of overweight and

obese women in pre and post circuit training or jogging, while Ozener and Duyar (2008) studied the labour effect during adolescent period in somatotype. The other factors are sex, age and socioeconomic statuses (SES). Sex influences personal somatotype because male and female have different trajectory of growth and development (Bhasin and Jain 2007). The children exhibit different somatotype pattern form adults (Rahmawati et al. 2004). SES such as parent education, parent

occupation and monthly income were widely influence the growth of children (Eiben and Mascie-Taylor 2004; Bener and Kamal 2005; Bala et al. 2010; Lazzeri

et al. 2011; Widiyani et al. 2011).

Growth and somatotype of children has been intensively studied at several populations in Indonesia such as Bogor (Puspita 2004), Bantul and Yogyakarta (Rahmawati et al. 2004), Karawang (Hermawan 2007), Purwakarta (Miharja

2008), Bandung (Aryo 2011), Magelang (Widiyani et al. 2011), and Arfak tribe in

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altitude Java and Sunda ethnics in Java island. However, the study of other ethnics is lacking.

The focus of this research is to evaluate the age-related body size and shape variations at different altitude in Sasak tribe. Sasak is one of dominant ethnics in Lombok island. The Statistics Indonesia (BPS) estimated 3.168.693 people live in Lombok with 40.63 % of them having age cohort of 0 to 19 years old. Based on BPS data, a half of populations (47.12%) work as farmer and 17.47% as merchant. One fifth (21.55%) of West Nusa Tenggara population live in under poverty where 36.15% of them not attended formal education (BPS 2011).

The subjects of this research are Sasak schoolchildren who live in three altitudes; low, medium, and high altitudes. The children in low altitude population were found to be higher and heavier than medium and high altitude populations. Until puberty, the children in medium population have similar stature and weight with those reside in high altitude population but shorter and lighter thereafter. There were significant differences in three altitudes for girl height and weight but no difference for boys.

Based on body shape differentiation, the Sasak children have an increased in endomorphy, a decreased in mesomorphy, and an increased in ectomorphy during growth. The children in low altitude more endomorphic in 7 to 16 y than the two others. Boys were more ectomorph and less endomorph than the girl. We also find different pattern of growth in medium altitude compare to the others. The children in medium altitude show delayed and slowly increasing of endomorphy and slowly decreasing of mesomorphy. This condition made the children have long central period of somatotype category before puberty. Family income and parental education exerted more influence to the differentiation than the altitude factor.

2 MATERIALS AND METHODS

Subject

The subjects in this research are the children of Sasak tribe who lived at different altitude in Lombok Island, West Nusa Tenggara province. After Sumbawa, Lombok with 4738.6 km2 is the second widest island in the province. The northern and south eastern part of Lombok is mountainous and hilly with lowland and plateau in between. Rinjani is the highest mountain (3726 m above sea level, asl) in Lombok (BPS 2011).

A cross sectional growth study was conducted during July to December 2012. The samples are students of kindergarten to senior high schools aged 3 to 19 years (Table 1). All of subjects are rural children who lives in low (16 to 28 m above sea level), medium (525 to 628 m asl), and high altitude (1130 to 1213 m asl). Global Positioning System (Garmin Etrex 10 GPS) used to determine the altitude.

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3 consent and completing a questionnaire on birth dates, ethnicity and other socioeconomic data. Data analysis was conducted at Section of Biosystematic and Ecology of Animals, Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University.

Table 1 Site sampling of Sasak children

Name of the School Number of Samples

Low Altitude 408

TK Satu Atap SD 1 Labuan Tereng , West Lombok 19

SD 1 Labuan Tereng, West Lombok 31

SD 4 Batulayar, West Lombok 46

SMP 1 Batulayar, West Lombok 144

SMK Pariwisata Batulayar, West Lombok 126

SMK Perikanan Lembar, West Lombok 42

Medium Altitude 271

PAUD Mawar Rindang Tetebatu, East Lombok 19

SD Sekedek, Central Lombok 96

SMP 3 Batu Kliang Utara, Central Lombok 82

MA Nurussalam Tetebatu, East Lombok 74

High Altitude 273

PAUD Sembalun Bumbung, East Lombok 17

SD 2 Sembalun Bumbung, East Lombok 113

SMP 2 Sembalun Bumbung, East Lombok 86

SMA 1 Sembalun, East Lombok 57

Total 952

TK and PAUD are Kindergarten School Level; SD is Elementary School Level; SMP is Junior High School Level; SMA, SMK and MA are Senior High School Level

Body Size and Somatotype Measurements

Ten antrophometric measurements were used to determine growth of size and somatotype of subjects. They are stature (BH), weight (BW), four skinfolds (triceps, subscapular, supraspinale, and medial calf), two bone breadths (biepicondylar humerus and femur), and two limb girths (upper-arm and calf). I followed the anthropometric measurement manual of NHANES III (1988).

