Deltoid Middle Fiber of the Isometric Contraction According to Elastic Band and Dumbbell on Various Shoulder Abduction Angle

Baseball coaches train pitchers to keep their shoulder abduction at 90º during delivery, because this angle is believed to maximize ball speed and reduce the stress on the throwing arm. In fact, however, the shoulder abduction angle for some pitchers, including professional pitchers, deviates from 90º. There likely are reasons for such deviation. The purposes of this study, therefore, were to investigate the effects of shoulder abduction angle on ball velocity and on the injury-related joint kinetic variable, and to determine why the shoulder abduction angle varies among pitchers. Eleven professional pitchers were videotaped with two high-speed cameras. The resulting kinematic data were used to simulate several pitching motions by varying the shoulder abduction angle from the actual angle. Maximum wrist velocity was used as a reasonable approximation of ball velocity. Elbow varus torque was used as a kinetic variable. The square torque for the throwing arm and torque change for the throwing arm were used to investigate the cause of the variation. It was found that the shoulder abduction angle of 90º did not always maximize wrist velocity nor minimize elbow varus torque. The actual shoulder abduction angle for each pitcher was highly consistent with the angle that minimized both square torque and torque change. The results suggested that the proficient throwers in this study moved their pitching arm so as to minimize mechanical cost while at the same time optimizing performance.

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Saturated Muscle Activation Contributes to Compensatory Reaching Strategies After Stroke

Journal of Neurophysiology ◽

10.1152/jn.00732.2004 ◽

2005 ◽

Vol 94 (5) ◽

pp. 2999-3008 ◽

Cited By ~ 57

Author(s):

Patrick H. McCrea ◽

Janice J. Eng ◽

Antony J. Hodgson

Keyword(s):

Muscle Activation ◽

Sagittal Plane ◽

Reaching Movements ◽

Abduction Angle ◽

Task Completion ◽

Shoulder Abduction ◽

Reaching Task ◽

Hand Motion ◽

Control Subjects ◽

Anterior Deltoid

The control and execution of movement could potentially be altered by the presence of stroke-induced weakness if muscles are incapable of generating sufficient power. The purpose of this study was to identify compensatory strategies during a forward (sagittal) reaching task for 20 persons with chronic stroke and 10 healthy age-matched controls. We hypothesized that the paretic anterior deltoid would be maximally activated (i.e., saturated) during a reaching task and that task completion would require activation of additional muscles, resulting in compensatory movements out of the sagittal plane. For reaching movements by control subjects, joint motion remained largely in the sagittal plane and hand trajectories were smooth and direct. Movement characteristics of the nonparetic arm of stroke subjects were similar to control subjects except for small increases in the abduction angle and the percentage that anterior deltoid was activated. In contrast, reaching movements of the paretic arm of stroke subjects were characterized by increased activation of all muscles, especially the lateral deltoid, in addition to the anterior deltoid, with resulting shoulder abduction power and segmented and indirect hand motion. For the paretic arm of stroke subjects, muscle and kinetic compensations increased with impairment severity and weaker muscles were used at a higher percentage of their available muscle activity. These results suggest that the inability to generate sufficient force with the typical agonists involved during a forward reaching task may necessitate compensatory muscle recruitment strategies to complete the task.

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Arm abduction angle at ball release influences shoulder forces and torques during the windmill softball pitch

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120s00407 ◽

2020 ◽

Vol 8 (7_suppl6) ◽

pp. 2325967120S0040

Author(s):

Donna Scarborough ◽

Ryan Fallon ◽

Eric Berkson ◽

Luke Oh, Shannon Linderman

Keyword(s):

