Aandagtekort-hiperaktiwiteitsversteuring (ATHV) is een van die deeglikste nagevorste opvoedkundig-sielkundige versteurings. Dit is ook een van die versteurings waarvan die voorkoms drasties vermeerder het oor die laaste drie dekades, met ʼn voorkoms by skoolkinders van 3 tot 17%. Dit kom ook by volwassenes voor. Stimulantmedikasie word algemeen in die behandeling van ATHV voorgeskryf. Ander algemene behandelingsmodaliteite sluit onder andere gedragsterapie, dieët aanpassings en arbeidsterapie in. Oefening as hulpmiddel in die bestuur van ATHV, word goed in die literatuur beskryf, maar word ten spyte hiervan nie algemeen voorgeskryf in die behandeling van ATHV nie. Die primêre doel van die studie was om die rol wat die biokinetikus as oefenkundige te speel het in die bestuur van ATHV, te ondersoek. Die hipotese was dat ATHV-pasiënte wat deelneem aan ʼn oefenprogram onder leiding van ʼn biokinetikus, ʼn verbetering sal toon in akademiese prestasie en gedrag. Die verband tussen ATHV-simptome, aërobiese fiksheid, soepelheid, liggaamsamestelling en balans is ook ondersoek. Deur middel van ʼn meervuldige gevallestudieontwerp is die rol van die biokinetikus in dié verband ondersoek. ʼn Gemengde benadering, met kwantitatiewe sowel as kwalitatiewe elemente, is gebruik ten einde ʼn ryk en omvattende studie te kon doen. Riglyne vir die assessering van ATHV-pasiënte, asook beste oefenpraktyke, is uit die literatuur afgelei. Vyf deelnemers het vir ʼn tydperk van twee tot drie skoolkwartale aan die studie deelgeneem. Die intervensie het bestaan uit ʼn oefenprogram van ongeveer 30 minute per dag, vyf dae per week. Al die deelnemers is vooraf, asook tydens en na die studie getoets aan die hand van die volgende: Liggaamsamestelling, aërobiese fiksheid, soepelheid en balans. Onderhoude met onderwyseresse en ouers, skoolrapporte en vraelyste is verder gebruik om inligting in te samel. Deelnemers het ook narratiewe verslae gelewer oor die belewenis van hulle deelname. Die resultate van hierdie studie het die hipotese ondersteun. Die deelnemers het verbeterings ten opsigte van akademiese prestasie en gedrag getoon. Hulle aërobiese kapasiteit, liggaamsamestelling, soepelheid en balans het ook verbeter en die verband tussen die onderskeie parameters en die ATHVsimptome van elke deelnemer, is aangetoon en individueel bespreek. ʼn Gedeelde sorgooreenkomsmodel is ontwikkel om die rol van die biokinetikus duidelik aan te dui. ʼn Evaluasieprotokol vir gebruik deur biokinetici is ontwikkel en riglyne vir programontwerp vir die ATHV-pasiënt is saamgestel. Die gevolgtrekking van die studie is dat die biokinetikus ʼn besliste rol te speel het in die bestuur van ATHV. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Biokinetics, Sport and Leisure Sciences / unrestricted

INTRODUCTION - Plasminogen activator inhibitor type-1 (PAI-1) has a known relationship with obesity and more specifically with central obesity. Traditionally the physiological contribution of PAI-1 is seen as an indicator of fibrinolysis with increased PAI-1 levels contributing to decreased fibrinolysis. In more recent years, assays have been developed that not only uses proxy markers, such as PA-1, which is considered to be representative of fibrinolysis , but global assays that report on the global fibrinolytic potential of an individual, often reported as clot lysis time (CLT). Investigations into the relationship of CLT with obesity are scarce. Preliminary evidence shows that the relationship of CLT with obesity may differ from that of PAI-1 with obesity although in depth investigations in this regard are lacking. Therefore, the aim of this study was to investigate the association between fibrinolysis markers (PAI-1act and CLT) and various markers of body composition in the South African Prospective Urban and Rural Epidemiology (PURE) data collected during 2010. METHODS - Data collected in the PURE study in 2010 were cross-sectionally analysed. The participants (n = 1288) were apparently healthy black South-African men and women 35 years and older, residing in urban and rural settlements in the North-West Province. Experimental methods included anthropometric measurements such as height, weight, hip circumference, waist circumference, skinfolds (triceps, chest, abdominal, thigh and supra iliac skinfolds) and body composition measurements by means of air-displacement plethysmography and biolelectrical impedance analysis. Laboratory analysis of fibrinolysis markers, PAI-1act and CLT were also performed. MAIN FINDINGS - In men, similarities were seen regarding the relationship between PAI-1act and body composition markers and the relationships observed between CLT and body composition markers. In contrast, in the women more and stronger associations were observed between CLT and body composition markers compared to that observed between PAI-1act and body composition markers. CLT showed a linear relationship with body composition markers where PAI-1act levels plateaued at higher body composition categories. Possible reasons for the observed differences may be related to differences in adipose tissue distribution and sequence of