Sport Specific Adaptions in Female Volleyball Players

Study Overview
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Brief Summary
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The shoulder joint is the second most affected body part of all overuse injuries in overhead athletes. Due to the repetitive throwing motion overhead athletes show the following characteristic adaptations of their dominant shoulder: Loss of internal rotation (IR) and gain of external rotation (ER), reduced muscle strength of the shoulder external rotators and scapular dyskinesis. On the one hand these adaptations are normal and necessary for a powerful throwing performance. On the other hand the amount of adaptation seems to play a crucial role in developing overuse symptoms and therefore becoming a risk factor. Most previous studies investigating throwing specific adaptations and risk factors focused on overhead sports like baseball, handball or tennis, whereas similar research in volleyball is still insufficient. Therefore the aim of this study is to evaluate if sport specific adaptations are present in female volleyball players and if yes, if there is a difference of the extent of these adaptations in volleyball players with overuse symptoms and players without.

Detailed Description
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Background The shoulder joint is the second most affected body part of all overuse injuries in overhead athletes.Prevalence of a history of shoulder problems related to overuse in volleyball players was reported to be approximately 60%. Typical overuse symptoms like pain seriously limit progress in performance and the individual career options of volleyball players. Due to the repetitive throwing motion overhead athletes show the following characteristic adaptations of their dominant (Ds), compared to the non-dominant (NDs) shoulder: 1) Loss of internal rotation (IR) and gain of external rotation (ER), by preserving the total rotational motion (TROM). 2) Reduced muscle strength of the shoulder external rotators (ER). 3) Scapular dyskinesis. On the one hand these adaptations are normal and necessary for a powerful throwing performance. On the other hand the amount of adaptation seems to play a crucial role in developing overuse symptoms and therefore becoming a risk factor; e.g. loss of IR, also known as glenohumeral internal rotation deficit (GIRD) of more than 20° side difference, and a loss of TROM of the Ds, were defined as risk factors in baseball players. Moreover decreased muscle strength of ER (OR: 0.71 per 10N decrease) in the Ds as well as obvious scapular dyskinesis were associated with increased risk of overuse related shoulder symptoms (ORSS). Nevertheless there are still overhead athletes showing these adaptations or risk factors without being symptomatic. Recently, several authors underlined the importance of core stability related to the kinetic chain during an overhead throwing task. It is hypothesised that symptomatic athletes may overload the shoulder girdle through altered biomechanics in an effort to compensate for insufficient power generated by the core musculature. The most reliable measurements to asses core stability components are core endurance tests. Most previous studies investigating throwing specific adaptations and risk factors focused on overhead sports like baseball, handball or tennis, whereas similar research in volleyball is still insufficient. Moreover, no one ever investigated core endurance and its possible association with (ORSS) in volleyball players. Objective The first aim is, to evaluate if sport specific adaptations such as IR ROM deficit, gain of ER ROM, ER strength deficit, alterations in TROM and scapular dyskinesis are present in female volleyball players and if yes, if there is a difference of the extent of these adaptations in volleyball players with ORSS and players without. The second aim is, to evaluate if there is a difference in core endurance in volleyball players with ORSS and players without and if there is a correlation of core endurance and shoulder related risk factors such as ER strength deficit and scapular dyskinesis?

Official Title
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Evaluation of Sport Specific Adaptations and Risk Factors at the Shoulder Joint and Core Stability Among Female Volleyball Players With and Without Overuse Related Shoulder Symptoms

Conditions
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Overuse Related Shoulder Problems

Intervention / Treatment
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* Other: shoulder range of motion in IR/ER, strength of the IR/ER muscles and Scapular Dyskinesis Test. Core endurance test.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: female being member of a Nat. League B/Nat. League A Volleyball Team in season 2017/2018 minimum age 16 years sufficient understanding/speaking of the German language signed informed consent Exclusion Criteria: having had any surgery at the shoulder joint of the dominant or non- dominant side within last six month having had any self reported trauma at the shoulder joint of the dominant or non-dominant side, which limits training or match participation of more than 50% limitation of more than 50% in training or match participation caused by a surgery or trauma at the core or lower extremity

Ages Eligible for Study
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Minimum Age: 16 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Other: shoulder range of motion in IR/ER, strength of the IR/ER muscles and Scapular Dyskinesis Test. Core endurance test.|Passive shoulder range of motion using a digital application Clinometer. Isometric strength of the shoulder IR/ER using a HHD measured. Scapular Dyskinesis Test uses a visual scoring system. Core Endurance is teste by measuring the time (s).|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| isometric strength of shoulder internal and extern rotators | Isometric strength is measured in Newton (N) using a digital handheld dynamometer (HHD; Model 01165, Lafayette Instrument Company, USA). The participants are placed in supine with their shoulder in 0° abduction (ABD) a small towel roll is used to maintain the humerus in a neutral position and their elbow flexed to 90°. The forearm is fixed to the core using a fixation band. The HHD is placed on the dorsal or ventral aspect of the forearm for ER and IR, directly proximal to wrist joint line. Players are asked to perform all strength measures twice with a rest of 30 sec. between the two attempts. The mean of the two attempts is recorded. | 2017 | 
| passive glenohumeral range of motion in internal and external rotation | Glenohumeral ROM is measured in degrees (°) on both sides using a digital application Clinometer (Plaincode Software Solutions, Peter Breitling, Stephanskirchen Germany, version 4.5 (1511062) on iOS). Participants are placed supine, the shoulder positioned in 90° of abduction, a small towel roll is used to maintain the position of the humerus in neutral and their elbow is flexed to 90°. A splint is fastened around the forearm, to attach the smartphone. The assessor palpates the coracoid process with the thumb and the spine of the scapula with the fingers to control for scapular movement. The shoulder is passively moved to the end of ROM (EOR) into IR and ER. EOR of IR and ER is defined at the point at which the scapula is moving. The mean of two trials for IR and ER is used for data analysis. | 2017 | 
| scapular dyskinesis | Scapular control is evaluated using the scapular dyskinesis test (SDT). In standing position players held two dumbbells each in one hand. Players are instructed to bilaterally elevate their arms overhead as far as possible to a 3-second count with thumbs positioned upwards and then lower to a 3-second count. Five repetitions are performed while they are visually observed from posterior. The final rating classifies scapula control as normal, subtle abnormal or obvious abnormal. | 2017 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| core stability | Core stability is assessed using core endurance tests in seconds (s). Tests are performed in a sit up position in 60° Flexion and in side plank position on both sides. Players are instructed to hold their back and hip to the upright position for as long as possible. The test terminates, when the player is not able to hold the position anymore. | 2017 |