Rugby has become a popular team sport worldwide with players training harder and competing more frequently, placing a great physiological demand on their bodies. To retain this performance level, players need to recover sufficiently between training and competitions. Two popular recovery techniques used are cold water immersion (CWI) and contrast water therapy (CWT). Despite numerous publications a lack still exists with regard to these specific recovery methods on physical and haematological parameters. Against this background, the main objectives of this study were firstly, to determine the effects of CWI compared to those of passive recovery (PAR) over a 48-hour period on physical and haematological parameters after an intense anaerobic exercise session in a cohort of male university-level rugby players. Secondly, to determine the effects of CWT compared to those of PAR over a 48-hour period on physical and haematological parameters after an intense anaerobic exercise session in a cohort of male university-level rugby players. Twenty-three rugby players of the North-West University participated in the study. The players were randomly assigned to either a control (n = 11; age: 20.1±0.3 y) or experimental (n = 12; age: 19.9±0.3 y) group. Participants reported to the laboratory where base line measurements were taken on certain physical (vertical jump test (VJT) height, VJT peak speed, VJT peak power and grip strength) and haematological (base excess (BEx), blood lactate (BLa-), calcium (Ca+), bicarbonate (HCO3), haemoglobin, haematocrit, pH level, partial oxygen level (PO2), partial carbon dioxide (PCO2), plasma glucose, potassium (K+), saturated oxygen (SO2), sodium (Na+) and total carbon dioxide (TCO2)) components. Thereafter participants were accompanied to the field to complete an intense anaerobic exercise session, followed by a recovery period of either CWI vs. PAR (week 1) or CWT vs. PAR (week 2). The recovery session comprised of either sitting passively in a still area (PAR), or immersion of CWI (8–10°C), or alternating immersions of five cycles between cold (1 min; 8–10°C) and warm water (3min; 40-42°C), totalling 20 minutes. Exactly three minutes, 24 and 48 hours after the recovery intervention all the measurements were re-taken to assess acute and longer-term effects of recovery. Descriptive statistics were followed by a linear mixed model analysis with an autoregressive 1 heterogeneous (AR1-Heterogeneous) structure, and between-group differences were examined using a one-way analysis of variance (ANOVA). Significance was set at p ≤0.05. Effect sizes were calculated to determine practical significance per recovery intervention as well as within groups. CWI indicated better recovery than PAR, with three out of the nine variables (BLa-, Na+ and haemoglobin) returning at 0 h post-recovery, and five (PO2, plasma glucose, VJT height, VJT peak power, VJT peak speed) only at 24 h post-CWI. In contrast, the PAR-group did not demonstrate recovery in any of the variables at 0 h post-PAR. However, an improvement was seen in VJT height across all time points. Four (BLa-, haemoglobin, VJT peak power and VJT peak speed) out of a possible nine variables recovered at 24 h with an additional two (PO2 and grip strength) variables showing recuperation at 48 h. A significant decrease (p ≤0.05) was seen in VJT height, PO2 and Na+ from post-anaerobic to immediately following either CWI or PAR (except for VJT height). Significant increases (p ≤0.05) were observed in VJT height, plasma glucose, and Na+ from 0 h post-recovery to 48 h post-recovery for both CWI and PAR. PO2 also significantly increased (p ≤0.05) from 0 h to 24 and 48 h post-CWI and for the PAR-group at 48 h. CWI tended to have a faster recovery rate than PAR over a 24-h period. The CWT vs. PAR showed the same trend, at 0-hours, six variables (BLa-, haemoglobin, VJT-height, VJT peak-power, VJT peak-speed and grip strength) was restored to base line, whereas plasma glucose recovered at 24-hours post-CWT. In addition, players’ jump and grip strength performance improved from base line. The PAR-group demonstrated recovery at 0 hours in four variables (BLa-, VJT height, VJT peak-speed and grip strength), and two variables (Na+ and haemoglobin) at 24-hours and plasma glucose at 48 hours. A significant decrease (p ≤0.05) was seen in haemoglobin and BLa- from post-anaerobic to either 24 or 48 hours for both groups. A significant increase in plasma glucose and PO2 from 0 to 24 hours was observed in both groups. No significant intergroup change in physical components was noticed. However, intergroup results indicated CWT to be superior to PAR with statistical significance observed in BLa- and grip strength (p ≤0.05) at various time points. The conclusion drawn from the above-mentioned results is that a recovery session comprising either 20-minutes of CWI or CWT may lead to significantly better physical components and restoration of haematological components in university-level rugby players compared to that of passive recovery. However, a detrimental effect was noticed in some components over the recovery period. / MA (Sport Science), North-West University, Potchefstroom Campus, 2015

