Kinetic Chain Sequencing in Overhead Athletes With and Without Shoulder Injury

Owens, Liam Paul (2023) Kinetic Chain Sequencing in Overhead Athletes With and Without Shoulder Injury. Doctoral thesis, Liverpool Hope University.

Text Full PhD Thesis (Liam Owens - 14012236) - Spring 2023 (Hardbound Submission Version).pdf - Submitted Version Restricted to Repository staff only until 1 April 2026. Available under License Creative Commons Attribution Non-commercial. Download (4MB)

Abstract

Background:
Overhead throwing performance is reliant on efficient Kinetic Chain (KC) sequencing and any breakdown in the transfer of energy during the co-ordinated segmental movements can result in shoulder injury occurrence in the overhead athlete. Although muscle functionalities and joint movements during dynamic protocols have been postulated, detailed investigations outlining changes in synchronised muscle activity patterns and joint kinematics influencing Kinetic Chain sequencing in relation to shoulder injury have not yet been detailed. This study aimed to determine differences in Kinetic Chain (Upper Limb, Trunk/Core, and Lower Limb) sequencing, imperative to prevention of shoulder injury, during everyday tasks and maximal throwing in overhead athletes with and without shoulder injury. This study also aimed to evaluate muscle activation patterns during exercises within the Advanced Throwers Ten Program and provide evidence-based recommendation for the prehabilitation and rehabilitation of throwing athletes in line with Kinetic Chain principles.

Method:
Thirty-six male overhead athletes, including eighteen with shoulder injury history and eighteen healthy throwers, participated in the study. The study developed a synchronised method between full-body kinematics and EMG systems to evaluate seventeen muscles and key joint movements across all segments of the Kinetic Chain. Three main protocols were investigated: functional everyday tasks (waist-up, eyes-down and internal/external rotation conditions), maximal overhead throwing and common rehabilitation exercises within the Advanced Throwers Ten Program.

Results:
During maximal overhead throwing, similar Kinetic Chain sequencing was evident in healthy and injured throwers with the exception of timing onsets for peak shoulder flexion and elbow extension angular velocities. There were also differences between the two groups for key peak joint angular velocities, key joint angles at overhead throwing phase markers and mean muscle activities (%MVC) during phases across all Kinetic Chain segments. Limited differences in mean muscle activity levels were evident during each everyday task, with only higher UT activity observed during the internal/external rotation task. However, there were temporal shifts in muscle activation timings and magnitudes during each everyday task. Muscle activity levels elicited by exercises within the Advanced Throwers Ten Program suggest a strengthening-based response from key muscles across certain Kinetic Chain segments, particularly of the rotator cuff and trapezius muscles when performed in a prone position. Low activity was evident across all abdomino-pelvic and lower limb segments and in muscles essential for energy transfer through the Kinetic Chain.

Outcomes:
There were variations in muscle activity patterns for all muscles across maximal throwing and everyday tasks. Variations in knee flexion angle after Foot Contact, and pelvic-thorax separation through to ball release could have reduced energy transfer efficiency through the Kinetic Chain. In turn, different muscle activity patterns were found between groups, with higher activity of key anterior shoulder musculature, scapula stabilisers and Gluteus Maximus activity exhibited by athletes with shoulder injury. It was proposed that this was required to assist glenohumeral and core stability as the body and throwing arm accelerated towards ball release. Relationships in Upper Trapezius and Supraspinatus, and Lower Trapezius and Infraspinatus activity were identified during the internal/external rotation everyday task, although these were not the case during maximal overhead throwing. Although exercises within the Advanced Throwers Ten Program elicit responses from muscles across each Kinetic Chain segment, limited strengthening stimulus is produced in lower limb and abdomino-pelvic musculature. Given their importance to initial kinetic energy generation and transfer through the Kinetic Chain, more specific exercises should be incorporated into rehabilitation programs to address muscle functionality across all Kinetic Chain segments.

Item Type:	Thesis (Doctoral)
Additional Information and Comments:	Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
Keywords:	Kinetic Chain, Overhead Throwing, Electromyography, Kinematics, Shoulder Rehabilitation
Faculty / Department:	Faculty of Human and Digital Sciences > School of Health and Sport Sciences
Depositing User:	Matthew Adams
Date Deposited:	04 Apr 2023 10:41
Last Modified:	04 Apr 2023 10:41
URI:	https://hira.hope.ac.uk/id/eprint/3830

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