UNIVERSITY OF LAGOS SCHOOL OF POSTGRADUATE STUDIES APPLICATION FOR APPROVAL OF TITLE AND SUPERVISORS SECTION A: PARTICULARS OF THE CANDIDATE NAME: MATRIC No: QUALIFICATIONS: DEGREE IN VIEW: STATUS: DATE OF REGISTRATION: FIELD OF STUDY: PROPOSED TITLE OF THESIS: IBEABUCHI, Nwachukwu Mike MS 2113 MB, BS (Lagos), 1985; M. Sc (Lagos), 1989. Ph. D. Applied Anatomy Staff Candidate M. Phil 1998; Conversion to Ph. D 2003. Kinanthropometry A kinanthropometric investigation of the body build and physical growth of adolescent Nigerian children in urban Lagos.

SECTION B: RESULTS OF COURSE-WORK EXAMINATION COURSE CODE ANT 901 ANT 902 ANT 903 ANT 951 ANT 952 TOTAL UNITS = PROPOSED SUPERVISORS 1. A.O. Okanlawon (Professor) Department of Anatomy S.I. Jaja (Associate Professor) Department of Physiology RECOMMENDATION: The Postgraduate Education Committee at its meeting held on Wednesday, 11 th May 2005, considered the application and recommended it to the Academic Board. The Provost is recommending the application on behalf of the Academic Board to the Board of Postgraduate Studies for necessary action. NUMBER OF UNITS 4 3 3 3 3 TOTAL G.P.A. = SCORE GRADE GRADE POINT

Professor S. O. Elesha Provost

Dr. (Mrs) A. F. Fagbenro- Beyioku Chairman, Postgraduate Education Committee. UNIVERSITY OF LAGOS

SCHOOL OF POSTGRADUATE STUDIES DEPARTMENT OF ANATOMY PROGRESS/SUPERVISORS REPORT IN RESPECT OF Ph.D. CANDIDATE SECTION A: PARTICULARS OF THE CANDIDATE NAME: MATRIC No: QUALIFICATIONS: DEGREE IN VIEW: STATUS: DATE OF REGISTRATION: FIELD OF STUDY: PROPOSED TITLE OF THESIS: IBEABUCHI, Nwachukwu Mike MS 2113 MB, BS Lagos 1985, and M.Sc Lagos 1989 Ph. D. Applied Anatomy Staff Candidate M. Phil 1998; conversion to Ph. D 2003. Kinanthropometry A kinanthropometric investigation into the physique and somatic growth of a socioeconomically diverse sample of adolescent Nigerian children in urban Lagos.

SECTION B: RESULTS OF COURSE-WORK EXAMINATION COURSE CODE ANT 901 ANT 902 ANT 903 ANT 951 ANT 952 NUMBER OF UNITS 4 3 3 3 3 TOTAL UNITS = TOTAL G.P.A. = SECTIONS C: CRITICAL EVALUATION OF THE RESEARCH 1. Originality of the work SCORE GRADE GRADE POINT

2.

Evidence of Competence in the Field

3.

Interim Assessment of the Candidates Candidate

4.

Potential Worth of the Content of the Research Material for purposes of Publication.

5.

Potential for Contribution to knowledge

SECTION D AN ASSESSMENT OF PROGRESS IN RESEARCH DURING THE PERIOD, INCLUDING ANY DELAY OR VERY RAPID PROGRESS IN THE STUDENTS WORK SECTION E: PARTICULARS OF SUPERVISORS I. II. III. IV. V. VI. NAME: DESIGNATION: DEPARTMENT: SIGNATURE: DATE: A.O. OKANLAWON PROFESSOR ANATOMY ------------------------------------------------------------------S.I. JAJA ASSOCIATE PROFESSOR PHYSIOLOGY ------------------------------------------------------

CHAPTER ONE

1.1 INTRODUCTION The physical structure of the growing child has been systematically studied for over 150 years (Tanner, 1981). The basic concepts are built on a strong historical foundation in the medical, anthropological and human biological sciences. These studies are often intertwined with studies of physical activity, performance and fitness of children and adolescents whose foundation is largely built on what was traditionally called physical education and what is now called kinesiology, human kinetics, the physical activity sciences or exercise and sports sciences. These aspects of human biology have been studied at the level of the individual as well as in samples of children within communities and national populations. The study of these phenomena has contributed to our understanding of human biologic variation. A significant portion of the biological variation evident among adults in any population has its origin during the years of growth and maturation, including the prenatal period. The usual way an individual can become an adult is through the processes of growth, maturation and development. These processes have been shown to be quite plastic. They may be influenced by a variety of environmental factors operating on the growing and maturing individualnutritional intake, infant and childhood diseases, patterns of physical activity and other environmental stresses, which may interact with the individuals genetic potential for growth and maturation. The net result is a wide range of variation among individuals. An important objective would, therefore, be to understand the biological variability evident during the growing years in terms of its origin, distribution among different populations and significance. A vital question would

be why does such variation exist and what does it mean to the individual? What is the significance of early or late maturity for behavior and performance of the individual? An issue of current interest has been the association between growth and maturity, on the one hand, and between growth and adult health on the other. This association, in turn, emphasizes the need to continue studies of growth into the adult years. Early sexual maturity has been associated with several cancers in adulthood. Overweight adolescents tend to become overweight adults. Although association does not demonstrate causality, the results emphasize the need to consider risk factors for adult diseases within a life span framework, beginning with fetal growth. In addition to the foregoing, the study of growth and maturation has provided basic information relative to several more specific issues. These include: status, progress, prediction, tracking, comparison and interpretation of growth and maturity.

1.1.1

Operational Definition of Terms

Growth- this is an increase in the size of the body as a whole and or the size attained by specific parts of the body.

Hyperplasia- this is an increase in cell number. Hypertrophy- this is an increase in cell size. Accretion - this is an increase in intercellular substance. Hyperplasia, hypertrophy and accretion all occur during growth, but the predominance of one or another process varies with age and the tissue involved.

The increase in number is a function of cell division (mitosis), which involves the replication of DNA and the subsequent migration of replicated chromosomes into functional and identical cells. The increase in cell size involves an increase in functional units within the cell, particularly protein and substrates, as is especially evident in the muscular hypertrophy that occurs during growth and especially with regular resistance training during adolescence. The intercellular substances are both organic and inorganic, and they often function to bind or aggregate the cells in complex networks, as collagen fibers do in providing the matrix for the adipocytes of adipose tissue. Postnatal life this is defined as life after the first month of birth. It is commonly, although somewhat arbitrarily, divided into three or four age periods. Infancy - this is the first year of life, up to but not including the first birthday. This definition is universally accepted, specifically in the context of worldwide public health. It is a period of rapid growth in most bodily systems and dimensions and of rapid development of the neuromuscular system. Infancy is further subdivided into the following: Perinatal - around the time of birth, the first week. Neonatal - the first month of life. Postnatal - the remainder of the first year period and onwards. Childhood - extends from the end of infancy (the first birthday) to the start of adolescence. It is often divided into: Early childhood - this includes the preschool years. In the context of public health, early childhood extends from the first birthday through 4 years of age (1.0

to 4.99 years). Early childhood continues the rapid growth and development of infancy, although at a decelerated rate. Middle childhood - this generally includes the elementary school years into primary five and six. Middle childhood extends from 5 years to the beginning of adolescence. It is a period of relative steady progress in physical growth and maturation and in behavioral development. The public health definition of infancy and early childhood is used for the estimation of infant and childhood mortality, both of which are accepted universally as indicators of the health and nutritional status in a community. Adolescence - This is a more difficult period to define in terms of chronological age because of the variation in the time of its onset and termination. The World Health Organization (WHO) defines the age of adolescence as between 10 and 18 years (WHO, 1995) but certain authorities (Rolland-Cachera et al., 1991; Suwa et al., 1992; Roche and Guo, 2001; Malina, Bouchard and Bar-0r, 2004) regard the age ranges of 8 to 19 years in girls and 10 and 22 years in boys as are more appropriate limits for normal variation in the onset and termination of adolescence. In this period, most bodily systems become adult both structurally and functionally, i.e. they reach maturity. Structurally, adolescence begins with acceleration in the rate of growth in stature, which marks the onset of the adolescent growth spurt. The rate of growth in height reaches a peak, then begins a slower or decelerative phase, and finally terminates with the attainment of adult stature. Functionally, however, adolescence is usually

viewed in terms of sexual maturity, which actually begins with changes in the neuroendocrine system before overt physical changes and terminates with the attainment of mature reproductive function.

Growth curves or tables of body dimensions, performance variables, and measures of physical activity are ordinarily presented by chronological age.

Status - This is defined as the attained size or level of maturity attained at a given point in time. A childs growth, maturity or performance status relates to how the child compares with other children of the same age and sex. It also refers to the status of a group of children in a community. This approach has often been used in the context of surveys of nutritional status, physical fitness and general health status. According to the WHO, for instance, the growth status of children is perhaps the best indicator of the overall health and nutritional circumstances in a community, especially in the developing world (WHO, 1995).

