**2. Materials and Methods**

This study used a cross-sectional cohort design with a population-based ad hoc sample. Overall, ten cohorts were followed yearly from 2012 until 2021. In the following, cohort always refers to the age group of 7–9-year-olds in the respective testing year. The International Physical Performance Test Profile—revised (IPPTP-R) was used to test the physical fitness in in the German federal state of Baden-Württemberg [28]. All data presented in this paper were from children from a small rural community with fewer than 5000 inhabitants located in the northeast of Baden-Württemberg that participated in the test procedure over the entire period of ten years.