BH and BW are the main dimensions of body size. BH is a linear measurement of the distance from the standing surface to the top (vertex) of the skull; it is a composite of linear dimensions contributed by the lower extremities, the trunk, the neck, and the head. It was measured to the nearest 1 mm using anthropometer. BW is a measure of body mass; it is a composite of independently varying tissues. BW was measured using digital weight scale with resolution 100 gram.

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somatotype components, i.e., endomorphy, mesomorphy, and ectomorphy of each participants were calculated following Heath-Carter method (Carter 2002). These three calculated number described the somatotype. The equation of Endomorphy

= − 0.7182 + 0.1451(X) − 0.00068 (X2) + 0.0000014 (X3) where X is sum of triceps, subscapular and supraspinale skinfolds. Mesomorphy were calculated with the formula: Mesomorphy = [(0.858 × humerus breadth) + (0.601 × femur breadth) + (0.188 corrected arm girth) + (0.161 × corrected calf girth)] − (height

× 0.131) + 4.5. Ectomorphy had three equations. If Height Weight Ratio (HWR) was greater than or equal to 40.75, Ectomorphy = HWR × 0.732 − 28.58, if HWR

was less than 40.75 but more than 38.25, then Ectomorphy = HWR × 0.463 −

17.63 and if HWR was equal to or less than 38.25 given a rating of 0.1. HWR was body height divided by cube root of body weight. Each component have score range between one to seven. The number one represented the lowest observed amount of the component and seven for the highest. All of the measurements were obtained on the right side of each subjects in the morning as far as possible.

Sosioeconomic Status

The sosioeconomic statuses (SES) of children are factor that affect growth of size and somatotype. It is ascribed to them based on the SES of their parents. SES is a concept to measure some aspect of education, occupation and social prestige of a person or a social group (Bogin 1999). It was measured by formal

education (schooling), occupation, monthly income of child’s parents, birth order of child, and number of children in the family. Six educational levels, ten occupational categories, five monthly incomes of parents, five birth order level, and five number of children category were used to identify socioeconomic status.

Data Analysis

BW and BH were presented as charts of age changes growth which were fitted by applying generalized additive models for location, scale and shape (GAMLSS) (Rigby and Stasinopoulos 2005). We predicted nine levels (3%, 5%, 10%, 25%, 50%, 75%, 90%, 95%, and 97%) of percentiles to describe the pattern of growth of the whole populations from small to big sizes. In order to evaluate the variation of body size in different altitudes, we computed the Z value of each individu. Z score is based on the statistical population mean and measured in unit of the standard deviation. By using Z score of BH and BW we effectively removed the effect of age changes on body sizes. One-way ANOVA were used to evaluate altitudinal effect on body size in each sex groups. The Tukey HSD (honest significant difference) post hoc test was used to evaluate the differences between each pair of altitudes.

For body shape evaluation, the percentile 50 of somatotype scores of each age group were plotted on a somatochart (Carter 2002), using the following axis :

X coordinate = ectomorphy - endomorphy and Y coordinate = 2 * mesomorphy - (ectomorphy + endomorphy). The somatotypes were classified into thirteen

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3 RESULT AND DISCUSSION

Result

Socioeconomic Backgrounds

The subjects from low altitude consisted of 203 boys and 205 girls from two villages, Batu Layar and Labuan Tering, located at coastal areas. A third of

father in this group were labor (majority work in brick production, porter in traditional market and construction), one fifth as fisherman, and 17% of them work as merchant. However, a half of their mothers were housewives or jobless, 20% merchant and 15% labor in brick production and home servant. Over half of their parents (50% of fathers and 56% of mothers) had received primary school, 28 and 18% attended secondary education (junior and senior high school) and only 0.5 to 4% of parents graduated in the college (diploma and bachelor). Whereas, one fifth of parents were not attended formal education.

