Structural abnormalities of the elbow joint in high school baseball players exposed to the COVID-19 pandemic during their elementary and junior high school years: a sonographic analysis of 354 players at high school entry

High school baseball players who experienced the COVID-19 pandemic during crucial growth periods exhibited a paradoxical increase in medial epicondyle hypertrophy along with a decrease in ligamentous abnormalities. Supplemental questionnaire data from a subset of participants suggested that abrupt increases in pitching volume after restrictions, rather than total cumulative load, may have contributed to hypertrophy. These findings indicate that sudden changes in throwing load and inadequate physiological adaptation during pandemic-related restrictions may have disrupted normal remodeling processes in the developing elbow. To prevent elbow abnormalities in growing baseball players, comprehensive throwing load management-including frequency and intensity, not just pitch count-is essential, with particular attention to gradual return-to-throwing programs after prolonged inactivity.