Background: Previous studies have shown that coronavirus disease 2019 (COVID-19) mitigation measures lead to reductions in health status and health-related fitness in children, whereas no data are currently available on the development of children after the removal of these mitigation measures. Therefore, we aimed to investigate the influence of different stringent measures, during and after COVID-19, on the longitudinal development of fitness and health status of primary school children. METHODS: A longitudinal cohort study of 331 primary school children in Austria aged 7.7 (SD-0.4) years at the start of the observation period was conducted. Before (Sept 2019), and during (June 2020, Sept 2020) and after (March 2021, June 2021, Sept 2021, and June 2022) the COVID-19 mitigation measures, fitness tests were carried out and anthropometric data of the children were collected. Age- and sex-specific standard deviation scores (SDSs) were calculated for seven individual fitness tests of the AUT FIT [1] test battery, body mass index, and waist-to-height ratio. In addition, children were classified into different fitness categories based on the AUT FIT summary score. Results: After the implementation of COVID-19 mitigation measures, cardiorespiratory fitness and action speed decreased dramatically, and the number of children with overweight or obesity increased. At the last measurement after the COVID-19 mitigation measures (June 2022), significant improvements in cardiorespiratory fitness and weight status were observed . However, pre-COVID fitness levels were not achieved and BMI was still higher compared to Sept 2019. Interpretation: Our study showed a trend reversal, in that the negative indirect effects of the COVID-19 measures on fitness and health parameters of children were followed by significant improvements in these parameters after the removal of those mitigation measures. At the end of the observation period, a positive trend in the development of fitness and health status was observed, although pre-COVID levels were not reached. Collaborative efforts are needed to reinforce the observed positive trend, and to continue to improve the level of fitness and health status of primary school children, and to mitigate the long-term negative health consequences of the COVID-19 pandemic. Funding: Austrian Federal Ministry of Arts, Culture, Public Service and Sports (GZ2021-0.361.671). 

The authors have declared no competing interest.

DRKS00023824

This study was funded by the Austrian Federal Ministry of Arts, Culture, Public Service and Sports (GZ2021-0.361.671).

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The study was registered in the German Clinical Trials Registry (ID DRKS00023824) and approved by the Research Ethics Committee of the University of Graz, Styria, Austria (GZ. 39/23/63 ex 2018/19).

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