Rugby has become a popular team sport worldwide with players training harder and competing more frequently, placing a great physiological demand on their bodies. To retain this performance level, players need to recover sufficiently between training and competitions. Two popular recovery techniques used are cold water immersion (CWI) and contrast water therapy (CWT). Despite numerous publications a lack still exists with regard to these specific recovery methods on physical and haematological parameters. Against this background, the main objectives of this study were firstly, to determine the effects of CWI compared to those of passive recovery (PAR) over a 48-hour period on physical and haematological parameters after an intense anaerobic exercise session in a cohort of male university-level rugby players. Secondly, to determine the effects of CWT compared to those of PAR over a 48-hour period on physical and haematological parameters after an intense anaerobic exercise session in a cohort of male university-level rugby players. Twenty-three rugby players of the North-West University participated in the study. The players were randomly assigned to either a control (n = 11; age: 20.1±0.3 y) or experimental (n = 12; age: 19.9±0.3 y) group. Participants reported to the laboratory where base line measurements were taken on certain physical (vertical jump test (VJT) height, VJT peak speed, VJT peak power and grip strength) and haematological (base excess (BEx), blood lactate (BLa-), calcium (Ca+), bicarbonate (HCO3), haemoglobin, haematocrit, pH level, partial oxygen level (PO2), partial carbon dioxide (PCO2), plasma glucose, potassium (K+), saturated oxygen (SO2), sodium (Na+) and total carbon dioxide (TCO2)) components. Thereafter participants were accompanied to the field to complete an intense anaerobic exercise session, followed by a recovery period of either CWI vs. PAR (week 1) or CWT vs. PAR (week 2). The recovery session comprised of either sitting passively in a still area (PAR), or immersion of CWI (8–10°C), or alternating immersions of five cycles between cold (1 min; 8–10°C) and warm water (3min; 40-42°C), totalling 20 minutes. Exactly three minutes, 24 and 48 hours after the recovery intervention all the measurements were re-taken to assess acute and longer-term effects of recovery. Descriptive statistics were followed by a linear mixed model analysis with an autoregressive 1 heterogeneous (AR1-Heterogeneous) structure, and between-group differences were examined using a one-way analysis of variance (ANOVA). Significance was set at p ≤0.05. Effect sizes were calculated to determine practical significance per recovery intervention as well as within groups. CWI indicated better recovery than PAR, with three out of the nine variables (BLa-, Na+ and haemoglobin) returning at 0 h post-recovery, and five (PO2, plasma glucose, VJT height, VJT peak power, VJT peak speed) only at 24 h post-CWI. In contrast, the PAR-group did not demonstrate recovery in any of the variables at 0 h post-PAR. However, an improvement was seen in VJT height across all time points. Four (BLa-, haemoglobin, VJT peak power and VJT peak speed) out of a possible nine variables recovered at 24 h with an additional two (PO2 and grip strength) variables showing recuperation at 48 h. A significant decrease (p ≤0.05) was seen in VJT height, PO2 and Na+ from post-anaerobic to immediately following either CWI or PAR (except for VJT height). Significant increases (p ≤0.05) were observed in VJT height, plasma glucose, and Na+ from 0 h post-recovery to 48 h post-recovery for both CWI and PAR. PO2 also significantly increased (p ≤0.05) from 0 h to 24 and 48 h post-CWI and for the PAR-group at 48 h. CWI tended to have a faster recovery rate than PAR over a 24-h period. The CWT vs. PAR showed the same trend, at 0-hours, six variables (BLa-, haemoglobin, VJT-height, VJT peak-power, VJT peak-speed and grip strength) was restored to base line, whereas plasma glucose recovered at 24-hours post-CWT. In addition, players’ jump and grip strength performance improved from base line. The PAR-group demonstrated recovery at 0 hours in four variables (BLa-, VJT height, VJT peak-speed and grip strength), and two variables (Na+ and haemoglobin) at 24-hours and plasma glucose at 48 hours. A significant decrease (p ≤0.05) was seen in haemoglobin and BLa- from post-anaerobic to either 24 or 48 hours for both groups. A significant increase in plasma glucose and PO2 from 0 to 24 hours was observed in both groups. No significant intergroup change in physical components was noticed. However, intergroup results indicated CWT to be superior to PAR with statistical significance observed in BLa- and grip strength (p ≤0.05) at various time points. The conclusion drawn from the above-mentioned results is that a recovery session comprising either 20-minutes of CWI or CWT may lead to significantly better physical components and restoration of haematological components in university-level rugby players compared to that of passive recovery. However, a detrimental effect was noticed in some components over the recovery period. / MA (Sport Science), North-West University, Potchefstroom Campus, 2015

