ABSTRACT
Previous studies have suggested an association of somatotype with body composition and the organ dimensions among individuals and populations. However, the relationship of somatotypes of medical students of Ahmadu Bello University (ABU), Zaria with body composition, organ dimensions and some anthropometric variables has not been evaluated. This cross-sectional study consisted of 350 apparently healthy medical students of ABU, Zaria (175 males and 175 females) aged 18-35 years. Stature, four skinfold sites, body mass, two bone breadths and two girths were measured according to the International Society for the Advancement of Kinanthropometry (ISAK). The body composition variables were computed using the Durnin and Wormersely method and hepatobiliary dimensions were measured with an ultrasound machine. Chi-square test, independent sample t-test, one-way Analysis of variance (ANOVA), somatotype analysis of variance (SANOVA), Pearson’s correlation, partial correlation and multiple linear regression were used. P < 0.05 was set at the level of significance. The mean somatoype was 1.61-4.28-3.04 (ectomorphic-mesomorph) for the males and 1.75-4.21-1.96 (balanced mesomorph) for the females and were significantly different (F=30.06, p<0.001). Seven major somatotype categories were found irrespective of the sexes: endomorphic-mesomorph, balanced-mesomorph, ectomorphic-mesomorph, mesomorph-ectomorph, mesomorphic- ectomorph, balanced-ectomorph and central. There was a significant association for male and female subjects based on the somatotype categories (χ2 = 44.87, p < 0.05). The height, body mass index (BMI), body surface area (BSA), skin folds, bone breadth and body composition variables showed significant sexual dimorphism based on the dominant somatotypes (p< 0.05). The BMI, BSA, gall bladder width, common bile duct diameter (CBDD) and body composition variables indicated significant differences according to the age groups in the dominant mesomorphs and
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ectomorphs (p< 0.05). Dominant endomorphy was positively correlated with some skin folds and body composition variables in both sexes. Mesomorphy correlated positively with upper arm girth, calf girth, BBH and BBF in both sexes. Ectomorphy showed more sparing correlation with other variables, i.e., it showed a significant positive correlation with BBH and BBF in male subjects only. No significant correlations were observed in blood pressure and hepatobiliary dimensions with the dominant somatotypes. Tricep skin fold, subscapular skin fold, and medial calf skin fold were the joint best predictors of percent body fat in both sexes (R2= 0.999). In conclusion, the relationship between dominant somatotypes with body composition, hepatobiliary dimensions and some anthropometric variables have been established.
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TABLE OF CONTENTS
Cover Page ………………………………………………………………………………………………….i
Fly Leaf ………………………………………………………………………………………………………ii
Title Page ……………………………………………………………………………………………………iii
Declaration………………………………………………………………………………………………….iv
Certification ………………………………………………………………………………………………..v
Dedication …………………………………………………………………………………………………..vi
Acknowledgement ……………………………………………………………………………………….vii
Table of contents …………………………………………………………………………………………viii
List of Tables ………………………………………………………………………………………………xii
List of Figures ……………………………………………………………………………………………..xiv
List of Plates ……………………………………………………………………………………………….xv
Abstract ………………………………………………………………………………………………………xvi
CHAPTER ONE
1.0 INTRODUCTION………………………………………………………………………………….1
1.1 Background …………………………………………………………………………………………..1
1.2 Statement of Problem …………………………………………………………………………….4
1.3 Justification and Significance of the Study ………………………………………………4
1.4 Hypothesis ……………………………………………………………………………………………..5
1.5 Aim and Objectives of the Study ……………………………………………………………5
1.5.1 Aim of the study……………………………………………………………………………………6
1.5.2 Objectives of the study…………………………………………………………………………..6
1.6 Scope of the Study ………………………………………………………………………………….6 1.7 Limitations …………………………………………………………………………………………….7
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CHAPTER TWO
2.0 LITERATURE REVIEW ………………………………………………………………………8
2.1 Historical Background of Somatotype …………………………………………………….8
2.1.1 Hippocrates ………………………………………………………………………………………….8
2.1.2 Rostan …………………………………………………………………………………………………8
2.1.3 Viola ……………………………………………………………………………………………………9
2.1.4 Barbara ………………………………………………………………………………………………..11
2.1.5 Kretschmer …………………………………………………………………………………………..11
2.1.6 Sheldon ……………………………………………………………………………………………….13
2.1.7 Heath and carter ……………………………………………………………………………………15
2.2 Sexual Dimorphism in Somatotype Components……………………………………..17