accumulation between men and women. PAI-1 is associated with visceral adipose tissue (VAT) where high amounts of stromal cells are found. In men preferential accumulation of VAT may explain similarities in the relationship of PAI-1act with body composition and that of CLT with body composition. Proportionally less VAT, but more subcutaneous adipose tissue in women may explain the observed increase in CLT compared to PAI-1act levels that plateaued over body composition tertiles and categories. CONCLUSION - PAI-1act has a stronger association with central obesity while CLT has a stronger association with total body fat. In women PAI-1act and CLT showed different associations with body composition markers, whereas associations of PAI-1act and CLT with body composition were similar in men. PAI-1act is strongly influenced by type of body fat accumulation whereas CLT is associated with obesity independent of type and sequence of body fact accumulation. Significant associations observed between CLT and body composition variables are, therefore, at least in part, independent of PAI-1act. Additional factors such as, thrombin activatable fibrinolysis inhibitor (TAFI), α-2-antiplasmin, plasminogen, prothrombin and fibrin clot structure that influence CLT and are also related to obesity may additionally contribute to the link between CLT and obesity. / MSc (Dietetics), North-West University, Potchefstroom Campus, 2014

INTRODUCTION - Plasminogen activator inhibitor type-1 (PAI-1) has a known relationship with obesity and more specifically with central obesity. Traditionally the physiological contribution of PAI-1 is seen as an indicator of fibrinolysis with increased PAI-1 levels contributing to decreased fibrinolysis. In more recent years, assays have been developed that not only uses proxy markers, such as PA-1, which is considered to be representative of fibrinolysis , but global assays that report on the global fibrinolytic potential of an individual, often reported as clot lysis time (CLT). Investigations into the relationship of CLT with obesity are scarce. Preliminary evidence shows that the relationship of CLT with obesity may differ from that of PAI-1 with obesity although in depth investigations in this regard are lacking. Therefore, the aim of this study was to investigate the association between fibrinolysis markers (PAI-1act and CLT) and various markers of body composition in the South African Prospective Urban and Rural Epidemiology (PURE) data collected during 2010. METHODS - Data collected in the PURE study in 2010 were cross-sectionally analysed. The participants (n = 1288) were apparently healthy black South-African men and women 35 years and older, residing in urban and rural settlements in the North-West Province. Experimental methods included anthropometric measurements such as height, weight, hip circumference, waist circumference, skinfolds (triceps, chest, abdominal, thigh and supra iliac skinfolds) and body composition measurements by means of air-displacement plethysmography and biolelectrical impedance analysis. Laboratory analysis of fibrinolysis markers, PAI-1act and CLT were also performed. MAIN FINDINGS - In men, similarities were seen regarding the relationship between PAI-1act and body composition markers and the relationships observed between CLT and body composition markers. In contrast, in the women more and stronger associations were observed between CLT and body composition markers compared to that observed between PAI-1act and body composition markers. CLT showed a linear relationship with body composition markers where PAI-1act levels plateaued at higher body composition categories. Possible reasons for the observed differences may be related to differences in adipose tissue distribution and sequence of accumulation between men and women. PAI-1 is associated with visceral adipose tissue (VAT) where high amounts of stromal cells are found. In men preferential accumulation of VAT may explain similarities in the relationship of PAI-1act with body composition and that of CLT with body composition. Proportionally less VAT, but more subcutaneous adipose tissue in women may explain the observed increase in CLT compared to PAI-1act levels that plateaued over body composition tertiles and categories. CONCLUSION - PAI-1act has a stronger association with central obesity while CLT has a stronger association with total body fat. In women PAI-1act and CLT showed different associations with body composition markers, whereas associations of PAI-1act and CLT with body composition were similar in men. PAI-1act is strongly influenced by type of body fat accumulation whereas CLT is associated with obesity independent of type and sequence of body fact accumulation. Significant associations observed between CLT and body composition variables are, therefore, at least in part, independent of PAI-1act. Additional factors such as, thrombin activatable fibrinolysis inhibitor (TAFI), α-2-antiplasmin, plasminogen, prothrombin and fibrin clot structure that influence CLT and are also related to obesity may additionally contribute to the link between CLT and obesity. / MSc (Dietetics), North-West University, Potchefstroom Campus, 2014