Progress - Progress implies change, which provides an estimate of rate. When taken at several points in time, measurements and observations of a child or a group of children have provided an indication of progress over time. A child who grows 6cm over a period of 1 year would have a growth rate of 6cm/year.

Maturity/ Maturation Maturation is a process, whereas maturity is a state. Progress also involves maturation. Is the level of a childs maturity early (advanced), late (delayed) or average (appropriate or on time) for the childs chronological age? Children advanced in biological maturity relative to their

chronological age characteristically progress at a more rapid rate of growth than do those who are delayed in maturity relative to chronological age and who progress more slowly. Tracking - This refers to the stability of a characteristic, or the maintenance of relative rank or position within a group, over time. Distance (size-attained) curve This curve is a graphical representation of agespecific and sex-specific averages of growth characteristics for boys and girls. They do not portray the wide range of normal individual variability apparent in any group of children. The pattern of age changes tends to be generally similar in all children, but the size attained at a given age and the timing of the adolescent growth spurt varies considerably from child to child. Reference data - Reference data, sometimes referred to as norms, are values on the growth and maturity status of a large sample of healthy children free from overt disease. When a group of children are studied, they are compared either with reference data or with other groups of children of the same age and sex. Somatic growth. This is growth of the external body organs including skin, subcutaneous tissue, skeletal muscles and bones. Body weight - This is a measure of body mass. However, the term weight is entrenched in the literature. Therefore, the terms body mass and weights are used interchangeably throughout this report. Stature This term refers to standing height. It is a linear measurement of the distance from the floor or standing surface to the top (vertex) of the skull. The two terms are used interchangeably throughout this report. Stature is a composite of

linear dimensions contributed by the lower extremities, the trunk, the neck, and the head. Recumbent length - This refers to the length while lying face up in a standardized position. From birth to age 2 or 3 years, a childs stature is measured as recumbent length. As a rule, an individual is longer when lying down than when standing erect. Sitting height This refers to the height while sitting. It is measured as the distance from the sitting surface to the top of the head with the child seated in a standard position. This measure is most valuable when used with stature. Leg length (subischial length, or lower extremity length) This measure refers to stature minus sitting height. It provides an estimate of length of the lower extremity (Carr et al., 1993).

Diurnal variation This refers to variation of a measurement during the course of the day. Body weight and stature show diurnal variation (Reilly, Tyrell and Troup, 1984; Wilby et al., 1985).

Skeletal Breadths These are breadth or width measurements ordinarily taken across specific bone landmarks and therefore provide an indication of the robustness or sturdiness of the skeleton. Four of the commonly taken skeletal breadths include biacromial, biiliocristal, humerus and femur breadths.

Biacromial breadth measures the distance across the right and left acromial processes of the scapulae and provides an indication of shoulder breadth.

Biiliocristal breadth measures the distance across the most lateral paths of the iliac crests and provides an indication of hip breadth.

Biepicondylar humerus breadth is taken across the epicondyles of the elbow while

Biepicondylar femur breadth is a measure of bone breadth across the knee. Both of these measures provide information on the robustness of the extremity skeleton.

Limb Circumference This refers to a measure of the circumference of the limb taken at a specific point the limb.

Skinfold Thickness This refers to the thickness of a double fold of skin and underlying subcutaneous tissue, can be picked up and measured at any number of body sites.

Somatotype - A somatotype is a classification of physique based on the concept of shape, disregarding size. The pre-eminent system of somatotype classification is the Heath-Carter somatotype. This shows the relative dominance of Endomorphy (relative fatness), Mesomorphy (relative musculo-skeletal

robustness) and Ectomorphy (relative linearity). Each component is identified in the sequence endomorphy-mesomorphy-ectomorphy and, when

anthropometrically-derived, expressed to the nearest one-tenth rating, e.g, 1.46.0-3.2, an ectomorphic mesomorph, or ecto-mesomorph. Ratings of 2 to 2.5 are considered low, 3 to 5 are moderate, 5.5 to 7 are high and 7.5 and above are very high(Carter,1996). The derivation equations for each component are as follows.

Anthropometry - Anthropometry is the study of the human body measurement for use in anthropological classification and comparison. Anthropometry

(anthropos = man, metry = measure) is a set of standardized techniques for systematically taking measurements of the body and parts of the body, that is, for quantifying dimensions of the body. Kinanthropometry - this is a branch of anthropometry. The most common definition is the measurement of human size, shape, proportion, composition, maturation and gross function as related to growth, exercise, performance and nutrition. An abbreviated definition is The quantitative interface between anatomy and physiology, between morphology and physiology, or between structure and function (Ross and Marfell-Jones, 1991, Carter and Ackland, 1994; Norton and Olds, 1996). Secular trend this refers to changes in a physical characteristic that occur from one generation to the next.

Overview of measurements

1.1.2.1

General

The measurements described herein are the traditional dimensions utilized in growth studies. They provide information on the size of the child as a whole (weight and stature) and of specific parts and tissues. Skeletal breadths describe the overall robustness of the skeleton; limb circumferences provide information about relative muscularity, while skinfold thickness is an indicator of subcutaneous adipose tissue. The specific dimensions include both the trunk and the extremities. Individuals may be similar in overall body size

and yet can vary in shape, proportions, and tissue distribution. Other dimensions may be measured, but the choice of measurements depends on the information desired in the context of a study.

1.1.2.2 Quality ControlImplicit in studies using anthropometry is the assumption that every effort is made to ensure the accuracy and reliability of measurement and standardization of technique. Also implicit is the assumption that the measurements are taken by trained individuals. These conditions are essential to obtain accurate and reliable data and to enhance the utility of the data from a comparative perspective. Reliable and accurate are especially critical in serial studies, in which the same child is followed longitudinally over time, either short-term or long-term, and in the definition of rather small changes may be necessary and technical errors associated with measurement can mask true changes. Error is the discrepancy between the measured value and its true quantity. Measurement error can be systematic or random. Random error is a normal aspect of anthropometry and results from variation within and between individuals in technique of measurement, problems with measuring instruments (e.g., calibration or random variation in manufacture), and errors in recording (e.g., transposition of numbers). Random error is nondirectional- it may be above or below the true dimension. In large- scale surveys, random errors tend to cancel each other and ordinarily are not a major concern. Systematic error, on the other hand, results from the tendency of a technician or a measuring instrument (e.g., an improperly calibrated skinfold caliper or weighing scale)

to consistently under measure or over measure a particular dimension. Such error is directional and introduces bias into the data. In addition, the child under observation may be a source of measurement variability. Replicate measurements of the same subject are used to estimate variability or error in measurement. Replicate measurements are taken independently from the same individual by the same technician after a period of time has lapsed, or they are taken from the same individual by two different technicians. If the interval between the replicate measurements is too long (e.g., about 1 month) growth may be a factor that contributes to the variability within or between technicians. Replicate measurements provide an estimate of within-technician measurement variability, whereas corresponding measurements taken on the same subjects by two different individuals provide an estimate of between-technician measurement variability. The technical error of measurement (TEM) is a widely used measure of replicability (Malina et al., 1973). It is defined as the square root of the squared differences of replicates divided by twice the number of pairs (i.e., the within-subject variance): = d / 2N The statistic assumes that the distribution of replicate differences is normal and that errors of all pairs can be pooled. It indicates that about two-thirds of the time, the measurement in question should fall within the TEM (Mueller and Martorell, 1988). Technical errors are reported in the units of the specific measurement. Within-technician (intra-observer) and between-technician (inter-observer) TEMs for a variety of anthropometric dimensions in national surveys and several more local studies are summarized in Malina (1995).

Although the TEM provides an indicator of the replicability of a measurement over a short interval of time, it may underestimate the true measurement error. Variation within an individual child is a source of error that may not be captured in replicate measurements. This source may be the result of normal variation in physiology (for example, muscle tension) and other factors specific to the child (for instance, temperament, cooperativeness, and stranger anxiety). This type of error is labeled undependability (Mueller and Martorell, 1988), and an important component of undependability is the child factor or the child effect (Lampl et al., 2001). Accuracy is another component of the measurement process. It refers to how closely measurements taken by one or several technicians approximate the true measurement. Accuracy is ordinarily assessed by comparing measurements taken by the technician(s) with those obtained by a well trained or criterion Anthropometrist (i.e., the standard of reference). However, well-trained, expert anthropometrists also make errors.

1.1.2.3 Ratios and Proportions

1.1.2.3.1. General In addition to providing specific information in their own right, measurements can be related to each other as indices or ratios. Ratios are influenced by the relationship between the two dimensions, and the two dimensions are assumed to change in a linear manner. Ratios may yield spurious results when they are based on different types of

dimensions, such as weight and stature or arm circumference and stature, or when the standard deviations of the dimensions differ considerably. The ratio may be between dissimilar (different units) or similar (same unit) measurements.

1.1.2.3.2

Weight and height ratios.

Ratios based on weight and heights have a long tradition in studies of growth and body build, in studies of undernutrition (low weight-for-height), and in studies of the risk of overweight and obesity (excess weight-for-height).