2.3 Body Composition ………………………………………………………………………………….18
2.3.1 Dimorphism in body composition …………………………………………………………..19
2.4 Role of Imaging in Measurement of Organ Size ………………………………………23
2.4.1 Methods of measurement ……………………………………………………………………….23
2.4.2 Sonographic assessment of the liver, caudate lobe, gallbladder
and common bile duct ……………………………………………………………………………………28
2.5 Somatotype, Body Composition, Organ Dimensions and Other
Anthropometric Variables …………………………………………………………………………..30
2.5.1 Relationship between somatotype and body composition ………………………….30
2.5.2 Relationship between somatotype and blood pressure ……………………………….31
2.5.3 Relationship between somatotype and organ sizes …………………………………….33 CHAPTER THREE 3.0 MATERIALS AND METHOD ………………………………………………………………34 3.1 Study Location ………………………………………………………………………………………34 3.2 Data Collection ………………………………………………………………………………………34
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3.3 Sample Size Determination …………………………………………………………………….34
3.4 Sampling Technique ………………………………………………………………………………36
3.4.1 Stage 1 (Selection of faculty) ………………………………………………………………….36
3.4.2 Stage 2 (Selection of students) ………………………………………………………………..36 3.5 Inclusion criteria ……………………………………………………………………………………37
3.6 Exclusion criteria ……………………………………………………………………………………………………………………………………………………………………….37 3.7 Ethical Approval ……………………………………………………………………………………38 3.8 Informed Consent ………………………………………………………………………………….38 3.9 Methodology ………………………………………………………………………………………….38 3.9.1 Materials ……………………………………………………………………………………………..38 3.9.2 Anthropometry ……………………………………………………………………………………..39
3.9.3 Body Mass Index (BMI) and Body Surface Area (BSA) ……………………………47
3.9.4 Fat mass index (FMI), Fat-free mass index (FFMI), Bone
mineral density (BMD), Total body potassium (TBK) and Body cell
mass (BCM) …………………………………………………………………………………………………47
3.9.5 Blood pressure (BP) ………………………………………………………………………………47
3.10 Equations for Somatotype Analysis ………………………………………………………48
3.10.1 The anthropometric somatotype ………………………………………………………..48
3.10.2 Plotting somatotypes on the 2-D somatochart ……………………………………..49 3.11 Scanning Technique ……………………………………………………………………………..49
3.11.1 Liver and the caudate lobe ……………………………………………………………………50
3.11.2 Gall bladder ………………………………………………………………………………………..53
3.11.3 Common bile duct ……………………………………………………………………………….55
3.12 Data Analyses ………………………………………………………………………………………57
CHAPTER FOUR
4.0 RESULTS ……………………………………………………………………………………………..58
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4.1 Descriptive Statistics of Study Population ………………………………………………58
4.2 Somatotype Profile of the Study Participants ………………………………………….62
4.3 Sexual Dimorphism in Organ Dimensions, Body Composition
and Other Anthropometric Variables According to the Dominant
Somatotype …………………………………………………………………………………………………79
4.4 Age Variations in Hepatobilary Dimensions, Body Composition
and Other Anthropometric Variables According to the Dominant
Somatotype …………………………………………………………………………………………………83
4.5 Relationship Between Dominant Somatotype with Organ
Dimensions, Body Composition and Anthropometric Variables ……………………87
4.6 Linear and Multiple Regression Equations ……………………………………………..95
CHAPTER FIVE
5.0 DISCUSSION ………………………………………………………………………………………..99
CHAPTER SIX
6.0 CONCLUSION AND RECOMMENDATIONS ………………………………………112
6.1 Conclusion …………………………………………………………………………………………….112
6.2 Recommendations ………………………………………………………………………………….113
6.3 Contribution to Knowledge …………………………………………………………………….113
References …………………………………………………………………………………………………..115
APPENDIX …………………………………………………………………………………………………128
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background
The interest in the classification and analysis of human physique or body types of individuals and populations has a long history going back to the ancient Greeks, Hippocrates (460-377 BC). Over the centuries, various systems for classifying physique have been proposed, leading to the system called somatotyping as proposed by Sheldon et al. (1940), and subsequently modified by others, notably Parnell (1958), Heath and Carter (1967) and Carter and Heath (1990). Sheldon believed that somatotype was immutable i.e., it relies solely on genetic basis, but the present view is that the somatotype is phenotypical and thus amenable to change under the influence of both internal and external factors such as growth (Carter and Heath, 1990), aging (Gakhar and Malik, 2002; Bhasin and Jain, 2007), sex (Kalichman and Kobliansky, 2006), nutrition (Chakrabarty et al., 2008), physical activity (Chandel and Malik, 2012), occupation (Singh and Singh, 2006), socioeconomic differences (Rahmawati et al., 2004; Singh, 2011) and pathological conditions (Williams et al., 2000; Eiben et al., 2004; Kalichman et al., 2004).
