Gymnastik- och idrottshögskolan, GIH

Introduction: It has been consistently demonstrated that low aerobic fitness is causally linked to increased cardio-metabolic risk. Aerobic fitness has also been causally related to cognitive function. From adolescence and onwards, the inter-individual stability ("tracking") in fitness is fairly high. An individual's fitness level in adolescence is therefore a central determinant for future health. However, childhood predictors of adolescent fitness levels are largely unknown. The present study aimed at identifying personal, school-specific and structural determinants in childhood (age 10 yrs) for adolescent aerobic fitness (at age 16 yrs).

Methods: Body mass index-based overweight status (normal weight vs overweight/obese, according to Cole et al.) and gross motor skills (based on the Tidén-Nyberg test) were measured at baseline in 209 Swedish children (mean [SD] age 9.8 [0.60] yrs) from randomly selected schools on Sweden. Immigration status (self-report) and average household income in quartiles on community level (register obtained) were used as possible structural confounders. Data on educational status of the PE teacher and lesson structure (gender-separated vs mixed classes) was obtained from the PE teacher. At the reexamination (at age 15.8 [0.33] yrs), aerobic fitness was estimated using the Åstrand-Ryhming nomogram. Low aerobic fitness was defined as below the first quartile (29.7 mL x min-1 x kg-1). Risk for low aerobic fitness was assessed using logistic regression

Results: Risk for low aerobic fitness at follow-up was lower in children who were normal weight (OR: 0.23.95% CI: 0.10 to 0.49) and in children with trained PE-teachers (OR: 0.40, 95% CI: 0.17 to 0.93), but higher among children with poor gross motor skills (OR:1.84, 95% CI 1.08 to 3.13) at baseline. Gender, immigration history, neighborhood economical status and lesson structure were all non-significant predictors of low adolescent fitness.

Discussion: The results stress the importance for early overweight prevention and treatment and for professional identification and treatment of children with impaired gross motor skills at young ages. In Sweden, a lagre proportion of PE-teachers in lower grades lack formal PE-teacher education, which according to the present study poses a threat to children's future health. Early screening and treatment of children with limited motor proficiencies seems may help children adapting a physically active lifestyle and avoiding low fitness levels in adolescence and young adulthood.