1.1.2.3.3 Weight-for-height. This ratio is commonly used with preadolescent children especially in the context of severe malnutrition (for example, kwashiorkor and marasmus) as soft tissues that constitute body weight (largely muscle and fat) are wasted. The same occurs in individuals with anorexia nervosa, a severe eating disorder related to the fear of becoming fat. Weight-for- stature is also used in the context of overweight. Youngsters who are overweight have a high weight-for-stature; the excess weight is related to fatness. However, not all children with excess weight-for-stature are fat, because muscle mass and other nonfat tissues may contribute to the increase in weight relative to stature. This increase is related to body composition. During the adolescent growth spurt, the relationship between stature and weight is temporarily changed. The growth spurt occurs, on the average, first in stature and then in weight, so the relationship between the two measurements is altered. After growth has ceased, weight-for-stature is once again a useful index.

1.1.2.3.4

Other weight-height ratios

Sometimes weight is simply expressed relative to height, or either height or weight is adjusted to account for the relationship between the two measurements. The adjustment has taken several forms, for example, weight divided by height squared (weight/height, the body mass index, BMI or Quetelet index), height divided by the cube root of weight (height/ weight, the height-weight ratio, HWR or reciprocal Ponderal index). Except for ratios of weight and height, the ratios described subsequently are based on similar measurements (e.g., two lengths or two skeletal breadths). These ratios are ordinarily calculated by dividing the larger measurement into the smaller measurement. These ratios provide information on shape and proportions. Three ratios commonly used in growth studies are weight-for-stature, sitting height/stature and shoulder-hip ratios.

1.1.2.3.5

Sitting height/stature ratio

This is the next most widely used ratio in growth studies. It is calculated as: (Sitting height/stature) x 100

This ratio, also known as the Skelic index (Meredith, 1979; Monyeki, Pienaar and de Ridder, 1997; Kekana and Monyeki, 1998), provides an estimate of relative trunk length. It basically asks the question: what percentage of height while standing is accounted for by height while sitting? By subtraction, the remaining percentage is accounted for by the lower extremities. Of two children with same stature, one may have a Skelic index of

54% and the other 51%. In the first child, sitting height accounts for 54% of stature, and by subtraction, the lower extremities account for 46%. This child is said to have relatively short legs-for-stature. In contrast, sitting height account for 51% of stature in the second child, and by subtraction, the legs account for 49%. The second child has relatively long legs-for-stature compared with the first child.

1.1.2.3.6

Shoulder-Hip Relationships

The ratio of biiliocristal to biacromial breadths is also used in growth studies. It relates the breadths of the hips (lower trunk) to that of the shoulders (upper trunk):

(Biiliocristal breadth/biacromial breadth) x 100

This ratio (also known as Androgyny Index) illustrates proportional changes in shoulder and hip relationships, which become especially apparent during adolescence. Shoulderhip relationships also vary among young athletes in several sports (e.g., track and field, gymnastics and water sports). Young athletes in these sports generally have proportionally wider shoulders compared to their hips, and female athletes tend to have proportionally wider shoulders than non-athletes.

1.1.2.3.7

Other Ratios

Ratios of skinfold thickness measured on the trunk and extremities are often used to estimate relative subcutaneous adipose tissue distribution. The ratio of waist and hip circumferences is also used as an indicator of relative adipose tissue distribution,

although muscle and skeletal structures also contribute to the hip girth measurement. Waist circumference by itself is primarily an indicator of adipose tissue in the abdominal area. The waist-hip ratio is often used with adults, but it has limited validity as an indicator of relative adipose tissue distribution in children and adolescents.

1.1.3

Growth in Stature and Body Weight

Stature and weight are the most commonly used measurements in growth studies. Both dimensions are often routinely measured on a regular basis (e.g., in hospitals, schools and sports clubs to monitor growth status and progress). From birth to early adulthood, both stature and weight tend to follow a four-phase growth pattern: rapid gain in infancy and early childhood, rather steady gain in middle childhood, rapid gain during the adolescent spurt, and slow increase until growth ceases with the attainment of adult stature. Body weight, however, usually continues to increase into adult life. The results of several studies from around the world suggest that both sexes tend to follow the same course of growth. Sex differences before the adolescent spurt are usually consistent although minor. Boys, on the average, tend to be taller and heavier than girls. During the early part of the adolescent spurt, girls are temporarily taller and heavier because of their earlier growth spurt. Girls soon lose the size advantage as the adolescent spurt of boys occurs; boys catch up with and eventually surpass girls in body size, on the average. Given the normal range of individual variation, overlap exists between the sexes

throughout growth and in young adulthood. Hence, some girls are taller and heavier than most boys at virtually all ages.

Reference Data and Growth Charts Distance curves are commonly used for assessing the growth status of a single child or a sample of children. In making such assessments, the size attained by a child or the average size of a group of children is compared and evaluated relative to growth data derived from a large sample of healthy children free from overt disease. These data are referred to as reference data. They are points of reference in assessing the growth status of a child or a group of children. The World Health Organization (1995) defines a reference as a tool for grouping and analyzing data and provides a common basis for comparing populations. Reference values are not standards. A standard is prescriptive and suggests the way things ought to be, and, as such it has an associated value judgment. Reference values are used. Reference data are most often presented in the form of several curves representing different percentiles to accommodate the range of normal variability among children of the age. Percentiles of reference data are smooth and ranges are quite broad. Growth charts used in the United States include the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentile while those used in the United Kingdom and South Africa include the 3rd and 97th percentiles in the list.

The growth charts for the United States (U.S.) children are based on national surveys that have been regularly conducted since the 1960s. The surveys are based on complex, multistage stratified sampling procedures that result in the selection of a sample that is representative of the noninstitutionalized civilian population. The National Health Examination Survey (NHES II and NHES III, 1963-1970), the National and Nutrition Examination Survey, NHANES I (1971-1974) and NHANES II (1976-1980) included adequate numbers of children and adolescents of Black (African American) and White (European American) ancestry. NHANES III (1988-1994) over sampled African Americans and Mexican Americans compared with their numbers in the total population of the U.S. in 1990. Since 1999, NHANES has become a continuous survey; the first 2 years of NHANES data collection (1999-2000) have been used to evaluate changes in overweight among American children and adolescents (Ogden et al., 2002) and adults (Flegal et al., 2002). In constructing growth charts for American children, data from the different ethnic groups were combined for two reasons. First, the differences in stature among Blacks, whites, and Mexican Americans was rather small and, second, the sample sizes for each ethnic group are not satisfactory to meet the statistical requirements for empirically deriving the percentiles at the extremes of the distribution (Roche et al., 1996). In addition, it is not clear whether the apparent growth differences among the three ethnic groups were genetic. Given the ethnic heterogeneity of the American population, ethnic- specific growth charts were not warranted.

Secular trends

The attainment of larger size and the acceleration of maturation over several generations are collectively labeled as the secular trend. In this context, the secular trend actually includes several trends- increase in height and weight during childhood and adolescence, reduction in the age at menarche and ages at attaining other indicators of biological maturity, and increase in adult stature- that have occurred over several generations in Europe and Japan and in areas of the world largely inhabited by populations of European ancestry (United States, Canada and Australia). The time at which secular changes are evident in different populations varies in part because of the limited availability of satisfactory data for earlier samples in some populations and because of differential rates of improvement in health and nutritional circumstances that underlie improvements in growth and maturity status. Secular trends are complex phenomena that reflect the remarkable sensitivity, or plasticity, of the processes of growth and maturation to the environmental conditions under which children and adolescents are reared. Secular trends may be positive, negative or absent. For instance, the observation that children today are, on average, taller and heavier and mature earlier than children of several generations ago indicates a positive secular trend. On the other hand, in some parts of the developing world, children and adults are shorter than those of a generation or two ago, or girls attaining menarche later, indicating a negative secular trend (Tobias, 1985). Lack of change in size or age at menarche over several generations indicates the absence of a secular trend, which reflects different situations (Malina, Bouchard and BarOr, 2004).

Secular trends are not universal and have been shown to be reversible. This is especially evident in times of war. The positive secular trend in the heights of children and adolescents have been temporarily stopped and even reversed in some countries during World Wars I and II in Europe (van Wieringen, 1986) and during World War II in Japan (Takaishi, 1995; Ali and Ohtsuki, 2000). When conditions improved after the wars, positive secular changes in height resumed. More recent examples of the reversibility of secular trends are apparent in the slightly later ages at menarche during the period of social and political change after the collapse of the Soviet dominated communist system in Poland in the 1980s (Hulanicka et al., 1993) and during the war conditions that characterized the political breakup of the former Yugoslavia in the 1990s (Prebeg and Bralic, 2000).

