Longitudinal 5-year tracking of isometric plank test strength in children and adolescents: a pre- and post-COVID-19 social distancing study

To compare the effects of plank strength levels over a 5-year period (2018 vs. 2023) considering the impact of the COVID-19 pandemic in children and adolescents.

This is a retrospective longitudinal case study with quantitative approach, involving schoolchildren from a school located in the South Brazil. The initial sample consisted of 221 students (58.8% boys) aged 6 to 11 years evaluated in 2018 (baseline). The same group of students was reevaluated in 2023 (follow-up) when they were aged 11 to 16 years. The assessment of isometric strength in the plank test was conducted by adapting the "core" strength test at first time in 2018. The test was performed twice within the same session, and the best measurement was recorded in 2023.

Regarding the results of the pre-pandemic (baseline) compared to the post-pandemic (follow-up) in girls, a significant negative effect over the 5-year period was observed in the comparison of raw values for isometric strength in the Plank Test's first three measurements at baseline, compared to the follow-up. Similar 5-year negative effects were observed in boys as those seen in girls, both in the raw values, and in the age-adjusted values, where no significant differences were found.

Isometric strength levels on the Plank test remained stable over the 5-year period, despite the impact of the COVID-19 pandemic, demonstrating consistent core strength in schoolchildren.