Television viewing is one of the most easily modifiable causes of obesity among children. The purpose of this study was to determine the relationship between body composition and TV viewing among adolescents attending high schools in the Tlokwe municipality area of the North West province of South Africa. A cross-sectional study design which is part of the Physical Activity and Health Longitudinal Study (PAHLS) was followed on 154 learners (58 boys and 96 girls) who were aged 14 years in the Tlokwe municipality area. All the learners underwent anthropometric measurements of height, weight, and two skinfolds (triceps and subscapular skinfolds). Percentage body fat (%BF) was calculated from the two skinfolds according to Slaughter‟s et al. (1988) equation. Children were classified into three groups (viz. normal, overweight and obese) according to BMI cut-off point suggested by Cole et al. (2000). Pearson correlation coefficients were used to determine the relationship between television viewing and body composition. The results show respectively high prevalence of overweight and obesity in girls (10.4%; 6.3%) as compared to the prevalence of 5% overweight in boys. With regard to TV viewing, the results show that 54% of the total group watch TV more than two hours a day, while only 11% watched TV less than one hour a day. The results show that the group that watches TV for more than 3 hours had high BMI (21.27kg/m²) and body mass (51.54kg). The group that watches TV for 1-2 hours had low BMI (18.36kg/m²) and body mass (44.79kg). There was a statisitcal significant relationship between BMI and body mass (p=0.001). A significant positive relationship between body mass and TV viewing (r=0.56; p=0.05) in overweight group was found, whilst in the obese group strong significant positive relationship was observed between percentage body fat and TV viewieng (r=0.94; p=0.01). It can be concluded that girls were more overweight and obese respectively as compared to the boys. Furthermore, both boys and girls had high percentages of TV viewing for more than two hours a day. In addition, the results indicated that adolescents who watched TV more than 3 hours are heavier and fatter. Therefore, it is recommended that parents and educational heads should encourage periods of daily physical activity. In addition, it is also important that parents play a more positive role in limiting the amount of hours their children spent watching television. / Thesis (MA (Biokinetics))--North-West University, Potchefstroom Campus, 2013.

Television viewing is one of the most easily modifiable causes of obesity among children. The purpose of this study was to determine the relationship between body composition and TV viewing among adolescents attending high schools in the Tlokwe municipality area of the North West province of South Africa. A cross-sectional study design which is part of the Physical Activity and Health Longitudinal Study (PAHLS) was followed on 154 learners (58 boys and 96 girls) who were aged 14 years in the Tlokwe municipality area. All the learners underwent anthropometric measurements of height, weight, and two skinfolds (triceps and subscapular skinfolds). Percentage body fat (%BF) was calculated from the two skinfolds according to Slaughter‟s et al. (1988) equation. Children were classified into three groups (viz. normal, overweight and obese) according to BMI cut-off point suggested by Cole et al. (2000). Pearson correlation coefficients were used to determine the relationship between television viewing and body composition. The results show respectively high prevalence of overweight and obesity in girls (10.4%; 6.3%) as compared to the prevalence of 5% overweight in boys. With regard to TV viewing, the results show that 54% of the total group watch TV more than two hours a day, while only 11% watched TV less than one hour a day. The results show that the group that watches TV for more than 3 hours had high BMI (21.27kg/m²) and body mass (51.54kg). The group that watches TV for 1-2 hours had low BMI (18.36kg/m²) and body mass (44.79kg). There was a statisitcal significant relationship between BMI and body mass (p=0.001). A significant positive relationship between body mass and TV viewing (r=0.56; p=0.05) in overweight group was found, whilst in the obese group strong significant positive relationship was observed between percentage body fat and TV viewieng (r=0.94; p=0.01). It can be concluded that girls were more overweight and obese respectively as compared to the boys. Furthermore, both boys and girls had high percentages of TV viewing for more than two hours a day. In addition, the results indicated that adolescents who watched TV more than 3 hours are heavier and fatter. Therefore, it is recommended that parents and educational heads should encourage periods of daily physical activity. In addition, it is also important that parents play a more positive role in limiting the amount of hours their children spent watching television. / Thesis (MA (Biokinetics))--North-West University, Potchefstroom Campus, 2013.

