The effect of physical activity on the body composition and health related fitness of 9 to 13 year old boys
Du Preez, Susanna Maria
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Physical activity plays a vital role in all children's lives. Physical activity prevents various life threatening diseases, including cardiovascular diseases, obesity, hypertension, cancer and many more. Physical activity also includes a number of other benefits of which psychological, cognitive, mental and academic improved performance are only a few to be mentioned. Unfortunately the modern century leads to a high prevalence of juvenile sedentary lifestyle. Physical activity is not one of the focus areas In schools or in homes. Modern technology causes children to spend more time being sedentary than physically active. It is essential to do further research on the influence of physical activity on the body composition and health related physical fitness of children. This provides an opportunity to emphasize the importance of physical activity during school time and as a lifestyle at home. Children, parents and physical educators need to realize the essence of the total well being of individuals and thus incorporate a physically active lifestyle in children's lives. This dissertation is comprised of five chapters of which two chapters (3 and 4) can be read independently as they are written in the form of research articles. A literature review was conducted in Chapter 2 to gain more insight on various topics related to physical activity, body composition and physical fitness. Aspects focused on in this review include the benefits of physical activity, physical fitness, the risks of physical inactivity and anthropometrical characteristics. The first objective of this study was to determine the influence of a ten month physical activity intervention programme on the body composition of 9 - 13 year old boys. The second objective was to examine the influence of a ten month physical activity intervention programme on the health related fitness of 9 - 13 year old boys. A cross-sectional experimental design was used. A total of 322, 9 -13 year old boys formed part of the study. The ten month physical activity intervention also included pre and post-tests. Two schools were selected to represent an experimental and a control group. School A, the experimental group (EG) was represented by 173 subjects and School B, the control group (CG) was represented by 149 subjects. The two schools are in the Gauteng Province, in South Africa and approximately seven kilometres from each other. The learners from the two schools also participated against each other during sporting events. The participants of school A took part in half hour sessions of physical activity twice per week and the participants from school B did not take part in the physical activity intervention programme. The study was explained to all the parents and also confirmed with a letter that was signed to give each child the appropriate permission to take part in this study. Anthropometric data were collected according to standard protocol proposed by International Society for the Advancement of Kinanthropometry (ISAK, 2001). The various measurements taken included body mass, stature, triceps skinfolds, subscapular skinfolds and calf skinfolds and humerus and femur breadths. These measurements were used to determine the body mass index and percentage body fat of the subjects. The criteria of EUROFIT tests protocol were used, as these are designed primarily for school-aged children (6-18 years). The EUROFIT test is a sensitive, individual and reliable instrument for assessing its various principal dimensions, cardiovascular endurance, agility, strength, muscular endurance, flexibility and speed. EUROFIT takes the normal school/class environment into account. These different dimensions are tested for the outcomes of different results. A pre-test was done in the beginning of the intervention period and a follow-up post-test evaluation was done ten months subsequent to the onset of the programme. The data were collected on the data sheets. To analyze the data the pre and post-tests were examined by the use of Statistica (Statsoft, Inc. 2008). Descriptive statistics were used to define information on all body composition and physical fitness variables. The pre and post-test comparisons were determined by use of a dependent t-test and age groups were compared by using independent t-tests (Thomas, Nelson & Silverman, 2005). Practical significance was also calculated (Thomas et ah, 2005). A small practically significant influence was determined by effect size d-value > 0.2, a medium or substantial practically significant effect was determined by an effect size d-value > 0.5 and whereas a large practically significant effect was determined by effect size d-value > 0.8. A p-value smaller to 0.05 was accepted as statistically significant (Ellis & Steyn, 2003; Steyn, 2005; Thomas et al., 2005). Comparisons between the EG and CG for the pre-test and post-test respectively were done by means of an independent t-test. The findings for the first objective were based on the research question of whether a ten month Physical Activity Intervention Programme (PAI) will have an influence on the body composition of 9 - to 13 year old boys. Statistically and practically significant improvements were found for the increase in stature. In addition significant decreases in percentage body fat and BMI for EG were evident after the ten month physical activity intervention. The CG showed that inactivity leads to an increase in the body mass index and percentage body fat. As for the second objective, the findings for the influence of the ten month physical activity intervention programme on health related physical fitness of 9 - 13 year old boys are reported, the results show that the EG improved statistically significant in all seven physical fitness components tested and improved practically significant in five of the seven physical fitness components tested. Improvements were evident in the 10 x 5m shuttle run, in the multi phase physical fitness test (Bleep-Test), the sit-up test, bent arm hang test, standing broad jump and in the grip strength test as opposed to the CG whose results did not change much from the pretest to the post-test. From the findings in the present study it can be concluded that when engaging in physical activity over a ten month period, health related physical fitness improves. Given the findings, the study further recommends the inclusion of physical activity programmes in schools and after school community physical activity programmes.
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