Shoulder Pain ◽

Shoulder Joint ◽

High Speed ◽

Frontal Plane ◽

Abduction Angle ◽

Shoulder Abduction ◽

Compression Force ◽

Ball Release ◽

Shoulder Flexion ◽

Relationship Of

Objectives: Shoulder pain and ligamentous injury is a common complaint among fast pitch softball pitchers. In addition to extreme shoulder joint motion during pitch delivery, sudden deceleration immediately after ball release places increased stress across the shoulder joint. Some pitchers release the ball with the throwing arm tucked close to the trunk, while others let the arm float outwards in a more abducted position. The position of the arm at ball release (BR) may be key to the mechanism of shoulder pain. Previous work demonstrated that during the change up pitch, softball pitchers with upper extremity pain demonstrated greater shoulder abduction at stride and less trunk lateral flexion at BR compared to athletes without pain (Oliver et al 2018). The purpose of this study was to test the hypothesis that placement of the arm closer to the trunk (shoulder adduction) at ball release will produce less shoulder stress during fastball windmill pitches. Methods: Twenty-six female fast pitch softball pitchers with a mean age of 18 +/- 6 y, including 16 high school, 7 collegiate, and 3 professional athletes, underwent 3D biomechanical pitch analyses using 20 Vicon high-speed motion capture cameras (240 hz). All pitchers threw the standard 13.11 m mound-to-plate distance at a strike zone target while a radar gun collected pitch speeds. The fastest, most accurate fastball pitches for each subject were selected for analyses (average of 5 pitches per subject). A total of 103 pitches were used to calculate: shoulder abduction angle and shoulder compression force during the BR phase (10 frames surrounding BR) and peak shoulder torques. Pearson correlations were performed to determine the relationship of shoulder frontal plane (adduction/abduction) angle during the ball release phase to these biomechanical measures. Results: The smallest abduction shoulder angle reached during the BR phase (avg: 14.06 +/- 6.71 degrees) demonstrated a significant positive correlation with shoulder compression force, p=0.008 and with peak flexion torque, p< 0.001 (Table 1). This shoulder abduction angle during the BR phase demonstrated negative correlations with peak shoulder adduction torque, p<0.001 and shoulder internal rotation torque, p< 0.001. Conclusion: These initial findings support the hypothesis that pitchers who release the ball with their arm close to their trunk demonstrate lower shoulder compression forces and shoulder flexion torques than those with a more abducted arm position. Future studies are needed to explore the interplay of pitching technique mechanics, shoulder joint stresses, and injury history to inform pitching instruction and injury prevention efforts. [Table: see text]

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Measurement of Shoulder Abduction Angles in Dogs: An Ex Vivo Study of Accuracy and Repeatability

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0039-1692410 ◽

2019 ◽

Vol 32 (06) ◽

pp. 427-432

Author(s):

Stephen C. Jones ◽

James Howard ◽

Judith Bertran ◽

Brittney Johnson ◽

Antonio Pozzi ◽

...

Keyword(s):

Ex Vivo ◽

Repeated Measurements ◽

Abduction Angle ◽

Shoulder Abduction ◽

Support Structures ◽

Shoulder Joints ◽

Shoulder Flexion ◽

Experienced Observer ◽

Accuracy And Repeatability ◽

Ex Vivo Study

Objective The aim of this study was to determine the accuracy and repeatability of the shoulder abduction test and to assess the effect of transection of the medial shoulder support structures in canine cadavers. Materials and Methods The shoulder abduction angle was measured by three separate observers, both with the shoulder extended and at a neutral angle. Shoulder abduction was then measured, using craniocaudal fluoroscopic images. Arthroscopy was performed in all shoulder joints, with the medial support structures transected in one shoulder of each dog. The three observers again measured shoulder abduction angles in all dogs. Shoulder abduction was measured again using fluoroscopy. Accuracy and repeatability of the abduction test were assessed using linear mixed models. Results All three observers had different measured abduction angles when compared with fluoroscopy (p < 0.01); however, the experienced surgeon had an error of only 2.9°. Inter-observer repeatability was poor, with all three observers having different abduction measurements (p < 0.001). Intra-observer repeatability, however, indicated no differences on repeated measurements (p = 0.26). Placing the shoulder at a neutral standing angle, and transection of support structures caused an average increase in abduction by 8.2° (p < 0.001) and 4.4° respectively. Conclusion Significant variation exists between observers performing this test, increased accuracy seen in the more experienced observer. Shoulder flexion angle can significantly affect measured abduction angles.

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Stress Radiography for the Diagnosis of Medial Glenohumeral Ligament Rupture in Canine Shoulders

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0039-1692469 ◽

2019 ◽

Vol 32 (06) ◽

pp. 433-439 ◽

Cited By ~ 1

Author(s):

Véronique Livet ◽

Mathieu Harel ◽

Mathieu Taroni ◽

Claude Carozzo ◽

Éric Viguier ◽

...

