A total of 214 junior high school students designated by the prefectural physical education association who received comprehensive examinations were considered for the study. Approval for this study was granted by the institutional review board of our university (Certified Clinical Research Review Board, Akita University, approval number 1704), and all subjects gave their informed consent to participate.
The subjects were divided into three categories: overhead sports group (total 75 players: 39 tennis players, 18 handball players, 12 badminton players, and 6 softball players), who raise the hand up over the head; the non-overhead sports group (total 80 players: 31 kendo players, 20 fencers, 19 basketball players, and 10 table tennis players), who mainly use one upper limb, but do not need to raise the hand up over the head; and the contact sports group (total 59 players: 22 judo players, 15 wrestlers, 13 soccer players, and 9 rugby football players), who do not primarily use the upper limb.
During the examinations, the range of motion of the shoulder was assessed in the supine position with a goniometer. In particular, internal rotation and external rotation range at 90° of shoulder abduction were measured, and their sum was defined as the total arc. Then, GIRD was defined as a dominant-nondominant side difference greater than 15° in the range of internal rotation of the shoulder, and the incidence of GIRD and the range of motion of the shoulder were compared among the three groups [8 (link),9 (link)]. In addition, the heel-buttock distance, straight leg raising angle, range of motion of the hip joint, and the presence of joint laxity were compared between the players with GIRD and those without. The subjects were also asked how many years they had been playing the sports, and how much their height had increased over the past year.
For statistical analysis, the chi-squared test was used to compare the incidence of GIRD, and the unpaired t-test was used to compare other factors between the players with and without GIRD. Significance was set at p<0.05.
The subjects were divided into three categories: overhead sports group (total 75 players: 39 tennis players, 18 handball players, 12 badminton players, and 6 softball players), who raise the hand up over the head; the non-overhead sports group (total 80 players: 31 kendo players, 20 fencers, 19 basketball players, and 10 table tennis players), who mainly use one upper limb, but do not need to raise the hand up over the head; and the contact sports group (total 59 players: 22 judo players, 15 wrestlers, 13 soccer players, and 9 rugby football players), who do not primarily use the upper limb.
During the examinations, the range of motion of the shoulder was assessed in the supine position with a goniometer. In particular, internal rotation and external rotation range at 90° of shoulder abduction were measured, and their sum was defined as the total arc. Then, GIRD was defined as a dominant-nondominant side difference greater than 15° in the range of internal rotation of the shoulder, and the incidence of GIRD and the range of motion of the shoulder were compared among the three groups [8 (link),9 (link)]. In addition, the heel-buttock distance, straight leg raising angle, range of motion of the hip joint, and the presence of joint laxity were compared between the players with GIRD and those without. The subjects were also asked how many years they had been playing the sports, and how much their height had increased over the past year.
For statistical analysis, the chi-squared test was used to compare the incidence of GIRD, and the unpaired t-test was used to compare other factors between the players with and without GIRD. Significance was set at p<0.05.
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