Tsai M-S1, Hsu A-T1, Wong Y-H1
1National Cheng Kung University, Physical Therapy, Tainan, Taiwan
Background: Connective tissues adapt in response to customary stress superimposed on them. It is expected that magnitudes of strains and stresses imposed on the capsuloligamentous structures of the glenohumeral joint (GHJ) are different in different sports. Therefore, differential structural adaptions may occur in athletes of different sports and lead to changes in mechanical properties of the associated structures. Recent advances in the robotic technology allow robotic arm to simulate the mobilization movements of a therapist making accurate assessment of the magnitude of force and displacement possible.
Purpose: The purpose of the study was to investigate the differential displacement and stiffness of GHJ encountered during anteroposterior glide mobilization (APG) in collegiate baseball and badminton athletes.
Methods: Two groups of collegiate athletes, Baseball Group (N=20, aged 21.85 ± 1.63 y/o) and Badminton Group (N=20, aged 22.10 ± 1.48 y/o), were recruited. A 6 DOF robotic manipulator equipped with 6-component load cell was employed to simulate a therapist performing APG on the GHJ. With the subject lying supine, the scapula stabilized by a wedge and the arm supported at the 30゜/30゜ (flexion/abduction) position, the APGs were performed randomly in 3 rotation angles: 60゜ external rotation (ER), neutral (NP), and 60゜ internal rotation (IR). A ramped APG force (maximum to 7Kg) was applied over the greater tubercle in a direction paralleled the glenoid surface, held for 5 seconds and repeated 5 times. The magnitudes of mobilization force and AP displacement were registered throughout the experiment. The load-displacement curves were established for analyses. The Mixed Model Three Way ANOVA with Repeated measures and post hoc tests were employed to assess effects of Group, Side and Position on AP displacement at 7 Kg (Dspl_7Kg) and the stiffness of the linear elastic region (Stiff_LE). Only Group effects of Dspl_7Kg and Stiff_LE of the dominant side are reported here.
Results: Group effects on Dspl_7Kg were observed in the dominant shoulders in ER position (t=5.565, p=.000) [Baseball Group (23.39 ± 4.23 mm) > Badminton Group (17.19 ± 2.63 mm)], in IR position (t=3.802, p=.001) [Baseball Group (19.76 ± 4.16 mm) > Badminton Group (15.43 ± 2.93 mm)] and in NP position (t=3.037, p=.004) [Baseball Group (22.28 ± 4.26 mm) > Badminton Group (17.95 ± 4.74 mm)]. The Group main effects on Stiff_LE of the dominant side were observed (F=28.815, p=.000) in ER position (t=5.374, p=.000) [Baseball Group (1.3740 ± 0.3684 kg/mm) > Badminton Group (0.8871 ± 0.1687 kg/mm)], in IR position (t=3.666, p=.001, α=0.05) [Baseball Group (1.1371 ± 0.3126 kg/mm) > Badminton Group (0.8308 ± 0.2048 kg/mm) and in NP position (t=2.537, p=.015) [Baseball Group (1.2960 ± 0.3956 kg/mm) > Badminton Group (0.9890 ± 0.3693 kg/mm)].
Conclusion(s): Results of the present study indicate that the collegiate baseball athletes have greater anteroposterior mobility and greater linear stiffness of the structures resisting APG of the GHJ than those of their badminton counterparts.
Implications: When assessing and treating GHJ of athletes of different sports physical therapists should be aware of the patterns of adapted mobility and stiffness encountered during the assessment, goal setting and treatment of these athletes.
Keywords: Glenohumeral Joint, Joint Mobilization, Load-Displacement Curve
Funding acknowledgements: Supported in part by a grant from the Ministry of Sciences and Technologies of Taiwan (MOST102-2314-B-006-082)
Purpose: The purpose of the study was to investigate the differential displacement and stiffness of GHJ encountered during anteroposterior glide mobilization (APG) in collegiate baseball and badminton athletes.
Methods: Two groups of collegiate athletes, Baseball Group (N=20, aged 21.85 ± 1.63 y/o) and Badminton Group (N=20, aged 22.10 ± 1.48 y/o), were recruited. A 6 DOF robotic manipulator equipped with 6-component load cell was employed to simulate a therapist performing APG on the GHJ. With the subject lying supine, the scapula stabilized by a wedge and the arm supported at the 30゜/30゜ (flexion/abduction) position, the APGs were performed randomly in 3 rotation angles: 60゜ external rotation (ER), neutral (NP), and 60゜ internal rotation (IR). A ramped APG force (maximum to 7Kg) was applied over the greater tubercle in a direction paralleled the glenoid surface, held for 5 seconds and repeated 5 times. The magnitudes of mobilization force and AP displacement were registered throughout the experiment. The load-displacement curves were established for analyses. The Mixed Model Three Way ANOVA with Repeated measures and post hoc tests were employed to assess effects of Group, Side and Position on AP displacement at 7 Kg (Dspl_7Kg) and the stiffness of the linear elastic region (Stiff_LE). Only Group effects of Dspl_7Kg and Stiff_LE of the dominant side are reported here.
Results: Group effects on Dspl_7Kg were observed in the dominant shoulders in ER position (t=5.565, p=.000) [Baseball Group (23.39 ± 4.23 mm) > Badminton Group (17.19 ± 2.63 mm)], in IR position (t=3.802, p=.001) [Baseball Group (19.76 ± 4.16 mm) > Badminton Group (15.43 ± 2.93 mm)] and in NP position (t=3.037, p=.004) [Baseball Group (22.28 ± 4.26 mm) > Badminton Group (17.95 ± 4.74 mm)]. The Group main effects on Stiff_LE of the dominant side were observed (F=28.815, p=.000) in ER position (t=5.374, p=.000) [Baseball Group (1.3740 ± 0.3684 kg/mm) > Badminton Group (0.8871 ± 0.1687 kg/mm)], in IR position (t=3.666, p=.001, α=0.05) [Baseball Group (1.1371 ± 0.3126 kg/mm) > Badminton Group (0.8308 ± 0.2048 kg/mm) and in NP position (t=2.537, p=.015) [Baseball Group (1.2960 ± 0.3956 kg/mm) > Badminton Group (0.9890 ± 0.3693 kg/mm)].
Conclusion(s): Results of the present study indicate that the collegiate baseball athletes have greater anteroposterior mobility and greater linear stiffness of the structures resisting APG of the GHJ than those of their badminton counterparts.
Implications: When assessing and treating GHJ of athletes of different sports physical therapists should be aware of the patterns of adapted mobility and stiffness encountered during the assessment, goal setting and treatment of these athletes.
Keywords: Glenohumeral Joint, Joint Mobilization, Load-Displacement Curve
Funding acknowledgements: Supported in part by a grant from the Ministry of Sciences and Technologies of Taiwan (MOST102-2314-B-006-082)
Topic: Sport & sports injuries
Ethics approval required: Yes
Institution: National Cheng Kung University
Ethics committee: Ethical Committee of National Cheng Kung University Hospital
Ethics number: B-ER-104-096
All authors, affiliations and abstracts have been published as submitted.
