Longitudinale veranderinge in oorgewig, obesiteit, bloeddruk en motoriese behendigheid van laerskoolleerders in die Noordwes Provinsie : die NW-CHILD studie

Abstract

Overweight and obesity are increasing among the child population. In addition to the health risk that an overweight and/or obese child may experience, increasing research indicates the negative association it has on motor proficiency. If a child is not motor proficient, it can in turn lead to a range of other disadvantages, including school performance and sports skills. A further concern about the increase in unhealthy body composition is the detrimental effects it can have on health. High blood pressure and/or hypertension is one such adverse health condition that can occur due to an unhealthy increase in body composition. Gender, race and socio-economic conditions are also taken into account as role players, among others, with the increase in body composition and blood pressure and the decrease in motor proficiency. This dissertation is based on three objectives. Firstly, it is aimed at comparing longitudinal change in body composition with the change in motor proficiency of primary school learners in the North West Province of South Africa over a seven-year period. Secondly, the change in motor proficiency over a seven-year period was studied in primary school learners in the North West Province of South Africa was investigated and lastly, the change in blood pressure over a seven-year period was studied in primary school learners in the North West Province of South Africa. The study was part of the North-West Child Health, Integrated with Learning and Development (NW-CHILD) longitudinal study. This study spanned over a period of seven years and made use of all three measurement points (baseline measurements in 2010 and two follow-up measurements in 2013 and 2016). The subjects were randomly selected from 20 schools and four school districts in the North West Province. Learners were selected from Quintile 1–to-Quintile 5 schools. For the purposes of the study, only subjects who had all the measurements for the particular outcomes were used. Different genders, races and socio-economic status (SES) were included in the NW-CHILD study and consequently the subjects are a good representative group of learners. Quintiles were used as the socio-economic measure. Objective one, used the 380 learners who had complete data across the baseline measurement (2010) and the two follow-up measurements (2013 and 2016). The learners had average ages of 6.87±0.38 in 2010, 9.89±0.38 in 2013 and 12.90±0.38 in 2016. Due to the size of the minority vii group, only white and black learners were used for statistical purposes, with 103 white learners and 277 black learners. There were 218 learners from low socio-economic status and 162, from high socio-economic status. The subjects' overweight/obesity was determined, with anthropometric measurements of body length and body mass. The formula body mass (kg)/body length (m)² was used to determine the learners' body mass index (BMI). Cole et al. (2000:243) cut-off points were used to determine the BMI classes. Motor proficiency was determined with the Bruininks Oseretsky Test of Motor Proficiency, second edition (BOT-2 SF). Objective two, included only the 380 learners who had full data sets. Learners' mean age, race and SES distribution were consistent with the previous objective. The subjects' motor proficiency was also determined with the Bruininks Oseretsky Test of Motor Proficiency, second edition (BOT-2 SF). Objective three included only the 380 learners with complete data points in 2010, 2013 and 2016. The gender, race and SES distribution are also in line with objectives 1 and 2. For the purposes of this objective, the Omron 705CP-II was used to determine blood pressure and the full procedure is set out in Chapter 5. Blood pressure was processed by means of the World Health Organization (WHO) cut-off points to determine normal, pre-hypertension and hypertension. Statistical analysis was done using the Statistica computer software (Statsoft, 2020). For the purposes of objective 1-to-3, data were analyzed using descriptive statistics (mean (), standard deviation (SD), minimum and maximum values). Objective one was further analyzed using two-way frequency tables to determine the number of learners in the different BMI categories according to gender, race and SES. The strength of the relationship is determined by the phi coefficient with w≥0.1 indicating a small effect, w≥0.3 indicating a medium effect and w≥0.5 indicating a large effect (Steyn, 2002). For objective 1-to-3, an analysis of variance (ANOVA) was used to compare groups (gender, race and SES) and statistical significance was set at p≤0.05. A Bonferonni post-hoc test was performed in order to confirm the statistical validity of analyses over time. Effect sizes were determined using Cohen (1988), where d=0.2, if small, d=0.5, medium and d=0.8 are large. Based on the above analyses, obesity was found to be the highest among boys during the final measurement in 2016 and statistically significantly (p≤0.05) gender differences were reported. Furthermore, the white learners showed higher percentages of overweight and obesity (p≤0.05) compared to the black learners, and learners from high SES also showed higher percentages of overweight and obesity compared to learners from low SES (p≤0.05). Moreover, it was only fine viii motor precision (p≤0.05) and the short form total (p≤0.05) that indicated statistical significance over time with the different BMI categories. With objective two, it initially appeared that motor proficiency did not decrease drastically from 2010 to 2016, but when studying the BOT-2 categories, it can be deduced that from 2010 to 2016, fewer learners fell into the above-average category and more learners in the below-average category. Boys seem to perform better in activities which require strength (p≤0.001) and coordination (p≤0.004), and the girls seem to have better fine motor skills such as manual dexterity (p≤0.005). Furthermore, the white learners performed better in the majority of motor proficiency with the exception of manual dexterity (p=0.032), balance (p=0.013) and running speed and agility (p≤0.001) sections. Learners from high SES performed better in the motor proficiency subtests, with the exception of balance. Objective three indicated that blood pressure increased over time, regardless of gender, race and SES, no statistically significant differences could be found. Only the ratio of time to blood pressure was statistically significant (p≤0.05). Based on the findings, the following deductions can be made: overweight and obesity are increasing among the child population, more so specifically among white and high SES learners. The link between body composition and motor proficiency is not as strong in our study as previously thought. Motor proficiency has deteriorated slightly from 2010 to 2016. Furthermore, it seems that blood pressure is increasing among the child population. Overall, it appears that the child population's body composition and health related risks (high blood pressure and/or hypertension) are increasing, which could lead to a decrease in motor proficiency. This information is important in order to put in place strategies to address the existing number and to coordinate interventions to address the health and motor proficiency of younger children at an early stage. This can be done by health professionals who determine early discrepancies in body composition and blood pressure and recommend the necessary intervention strategies, furthermore, motor proficiency interventions through well-chosen activities in the life orientation program in schools can be addressed by experts such as Kinderkineticists and prevent motor delays earlier.