Mobility of extremities and muscle tightness associated with the development of throwing shoulder injury in junior high school baseball players: a one-year prospective cohort study

Abstract

The purpose of this study was to identify risk factors for throwing shoulder injury. 50 junior high school baseball players were included in the study. Data were collected on baseline information, limb mobility,muscle tightness, and the development of throwing shoulder injury. 1 year after the baseline measurements, the same measurements were taken again, and the subjects were divided into 2 groups according to whether or not they had developed throwing shoulder injury. All data were compared between groups by t-test or Mann Whitneyʼs U test. The variables with p＜0.25 for between-group comparison were used as explanatory variables,and risk factors for throwing shoulder injury were analyzed by logistic regression analysis. 47 patients were in cluded in the analysis, 14 of whom were in the throwing shoulder injury development group. The group with im paired shoulder had significantly restricted non-throwing side HBD (p=0.007), which was a risk factor for impaired shoulder (Odds ratio: 1.201, 95% CI: 1.058-1.374). Tightness of the rectus femoris muscle of the non-throwing lower extremity was found to be a risk factor for the development of throwing shoulder injury.