Socioeconomic status The socioeconomic position or status has been defined as the relative position of a family or individual in a social structure, based on their access to scarce and valued resources such as education, wealth and prestige (adapted from Western, 1983). Three broad conceptualizations of socioeconomic position or background (social class, socioeconomic status and disadvantage) have been discussed at length in the sociological, educational, medical and health literature. An overview of the major issues which have a bearing on the conceptualization of the socioeconomic position of schoolchildren, has been presented in a number of general papers on the history of, and current approaches to, the conceptualization of social class and socioeconomic status (Western, 1993; Graetz, 1995a; Jones and McMillan, 2000) while the conceptualization of socioeconomic

background in educational contexts has been discussed at length in relation to schooling (Graetz, 1995b) and higher education (McMillan and Western, 2000; Western et al., 1998). Several studies have been published in central Europe (Farkas, 1978, 1979, 1980, 1982, 1986; Eiben, 1989, 1994; Eiben et al 1991; Romon et al., 2005), the United States (Adler et al., 1994; Adler and Ostrove,1999; Averett and Korenman,1999; Lohman et al., 2000; Mayer et al., 2005; Rouse and Barrow, 2006), the United Kingdom (Townsend et al., 1998; Saxena et al., 2004; Wardle et al.,2003, 2004, 2005, 2006), the Meditteranean (Garcia et al., 1993; Rebato et al, 2003), Australia (Norgan, 1994; Marks et al., 2000; Adams et., 2002) central Asia (Leung et al., 1996; Ahmed et al., 1998; de Onis et al., 2001; Wang, 2001), Latin America ( Spurr et al., 1983; Delgado and Hurtado, 1990; Martinez et al., 1993) and Africa (Toriola, 1990; Cameron, 1992; Simondon et al., 1997; Benefice et al., 1999; Pawloski, 2002; Gillett and Tobias, 2002; Prista et al., 2003; Brabin et al., 1997, 2003) that analyze and demonstrate the relationship between environmental factors such as nutrition, energy expenditure associated with physical work and the sociocultural lifestyle and the adolescent childs physical development. Many of them suggest that remarkable differences in body dimensions and maturity status may exist between children when their social background is dissimilar. When material resources available to the family are ample, the children are often taller and heavier and reach their respective stages of maturity at a younger age than their less privileged peers. One of the probable mechanisms through which these environmental factors may exert their influence the physique could be energy balance regulation.

In studying these aspects, research often considers factors that have been shown to reflect the socio-economic status of the parents reliably (Townsend et al., 1998; Wardle et al., 2003). Previously employed indicators include parental level of education (Cesaroni et al., 2003; Michel et al., 2006; Hagquist, 2007), parental profession or occupation (Vrijheid et al., 2000; Halldrsson et al., 2002; Wright and Parker, 2004), family size (Wright, 2000; Blair et al., 2004; Khang and Kim, 2005), per-capita income (Woodroffe et al., 1993; Pattenden et al., 1999; Vrijheid et al., 2000; Alvarez-Dardet and Ashton, 2005;), the grade of provision with modern conveniences of the habitat (Cooper et al., 1998; Saxena and Majeed, 1999; Saxena et al., 2002), the settlements level of urbanization and the number of inhabitants living in the community (Office of Population, Censuses and Surveys. 1993; Forrester et al., 1996; Office for National Statistics, 2002), the level of health care and access to medical services (Newton and Goldacre, 1994; Roland et al., 1996;Department of Health, 2001; Hippisley-Cox et al., 2002; Office for National Statistics, 2002; Petrou and Kupek, 2005). The socio-economic status of the family is often reflected in the type of school attended by the children in the family ((McMurray et al., 2002; Wardle et al., 2006 etc). Economically advantaged families often prefer fee-paying, private school to minimal feepaying public school because the former tend to be better funded to provide adequate educational facilities and a good learning environment (Heckman and Lochner, 2000; Vegeris and Perry, 2003;US Department of Education NCES-2005). Furthermore, the discriminatory tendency in the funding pattern of public schools in various countries has been well documented (Hedges et al., 1989, 1994; Hanushek 1996; Ellwood and Kane 2000; Krueger, 2003; Adelman et al., 2003) and is a reflection of

institutionalized social class as well as the inequalities and disadvantage consequent for the poorer segments of the society. Socioeconomic disadvantage has been measured in epidemiological studies by both individual indicators (education, occupation, house ownership, quality and amenities, income) and by area-based indicators which are indices based on an array of social characteristics of residential areas drawn from census data or aggregate income (Krieger et al., 1997; Geronimus and Bound, 1998; Geyer and Peter, 2000). This would have implications for the attainment of the full educational, psychological and physical growth potential of the adolescent child (Barrow and Rouse, 2004; Spencer, 2005). Although different by definition, social class and socioeconomic status are closely intertwined (Graetz 1995a; Jones & McMillan 2000; Western 1993). However, their combined roles in influencing the health and growth status of children especially in Africa is more readily apparent because the public welfare institutions expected to provide the social support services that could ameliorate the effects of social inequality are either moribund or non-existent (Spencer et al., 1999; Marks et al., 2000; Snyder et al., 2003; Hanushek et al., 2005). In several countries, attempts have been made to address this problem comprehensively but differ in specific actions or in the focus of their educational reforms (Rouse, 1997; Marks et al., 2000; Howell and Peterson, 2002; Mullis et al., 2002; Bifulco and Ladd, 2004; Hanushek et al., 2005). Two options, decentralization of the school system and free school choice, have become a part of the global trend in educational reform (Chapman, 1996; Gonnie van Amelsvoort and Scheerens, 1997). The methods used have varied with the countries (Liberatos et al., 1988; Durkin et al., 1994; Statistics Norway, 1984), with the age group of children (Mueller and Parcel, 1981; Anderssen, 1995; Currie et al., 1997) and with the nature of

study (Abramson, 1982). Some studies measured or classified the socioeconomic status of schools for the purposes of government-funding of public and privately-owned schools (DETYA, 1999; Marks et al., 2000; Rouse and Barrow, 2006). Commonly- adopted procedures include such parameters as the facilities provided by the school (Hedges et al., 1994; Hanushek, 1996; Snyder et al., 2003; Aaronson et al., 2005) and the demographic characteristics of its geographical location (Australia Board of Studies 1990, 1994, 1998). Sometimes the classification may be census-based (Ross, 1983; Ross et al., 1988) wherein the process is integrated into the countrys national demographic survey (Linke et. al. 1988; Western et. al. 1998). In other situations, it has been determined by the socioeconomic status of the parents of the schoolchildren (Chen et al., 2006). Some authorities recommend that the socioeconomic status of the parental breadwinner only or the entire family income (Morris et al., 2004; Dahl and Lochner, 2005) or a scored-index representing the combination of a number of criteria (Graetz 1995; Townsend et al., 1988; DETYA, 1998; Wardle et al., 2002) be used to determine the socioeconomic status for the study. Other authorities have considered the characteristics of the school only as an adequate indicator of the socio-economic status of the study children, thereby avoiding the intrusiveness often associated with trying to obtain accurate information about a familys wealth (Finn and Achilles, 1990; Angrist and Lavy, 1999; DETYA, 1999; Hoxby, 2000; Snyder et al., 2003). Sometimes the information has been obtained from the childs self-reporting of fathers income (Looker, 1989; West et al., 2001; Lien et al., 2001). The non-uniformity of the classification systems is further complicated by confounding issues such as misclassification of individuals and schools due to assumed homogeneity of the population characteristics (Western, 1988; Starfield et al., 2002). Whichever method is

adopted the principle has been that proper validation would be required in the context of the specific study (Starfield, 1985; Ainley & Marks 1999; DETYA, 1999; Janssen et al., 2006). A review of relevant literature from different regions of Africa (Pawloski, 2002; Prista et al., 2003) and Nigeria (Omololu et al., 1981; Brabin et al., 1997; Abidoye and Nwachie, 2001) suggests that usually it is the minimal criteria that have been adopted among the adolescent age group. The Nigeria DHS EdData Survey (2004), jointly published by the National Populations Commission of Nigeria (NPC) and the Federal Ministry of Health in collaboration with ORC Macro of Calverton, Maryland, USA and the United States Agency for International Development (USAID) presents health and demography data for the Nigerian population based on the 1991 Census data. In accordance with the WHO recommendation, anthropometric measurements were taken to derive three nutritional status indices including: height-for-age, weight-for-age and height-for-weight. These data for Nigerian schoolchildren have been compared with the international reference population defined by the US National Centre for Health Statistics (NCHS) and accepted by the Center for Disease Control and Prevention (CDC). Each of the status indices has been expressed in standard deviation units (z-scores). The use of this reference population was based on the finding that well-nourished children from all populations (where data exist) follow very similar growth patterns up to the onset of puberty (Drake et al., 2002; Partnership for Child Development, 2000). Consequently, the NDES has not used data for children older than 9 years 11 months. The age range of the current dissertation is from 9 years 6 months to 16 years 6 months.

Somatotype A somatotype is a classification of physique based on the concept of shape, disregarding size. The pre-eminent system of somatotype classification is the Heath-Carter somatotype. This shows the relative dominance of Endomorphy (relative fatness), Mesomorphy (relative musculo-skeletal robustness) and Ectomorphy (relative linearity). Each component is identified in the sequence endomorphy-mesomorphy-ectomorphy and, when anthropometrically-derived, expressed to the nearest one-tenth rating, e.g, 1.46.0-3.2, an ectomorphic mesomorph, or ecto-mesomorph. Ratings of 2 to 2.5 are considered low, 3 to 5 are moderate, and 5.5 to 7 are high and 7.5 and above are very high (Carter, 1996).