The children from medium altitude live at agricultural villages near Rinjani National Park. The subjects comprised of 123 boys and 148 girls from three villages (Sekedek, Seteleng, and Tete Batu). A half of their fathers work as farmer and the others (30%) work as labor (majority in brick production, construction, and migrant worker/TKI). A third of their mother (34%) were not working or housewives, 30% worked as farmer, and the other as labour and harvesting natural products. This group has a high percentage of parents not attended formal education (50%), only 36% of parents had received primary school, and the other had secondary education.

In high altitude, the children live at agricultural villages at Rinjani Mountain. The subjects of the third group consisted 133 boys and 140 girls from four villages (Sembalun Lawang, Sembalun Bumbung, Jorong and Telaga). Majority of the fathers in high altitude are farmers (86%). Over half of mothers (52%) also worked as farmer and a quarter of it as housewives. A third of father (37%) and over half of mother (58%) were not attended formal education, a third other had formal education until elementary school, and only one fifth of father and 10% of mother had secondary education.

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General Body Size (Stature and Weight)

Growth rate can be evaluated from body height (BH) and body weight (BW) measurements. It provides general information of body size. The relationships between their age-related changes in BH and BW are shown in Figures 1 to 6.

A. Stature

The relationships between age-related changes in BH are shown in Figures 1 and 2. According to the 50th percentile, the 3 years old girls of Sasak have 89 to 91 cm BH. When they reached 19y the body height both of low and high altitude girls increased to 160 cm, while the girls in the medium 146 cm. The trends of age related changes in boys were the same as with girls. The 3y boys in low altitude have 93 cm height and increased to 165 cm at 19y, whereas the boys in high altitude started from 93 cm and increased to 170 cm at 19y. The boys in medium altitude have the smallest body height (86 cm in 3y and increased to 161 cm in 19y).

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Figure 2 Growth pattern of body height of Sasak children. The patterns are taken from 50th percentile (see Figure 1). Boys, open; girls, closed.

In the early development, the BH growth of girls in low and medium altitudes were relatively stable (Figure 3). The velocity started to declined at 6.5y in lowland. In the age 15.5y, the velocity turned flat at 2.3 cm year-1. The girls in the medium altitude were practically stopped to grow in the age 15.5y and tend to grow negatively between 16.5 to 18.5y. The growth rate in highland started to increase at 3.5y with velocity 4.4 cm year-1, reached maximum at 10.5y with acceleration of 6 cm year-1 and decreased after that. Reaching the age 18.5 years, the velocity in highland was relatively stable at 2.6 cm year-1.

Figure 3 Annual velocities of body height of Sasak children. The patterns are taken from 50th percentile. Boys, open; girls, closed.

The growth of BH in boy in low altitude was relatively stable into 5.5y, decreased after that, increased again in 9.5y, reached maximum in 12.5y and than declined after that. The boys in medium altitude have a decreased BH velocity 6.3 cm year-1 at 3.5y to 0.78 cm year-1 at 18.5y, without growth spurt. On the other hand, the boys in high altitude increased their velocity, reached maximum spurt at 13.5y and declined after that.

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average stature below population mean with negative BH Z score values. According to the ANOVA results (appendix 5), the elevation influenced the body height in girls with P < 0.05 and not significant differed in boys (P > 0.05).

Tukey’s Honest Significant Difference test was used to determine which groups differ from each other. Based on this test, body height of girls in low altitude differed with girls in medium and high altitudes with P < 0.05, whereas the girls in medium did not differ with high altitude (appendix 6).

B. Weight

According to the 50th percentile of body weight (Figure 4 & 5), the 3 years old girls of Sasak tribe live in different altitudes have 8 to 11 kg of BW. When they reached 19y the body weight of low and high altitude girls increased to 52 kg, while in medium altitude only 43 kg. The 3y boys in low altitude weighed 10 kg and increased to 53 kg in 19y. The boys in medium altitude have a weight of 9 kg in 3y and increased to 51 kg in 19y, whereas the boys in high altitude 12 kg and increased to 57 kg at the same ages.

In Figure 6, girls BW in all altitudes started to ascend between 6.5 to 7.5y at 2.6, 1.4, and 1.7 kg year-1 (low, medium, and high altitudes, respectively). The peaks achieved between ages 11.5 to 12.5y with velocity 3.1, 4.1, and 4.1 kg year

-1_{, and then decreased after that. BW grew relatively stable in age 17.5 to 18.5 with}

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Figure 4 Weight-for-age percentiles of Sasak boys and girls aged 3 to 19 years at different altitudes.

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Figure 6 Annual velocities of body weight of Sasak children. The patterns are taken from 50th percentile. Boys, open; girls, closed.