Studies in both children and adults indicate that waist circumference (WC), a measure of abdominal obesity is closely related to cardiovascular risk factors. The accurate identification of abdominally obese children in health screening programmes for early intervention is of importance. There are, however, concerns about using international definitions for screening purposes because in most instances these have been derived from Western populations and, therefore, may have limited usefulness to children in other parts of the world. When these cut–off points are used in developing countries, they ignore the fact that the growth patterns of children and burdens of disease vary between countries. Due to lack of population specific cut–off points for children in the developing world it may be tempting and convenient to use the same cut–off points as for children in developed countries, but such a practice runs the risk of exporting failure. Ideally, a screening tool should have both high sensitivity and specificity, and these are important considerations in choosing the definition for the detection of childhood abdominal obesity. High sensitivity is necessary to avoid failure of identifying obese children and high specificity of the screening tool ensures that non–obese children are not misclassified as obese, which may otherwise lead to unnecessary treatment and psychosocial implications of stigmatisation. Failure to identify the abdominally obese child may have more serious consequences than misclassification, since it results in an increase in adult morbidity and mortality. Therefore, the main aim of this thesis was to examine fat distribution patterns of black South African (SA) children in relation to health risk. The specific objectives were to: compare the body composition of black stunted and non–stunted children from two rural communities in South Africa; to describe and compare the age and sex specific WC percentile distribution for black SA children from different study populations and compare the WC percentile distribution with those for African–American (A–A) children and to assess the diagnostic accuracy of waist–to–height ratio (WHtR) as a marker for high blood pressure, a cardiovascular risk factor in SA children. Findings of this study demonstrated increased total adiposity in non–stunted children, but trends of increased central adiposity, measured as WHtR in stunted children. This warrants further investigation on this relationship among children older than 13 years in the African context where many children are stunted. The differences observed between the different data sets and between SA and A–A children suggest that nationally representative data should be used to develop age, sex and ethnic specific WC percentiles for this population. The results indicate clearly that the median WC of children from SA studies is smaller than those of A–A children, with a medium to large effect size for the difference. Results also suggest concern with respect to high WC values (> 80 cm) among some children. The recommended universal WHtR cut–off value of 0.5 for assessment of cardiovascular risk is not suitable for black SA children because it had low sensitivity in predicting high blood pressure. The absence of locally developed cut–off values for WC and WHtR for children warrants research due to the associations between being overweight and obese and disease outcomes. It is fundamental to detect risk at an early stage so that appropriate intervention can be initiated timeously. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2011.

Studies in both children and adults indicate that waist circumference (WC), a measure of abdominal obesity is closely related to cardiovascular risk factors. The accurate identification of abdominally obese children in health screening programmes for early intervention is of importance. There are, however, concerns about using international definitions for screening purposes because in most instances these have been derived from Western populations and, therefore, may have limited usefulness to children in other parts of the world. When these cut–off points are used in developing countries, they ignore the fact that the growth patterns of children and burdens of disease vary between countries. Due to lack of population specific cut–off points for children in the developing world it may be tempting and convenient to use the same cut–off points as for children in developed countries, but such a practice runs the risk of exporting failure. Ideally, a screening tool should have both high sensitivity and specificity, and these are important considerations in choosing the definition for the detection of childhood abdominal obesity. High sensitivity is necessary to avoid failure of identifying obese children and high specificity of the screening tool ensures that non–obese children are not misclassified as obese, which may otherwise lead to unnecessary treatment and psychosocial implications of stigmatisation. Failure to identify the abdominally obese child may have more serious consequences than misclassification, since it results in an increase in adult morbidity and mortality. Therefore, the main aim of this thesis was to examine fat distribution patterns of black South African (SA) children in relation to health risk. The specific objectives were to: compare the body composition of black stunted and non–stunted children from two rural communities in South Africa; to describe and compare the age and sex specific WC percentile distribution for black SA children from different study populations and compare the WC percentile distribution with those for African–American (A–A) children and to assess the diagnostic accuracy of waist–to–height ratio (WHtR) as a marker for high blood pressure, a cardiovascular risk factor in SA children. Findings of this study demonstrated increased total adiposity in non–stunted children, but trends of increased central adiposity, measured as WHtR in stunted children. This warrants further investigation on this relationship among children older than 13 years in the African context where many children are stunted. The differences observed between the different data sets and between SA and A–A children suggest that nationally representative data should be used to develop age, sex and ethnic specific WC percentiles for this population. The results indicate clearly that the median WC of children from SA studies is smaller than those of A–A children, with a medium to large effect size for the difference. Results also suggest concern with respect to high WC values (> 80 cm) among some children. The recommended universal WHtR cut–off value of 0.5 for assessment of cardiovascular risk is not suitable for black SA children because it had low sensitivity in predicting high blood pressure. The absence of locally developed cut–off values for WC and WHtR for children warrants research due to the associations between being overweight and obese and disease outcomes. It is fundamental to detect risk at an early stage so that appropriate intervention can be initiated timeously. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2011.