Kinanthropometry Kinanthropometry is a scientific specialization in exercise science that has brought specialists from human anatomy, human biology, physical anthropology, physical education, exercise physiology, sports science, sports medicine, and nutrition, pediatrics, gerontology, cardiology, respiratory medicine, neurology, orthopedics and several other medical disciplines into close alliance. Thus, its scope and applications are broad (Carter, 1996). Kinanthropometry deals with the measurement of humans in a variety of morphological perspectives, its application to movement, and those factors which influence movement, including: components of body build, body measurements, proportions, composition, shape, and maturation, motor abilities and cardiorespiratory capacities, physical activity including recreational activity as well as highly specialized sports performance.

Ross (1978) presented an elegant overview of the specialization. The definition of size includes the measurement of absolute dimensions of the body, both external and internal; shape refers to the assessment of the form of the body; proportion refers to the relative size or relationship of body parts of one another or to the whole body; composition includes the assessment of the various tissues, fluids and compartments of the body; maturation refers to the assessment of the biological age or maturity status of the person; and gross function includes performance in sports, events, tasks, occupation or fitness tests. Although kinanthropometrists often examine the technology within one of the above areas, a kinanthropometric study would have at least one element of morphology or structure along with gross motor performance or application in one of the areas of growth, exercise, performance or nutrition.

Uses of Kinanthropometry Kinanthropometric measurements, when analyzed statistically, may be utilized in a wide variety of ways including: somatotyping, fractionation of body mass into bone, muscle, fat and residual components, body proportionality estimates, prediction of body density and composition, determination of chronological and biological age, assessment of nutritional status and monitoring of nutrition interventions, assessment of growth patterns and estimation of growth indices in children and the youth, prediction and assessment of adult stature, prediction of performance, health and survival in the general population, assessment and monitoring of lifestyle- related illnesses, monitoring of athletic development and performance, comparison between national and international sample groups, physical anthropological classification of population groups, guiding public

health policy and clinical decisions, design of office and home furniture, design of shoes and garments, design of orthopedic and physiotherapy aids and gadgetry, design of indoor and outdoor fitness and wellness equipment, management of life insurance policies and production and revalidation of reference values, (Astrand and Rodahl, 1970; Ross and Marfell-Jones, 1991; Amusa, Igbanugo and Toriola, 1998).

Anthropometric assessment protocols The protocols for specific measurements have been discussed in Lohman et al. (1988), Ross and Marfell-Jones (1991), and Norton and Olds (1996). Anthropometry depends upon strict adherence to particular rules of measurement as determined by national and international standards bodies. Anthropometry is a very old science, and like many old sciences, has followed a variety of paths. The diversity of anthropometric paths is both its richness as well as its bane. One of the consequences of multiple anthropometric traditions has been the lack of standardization in the identification of measurement sites, and in measuring techniques. This has made comparison across time and space extremely difficult. In the year 2001, the International Society for the Advancement of Kinanthropometry (ISAK) published its reference manual, International Standards for Anthropometric Assessment, as a practical tool for use in teaching, in the laboratory and in the field. Derived in a large part from a previous, well- recognized standard, Chapter 2 of Anthropometrica, edited by Norton and Olds (1996) as well as from a series of classic textbooks and congress reports generated throughout the 20th century, this reference manual was developed over a period of five years after extensive consultation within its

Executive council, with all ISAK Criterion Anthropometrists and many ISAK Level 3 anthropometrists. It is an update on all the protocols currently in use for anthropometry worldwide. It was endorsed by United Nations Educational, Scientific and Cultural Organization (UNESCO) and the Supreme Council for Sports in Africa (SCSA) for use during the 8th All-Africa Games in Abuja, Nigeria (October 4- 18, 2003) by the Nigeria All-Africa Games Kinanthropometry Project (NAAGKiP) Research Team, that obtained kinanthropometric data from the elite athletes competing at those Games. The anthropometric sites and measurement procedures preferred for the current study are those based the international standards recommended by ISAK. These measurements provide a comprehensive description of the kinanthropometric data, which could be used to derive additional computations such as: estimates of relative body fat (using a large number of prediction equations), estimates of bone, muscle, adipose and residual masses using fractionation of body mass techniques (Drinkwater and Ross, 1980; Kerr, 1992), calculation of skeletal mass and skeletal muscle mass by various methods (Martin et al., 1990; Martin, 1991; Janssen et al., 2000; Lee et al., 2000).

CHAPTER TWO

2.1

LITERATURE REVIEW

2.1.1 Growth Studies: Sources of Data A review of the history of the study of growth suggests that the earliest published work on the subject was based on data generated from North America and Europe. A detailed account was published in Origins of the Study of Human Growth, (Boyd, 1980), and A History of the Study of Human Growth, (Tanner, 1981). Boyd (1980) was based on the unfinished manuscripts of Richard Scammon, which were first reported in 1923 in the 11th edition of Morris Anatomy and subsequently republished in his 1930 Sigma XI lecture (Scammon, 1930). Boyd (1980) considered early discussions of the life cycle (including description of prenatal and postnatal stages) from antiquity to 1700 and then more specific studies of growth in Europe and North America from 1700 to 1940. Tanner (1981) briefly considered the ancient world, the middle Ages, and the Renaissance and then presented a comprehensive discussion of growth studies from the 18th century through the major North American and European longitudinal studies. Earlier reports provide an excellent background to the relatively long history of the study of growth in Europe and the United States. Meredith (1936) reviewed American research on growth of children before 1900, and Krogman (1941) provided a comprehensive compilation of European and North American growth studies before 1940, focusing primarily on data from the 1920s and 1930s. The compilation also included several studies of active youth and of motor performance. Krogman (1950, 1955) also presented a syllabus of concepts and techniques for the study of growth, including motor skills, which was followed by a summary of related literature published between 1950 and 1955. Meredith (1969, 1971, and 1987) also reported summaries of data from different

areas of the world dealing with specific body dimensions in specific age groups between birth and adulthood. Roche and Malina (1983) provide detailed tabular summaries for a variety of indicators of growth and maturity in North American since 1940 in a two-volume compendium, Manual of Physical Status and Performance in childhood. Eveleth and Tanners (1990) Worldwide Variation in Human Growth is a compendium of data on growth and maturation from many regions of the world and also includes a discussion of factors that influence these processes.

Longitudinal Studies of Growth and Maturation 2.1.2.1 United States Studies. Several longitudinal studies were begun in the United

States in the 1920s and early 1930s: the Harvard School of Public Health in the Boston area; the Brush Foundation Study at the Western Reserve University (now Case Western Reserve University) in Cleveland, Ohio; the Fels Research Institute in Yellow Springs, in south-central Ohio (now a part of the Wright State University School of Medicine); the Child Research Council in Denver, Colorado; and the Guidance Study of the University of California at Berkeley (Tanner 1948, 1981). These major United States studies included children between 11 and 17 years of age (Espenschade, 1940; Jones, 1949). Two more recent American longitudinal studies of growth took a different approach than the traditional studies. The first was based on a longitudinal series of about 340 middleclass girls from Newton, Massachusetts, followed from 9 or 10 years of age to young adulthood. The study was begun in 1965 and included stature and weight and age at menarche. This study is unique in that the data were reported by the mothers of the girls

in questionnaires sent at monthly or 6-week intervals. The reported data were supplemented by semiannual or annual height and weight measurements made by the physical education department of the local school system, beginning when the girls were 5 or 6 years of age. Measurements of growth and maturity that span childhood and adolescence provide the basis for many longitudinal analyses. Other growth studies, some of which of which included a longitudinal component, were carried out since 1917 at the Iowa Child Welfare Research Station at the University of Iowa in Iowa City. The Philadelphia Center (now the W.M. Krogman Center) for Research in Child Growth at the University of Pennsylvania carried out a mixed- longitudinal study of school-age American Black (African American) and White (European American) children from the late 1940s through the late 1960s (Krogman, 1970). Many of the subjects of the Fels study were followed into adulthood in a series of studies that continues at present (Roche, 1992). Data from the Fels and Harvard studies are also being analyzed in the context of tracking of fatness and other risk factors for disease from childhood into adulthood and tracking of precursors of morbidity and mortality in adulthood (Casey et al., 1992; Must et al., 1992; Guo et al., 1994). In addition to the Guidance Study at the University of California, a second study, the Adolescent Growth Study of children in Oakland, California, was conducted. This study included measurements of strength and motor performance of children and adolescents age (Zacharias and Rand, 1983). The second study, the Harvard Six Cities Study, is part of an examination of the health effects of indoor and outdoor pollution on children from six regions of the United States (localities in Massachusetts, Tennessee, Ohio, Missouri,

Wisconsin and Kansas). Annual examinations included height and weight measurements, in addition to spirometry, a measure of lung function (Berkey et al., 1993).

