Background:

South African children show the same tendencies in overweight and obesity as children in developed countries a decade ago. Childhood overweight is associated with chronic diseases, early mortality in adulthood and psycho-social effects with lifelong consequences. This study aimed to determine relationships between overweight, obesity and physical fitness of nine- to twelve-year-old South African children.

Methods:

Anthropometric (body-mass index [BMI], fat percentage) and physical fitness (cardiovascular endurance, body composition, muscle strength, muscle endurance, flexibility) measurements were obtained from 280 children aged nine to twelve years (128 boys, 152 girls) using the Fitnessgram and Bruininks-Oseretsky Test of Motor Proficiency II. International cut-off points were used to categorise children into normal-weight, overweight or obese categories. Data were analysed using descriptive statistics, Spearman rank order correlation and variance of analysis.

Results:

One in five children was overweight or obese, while girls were twice as likely as boys to be obese. Aerobic capacity and muscle strength, especially leg strength, decreased progressively with an increase in BMI. A progressive but nonsignificant decline was found in muscle endurance with increasing BMI, while flexibility showed the poorest relationships with various degrees of weight. Variance of analysis indicated significant relationships between BMI, cardiovascular endurance and strength (p < 0.05), while different relationships were found when gender was taken into consideration.

Conclusions:

Health-enhancing physical fitness of young children is negatively affected by overweight and obesity, and intervention strategies are recommended to improve the quality of life of such children but also to prevent early mortality during adulthood.