Obesity and physical inactivity (PI) are major health problems world-wide, and leading contributors to the high incidence of overweight, cardiovascular and metabolic diseases in children both globally and in South Africa in particular. Despite the importance of physical activity (PA), health-related physical fitness (HRPF) and body composition to health, very few studies have investigated the longitudinal relationship between these variables in children. Three articles based on this research were written in which a total of 283 adolescent learners (111 boys and 172 girls) with a mean age of 14.90±0.72 years from the Physical Activity and Health Longitudinal Study (PAHLS) participated. The students’ physical characteristics were measured using the protocol of the International Society for the Advancement of Kinanthropometry (ISAK); the EUROFIT test protocol and International Physical Activity Questionnaire (IPAQ) were used to assess the children’s HRPF and PA levels, respectively. In the first article, the results showed that girls had a slightly higher significant BMI (21.43±4.37 kg/m²) than the boys (20.01±3.71kg/m²) (p=0.002), and were substantially more overweight (32.4%) and fatter (%body fat=26.01±8.51) than the boys (17.1%)). A total of 85 (30%), 78 (27.5%) and 88 (31.1%) of the students had low, moderate and high PA involvement. It was concluded that girls were more overweight and less active than boys. The second article examined the relationships between body composition, health-related fitness and PA. Inverse relationships were found between BMI and the health-related fitness items of SBJ and BAH. Furthermore, BMI negatively associated with SAR and endurance performance, especially in girls. Percentage body fat was negatively related to SBJ, BAH, SAR and endurance performance. The aim of the third article was to evaluate the longitudinal development of HRPF, anthropometry and body composition status among the children. Regression coefficients showed that changes in BMI were inversely associated with those in health-related physical fitness. The changes in %BF were negatively associated with SBJ, BAH and aerobic capacity (VO2max) in the boys and girls. The results also yielded a low significantly positive association between changes in WHtR and SBJ in both genders, while low inverse associations were found between WHtR and BAH in girls, and VO2max in both genders. It is concluded that the incidence of overweight and PI was especially high in girls and excessive fatness negatively affected the girls’ fitness performances. Changes in BMI, % body fat and WHtR were negatively related with the children’s strength and running performances, especially among the girls in which the relative increase in overweight negatively affected their endurance running and static strength performances. In view of the health implications of the findings, it is necessary to create an enabling environment and opportunities to promote physically active lifestyles and develop life-long positive attitudes towards PA among students. Community-based strategies targeted at facilitating sustainable PA intervention programmes in schools are recommended. / PhD (Human Movement Science), North-West University, Potchefstroom Campus, 2014

Obesity and physical inactivity (PI) are major health problems world-wide, and leading contributors to the high incidence of overweight, cardiovascular and metabolic diseases in children both globally and in South Africa in particular. Despite the importance of physical activity (PA), health-related physical fitness (HRPF) and body composition to health, very few studies have investigated the longitudinal relationship between these variables in children. Three articles based on this research were written in which a total of 283 adolescent learners (111 boys and 172 girls) with a mean age of 14.90±0.72 years from the Physical Activity and Health Longitudinal Study (PAHLS) participated. The students’ physical characteristics were measured using the protocol of the International Society for the Advancement of Kinanthropometry (ISAK); the EUROFIT test protocol and International Physical Activity Questionnaire (IPAQ) were used to assess the children’s HRPF and PA levels, respectively. In the first article, the results showed that girls had a slightly higher significant BMI (21.43±4.37 kg/m²) than the boys (20.01±3.71kg/m²) (p=0.002), and were substantially more overweight (32.4%) and fatter (%body fat=26.01±8.51) than the boys (17.1%)). A total of 85 (30%), 78 (27.5%) and 88 (31.1%) of the students had low, moderate and high PA involvement. It was concluded that girls were more overweight and less active than boys. The second article examined the relationships between body composition, health-related fitness and PA. Inverse relationships were found between BMI and the health-related fitness items of SBJ and BAH. Furthermore, BMI negatively associated with SAR and endurance performance, especially in girls. Percentage body fat was negatively related to SBJ, BAH, SAR and endurance performance. The aim of the third article was to evaluate the