2.1.2.2 European Studies. After the initial series of longitudinal studies in the United States, the emphasis on longitudinal growth studies shifted to Europe. The Harpenden Growth Study in the suburbs of London was begun in 1948 and included measurements of size, physique, body composition and maturation (Tanner, 1981). The setting for the study was a childrens home. Before entering the home, most of the children had probably lived under socially disadvantageous conditions. However, the children were well cared for at the home and lived in relatively small cottages or family groups. The Harpenden Growth Study was followed by a series of longitudinal studies in several European cities that were begun in the mid-1950s. The studies were coordinated by the International Childrens Center in Paris and included separate longitudinal samples in Brussels, London, Paris, Stockholm and Zurich (Tanner, 1981). These studies focused primarily on growth and maturation from birth through adolescence. Another European longitudinal study, independent of those coordinated by the International Childrens Center, was the Wroclaw Growth Study in southwestern Poland, which was begun in 1961. A large cohort of boy and girls was followed from 8 to 18 years of age (Bielicki and Waliszko, 1975; Waliszko and Jedlinska, 1976). The study also focused primarily on measures of growth and maturation. Some other European studies require mention. Height, weight, and secondary sexual characteristics of about 700 urban schoolchildren from several centers in Sweden were monitored from 10-16 years of age in girls and from 10-18 years in boys between 1964

and 1971 (Lindgren, 1979). In a similar study, about 1400 schoolchildren in Newcastleupon- Tyne, England, were followed from 9 to 17 years of age beginning in 1971 (Billewicz et al., 1983). The variables included measures of growth and secondary sex characteristics. In both studies, children were examined twice a year at approximately half-yearly intervals. Two generally similar longitudinal studies were begun in the Netherlands in the 1970s, the Nijmegen Growth Study (Prahl-Andersen et al., 1979) and the Study of the Growth and Health of Teenagers in Amsterdam (Kemper, 1995). The Amsterdam Study includes measurements of growth, maturity, motor performance, aerobic power and habitual physical activity and also continues into adulthood with a cohort of males and females followed at about 21, 27 and 30 years of age. A sampling procedure that allows for the proportionate representation of the ethnic African and Caribbean communities resident in this particularly multicultural metropolis makes the study quite unique. This effort later inspired the commencement, in South Africa, of the Ellisras Longitudinal Study in 1996, the first of its kind in sub- Saharan Africa (Monyeki et al., 1999).

2.1.2.3 Risk Factors for Disease in Longitudinal Studies. Given concern for coronary heart disease in adults, several relatively recent studies have focused on the development of risk factors for coronary heart disease (e.g., high levels of serum lipids with abnormal lipoprotein profile, hypertension and obesity) in children and youth. Coronary heart disease is one the leading causes of death in North American adults, and many of the risk factors for the disease develop during childhood (Berenson, 1986; Kannel et al., 1995). Several studies have attempted to track or follow the development of risk factors during

childhood and adolescence; the studies thus have a longitudinal component. These studies include, for example, the Bogalusa Heart Study of black and White children in Louisiana (Berenson et al., 1995), the Muscatine Study of primarily White Iowa school children (Lauer et al., 1993), and the Cincinnati Lipid Research Clinics study of Black and White children in the Princeton school district (Morrison et al., 1979). The studies were begun in the 1970s and include a variety of coronary heart disease risk factors in addition to measures of growth and maturation. The studies so far described all include a longitudinal component, but given the logistical problems encountered in doing such studies and the relatively large data sets involved, the studies are basically mixed-longitudinal. Results of the longitudinal and mixedlongitudinal components of these are used subsequently to illustrate patterns of growth, maturation and the range of normal variation inherent in any group of children.

2.1.2.4 African Studies Omololu et al. (1981) reported a transverse- longitudinal study of heights and weights of children in a Nigerian village. In May 1996, the University of the North, Sovenga, in the Northern Province of South Africa, initiated a longitudinal study in the Ellisras rural community in the Northern Province (now Limpopo Province) of South Africa. This study examined physical growth patterns, nutritional status and socioeconomic indices of rural children. Three years later, the Vrije University, Amsterdam, in the Netherlands, joined the project and then other lifestyle related parameters such as blood pressure, 24hours recall of nutritional intake of children and oral glucose tolerance test were included in the project (Monyeki, 2003). Subsequently, a 3-year prospective study on high levels

of habitual physical activity in West African adolescent girls and relationship to maturation, growth, and nutritional status, was reported from Senegal (Benefice, Garnier and Ndiaye, 2003).

2.1.3. Cross-sectional Surveys of Growth and Maturation. 2.1.3.1. General Overview. In addition to the longitudinal studies, a variety of crosssectional studies provide important information. These studies include several national surveys. For example, nationwide surveys of height, weight and sexual maturation of Dutch children in the Netherlands were conducted in 1955, 1965 and 1980 (Roede and van Wieringen, 1985). In Western Australia, the Busselton Survey is a population survey that has been held every three years in the Perth metropolitan area and rural Busselton since the 1970s. In 1994-1995 a re-survey was held of all past participants and 8,502 attended. The measurements included stature, body weight, skinfolds, limb and trunk circumferences and blood pressure. The significance of this survey is that financial constraints have precluded the employment of full-time staff for data collection and is, therefore, done by unpaid lay volunteers (Adams et al., 2002). Since the 1960s, the United States National Center for Health Statistics has conducted national surveys on a regular basis. Most of the surveys include height and weight, and several include a more extensive series of body measurements. These national surveys are unique in that all of them use a sampling design that permits estimates for the total United States population or for specific ethnic groups. Data from the United States national surveys provide the basis for charts of height, weight and other dimensions or indices that are used to assess the growth status of children and adolescents around the world.

2.1.3.2. African Studies. A number of studies have examined stature and weight in selected populations, as well as growth and development in children. Tobias (1975), working in South Africa, summarized adult stature from 123 samples and noted that there was no secular trend. However, a reduced sexual dimorphism did exist with respect to stature in African populations compared to Europeans. More recent studies by other groups in South Africa led by Cameron (Cameron, 1984, 1991, 1992; Cameron et al., 1992; Cameron and Getz, 1997; Monyeki, 1999, 2000; Monyeki et al., 1999, Monyeki et al., 2000) and Walker (Walker et al., 1979; Walker et al., 1989; Walker et al., 1990) have compared rural and urban communities in addition to examining various body composition parameters such as obesity, body fat patterning, lipidemias and other risk factors for adult diseases. Other more recent cross-sectional studies include the prevalence and severity of malnutrition and age at menarche among adolescent schoolgirls in western Kenya (Leenstra et al., 2005), a cross-cultural comparison of growth, maturation and adiposity indices of two contrasting adolescent populations in rural Senegal (West Africa) and Martinique (Caribbean) (Benefice, Caius and Garnier, 2004), the nutritional status, growth and sleep habits among Senegalese adolescent girls (Benefice, Garnier and Ndiaye, 2004), the impact of the health and living conditions of migrant and non-migrant Senegalese adolescent girls on their nutritional status and growth (Garnier et al., 2003), and the timing of reproductive maturation in rural versus urban Tonga and Zambia boys (Campbell, Gillett-Netting and Meloy, 2004). Several other studies including the influence of urban migration on physical activity, nutritional status and growth of Senegalese adolescents of rural origin

(Garnier, Ndiaye and Benefice, 2003), have related growth to performance and physical activity.

2.1.3.3. Nigerian Studies. The profile of growth studies conducted in Nigeria is not very illustrious. The earliest known report of any related study was that of the prevalence of obesity among Nigerian school children living in the Abeokuta metropolis in southwest Nigeria by Akesode and Ajibode (1983). Other reports are few and far between. Owa and Adejuyigbe (1997) reported a comparison of measurements of fat mass, fat mass percentage, body mass index and mid-upper arm circumference taken by anthropometric and bioelectric impedance techniques in a healthy population of Nigerian school children aged 5-15 years resident in Ile- Ife, also in Southwest Nigeria. More recent studies by Ansa et al. (2001) examined the profile of body mass index and obesity in Nigerian children and adolescents aged 6-18 years resident in Calabar, in the deep-south Nigerian region, while the freshly published report on the body composition of normal and malnourished children aged 3-11 years in the Niger Delta region by Eboh and Boye (2005) has given an indication of current research directions. However, since the pioneer efforts of Toriola and Igbokwe (1985) in determining the relationship between perceived physique and somatotype characteristics of 10-18 year old boys and girls resident in Iseyin in rural southwest Nigeria, only the singular report by Owolabi and Makpu (1994) on the body composition and somatotype of professional Nigerian division one male soccer and basketball players have been cited in the literature regarding the study of the shape and physique of Nigerian children and youth. These observations, therefore,

underscore the depth of the inadequacy of information regarding the growth, maturation, physical and nutritional status among Nigerians.

