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Title: Shoulder proprioception and motor control
Author: Rodrigues, Sandra
ISNI:       0000 0004 7427 0601
Awarding Body: University of Brighton
Current Institution: University of Brighton
Date of Award: 2016
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The shoulder is an inherently unstable joint and requires well-coordinated muscle work and an appropriate sensorimotor system for it to remain stable. The sensorimotor system is defined as all the sensory, motor, central integration and processing components involved in maintaining joint stability. Shoulder action involving overhead work places great demands on the shoulder joint and can result in shoulder lesions, such as impingement syndrome. Moreover, activities requiring repetitive arm movements, including high velocity actions, have also been identified as a risk factor for shoulder impingement. Within the literature there is a notional link suggested between this condition and neuromuscular alterations with proprioceptive loss, however scientific exploration of such hypothesis has not yet been fully explored. The aims of the study are to establish normal patterns of proprioception in the shoulder and to establish what the normal patterns of shoulder motor control are. To achieve this, several studies to test reliability and validity of the protocols to measure surface electromyographic activity (sEMG), joint positional sense and force reaction of the shoulder were developed. 32 participants agreed to take part in a body of work to explore measurement of positional sense, in which the ability to replicate three criterion positions (0º, 45º and 80º of shoulder rotation) were investigated. 26 participants agreed to take part in a study to measure force reaction, in which the ability to produce a predetermined amount of force was studied. Both positional sense and force reaction (proprioceptive skills) were measured using an isokinetic dynamometer device. A third study, with 14 participants, was undertaken to measure the electromyographic activity during the movement of shoulder abduction and a volleyball throwing specific task. For positional sense measurement, there were no significant differences between criterion angles/positions and between trials (p > 0.05). However, the relative reliability indicated poor to fair agreement (ICC between 0.14 and 0.38) and repeatability was poor (Bland &Altman between 14.49º and 18.31º). This may have been due to absence of variability in the data and the nature of the unconstrained movement. The force reaction study indicated that the participants underestimated the target. Moreover the amount of errors decreased in relation to the increase in the angle of external rotation (p=0.001). This was the opposite for internal rotation (p=0.017). The ICC results were excellent (ranged between 0.75 and 0.87) and internal rotation (middle range) measurements demonstrated better coefficients of repeatability (between 1.42 and 2.61N.m.). The study investigating timing of shoulder muscle onset indicated that there were no differences between trials (p>0.05), with exception of the clavicular portion of the pectoralis muscle, during abduction in the scapular plane movement (p=0.046). There was also pre-activation of all portions of the deltoid muscle and infraspinatus in both movements. The serratus anterior muscle and supraspinatus were also preactivated during abduction in the scapular plane. While relative coefficients of reliability ranged from poor to Excellent (ICC between 0.05 and 0.79), repeatability values were good for the prime movers, suggesting that small changes can be interpreted as meaningful changes. On the contrary, changes in muscle onset timing of muscles that were neither agonists nor synergists for the desired movement were more variable.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available