Prospective annual evaluation of sports motor performance, BMI and social index in Swiss first graders over a period of 12 years

Abstract

Abstract Understanding factors that influence children’s motor development is of major public health relevance, given its association with physical activity, health trajectories, and long-term well-being. This study evaluates neuromotor development alongside environmental factors in first graders, with a particular focus on how body mass index (BMI) and social index (SI) influence sports motor performance (SMP). This cross-sectional study presents the results of the annual monitoring of all first grades of the City of Zurich, Switzerland, from all seven school districts between 2012 and 2023. 38,977 first graders (49% girls) aged 6.9 (± 0.37) years completed the assessment of SMP (20-m sprint, standing long jump, tapping, lateral hops, shuttle run) and bodyweight and height. Main outcomes were the children’s results of the SMP test in relation to their BMI and social indices of their school district in the respective year. SMP, monitored over twelve years, correlated with both SI and BMI, with SI and BMI also being highly correlated. The mean and median BMI in Zurich remained stable over the period. On a population level, BMI explained more than half of the variation in SMP scores, while SI did not add significant explanatory power. Individual test scores showed weaker BMI associations, with the highest variance explained by BMI in the shuttle run and the lowest in the tapping score. Despite numerous free services for low-income families, SMP in Zurich children is closely linked to the SI of their school districts; however, this relationship appears to be influenced by differences in BMI. BMI is a strong predictor of SMP at the population level but less so at the individual level. Future research should assess the socioeconomic status of each child’s family to explain these differences further.