Cross- Sectional Surveys of Performance and Physical Activity. The American Alliance for Health, Physical Education and Recreation (1976) has conducted national surveys of the motor fitness of American school-age children in 1958, 1965, and 1975, and the Presidents Council on Physical Fitness and Sport (Reiff et al., 1986) conducted a similar survey in 1985. National surveys of the health-related physical fitness of children 6 to 9 and 10 to 17 years of age, respectively, the first and second National Children and Youth Fitness Surveys, were conducted in 1984 and 1986 (Pate and Shephard, 1989). Motor fitness focuses on performance in a variety of tasks, whereas health-related fitness focuses on indicators of cardiovascular fitness, strength, flexibility, and fatness. The National Children and Youth Fitness Surveys also included indicators of habitual physical activity. The Canadian Fitness Survey (1985), carried out in 1981, included measurements of physical activity, body size, fatness, physical performance and physical activity for a nationally representative sample of children and youth. A subsample of the Canada Fitness Survey was measured again 7 years later (Stephens and Craig, 1990). The Africa Association for Health, Physical Education, Recreation, Sport and Dance (AFAHPER-SD), modeled after the pattern of the American Alliance, organized its first Africa Regional Conference on Physical, Health Education, Recreation and Dance (ARCPHERD), in October 1994 at Gaborone, Botswana. The proceeding of the conference was published in the same year as Health, Physical Education, Recreation

and Dance in Africa (Amusa, 1994). Subsequently, the African Journal for Physical, Health Education, Recreation and Dance (AJPHERD), a peer-reviewed biennial publication of the association, was established. The first issue of this journal was released in April 1995. The journal has since become a cornerstone in the literature and an arrowhead in the advancement of kinanthropometry and growth research in Africa, in particular, through its numerous and regular publications, frequently contributed by frontline researchers worldwide. Another significant direct consequence of the Gaborone meeting was the establishment of the All- Africa Games Kinanthropometry Project (AAGKiP) by top researchers from all over Africa based in Southern Africa. Work commenced in October 1995 at the 6th AllAfrica Games held in Harare, Zimbabwe during which the kinanthropometric characteristics of the elite Africa athletes participating at those Games were profiled. This was the first of its kind anywhere in Africa, by African researchers on African athletes. The Supreme Council for Sport in Africa (SCSA) endorsed the project. It was modeled after the protocols used to assess athletes attending the Olympic Games, beginning in 1928, and later modified by Carter and his colleagues at the Montreal Olympics in 1976 and also at the 1991 World Swimming Championships, Melbourne, Australia. The success of the Harare AAGKiP encouraged the team to repeat the exercise at the 1999 edition held in Johannesburg, South Africa. By this time, the project had come to enjoy the additional and full support of the United Nations Educational and Scientific Organization (UNESCO). Prior to the commencement of the 3rd edition of the project at the 8th All-Africa Games held in Abuja, Nigeria in October 2003, the International Society for the Advancement of Kinanthropometry (ISAK) held its first ever

Anthropometry Accreditation and Certification Course for Level 2 Technicians in Africa in the month of September, 2003 in Abuja. This course, moderated by J.E.L. Carter, was designed to train the anthropometry technicians in preparation for the Nigeria All-Africa Games Kinanthropometry Project (NAAGKiP) and to upgrade the protocol used at the previous two editions (de Ridder, 2003). Through encouragement and careful guidance by the late A.O. Ajiduah, the exercise physiologist and Professor of Human Kinetics and Health Education in the University of Lagos, this investigator was able to receive training and to participate in the NAAGKiP as Anthropometry technician- Level 2. The All-Africa Games Kinanthropometry Project, therefore, has become Africas first continental survey for performance and physical activity. It is pertinent to note, however, that the effort has been directed at generating data from the adult, elite athlete and not the junior, growing athlete. The uses of anthropometry as a tool for investigating the relationship between growth, maturity, physical activity, health and performance has been much more vigorously explored by researchers in physical education (currently referred to as human kinetics), exercise physiology and sports medicine. Investigators in these fields of endeavor interact frequently through annual conferences and participation at University, National and International Sports meetings. In Nigeria, they collaborate through an umbrella body known as the Nigeria Association for Sports Science and Medicine (NASSM) and the results of these efforts are published regularly in their journal, the Nigerian Journal of Sports science and Medicine. However, their efforts have usually been directed towards the care of the injured athlete and other factors related to health, fitness, physical activity and performance, with very limited input from investigators involved in growth research.

Only a few papers have appeared in the literature in recent times (Musa and Lawal, 2001; Emiola, 2002; Okuneye et al., 2004; Okuneye, Ogunleye and Ibeabuchi, 2004), which reported on children. Although national surveys are cross-sectional, they are useful because the subjects selected to participate in the surveys are chosen to be representative of the population as a whole. Such samples are known as national probability samples. Results of such largescale national or continental surveys are the primary source for the construction of reference data used in comparing and evaluating the growth, maturity and performance status of children.

Current status of somatic growth research

Thus, it has been shown that the study of growth and maturation has a long history spanning over 150 years in the disciplines of medicine, human biology, biological anthropology and the sports sciences (Krogman, 1970; Meredith, 1971, 1987; Malina, 1978; Garn, 1980; Tanner, 1981, 1989; Malina and Roche, 1983; Roche and Malina, 1983; Faulkner and Tanner, 1986; Eveleth and Tanner, 1990; Roche, 1992). The concepts and principles that underlie the study of growth and maturation during the first two decades of postnatal life have been well elaborated and developed in the early part of the 20th century (Scammon, 1930; Krogman, 1948). The major sources of information, longitudinal and cross-sectional studies for the understanding of growth and maturation, have also been identified (Krogman, 1970; Meredith, 1971, 1978, 1987; Bielicki and Waliszko, 1975; Eveleth and Tanner, 1976, 1990; Waliszko and Jedlinska, 1976; Malina,

1978; Lindgren, 1979; Tanner, 1981; Malina and Roche, 1983; Roche, 1992; Guo et al., 1994; Billewicz et al., 1983; Adams et al., 2002; Monyeki, 2003). The study of growth is largely synonymous with measurement (McCammon, 1970; Malina and Roche, 1983; Tanner, 1989). The systematic study of these features, which are characteristic for every individual, requires measurements taken at different ages during infancy, childhood and adolescence and continuing into young adulthood (Lohman, Roche and Matorell, 1988; Mueller and Matorell, 1988; Malina, 1995; Norton and Olds, 1996; ISAK, 2001; Lampl et al., 2001). Measurements commonly used in growth studies have been described and the changes in body size and specific dimensions and body proportions that occur as the individual passes from infancy through childhood and adolescence into young adulthood have been reviewed and summarized (Malina, Hamill and Lemeshow, 1973, 1974; Meredith, 1978; Roche and Himes, 1980; Tanner 1981; Matorell et al., 1988; Lindgren et al., 1994; Kuczmarski et al., 2000). Two measurements that are basic to most growth studies, height and weight, and more recently, the body mass index (BMI, weight/ height ) have been used in many nutritional surveys (Tanner, Whitehouse and Takaishi, 1966; Roche, 1972; Roche, Guo and Yeung, 1989; Kuczmarski and Johnson, 1991; Roche, Guo and Moore, 1997). Size attained provides an indicator of growth status, and if the individual is followed over time, an indicator of growth rate (Kuczmarski et al., 2000). Generally, however, corresponding data for other body dimensions are very limited (Walker, 1979; Johnson et al., 1981; Roche et al., 1987; WHO, 1995). Most body dimensions, however, with the exception of subcutaneous adipose tissue and dimensions of the head and face, tend to follow the same pattern of growth as height and weight

(Bloom, 1964; Tanner and Whitehouse, 1982), whereas body proportions show different patterns (Roche and Malina, 1983; Schmidt-Nielsen, 1984). The evaluation of growth status requires reference data or growth charts (WHO, 1995). The new growth charts for United States children and adolescents developed in 2000 by the National Center for Health Statistics (NCHS) in collaboration with Centers for Disease Control and Prevention (CDC) have become norm reference worldwide (Roche et al., 1996; Roche, 1999; Kuczmarski et al., 2000; Roche and Guo, 2001; Ogden et al., 2002) and now include BMI-for-age percentiles for boys and girls from age 2 to 20 years of age (CDC, 2000). The evidence from these data suggests that height and weight are rather stable (i.e. they track well across childhood and adolescence), although low tracking of stature is observed at adolescence when height velocity is high. BMI curves show that most changes have their origin during the first years of life. The BMI also tracks well but interpretation of the BMI as an indicator of fatness in children and adolescent needs caution due to inconsistencies (Rolland-Cachera et al., 1987; Rolland-Cachera 1993; Siervogel, 1991; Guo et al., 1994; Power et al., 1997; Dietz and Robinson, 1998; Cole et al., 2000). Nutrition affects fatness and stature, but the consequences of under- and over-nutrition differ between early childhood and adolescence. The growth of individual children tends to remain at or near certain percentile levels on reference charts after about 2 or 3 years of age until adolescence (Cameron, 1984, 1991, 1992). However, before this period, percentile levels of individual children often change. Shifts usually occur between adjacent channels or percentiles on the growth chart but may occasionally cross two or more percentile lines. Such a shift in longitudinal data is known as decanalization (Roche and Li, 1998). Decanalization,