The children in lowland have above average weight (mean Z score are 0.2458 for girls and 0.0577 for boys). Both of children in medium and high altitudes have average weight below population mean with negative Z score. Analysis of variance showed a significant influnce of elevation to body weight in Sasak girls but not in the boys (appendix 5).

According Tukey’s Honest Significant Difference test, body weight of girls in low altitude significant differed to medium and high altitudes with P < 0.05. In the other hand, the girls in medium did not significant differ to high altitude with P > 0.05 (appendix 6).

Body Shape

Body shape can be evaluated using somatotypic measurements. Somatotype is a description of the morphological state of individual at a given moment. This method had yielded much information about human physique and compositions.

A. Somatotype Compositions

Somatotype comprises of three components, they are relative adiposity (endomorphy), musculo-skeletal robustness (mesomorphy), and linearity (ectomorphy) (Carter and Heath 1990). Figure 7 shows the three components of somatotype compositions in age group comparison.

a. Endomorphy

In low altitude, the first somatotypic component of girls slowly increased from 3 to 9y, quickly grew in 10 to 15y and came to flat afterward. In medium altitude, the scores grew relatively stable in 3 to 11y old period and quickly increased until 19y. On the other hand in high altitude, the score decreased from 3 to 11y before increasing.

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The older girls (16 to 19y) in low and high altitudes were more endomorphic than in the medium altitude; on the contrary, the boys are either equal or differ with no more than 0.5 units for all altitudes. We found sex differences (the score difference of more than 1 unit) in endomorphic score along childhood into adulthood (the ages between 13 to 19y). The girls were more endomorphic than the boys.

b. Mesomorphy

Mesomorphy, the second component of physique is an indicator of relative musculo-skeletal development per unit of length. The scores are decline quickly at both younger (3 to 9y) boys and girls in lowland, relatively stable in medium altitude, and drop slowly in high altitude. Both of younger boys and girls in low altitude are mostly mesomorphic than the other two altitudes. In older age groups (10 to 19y), the scores were relatively stable for both of boys and girls in all altitudes. This result does not mean that younger ones are more muscular than the older ones, partly because of the fact that mesomorphy is adjusted for height.

The mesomorphy did not display any sex difference along age groups in each altitudes. However, although the differences were less than 1 unit, boys had higher mesomorphy. As this component is adjusted for height and boys being taller especially after 14y of age, they were stronger and muscular than the girls.

c. Ectomorphy

Ectomorphy or the relative linearity of individual physique demonstrates a steady increase with age until 11y both in boys and girls at all altitudes. The scores then decreased slowly in older girls (12 to 19 years). In other hand, in older boys, the scores are relatively stable. We found sex differences in ectomorphic score after 11y where the boys more ectomorphic than the girls.

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B. Somatotype: Category

Somatotypic categories are classification of body shape based on combination of the three components of somatotype. The results of age changes in somatotypic categories and their comparison between sex and altitude differentiations are showed in Figure 8, 9, 10, and appendix 4, respectively.

The girls in low altitude have endomorphic-mesomorph category in age 3 to 5y, changed to mesomorph-endomorph in 6y, go to central in age 7 to 9y, and balanced endomorph after that until 19y. The boys have endo-mesomorph category at 3 to 5y, move to balanced mesomorph at 6y, changed to central at 7 to 9y, move to balanced ectomorph at 10 to 12y and back to central until 19y (Figure 8).

Figure 8 Somatoplot of the 50th percentile somatotype score of Sasak children in low altitude; boy (black square) and girl (grey triangle).

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Figure 9 Somatoplot of the 50th percentile somatotype score of Sasak children in medium altitude; boy (black square) and girl (grey triangle).

The girls from high altitude have mesomorph-endomorph category in age 3 to 6y, move to central in 7 to 12y, and changed to balanced endomorph until 19y. Whereas the boys have mesomorph-endomorph category in 3 to 5y, move to balanced mesomorph at 6y, changed to central at 7 to 12y, move to balanced ectomorph until 18y and back to central at 19y (Figure 10).

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15 Discussion

Genetic and enviromental factors affect the physical growth and development of children. Sex differentiaton, age, and tribe are the genetic factors. Human activities, sosioeconomic statuses, and location where human live are several factors of environment. Hypoxic stress in high altitude is one of factors causing delay and modifying the growth spurt in children (Malhotra et al. 2006).

