Temporal trends of physical fitness in northern Italian children (2014–2019): a repeated cross-sectional study

Background: Physical fitness (PF) is a crucial indicator of long-term health in children, influencing risks for cardiovascular disease, obesity, and overall mortality. Despite its significance, Italy lacks a national surveillance system able to track PF trends in children, hindering efforts to combat rising obesity rates. This study aims to evaluate temporal trends in PF through a possible surveillance system in elementary school children. Methods: A repeated cross-sectional study was performed and consisted of assessing five PF domains: balance, upper and lower limb strength, cardiorespiratory fitness (CRF), and, speed-agility, along with BMI z-scores. PF trends were analyzed by age and sex, with logistic regression assessing the link between PF and obesity risk. Effects sizes (ES, Cohen's d) were computed to describe the trend's magnitude. Results: CRF improved across all ages, especially in 10-11-year-olds (ES > 1.00). Younger children (6-9 years) showed gains in speed-agility, upper and lower limb strength, but these plateaued in older groups. We observed a decline in balance in 10-year-old boys. Conclusions: Overall, PF levels increased over time, with the most notable improvements observed in CRF. Implementing a nationwide PF surveillance system would facilitate continuous tracking of fitness trends, enabling policymakers to identify declines and develop targeted interventions.