Affiliations: [a] Department of Physical Therapy, Sunmoon University,
Asan-si, Korea | [b] Department of Physical Therapy, Kyungnam University,
Changwon-si, Gyeongsangnam-do, Korea
Note: [] Corresponding author: Gyu-Chang Lee, PT, Department of Physical
Therapy, College of Natural Sciences, Kyungnam University, 499 Woryeong-dong,
Masanhappo-gu, Changwon-si, Gyeongsangnam-do, Korea. Tel.: +82 55 249 2739;
Fax: +82 55 999 2173; E-mail: leegc76@kyungnam.ac.kr
Abstract: BACKGROUND: A decrease in the range of internal rotation known as
glenohumeral internal rotation deficit (GIRD) which caused by repetitive
overhead throwing is known to take place in elite baseball players. However few
attempts at studying the differences in the range of motion (ROM), muscle strength, and endurance
according to the duration of the involvement of players have been made. OBJECTIVE: To investigate the difference in ROM, muscle strength,
endurance of shoulder among amateur pitchers. METHOD: Forty-two right-handed amateur pitchers in their 20 s and 30
s, with similar physical characteristics participated in the study. They were
divided into three groups according to their pitching experience. Range of
motion, shoulder external and internal strength and endurance and grip strength
were measured and compared. RESULTS: The ROM was significantly different among the 3 groups
(P< 0.05), especially with respect to external rotation, internal rotation,
and external rotation on side-lying. The peak torque of the right external
rotators differed significantly between 2 and 3 year experience groups (P<
0.05). Further, the peak torque and the endurance of external rotator
significantly differed between dominant and non-dominant shoulders in between 1
year group and 2 years group (P< 0.05). In external rotation endurance,
there were significant differences between the 1 and 2 years groups, and
between the 2 and 3 years group (P< 0.05). CONCLUSIONS: In conclusion, repetitive overhead throwing for more
than a year caused structural changes in shoulder joints, which were possible
responsible for changes in the range of motion and decrease external rotators
performance. Such changes in the shoulder could generate a pattern shift in
motion and cause secondary injuries such as internal impingement syndrome.
Keywords: Shoulder, range of motion, muscle strength, endurance