The iron ore mining industry makes use of various processes that result in the release of airborne dust into the surrounding atmosphere where workers are exposed, to produce a final product. The deposition in the lung and toxicological influences of airborne dust can be determined by their physical- and chemical characteristics. The Occupational Health and Safety Act (OHSA) regulations for hazardous chemical substances have no current system of how the physical- and chemical properties of particulates originating from specific areas will influence a worker‘s exposure and health, especially for ultrafine particles (UFP). It is therefore imperative to characterise airborne dust containing micrometer and UFP size particles originating from specific areas to determine if there are physical- and chemical characteristics that may or may not have an influence on the workers‘ health. Aim: This pilot study is aimed at the physical- and chemical characterisation of the airborne iron ore dust generated at the process areas of an opencast iron ore mine. Method: Sampled areas included the Primary-secondary crusher, Tertiary crusher, Quaternary crusher and Sifting house. Gravimetric sampling was conducted through the use of static inhalable- and respirable samplers in conjunction with optical- and condensation particle counters that were placed near airborne dust- emitting sources. Physical- and chemical characterisation was done with the use of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results: The results found in the study indicate high mass concentration levels of inhalable dust at all four process areas, as well as high levels of respirable dust found at the primary- secondary crusher area. Particle size distribution optical particle counter (OPC) results indicate that the majority of particles at all four process areas are in the region of 0.3 μm in size. Condensation particle counter (CPC) results integrated with OPC results indicate that at the primarysecondary and Tertiary crushers the majority of particles are found to be in the size fraction <0.3 μm. SEM analysis indicates that particle agglomeration largely occurs in the airborne iron ore dust. Particle splinters originating from larger particle collisions and breakages are present in the airborne dust. EDS analysis indicates that the elemental majority of the airborne iron ore dust consists of iron, oxygen, carbon, aluminium, silicon, potassium and calcium. The elemental percentages differ from each process area where an increase in iron and decrease in impurities can be seen as the ore moves through the beneficiation process from the Primary-secondary crusher to the Sifting house. Conclusion: The results obtained from the physical- and chemical properties of the airborne iron ore dust indicate high risk of over-exposure to the respiratory system, as well as possible ultrafine particle systemic exposure, that may overwhelm the physiological defense mechanisms of the human body and lead to reactive oxygen species (ROS) formation and the development of pathologies such as siderosis, silicasiderosis and lung cancer. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

The iron ore mining industry makes use of various processes that result in the release of airborne dust into the surrounding atmosphere where workers are exposed, to produce a final product. The deposition in the lung and toxicological influences of airborne dust can be determined by their physical- and chemical characteristics. The Occupational Health and Safety Act (OHSA) regulations for hazardous chemical substances have no current system of how the physical- and chemical properties of particulates originating from specific areas will influence a worker‘s exposure and health, especially for ultrafine particles (UFP). It is therefore imperative to characterise airborne dust containing micrometer and UFP size particles originating from specific areas to determine if there are physical- and chemical characteristics that may or may not have an influence on the workers‘ health. Aim: This pilot study is aimed at the physical- and chemical characterisation of the airborne iron ore dust generated at the process areas of an opencast iron ore mine. Method: Sampled areas included the Primary-secondary crusher, Tertiary crusher, Quaternary crusher and Sifting house. Gravimetric sampling was conducted through the use of static inhalable- and respirable samplers in conjunction with optical- and condensation particle counters that were placed near airborne dust- emitting sources. Physical- and chemical characterisation was done with the use of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results: The results found in the study indicate high mass concentration levels of inhalable dust at all four process areas, as well as high levels of respirable dust found at the primary- secondary crusher area. Particle size distribution optical particle counter (OPC) results indicate that the majority of particles at all four process areas are in the region of 0.3 μm in size. Condensation particle counter (CPC) results integrated with OPC results indicate that at the primarysecondary and Tertiary crushers the majority of particles are found to be in the size fraction <0.3 μm. SEM analysis indicates that particle agglomeration largely occurs in the airborne iron ore dust. Particle splinters originating from larger particle collisions and breakages are present in the airborne dust. EDS analysis