common in infancy and early childhood, is of no concern in the absence of disease and, commonly, is a gradual expression of the childs genetic potential for height. To some extent body composition reflects nutritional status. It is also influenced by age, sex, race, physical activity and disease. The method used to measure body composition depends on the variable to be quantified. It may also depend on the practical conditions of the study (Rolland-Cachera, 1993). Detailed methods, such as densitometry, isotope dilution (neutron activation), bioelectrical impedance (BIA) and dual-energy x-ray absorptiometry (DEXA) give more accurate information, but they are commonly based on hypotheses established in adults. Anthropometric measurements can be used directly or as ratio or regression equations. At adolescence, the body mass index (BMI) is preferred to weight for height as age is taken into account. In addition, the BMI pattern reflects real changes in body shape, and early in life it is an indicator of later development. In addition to measuring weight and height, skinfold measurement is usually carried out. The triceps skinfold is usually recommended and widely used as it is better than the subscapular skinfold to predict percent body fat, although some of the popular algorithms factorize the two skinfolds. Trunk skinfolds, such as the subscapular, iliac crest, supraspinale and abdominal are better than extremity skinfolds for their association with internal fat and their good correlations with risk factors and response to nutritional interventions. However, many authorities, nowadays, prefer the sum of four to eight skinfolds taken directly as a measure of body fat to percent fat because it eliminates the problems arising from assumptions factorized into the derivation of the equations. Body density (Db) declines in males from about 8 to 10 years but then increases more or less linearly to about 16 to 17 years of age. In females on the other hand, Db decreases

from about 8 to 11 years of age, then increases only slightly, and finally reaches a plateau by about 14 years of age. Both sexes also show a slight decline in Db in late adolescence and young adulthood (Malina et al., 1988; Malina, 1989). The results of pooled samples taken from Japanese adolescent children 11 to 18 years of age grouped by age and sex are consistent with that for American adolescents (Tahara et al., 2002). The accurate application of the principles and methods for estimating body composition to children requires that a determination be made as to when, during growth, adult values for the primary components of the fat-free mass are attained. This idea led to the development of the concept of chemical maturity. Changes in the chemical composition of the body during growth can be appreciated in a comparison of the infant and young adult reference males (Brozek, 1963; Fomon, 1966; Forbes, 1986). The point of chemical maturity, defined by Moulton (1923) as the point at which the concentration of water, proteins and mineral salts becomes comparatively constant in the fat-free cell, does not occur until after puberty, but most changes occur early in life. At present, chemical composition data for a young adult reference female or for the years between infancy and adulthood are not available (Forbes, 1987; Malina, Bouchard and Bar-Or, 2004). However, presently available longitudinal data suggests that the fat-free mass tracks moderately well from childhood through adolescence in both sexes, whereas fat mass and percent body fat are less stable characteristics (Fomon et al. 1982; Houtkooper et al. 1992; Guo et al. 1997; Tahara et al. 2002). Tracking is the maintenance of an individual in the same percentile range across age and varies according to the growth parameter and to the period of growth. Low tracking of fatness (up to the age of 8 years) corresponds to the period of rapid chemical changes.

The accumulation of body fat and changes in the relative distribution of fat, both subcutaneous and visceral, associated with differential timing of sexual maturation, are implicated as risk factors for overweight and/or obesity. Earlier studies (Forbes, 1964; Cheek, 1970) as well as more recent efforts (Malina and Bouchard, 1988; Malina et al., 1989, 1995; Beunen et al., 1994; Kuczmarski et al., 2000) indicate that obese children are taller, on the average, and more advanced in skeletal maturity compared with non-obese children of the same chronological age. Males accumulate proportionally more subcutaneous adipose tissue on the trunk during adolescence compared with females. Although the exact mechanism is not clear, hormonal factors have been implicated (Horswill et al., 1997). A history of obesity during childhood and adolescence also has implications, or consequences for adult health. The increased prevalence of obesity among children and adolescents has been accompanied by an increased prevalence of obesity in adults in many countries throughout the world (WHO, 1998; British Nutrition Foundation 1999; Flegal and Troiano, 2000; Flegal et al., 2002; Katzmarzyk, 2002a, 2002b). The age at adiposity rebound has also been identified as a risk factor for adult overweight/obesity (Rolland-Cachera, 1984, 1987, 1991). Variation in the distribution of fat is a known risk factor in the development of several diseases in adults, such as adult onset dependent diabetes mellitus and cardiovascular diseases (Guo et al., 1994; Gutin and Barbeau, 2000). However, studies done on African populations are sparsely reported (Steyn, Joubert and Roussouw, 1990). In addition to hormonal factors, intraindividual and interindividual differences in the profile of fat deposition have been associated with the metabolic properties of the adipocytes (fat-secreting cells). The traditional view of the adipose cell was one in which

the cell provided a storage structure for fatty acids in the form of triacylglycerol molecules and for the release of fatty acids when metabolic fuel was needed. Of course fat cells are responsible for these critical functions. However, the adipose cell is now better appreciated as a complex organ whose functions are not limited to storage of unneeded calories and delivery of metabolic fuel in times of fasting or starvation or other kinds of biological passivity. Its functions are now known to include the regulation of energy balance, glucose and insulin metabolism, lipid metabolism, immunity, feedback regulation of adipogenesis, production of estrogens and the regulation of blood pressure (Ailhaud and Hauner, 1998; Romanski et al., 2000; Fruhbeck et al., 2001). The

reporting of the discovery of Leptin in 1994 has resulted in the opening of an entirely new chapter in the biological sciences (Zhang et al., 1994). The understanding that leptin, a cytokine-like molecule synthesized and secreted by adipocytes in proportion to fat mass in most people, is implicated in the regulation of food intake, energy expenditure, glucose and lipid metabolism, puberty, reproductive functions, angiogenesis, and other processes is important (Masuzaki et al., 1997). New technologies such as computerized tomography (CT) and magnetic resonance imaging (MRI) now permit differentiation of subcutaneous and visceral adipose tissue in the abdominal area, and a sex difference in visceral adiposity appears to occur during late adolescence when males accumulate proportionately more visceral adipose than females (Bouchard, 1994; Goran, 1995, 1999; Huang et al., 2001). Ratios of trunk and extremity skinfolds suggest that subcutaneous fat distribution is not stable during childhood. During growth, some fat individuals move away from the high fatness categories, whereas some lean children move into these categories (Katzmarzyk

et al., 1999; Campbell et al., 2001). However, few studies have examined the stability of relative adipose tissue distribution from childhood to adulthood.

Body dimensions and growth curves The course of growth in stature and weight from birth to 19 years of age has been amply illustrated as distance or size-attained curves (Kuczmarski et al., 2000) and velocity curves (Tanner, Whitehouse and Takaishi, 1966) in several authoritative texts, journal reports and growth charts (Flegal et al., 2002; Malina, Bouchard and Bar-Or, 2004). Other curves already generated are distance curves for body mass index (RollandCachera et al., 1991) as well as growth patterns for other body dimensions such as sitting height and leg lengths (Martorell et al., 1988), biacromial and biiliocristal breadths (McCammon, 1970; Roche and Malina, 1983), distance curves for arm and calf circumference (Johnson et al., 1981). Ratios such as sitting height as percentage of stature (Roche and Malina, 1983) and biiliocristal to biacromial breadths (Roche and Malina, 1983) are also available. Percentile curves useful in evaluating the growth status of individual children have been developed and revised since the late 1950s in the United States (U.S.) as the National Health Examination Survey (NHES, 1959-1970), National Health and Nutrition Examination Survey (NHANES, 1971-2000), and Hispanic Health and Nutrition Examination Survey (HHANES, 1982-1984). Some of these data have been incorporated into these percentile growth charts developed and also revised by the U.S. Center for Disease Control and Prevention (CDC Growth Charts 1973, 1988 and 2000). The curves represent age-specific and sex-specific averages for boys and girls and do not

portray the wide range of normal individual variability apparent in any group of children. The pattern of changes is generally similar in all children, but the size attained at a given age and the timing of the adolescent growth spurt varies considerably from child to child. From birth to early adulthood, both stature and weight follow a four-phase growth pattern: 1) rapid gain in infancy and early childhood, 2) rather steady gain during middle childhood, 3) rapid gain during the adolescent spurt, and 4) slow increase until growth ceases with the attainment of adult stature (Kuczmarski et al., 2000). Body weight, however, usually continues to increase into adult life. Adolescence is a difficult period to define in terms of chronological age because of the variation in the time of its onset and termination. The World Health Organization (WHO) defines the age of adolescence as between 10 and 18 years, but the age ranges 8 to 19 years in girls and 10 and 22 years in boys are more appropriate as limits for normal variation in the onset and termination of adolescence. In this period, most bodily systems become adult both structurally and functionally, i.e. they reach maturity. Structurally, adolescence commences with acceleration in the rate of growth in stature, which marks the onset of the adolescent growth spurt. The rate of growth in height reaches a peak, then begins a slower or decelerative phase, and finally terminates with the attainment of adult stature. Functionally, adolescence is usually viewed in terms of sexual maturity, which actually begins with changes in the neuroendocrine system before overt physical changes and terminates with the attainment of mature reproductive function. From a biological perspective, the period of adolescence includes two major events, the adolescent growth spurt (somatic maturation) and sexual maturation. Youth enter this phase of growth at varying ages (differential timing) and proceed through it at variable

rates (differential tempo). Timing and tempo are highly individual characteristics and are unrelated. Girls are, on average, in advance of boys in the timing of maturation, but tem