The altitude had inverse correlation with oxygen content in the air; the higher altitude, the lower oxygen content in the air. The reduction in the partial pressure of oxygen is more significant above 3000 m (Virués-Ortega et al. 2006). As

expected Hastuti (2005) reported no significant differences in BH and BW of girl or boy between Samigaluh district (high altitude, less than 1000 m asl) and Galur district (low altitude, coastal area) at Kulon Progo regency. Those indicated that altitude below 3000 m has relatively little effect on body size. However, the Sasak girls in low altitude (16 to 28 m asl) were heigher in age 3 to 12y and heavier in age 6 to 14y than medium (525 to 628 m asl) and high altitude (1130 to 1213 m asl) populations. These differences were statistically significant. The trends in boys were the same as girls but the altitudinal differences were not statistically significant. Both sexes of children in medium altitude have similar stature and weight to the population age 5 to 15y who reside in high altitude, but shorter and lighter thereafter. According to their body size, biggest to smallest population are from low, highland and medium altitudes respectively. There is an evidence that the high altitude children have lower stature. It is partly caused by smaller size at birth. Infants born at high altitude were often experience intrauterine growth restriction in contrast to preterm birth (Jensen and Moore 1997, Lestari 2006). For medium altitude population of Sasak, we should not expect 500 m asl altitude has adverse effect on intrauterine growth to make their size smaller. Therefore the different body sizes in girls of Sasak children might be better explained by differences in SES.

Family income and parental education would be better indicators of SES (Julia et al. 2004; Moestue and Huttly 2008). In low altitude, 88.7% of parents

have monthly income less than 1 100 000 IDR or lower than regional minimum wage, whereas high and medium populations are 91.3% and 92.4%, respectively. Majority of parents in low altitude were fishermen, while in medium and high altitudes were farmers. This presented an advantage to the children in lowland in having higher intake of protein from animal food (especially fishes and sea food). Furthermore the children in medium and high altitudes have more parents without formal education. These differences in family income and parental education gave more influence to the body size differentiation than the altitude factor.

The effect of SES to growth of children can also be seen in the comparison between Sasak and other populations in Indonesia. Growth of children has been intensively studied at several populations in Indonesia such as Bantul and Yogyakarta (Rahmawati et al. 2004), Karawang (Hermawan 2007), Purwakarta

(Miharja 2008), Magelang (Widiyani et al. 2011), and Arfak tribe in Papua

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de Waal 1993; Shen et al. 1996; Mueller and Smith 1999; Rahmawati et al. 2004; Artaria and Henneberg 2007). Yogyakarta, Karawang and Magelang samples came from urban populations with higher SES level than Sasak Children; hence they had better nutrition and optimum living conditions. On the other hand, Purwakarta and Bantul samples came from rural population with SES relatively similar with Sasak Children. In all study populations of Sasak children, the monthly income of parents was unstable and lower than the regional minimum wage of NTB. In general, they were shorter and lighter than urban populations and relatively in similar proportion with rural population in Java (Figure 11). The growth constraints of body size is strongly associated with poverty (Julia et al.

2004; Water et al. 2004).

Figure 11 Comparison of body height and body weight at several populations in Indonesia

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17 Yogyakarta (Rahmawati et al. 2004, Widiyani et al. 2011), the Sasak boys in low altitude appear more endomorphic than the others populations expect the boys in Yogyakarta and more ectomorphic than Yogyakarta but relatively balanced with the others. The girls in low altitude are more endomorphic than the other and less ectomorphic than Bantul.

The Sasak children in medium altitude (525 to 628 asl) exhibit generally higher values of endomorphy and mesomorphy than Sundanese population in Bandung who life at medium altitude (~791 asl) (Aryo 2011). Whereas, the last group of Sasak children are more endomorph than Spitian population who life at high altitude (3500 – 4200 asl) in India (Singh et al. 2007).

Based on Somatotype categories, before puberty, the children in low altitude, were distributed in endomorphic-mesomorph to central in both sex. The children in high altitude were distributed in mesomorph-endomorph to central before puberty. After puberty, the boys were distributed at balanced ectomorph to central whereas the girls were distributed to balanced endomorph. This pattern is relatively similar with common somatotype categories in Bandung, Magelang, and Yogyakarta. The difference pattern can be find in Bantul population where the boys and girls have ectomorphic category before puberty.

Rahmawati et al. (2004) suggest two phenomena in somatotype variation

related to age changes. First, the somatotype of well-off children shifts in puberty from endo-mesomorphy to ectomorphy in the boys, and to endomorphy in the girls. Second, the somatotype of lower-income children remains ectomorphic both before and after puberty, but the girl after puberty seem to shift to endomorphy while the boys become more and more ectomorpic according to age.

