Physical fitness changes among school-aged children during the COVID-19 lockdown evaluated within the Hungarian National Student Fitness Test cohort.

This cohort-based analysis aims to compare the health-related physical fitness levels of Hungarian youth before and one year after the first wave of the COVID-19 pandemic. We also aimed to analyze the impact of the school environment on students’ physical fitness. A cohort study was conducted to evaluate various physical fitness components, including body mass index (BMI), body fat percentage (BF%), cardiorespiratory fitness, musculoskeletal fitness, and flexibility, measured via the Hungarian National Student Fitness Test (NETFIT®). The analysis included 285,465 students across the pre-pandemic (2018/2019) and post-pandemic (2021/2022) academic years. Generalized linear mixed-effects models were used to quantify differences. The findings indicated a decline in BMI, BF%, cardiorespiratory fitness, flexibility, and musculoskeletal fitness measured with push-up and curl-up tests. However, standing broad jump, trunk-lift, and handgrip strength increased during the COVID-19 pandemic. Moreover, significant variations in students’ physical fitness across schools suggest that school-level factors play a crucial role in shaping students’ physical performance. This study highlights a general decline in adolescents’ physical fitness, likely linked to reduced physical activity due to COVID-19 pandemic related restrictions, which contributed to increased sedentary behavior and fewer outdoor activities. The extent of these changes varied across schools.