indicates that the elemental majority of the airborne iron ore dust consists of iron, oxygen, carbon, aluminium, silicon, potassium and calcium. The elemental percentages differ from each process area where an increase in iron and decrease in impurities can be seen as the ore moves through the beneficiation process from the Primary-secondary crusher to the Sifting house. Conclusion: The results obtained from the physical- and chemical properties of the airborne iron ore dust indicate high risk of over-exposure to the respiratory system, as well as possible ultrafine particle systemic exposure, that may overwhelm the physiological defense mechanisms of the human body and lead to reactive oxygen species (ROS) formation and the development of pathologies such as siderosis, silicasiderosis and lung cancer. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

The purpose of this research was to determine whether adolescents who participate in sport perform better academically in comparison to their non–participating counterparts. An availability sample of 210 learners between 14 and 24 years from a secondary school in the Dr Kenneth Kaunda District took part in this research. The participants were assessed by a Biographical Questionnaire adapted from Mpshe (1996); an adapted version of The Physical Activity Index of Sharkey (1979); the General Scholastic and Aptitude Test (GSAT)(Claassen, De Beer, Hugo & Meyer,1998); The revised two–factor Study Process Questionnaire: R–SPQ–2F of Biggs (1987a, 1987b); The Rosenberg Self–Esteem Scale (RSES), Rosenberg (1965); an adapted version of The Self–concept and Motivation Questionnaire of Bester (2003), and The Psychological Wellbeing (PWB) Scales of Ryff (1989). To obtain an overview of the participants’ academic performance, averages obtained in the June 2010 examinations in the four compulsory learning areas, i.e. Setswana First Language, English First Additional Language, Life Orientation and either Mathematics or Mathematical Literacy, were calculated. A significant relationship between sport participation and academic performance was yielded by a cross–tabulation with a practical significance of 0.09. Univariate regression models with academic performance as dependent variable and the following variables as independent variables were calculated as separate models, namely: IQ, Deep approach and Surface Approach as dimensions of the R–SPQ–2F, Motivation, Self–esteem and Psychological well–being. Only self–esteem was found to significantly predict academic performance. A further analysis using an interaction between sport participation and self–esteem did not yield a significant finding. It was concluded that it is important that Educational planners should take cognisance of the literature and research findings of this study. In future studies bigger samples can be used and the interaction between cognitive, non–cognitive and sociodemographic variables in the prediction of academic performance can be studied. / Thesis (M.A. (Research Psychology))--North-West University, Potchefstroom Campus, 2011.

The purpose of this research was to determine whether adolescents who participate in sport perform better academically in comparison to their non–participating counterparts. An availability sample of 210 learners between 14 and 24 years from a secondary school in the Dr Kenneth Kaunda District took part in this research. The participants were assessed by a Biographical Questionnaire adapted from Mpshe (1996); an adapted version of The Physical Activity Index of Sharkey (1979); the General Scholastic and Aptitude Test (GSAT)(Claassen, De Beer, Hugo & Meyer,1998); The revised two–factor Study Process Questionnaire: R–SPQ–2F of Biggs (1987a, 1987b); The Rosenberg Self–Esteem Scale (RSES), Rosenberg (1965); an adapted version of The Self–concept and Motivation Questionnaire of Bester (2003), and The Psychological Wellbeing (PWB) Scales of Ryff (1989). To obtain an overview of the participants’ academic performance, averages obtained in the June 2010 examinations in the four compulsory learning areas, i.e. Setswana First Language, English First Additional Language, Life Orientation and either Mathematics or Mathematical Literacy, were calculated. A significant relationship between sport participation and academic performance was yielded by a cross–tabulation with a practical significance of 0.09. Univariate regression models with academic performance as dependent variable and the following variables as independent variables were calculated as separate models, namely: IQ, Deep approach and Surface Approach as dimensions of the R–SPQ–2F, Motivation, Self–esteem and Psychological well–being. Only self–esteem was found to significantly predict academic performance. A further analysis using an interaction between sport participation and self–esteem did not yield a significant finding. It was concluded that it is important that Educational planners should take cognisance of the literature and research findings of this study. In future studies bigger samples can be used and the interaction between cognitive, non–cognitive and sociodemographic variables in the prediction of academic performance can be studied. / Thesis (M.A. (Research Psychology))--North-West University, Potchefstroom Campus, 2011.