Keyword(s):

Image Analysis ◽

Abduction Angle ◽

Shoulder Abduction ◽

Objective Data ◽

Stress Radiography ◽

Glenohumeral Ligament ◽

Ligament Rupture ◽

Angle Difference ◽

Before And After ◽

Repeatability And Reproducibility

Objectives This study aimed to describe a stress radiography to detect medial glenohumeral ligament rupture and to investigate the repeatability and reproducibility of this test. Materials and Methods Six adult Beagle cadavers were used. Both shoulders of each dog were randomly assigned into two groups: a normal shoulder group (NS group) and an affected shoulder group (AS group) where the medial glenohumeral ligament was arthroscopically transected. Goniometry, image analysis and radiography (normal and stress views) were performed before and after arthroscopic procedures. An abduction angle was determined for each stress view and an evaluation of the repeatability and the reproducibility was performed. Results Abduction angles were significantly larger in the AS group as measured by goniometer (p < 0.001), image analysis (p < 0.001) and radiographic stress view (p < 0.001) than in the NS group. The abduction angle difference varied from 12° to 29.3° (median difference of 19.4°) between NS and AS groups. There were good intra-observer and very good inter-observer agreements. A very good (r = 0.74; r = 0.72, respectively) significant (p < 0.001) positive correlation between goniometric and radiographic techniques and between image analysis and radiographic techniques was observed. Clinical Significance Shoulder abduction angles measured with a stress radiograph-specific view provide objective data that may contribute to diagnosis of medial shoulder instability in dogs.

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Influence of Shoulder Abduction and Lateral Trunk Tilt on Peak Elbow Varus Torque for College Baseball Pitchers during Simulated Pitching

Journal of Applied Biomechanics ◽

10.1123/jab.22.2.93 ◽

2006 ◽

Vol 22 (2) ◽

pp. 93-102 ◽

Cited By ~ 44

Author(s):

Tomoyuki Matsuo ◽

Glenn S. Fleisig ◽

Naiquan Zheng ◽

James R. Andrews

Keyword(s):

Regression Model ◽

Multiple Regression Model ◽

Abduction Angle ◽

Shoulder Abduction ◽

Regression Analyses ◽

Elbow Injury ◽

Simple Regression Model ◽

College Baseball ◽

Baseball Pitchers ◽

Trunk Tilt

Elbow varus torque is a primary factor in the risk of elbow injury during pitching. To examine the effects of shoulder abduction and lateral trunk tilt angles on elbow varus torque, we conducted simulation and regression analyses on 33 college baseball pitchers. Motion data were used for computer simulations in which two angles— shoulder abduction and lateral trunk tilt—were systematically altered. Forty-two simulated motions were generated for each pitcher, and the peak elbow varus torque for each simulated motion was calculated. A two-way analysis of variance was performed to analyze the effects of shoulder abduction and trunk tilt on elbow varus torque. Regression analyses of a simple regression model, second-order regression model, and multiple regression model were also performed. Although regression analyses did not show any significant relationship, computer simulation indicated that the peak elbow varus torque was affected by both angles, and the interaction of those angles was also significant. As trunk tilt to the contralateral side increased, the shoulder abduction angle producing the minimum peak elbow varus torque decreased. It is suggested that shoulder abduction and lateral trunk tilt may be only two of several determinants of peak elbow varus torque.

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Active Scapular Retraction and Acromiohumeral Distance at Various Degrees of Shoulder Abduction

Journal of Athletic Training ◽

10.4085/1062-6050-318-17 ◽

2018 ◽

Vol 53 (6) ◽

pp. 584-589 ◽

Cited By ~ 4

Author(s):

Gulcan Harput ◽

Hande Guney-Deniz ◽

İrem Düzgün ◽

Uğur Toprak ◽

Lori A. Michener ◽

...