The technique of somatotyping is used to appraise body shape and composition (Bailey et al., 2009). The resulting somatotype gives a gestalt or quantitative summary of the physique as a unified whole (Carter, 1996; Rajajeyakumar, 2015). Somatotyping is defined as the quantification of the present shape and composition of the human body independent of the body size (Carter and Heath, 2002; Zorka and Dragan, 2013). According to Carter and Heath (2002), the somatotype is usually expressed in a three
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number rating representing endomorphy (relative adiposity), mesomorphy (relative musculoskeletal robustness) and ectomorphy (relative linearity or slenderness of a physique) respectively, always in that order. For example, a 3-5-2 rating is recorded in this manner and is read as three, five, and two. These numbers give the magnitude of each of the three components. Ratings on each component 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 and Heath, 1990). Theoretically, there is no upper limit to the ratings, and values of 12 or more occur in very rare instances. Because the components are rated relative to stature, the somatotype is independent of, or normalized for stature.
There are three methods of obtaining the somatotype: (a) the photoscopic method, in which ratings are made from a standardized photograph; (b)the anthropometric method, in which anthropometry is used to estimate the criterion somatotype; and (c) the criterion method, which combines anthropometry and ratings from a photograph (Carter and Heath, 2002). Because most people do not get the opportunity to become criterion raters using photographs, the anthropometric somatotype has proven to be the most useful for a broad range variety of applications. It can be used in the field or laboratory, requires little equipment and calculation, and measurements can be made with relative ease on subjects dressed in minimal clothing.
Neither Sheldon et al. (1940, 1954) nor Parnell (1954, 1958) attempted to describe the components of somatotype in terms of body composition. However, the selection of the anthropometric dimensions for the Parnell method covertly proposed a relationship between the components of body composition (fat mass and lean body mass) and the components of somatotype. The skin fold thickness measurements imply a relationship between endomorphy and relative fatness, and the muscle girth and the bone breadth
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measurements imply a relationship between mesomorphy and relative lean body mass. However, the third component, ectomorphy, was described by the linearity of physique, a morphological characteristic without reference to body composition.
It is not surprising, then, that many studies have attempted to relate somatotype and body composition variables (Dupertius et al., 1951; Tanner et al., 1960; Wilmore, 1970; Slaughter and Lohman, 1976; Bulbulian, 1984; Bolonchuk et al., 1989, 2000). These studies revealed that, on average, endomorphs were fatter, heavier and taller than mesomorphs or ectomorphs; the mesomorphs had greater fat-free weights and were shorter than endomorphs or ectomorphs and ectomorphs had lower bodyweights and less fat than mesomorphs or endomorphs. Thus, these findings suggest a general association between body somatotype and structure.
Similarly, two people of the same sex and body weight may look completely different from each other because they have a different body composition (Wells et al., 2006) and body type (Chaplygina et al., 2013). To further support this logic, Singh (2007) emphasized that it is highly unlikely that persons of different body types have a similar body composition or body organ dimensions (Adamu et al., 2007). Thus, individuals at the top or bottom of the ladder of body habitus cannot share the same range of values for a given organ. For instance, Adamu et al. (2007) reported that endomorphic subjects have larger dimensions of internal organs than the ectomorphic subject. A positive correlation was observed in the evaluated data of ultrasound examination of the thyroid gland in relation to the body types (Zmeev, 2010; Chaplygina and Kuchieva, 2012). Similarly, Chaplygina and Guber (2014) observed significant differences in the values of the linear dimensions of the liver in patients with different somatotypes. In another study, the liver
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volume was found to be dependent on the variability of the macroscopic structure of the body (Chaplygina et al., 2013).