longitudinal development of HRPF, anthropometry and body composition status among the children. Regression coefficients showed that changes in BMI were inversely associated with those in health-related physical fitness. The changes in %BF were negatively associated with SBJ, BAH and aerobic capacity (VO2max) in the boys and girls. The results also yielded a low significantly positive association between changes in WHtR and SBJ in both genders, while low inverse associations were found between WHtR and BAH in girls, and VO2max in both genders. It is concluded that the incidence of overweight and PI was especially high in girls and excessive fatness negatively affected the girls’ fitness performances. Changes in BMI, % body fat and WHtR were negatively related with the children’s strength and running performances, especially among the girls in which the relative increase in overweight negatively affected their endurance running and static strength performances. In view of the health implications of the findings, it is necessary to create an enabling environment and opportunities to promote physically active lifestyles and develop life-long positive attitudes towards PA among students. Community-based strategies targeted at facilitating sustainable PA intervention programmes in schools are recommended. / PhD (Human Movement Science), North-West University, Potchefstroom Campus, 2014

Obesity in children and adolescents is on the rise and is a major risk factor for chronic disease, thus posing one of the greatest public health challenges for the 21st century. Although adolescent obesity is increasing in all ethnic groups, its prevalence is higher in non–Caucasian populations. A possible explanation for ethnic differences in the development of obesity could be ethnic differences in resting metabolic rate (RMR). A low RMR would pre–dispose an ethnic group to obesity. In South Africa limited research has been published with regards to body composition (BC) and RMR in adolescents and the possible association of RMR with BC. The first aim of this study, therefore, was to determine differences in BC and RMR between 14 year old black and Caucasian South African adolescents from the Tlokwe municipality of the North West Province, South– Africa. The second aim was to investigate whether significant relationships between the body composition characteristics body mass index (BMI), percentage body fat (%BF), fat free mass (FFM) and RMR exist in this group. The baseline data of participants in the Physical Activity and Health Longitudinal Study (PAHLS) was used. Anthropometric measurements included stature, body mass, triceps and subscapular skinfolds, and waist girth to determine BMI, %BF, FFM and waist–to–height ratio (WHTR). RMR was measured by the FitMate Pro Indirect Calorimetry (Cosmed). An independent t–test was used to compare the two groups (black vs. Caucasian, boys and girls respectively) with regards to body composition and RMR. Pearson correlation coefficients (adjusted for gender and ethnicity) were calculated, to study the relationship between RMR and body composition. Significant difference levels were set at p<0.05. The present cross–sectional results revealed significant differences in BC and RMR in black and Caucasian adolescents of the Tlokwe municipality, with Caucasian adolescents of both genders having a higher RMR and FFM compared to their counterpart black adolescents. The results further indicated that Caucasian adolescents were significantly (p<0.05) taller, heavier and had a higher %BF, WHTR, FFM and RMR than the black adolescents of both genders. Boys of both ethnicities had a higher RMR than the girls, with black girls having the lowest RMR. Both underweight and overweight/obesity were present in both ethnic groups and genders emphasizing the double burden of disease prevalent in South Africa. The overweight/obese group of both ethnicities had a higher FFM and RMR than the normal and underweight group. After adjusting for gender and ethnicity a high non–significant negative relationship was observed between RMR and FFM in the overweight group. The reasons for these persistent differences in ethnic groups for RMR in adolescents are not clear. A positive association between anthropometric indicators of BC and RMR influenced by gender and ethnicity was indicated. Whether the observed ethnic differences in RMR predict future weight gain and obesity awaits the results of longitudinal analyses. It is suggested that intervention programmes be implemented focusing on the prevention of obesity in adolescents, but especially black adolescent girls, as they are indicated to be the group more prone to obesity. These results supported the literature findings and identified the need for longitudinal data regarding RMR and BC in adolescents. The PAHL–Study will continue to follow–up these adolescents over a period of time as some of the conclusions made will further be cleared, including whether the observed ethnic differences in RMR predict future weight gain and obesity. / Thesis (M.Sc. (Biokinetics))--North-West University, Potchefstroom Campus, 2012.