Since 2010, researchers conducting the Physical Activity and Health Longitudinal study (PAHLS) have been following the growth, weight and health-related physical fitness status of 256 adolescents at six schools in the Tlokwe (Potchefstroom) local municipality.
All the learners – 100 boys and 156 girls - volunteered for the study and were 14 years old on average when it began; they will be 18 when the project is concluded toward the end of 2014.
“In South Africa, despite reported high prevalence of underweight and obesity, scanty information exists regarding the relationship of body composition with physical fitness.
Understanding the trends of overweight or obesity and underweight in adolescents is important because it is associated with adverse effects on health and social repercussions in both adolescence and adulthood,” says project leader Prof Andries Monyeki of the Physical Activity, Sport and Recreation (PhasRec) research focus area on the Potchefstroom Campus.
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Fit for the future
Once a year, the children from each school spend a day at the School of Biokinetics, Recreation and Sport Science of the Potchefstroom Campus, where a team of researchers measure their body weight, height, and triceps and subscapular skinfolds, which are in turn used to calculate their body fat and body mass index (BMI).
The learners are then put through their paces, doing exercises designed to assess health-related physical fitness according to the EUROFIT fitness standard procedures. They do standing broad jumps to test explosive strength; bent arm hangs to measure static arm strength, and sit-ups to measure functional strength. They also do a 20-metre ‘shuttle run’ to test cardiorespiratory endurance (according to the Australian Sports Commission).
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Next, their fitness levels are analysed and linked to one of three BMI categories – underweight, normal weight and overweight. The aim is to determine the weight prevalence of the teenagers and to assess the link between body composition and physical fitness.
In the total group, a sizeable percentage of the learners, 35%, are underweight, while 13,7% are overweight obese. However, boys are more underweight than girls (44% of boys compared to 30.7% of girls). While only 8% of boys are overweight, the figure is 17% for girls.
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Girls are fatter and less fit
When it comes to physical fitness, the boys consistently perform better than the girls in all four fitness tests.
Among the girls, underweight girls perform better in the fitness test items than the girls in the normal weight group, who in turn perform better than the girls in the overweight group.
On the other hand, overweight girls with high fitness scores have more favourable BMI measurements than overweight girls with low fitness scores.
Physical inactivity is high among the group as a whole, with fewer than half taking part in moderate or high physical activity in their day-to-day lives. More girls than boys watch television for over three hours a day (19% compared to 16%), and girls are generally more overweight and less active than boys.
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“Our study indicates the co-existence of both underweight and overweight in the Tlokwe municipality,” says Prof Monyeki.
“In a country like South Africa with a double paradox of weight status, well-structured fitness programmes are needed. The objective should be low fat mass for overweight adolescents and fat-free mass muscular fitness for underweight adolescents.”
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Image: fat/thin, Shutterstock