The girls in medium altitude show delayed and slowly increasing of endomorphy and slowly decreasing of mesomorphy. The low ratings of the endomorphy component signify physiques with a small amount of body fat, while high value of mesomorphy implies marked musculoskeletal development (Jürimäe and Jürimäe 2000). Moreover, the girls in this altitude have a long period of central somatotype (7 to 13 y), that indicated all three of somatotype are equal or differ no more than one unit. The pattern is uncommon for the girls development. For puberty preparation, the girls need to deposit the fat with increasing endomorphy value and decreasing mesomorphy (Jürimäe and Jürimäe 2000).

4 CONCLUSION

The children in low altitude population were higher and heavier than medium and high altitude populations. Until puberty, the children in medium population have same stature and weight with those reside in high altitude populations but shorter and lighter thereafter. The difference of height and weight are statistically significant in girls and not in boys.

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Appendix 2 Parents education of Sasak Children included the study

Parents Education

Elevation

Low Middle Height

Male Female Male Female Male Female

n % n % n % n % n % n %

Father Education

Not Schooling 47 22.07 26 14.05 56 45.90 69 47.92 52 39.69 49 34.75

Primary School 102 47.89 95 51.35 47 38.52 46 31.94 43 32.82 60 42.55

Junior Hight School 31 14.55 27 14.59 5 4.10 16 11.11 17 12.98 20 14.18

Senior Hight School 22 10.33 31 16.76 8 6.57 11 7.64 14 10.69 7 4.96

College (Diploma and Bachelor) 10 4.70 6 3.24 5 4.10 2 1.39 5 3.82 5 3.55

Post Graduate (Master and Doctoral) 1 0.47 0 0.00 1 0.82 0 0.00 0 0.00 0 0.00

Mother Education

Not Schooling 65 30.81 36 19.25 60 49.18 84 58.33 80 61.07 76 53.90

Primary School 103 48.82 116 62.03 50 40.98 47 32.64 38 29.01 47 33.33

Junior High School 34 16.11 23 12.30 8 6.56 12 8.33 6 4.58 15 10.64

Senior High School 8 3.79 11 5.88 2 1.64 1 0.69 5 3.82 3 2.13

College (Diploma and Bachelor) 1 0.47 1 0.53 2 1.64 0 0.00 2 1.53 0 0.00

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23 Appendix 3. Family size of Sasak Children included the study

Family Size

Elevation

Low Middle Height

Male Female Male Female Male Female

n % n % n % n % n % n %

Birth Order

1st born 85 39.53 74 39.57 49 40.16 64 44.44 43 34.40 45 34.09

2nd born 65 30.23 44 23.53 39 31.97 26 18.06 36 28.80 38 28.79

3rd born 30 13.95 35 18.72 16 13.11 21 14.58 20 16.00 28 21.21

4th born 18 8.37 14 7.49 9 7.38 9 6.25 15 12.00 14 10.61

5th + born 17 7.91 20 10.70 9 7.38 24 16.67 11 8.80 7 5.30

Number of Children in The Family

1 child 20 9.43 20 10.75 4 3.28 7 4.96 5 5.62 9 8.74

2 children 75 35.38 57 30.65 54 44.26 47 33.33 29 32.58 24 23.30

3 children 52 24.53 50 26.88 30 24.59 41 29.08 23 25.84 35 33.98

4 children 29 13.68 25 13.44 19 15.57 12 8.51 13 14.61 22 21.36

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Appendix 4 Somatotype score and somatotype categories, by age, sex and altitude

Age Boys Girls

Somatotype Score Somatotype Category Somatotype Score Somatotype Category

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25 Appendix 5 One-way ANOVA results of body height and body weight in Sasak

children

Df Sum of Square

Mean Square

F Value Pr (>F) Body Height

Girls Elevation 2 15.52 7.76 7.9763 0.000394*** Residuals 453 440.62 0.97

Boys Elevation 2 4.56 2.28 2.287 0.1027ns

Residuals 451 449.43 1.00 Body Weight

Girls Elevation 2 16.62 8.31 8.563 0.0002239*** Residuals 453 439.57 0.97

Boys Elevation 2 1.18 0.59 0.5859 0.557ns

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27

CURRICULUM VITAE

The author was born in Kudus on November 3rd,1981 as the third daughter of Karno Rustam and Suntari. The author got married with Yuliadi Zamroni and have one daughter (Annisa Hishnul Izza).

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