Various researchers have indicated the importance of graphs in physical sciences and the difficulties that learners may experience with graphs. More specifically, learners’ problems with motion graphs have been reported in literature. Learners’ difficulty in the application of basic concepts in graphs to solve kinematics graphs problems leads to underperformance in physical sciences. Their ability to handle problems in kinematics graphs is enhanced if they have an effective knowledge base or conceptual resources on graphs. In South Africa there seems to be a gap between the GET [General Education and Training] and FET [Further Education and Training] band’s requirements on graphs. A smooth learning progression is needed. For this reason this study selected to investigate the conceptual resources acquired by grade 10 learners from grade 9 that can be used productively for the learning of kinematics graphs in grade 10. The primary aim of the study was to determine and analyse grade 10 learners’ conceptual resources for learning kinematics graphs in physical sciences. The use of a mixed method approach was considered appropriate for this study. The mixed method depended on the quantitative method to produce precise and measurable data, while a qualitative method was to enhance the understanding of the data produced by the quantitative method. Data obtained by quantitative methods was drawn into tables and graphs, and the consistency in responses determined. Patterns and trends in learners’ reasoning were probed with the aid of qualitative method. In the study it was reported that the quantitative data in the form of a questionnaire was completed by 201 learners. Qualitative data was also obtained by interviewing three learners with varying abilities. The results showed that many learners could answer mathematics questions, but struggled with similar questions in kinematics. The results further showed that the learners did not answer the questionnaire consistently, but their responses depended on the context of the questions. In the interviews learners used everyday applications to explain scientific concepts, instead of using scientific principles. Still, some of the everyday applications may be used as resources for teaching the science concepts. From the results it can be deduced that learners’ conceptual resources can influence their understanding of kinematics graphs in physics. These resources are gained from everyday experiences and previous learning in mathematics and the natural sciences. A constraint is that many learners do not efficiently integrate their mathematics and physics knowledge. iv In the study some learners did not transfer their mathematics knowledge to physics, while others could not transfer their physics knowledge to mathematics. From the results recommendations can be made for the teaching of graphs in the GET band for easier progress into the FET band. The strategy to improve understanding of kinematics graphs is to progressively integrate mathematics and physics from grade nine. Line graphs should be treated in more detail in grade 9 to form proper conceptual resources for kinematics graphs in grade ten. / MEd (Natural Sciences Education), 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

Various researchers have indicated the importance of graphs in physical sciences and the difficulties that learners may experience with graphs. More specifically, learners’ problems with motion graphs have been reported in literature. Learners’ difficulty in the application of basic concepts in graphs to solve kinematics graphs problems leads to underperformance in physical sciences. Their ability to handle problems in kinematics graphs is enhanced if they have an effective knowledge base or conceptual resources on graphs. In South Africa there seems to be a gap between the GET [General Education and Training] and FET [Further Education and Training] band’s requirements on graphs. A smooth learning progression is needed. For this reason this study selected to investigate the conceptual resources acquired by grade 10 learners from grade 9 that can be used productively for the learning of kinematics graphs in grade 10. The primary aim of the study was to determine and analyse grade 10 learners’ conceptual resources for learning kinematics graphs in physical sciences. The use of a mixed method approach was considered appropriate for this study. The mixed method depended on the quantitative method to produce precise and measurable data, while a qualitative method was to enhance the understanding of the data produced by the quantitative method. Data obtained by quantitative methods was drawn into tables and graphs, and the consistency in responses determined. Patterns and trends in learners’ reasoning were probed with the aid of qualitative method. In the study it was reported that the quantitative data in the form of a questionnaire was completed by 201 learners. Qualitative data was also obtained by interviewing three learners with varying abilities. The results showed that many learners could answer mathematics questions, but struggled with similar questions in kinematics. The results further showed that the learners did not answer the questionnaire consistently, but their responses depended on the context of the questions. In the interviews learners used everyday applications to explain scientific concepts, instead of using scientific principles. Still, some of the everyday applications may be used as resources for teaching the science concepts. From the results it can be deduced that learners’ conceptual resources can influence their understanding of kinematics graphs in physics. These resources are gained from everyday experiences and previous learning in mathematics and the natural sciences. A constraint is that many learners do not efficiently integrate their mathematics and physics knowledge. iv In the study some learners did not transfer their mathematics knowledge to physics, while others could not transfer their physics knowledge to mathematics. From the results recommendations can be made for the teaching of graphs in the GET band for easier progress into the FET band. The strategy to improve understanding of kinematics graphs is to progressively integrate mathematics and physics from grade nine. Line graphs should be treated in more detail in grade 9 to form proper conceptual resources for kinematics graphs in grade ten. / MEd (Natural Sciences Education), 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