1.2 Statement of the Problem
In literature, there are some studies on the Caucasians about the dependence of the morphological and functional characteristics of individual organs and body composition on the human dominant somatotype components (Slaughter and Lohman, 1976; Bolonchuk et al., 1989; Bolonchuk, 2000; Gorbonov, 2001; Adamu et al., 2007; Marek and Aneta, 2013; Chaplygina and Guber, 2014). However,a thorough literature search yielded dearth of documented reports of such kind of studies on the Negroid especially in Nigeria. Hence, this underscores the importance of conducting this cross-sectional study in our surroundings.
1.3 Justification and Significance of the Study
There is a need for baseline anthropological data among medical students of Ahmadu Bello University, Zaria, especially with respect to somatotype profiles, body composition and sonographic hepatobiliary dimensions. Extraction of various forms of variables associated with somatotype, body composition and hepatobiliary dimensions will enrich the information regarding the three profiles, hence serve as database and reference information as the need may arise. Establishment of the relationship of dominant somatotype with body composition, organ dimensions and other anthropological variables has received less attention in the literature with little or no such attempt among a Nigerian population. Thus, the need to conduct this study on our population.
The evaluation of the data of ultrasound of hepatobiliary system, taking into account the somatotype of the individual gives the clinician the ability to differentiate the
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constitutional norm, detect early subclinical pathologic changes in the body and institute preventive measures (Chaplygina et al., 2014).
Information about the individual typological characteristics of both sexes, i.e., the study population, can be used by the medical institution of the University in the selection of preventive measures to protect high somatotype risk group, selection of athletes for sports and will also help government defense agencies in the survey of young men of military age.
Finally, this work will bring the subject matter to the limelight, especially in the science community and will also serve as an impetus in stimulating the interest of researchers to explore this crucial area that has enjoyed little attention so that this important lacuna in knowledge can be filled.
1.4 Hypothesis
There is a relationship between somatotypes and hepatobiliary dimensions, body composition, and some anthropometric variables of students in Ahmadu Bello University, Zaria.
1.5 Aim and Objectives of the Study
1.5.1 Aim of the Study
The aim of the study was to determine the relationship between somatotypes and hepatobiliary dimensions, body composition, and some anthropometric variables of students in Ahmadu Bello University, Zaria.
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1.5.2 Objectives of the study
i. To determine the somatotype profiles of medical students of Ahmadu Bello University Zaria, using the Heath and Carter method.
ii. To investigate sexual dimorphism in hepatobiliary dimensions (liver, caudate lobe, common bile duct, and gallbladder), body composition and other anthropometric variables according to the dominant somatotype.
iii. To examine the age variations in hepatobiliary dimensions, body composition and other anthropometric variables according to the dominant somatotype.
iv. To study the relationship between dominant somatotypes with hepatobiliary dimensions, body composition and some anthropometric variables.
v. Prediction of body composition variables (% body fat BF% and fat mass FM) from anthropometric variable (height) and somatometric variables (subscapular skin fold, triceps skin fold and medial calf skin fold).
1.6 Scope of the Study
This research work focussed on the determination of the relationship between somatotypes and hepatobiliary dimensions, body composition, and some anthropometric variables of students in Ahmadu Bello University, Zaria. Anthropometric somatotype was used in the field. To calculate the anthropometric somatotype, ten anthropometric dimensions were needed, these include the:body mass,stretch stature (height),four skin folds (subscapular,medial calf, triceps and supraspinal), two bone breadths (biepicondylar breadth of thehumerus and femur) and two limb girths (calf, tensed andarm flexed). Blood pressure was measured, and the dimensions of the liver, caudate lobe common bile duct and gallbladder were determined sonographically.
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1.7 Limitations
The following limitations were considered while interpreting the result:
i. One of the limitations in our study is the smaller sample size. The sample size must be large enough to detect the clinically important relationship between dominant somatotype and organ dimensions (Altman, 1980). However, because of cost implication study with an overlarge sample is not necessary as it seems unethical to involve unnecessary extra subjects (Kirby et al., 2002).
ii. Although percent body fat can be assessed more objectively with greater precision by the use of such sensitive methods such as, underwater weighing or hydrostatic, ultrasonography, Computed Tomography Scan, Lunar Prodigy DXA scanner, and Magnetic Resonance Imaging; only skin fold measurement was used to estimate percent body fat in this study because it is simple and easy to use.
iii. In order to avoid inter observer error and establish a standardized techniques, all anthropometric measurement should be done by one person. However, considering the cultural background of the study area, male subjects were all measured by a trained anthropometrist and female subjects by a trained female anthropometrist.
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