Browsing by Author "van Biljon, Anneke"

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    Identification and modification of cardiometabolic disease risk factors in South African urban primary school children
    (University of Zululand, 2018) van Biljon, Anneke; Semple, S.J.; McKune, A.; Kolanisi, U.
    The initial asymptomatic process of atherosclerosis is known to develop in childhood and is associated with increases in cardiometabolic disease (CMD) risk factors. Low physical activity (PA) levels and sedentary lifestyles have been identified as contributory factors to CMD. In addition, PA levels are known to influence the function of the cardiac autonomic nervous system (ANS), and are a possible mechanism for explaining the association between insufficient PA, morbidity and mortality. Consequently, it has been proposed that sufficient PA may enhance cardiac ANS activity in children. However, there is still a lack of consensus on the exact dosage of exercise required for optimal ANS adaptation. This thesis aims to identify and modify the risk for CMD in urban primary school children. A cross-sectional study was performed to establish PA levels in South African primary school children. This was followed by a study that examined associations between individual CMD risk factors and altered ANS activity. The effect of two different exercise doses on CMD risk factors in overweight children was explored in a pilot study that lead to the quasi experimental study where the effectiveness of isocaloric exercise protocols on CMD risk factors and cardiac autonomic modulation in children were explored. Exercise interventions were set at either 65% to 70% of the maximum heart rate (MHR) in the moderate-intensity continuous training (MICT = 29) group or >80% MHR in the high-intensity interval training (HIIT = 29) group, or the interventions were combined in the alternate (ALT = 27) group. Heart rate variability (HRV) was used to measure cardiac ANS activity. Overall, we found significant discrepancies in PA levels among gender, age and ethnic groups, raising important questions about population group equality in terms of access to participate in PA. The second cross-sectional study established strong associations between individual CMD risk factors and cardiac ANS activity. Lastly, the pilot study showed different cardiometabolic effects induced by moderate-intensity and vigorous-intensity. While the quasi experimental study demonstrated that both the magnitude and components of CMD risk factors and ANS relate to exercise intensity. When the effects of these interventions were examined, enhanced vagal activity (RMSSD, pNN50, SD1) seemed to be achieved through high-intensity interval training (HIIT), when compared with moderate-intensity continuous training (MICT). In conclusion, this thesis provides evidence that HIIT induces more superior cardioprotective effects in children than does MICT. The favourable outcomes of HIIT may have important clinical implications in regards to reducing the risk of developing CMD; however, studies that implement longer terms are required to confirm the findings.
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    The influence of exergaming on the physical fitness; attitude towards physical activity; and self-concept in overweight and obese children
    (2010) van Biljon, Anneke; Longhurst, G.K.
    The rapidly growing rate of childhood obesity makes it imperative to develop an effective intervention program for obese children. This stud y was an attempt to answer the question as to whether exergaming can drive overweight and obese children towards adopting a healthier lifestyle, becoming more physically active for life and improving their self-concept. The study consisted of a 6-week intervention on the Nintendo Wii. Participants were aged between 9-12 years old. Subjects were assigned to thee groups according to location: experimental group (n=11), control group A (n=10) and control group B (n=10). The experimental group participated in the exergaming intervention program, control group A had access to traditional video games and control group B continued with their everyday life activities with no intervention. Healthrelated- and functional- fitness protocols were used to assess the physical fitness of the subjects. The Cratty Self-concept questionnaire determined self-concept amongst subjects and a closedended interview was conducted to conclude changes in attitude towards physical activity. Statistical calculations revealed that the experimental group showed significant improvement in their level of functional fitness (p<0.05). Coordination, reaction time, speed and agility increased by magnitudes of 28%, 94% and 37% respectively. Reductions in resting- blood pressure and heart rate mean scores were observed. Both the control groups displayed marginal increases in their overall level of fitness that were not significant. No changes were observed and recorded for self- concept and attitude towards physical activity across the board. These results support the concept that exergaming can be used as an alternative means to improve the level of functional fitness as well as promoting physical activity in children.