Kinematics and Muscle Performance of the Trunk and Shoulder in Volleyball Players With Subacromial Impingement Syndrome
Condition: Biomechanical Phenomena
MeSH terms: Shoulder Impingement Syndrome
Study type: Observational

Summary: 
      Volleyball players repetitively place the arm into extreme positions, and thus expose the
      athletes' shoulders to a large load and increase the risk of injuries. The shoulder complex
      is identified as one of the most injured joints in volleyball sports. Although many studies
      have revealed alterations in the function, morphology and biomechanics of the shoulder
      complex in volleyball players with shoulder pain, some researchers suggested that a smooth
      energy transfer from the axial skeleton, through the shoulder complex, to the arm and hand is
      crucial for overhead sports performance and injury prevention, with little evidence showing
      the link between trunk muscle performance and shoulder pain in volleyball players.

      Therefore, the main purposes of present study are (1) to compare the trunk muscle performance
      (muscle strength, power and endurance) in volleyball players with and without subacromial
      impingement syndrome (SIS); (2) to compare trunk and shoulder muscles activity during spiking
      in volleyball players with and without SIS.
    

Detailed description: 
      Volleyball players repetitively place the arm into extreme positions, and thus expose the
      athletes' shoulders to a large load and increase the risk of injuries. The shoulder complex
      is identified as one of the most injured joints in volleyball sports. Although many studies
      have revealed alterations in the function, morphology and biomechanics of the shoulder
      complex in volleyball players with shoulder pain, some researchers suggested that a smooth
      energy transfer from the axial skeleton, through the shoulder complex, to the arm and hand is
      crucial for overhead sports performance and injury prevention, with little evidence showing
      the link between trunk muscle performance and shoulder pain in volleyball players.

      Therefore, the main purposes of present study are (1) to compare the trunk muscle performance
      (muscle strength, power and endurance) in volleyball players with and without subacromial
      impingement syndrome (SIS); (2) to compare trunk and shoulder muscles activity during spiking
      in volleyball players with and without SIS.

      We hypothesize that volleyball players with SIS will change in trunk muscle performance and
      in trunk and shoulder muscles activity during spiking.

      This is a cross-sectional case-control exploratory study.The investigators plan to recruit 35
      volleyball players with SIS and 35 age, gender, experience matched healthy players in each
      group, totally 70 volleyball players in this study. Surface electromyography (sEMG) (Noraxon,
      USA) will be used to collect trunk and shoulder muscles activity during spiking. The
      kinematics were recorded using the electromagnetic motion tracking system (LIBERTY™).
      Isokinetic dynamometer (Biodex Multi-Joint System 4 Pro) and (BTE Primus RS) will be used to
      measure trunk and shoulder muscles torque and power at 60°/s and 180°/s in trunk and 90°/s,
      180°/s and 240°/s in shoulder. Flexor, extensor and lateral flexor endurance tests will be
      used to assess trunk muscles endurance.

      SPSS software (version 24.0) will be used to analyze data. The Independent t test or Chi
      square test will be used to compare demographic data. The Independent two-sample t test will
      be used to examine group differences in all outcome measures with the significance level
      setting at 0.05.
    

Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        -  Volleyball players with more than 2 years' experience on a collegiate team.

          -  Volleyball players have been trained by professional coach over half a year.

          -  Playing or training for volleyball over 8 hours per week.
      
Keywords: Subacromial impingement; muscle performance; volleyball players