The mediating effect of physical fitness on long term influences of overweight in primary school girls' academic performance.

Background: Overweight and obesity contribute to multiple health risks in children, while also impacting negatively on educational performance. Physical fitness can impact outcomes beyond health related measures therefore it can play a mediating role in combating the negative effects of being overweight.

Methods: One hundred and seventy-two primary school girls aged 6-13 years old from the North West Province of South Africa formed part of this random stratified longitudinal research design in which three follow-up measurements took place over seven years. Body Mass Index was used to compile obesity profiles, while the progressive aerobic cardiovascular endurance run (PACER) was used to determine cardiovascular fitness. Academic school achievements for grades 1, grade 4 and grade 7, as well as national and provincial values were correlated with academic performance. Data were analyzed by a repeated measure over time ANOVA as well using a latent growth curve model from the structural equation modelling framework (SEM).

Results: No differences (P>0.05) were found in the academic performance of obese and normal weight girls, although obese girls showed poorer physical fitness values (P<0.05). The SEM model was a good fit for all requirements (RMSEA, 0.60; CMIN DF, 2.837; CFI, 0.966). VO2max had a standardized indirect mediation effect (-132) while body composition showing a standardized direct effect (0.183) with academic achievement. Physical fitness showed a mediation effect with regard to obesity and academic achievement in grade 7 girls.

Conclusions: Although the academic performance of obese girls did not show impairment before the age of 12 years, physical fitness had a reversible effect on relationships between obesity and academic achievement. This substantial influence of physical fitness should be used strategically in preventive intervention programs necessary to enhance cognitive functioning, academic performance and brain health among overweight children.