Background In 2020, COVID-19 spread across the world and brought the world to a halt, causing the shutdown of nearly everything in order to prevent its spread. The NFL, like most of the world, faced shutdowns leaving athletes unable to train in some of the most advanced facilities with many of the best trainers in the world. Through a previous study, COVID-19 Return to Sport Injury Prevalence Analysis, it was determined that there was increased injury prevalence during the 2020 season likely due to decreased physiological adaptations within athletes bodies that resulted from facility shutdowns. Understanding injury epidemiology is vital in the prevention of injuries and the development of return-to-play protocols. Objective: The objective of this study is to perform a follow up study to COVID-19 Return to Sport Injury Prevalence Analysis in order to to examine the longitudinal effects of the COVID-19 pandemic on injury epidemiology. This study will examine if there was a recovery to baseline or lingering effects from the COVID-19 pandemic-induced spike in injuries. Methods Injury tallies collected from the 17-week-long 2020 NFL regular season, played after COVID-19 restrictions, were compared with the injury tallies collected from the 18-week-long NFL regular seasons (2021, 2022), in order to determine if there was a change in injury prevalence. An unpaired t-test was conducted to compare the mean injuries per team per week between each of the 2020, 2021, and 2022 regular seasons. Results The 2022 and 2021 NFL regular seasons produced lower numbers of total injuries than the 2020 NFL regular season that was impacted by COVID-19. The comparison of the mean number of injuries per team per week of the 2020 season compared with the 2021 regular season was statistically significant (P=.03). The comparison of the 2020 and 2022 regular seasons was also statistically significant (P=.02). Conclusions The results of this follow-up study and our previous study show that extended training interruptions have the ability to induce detraining and lead to increased injuries. Additionally, the results of this study show that retraining can occur and lead to injury protective factors. This is the first large scale opportunity to demonstrate the effects of these principles and how they are important to understanding injury epidemiology.

The authors have declared no competing interest.

This study did not receive any funding.

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