Development of physical fitness in Austrian primary school children: A longitudinal study among overweight and non-overweight children over 2.5 years

Summary Background Physical activity and physical fitness play an important role in the prevention of overweight and obesity in childhood and adolescence and reduce the risk of becoming overweight or obese in adulthood. Aim To evaluate the development of physical fitness in overweight and non-overweight primary school children from the first to third grades. Methods Using a longitudinal study design, body height and weight as well as physical fitness of primary school children from Tyrol, Austria were measured five times during a period of 2.5 years using the German motor performance test (DMT 6–18). Results In total, 266 children (55% boys) with a mean age of 6.4 ± 0.5 years at baseline participated. The proportion of overweight children was 11% at baseline and 22% at the fifth time point. Overweight children showed a significantly lower physical fitness level (mean total z‑score of DMT6–18) at all 5 time points (Hedges g: 0.64–1.09). Repeated measurement analyses of variances showed a significant increase of physical fitness over time among overweight (partial η 2 : 0.12) and non-overweight (partial η 2 : 0.29) children. With respect to gender, physical fitness significantly increased over time among overweight (partial η 2 : 0.20) and non-overweight (partial η 2 : 0.28) girls, as well as among non-overweight boys (partial η 2 : 0.31) but not among overweight boys (partial η 2 : 0.07). Conclusion Overweight and non-overweight primary school children significantly increased their physical fitness over the study period; however, overweight children showed a significantly lower physical fitness level at all test time points and did not even achieve the mean baseline fitness level of non-overweight children. With respect to the increasing percentage of overweight children over the study period, evidence-based preventive measures to reduce overweight and increase physical fitness should be implemented at the earliest in primary schools with a special focus on overweight boys.