Keyword(s):

Real Time ◽

Repeated Measures ◽

Cross Sectional Study ◽

Abduction Angle ◽

Shoulder Abduction ◽

Minimal Detectable Change ◽

Ultrasound Images ◽

Cross Sectional ◽

Acromiohumeral Distance ◽

Asymptomatic Individuals

Context: Performing shoulder-abduction exercises with scapular retraction has been theorized to reduce the potential for shoulder impingement. However, objective data to support this premise are lacking. Objective: To evaluate the influence of active scapular retraction on acromiohumeral distance (AHD) at 4 shoulder-abduction angles using real-time ultrasound. Design: Cross-sectional study. Setting: University laboratory. Patients or Other Participants: Twenty asymptomatic individuals (10 men, 10 women; age = 22.9 ± 2.8 years, height = 169.3 ± 9.5 cm, mass = 65.5 ± 12.9 kg) were recruited. Main Outcome Measure(s): Real-time ultrasound images of AHD were obtained during nonretracted and retracted scapular conditions at 0°, 45°, 60°, and 90° of shoulder abduction. A 2-factor analysis of variance with repeated measures was used to evaluate the influence of shoulder retraction on AHD across shoulder-abduction angles. Results: A scapular-retraction condition × shoulder-abduction–angle interaction for AHD was found (F3,57 = 4.56, P = .006). The AHD was smaller at 0° (10.5 versus 11.2 mm, respectively; t19 = 2.22, P = .04) but larger at 90° (9.4 versus 8.7 mm, respectively; t19 = −2.30, P = .04) of shoulder abduction during the retracted than the nonretracted condition. No differences in AHD were observed between conditions at 45° (t19 = 1.45, P = .16) and 60° (t19 = 1.17, P = .86) of abduction. Conclusions: The observed differences in AHD at 0° and 90° of shoulder abduction were small and did not exceed the established minimal detectable change for either angle. Our findings suggest that active scapular retraction during shoulder abduction has a minimal influence on AHD at 0° and 90° in healthy individuals. Further investigations are needed to determine whether scapular retraction influences AHD in individuals with subacromial impingement.

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Effect of Shoulder Abduction Angle on Biomechanical Properties of the Repaired Rotator Cuff Tendons With 3 Types of Double-Row Technique

The American Journal of Sports Medicine ◽

10.1177/0363546510388152 ◽

2010 ◽

Vol 39 (3) ◽

pp. 551-556 ◽

Cited By ~ 33

Author(s):

Teruhisa Mihata ◽

Tetsutaro Fukuhara ◽

Bong Jae Jun ◽

Chisato Watanabe ◽

Mitsuo Kinoshita

Keyword(s):

Rotator Cuff ◽

Biomechanical Properties ◽

Abduction Angle ◽

Shoulder Abduction ◽

Double Row

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Evaluation of the propulsion technique and motor performance of wheelchair basketball players

Revista Brasileira de Educação Física e Esporte ◽

10.11606/1807-5509201900020313 ◽

2019 ◽

Vol 33 (2) ◽

pp. 313-322

Author(s):

Allan James de Castro Bussmann ◽

Márcia Greguol ◽

Emanuel Messias Oliveira de Carvalho ◽

Felipe Arruda Moura

Keyword(s):

Sagittal Plane ◽

Abduction Angle ◽

Test Time ◽

Shoulder Abduction ◽

Left Shoulder ◽

Speed Test ◽

Left Elbow ◽

Maximum Angle ◽

Significant Difference ◽

The Right

The objective of this study was to evaluate the propulsion technique of wheelchairs basketball athletes. The group of study was formed for 11 athletes practicing, the modality studied, with an average age of 30.27 ± 6.51 years. The sample was divided in two groups (faster, slowest) according to the performance in the agility and speed tests. To analyze the angular kinematics of the upper limbs, each person performed threeattempts to “round trip” in a distance of 5 meters. The results indicate a strong positive association between the results obtained in the speed and agility tests (r = 0.83; p = 0.002) and negative between speed test time and sports practice time (r = −0.68; p = 0.02). For the analysis of angular behavior significant difference was observed (p = 0.02), only in the variable maximum angle of the left elbow and the faster group presentedthe highest values. The angular behavior analyzes during all the movement, present significant difference at some point of the cycle, for the variables abduction angle on the left shoulder, absolute angle of the right and left forearm, absolute angles of the shoulder in the sagittal plane left and right, maximum angle of the right and left elbow. The results indicate that the athletes present specific characteristics of propulsion, andthat some angular movement characteristics, as a smaller angle of shoulder abduction during early stages of the propulsion, influence the performance in the speed test.

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