
==== Front
Int J Sports Phys Ther
Int J Sports Phys Ther
2159
International Journal of Sports Physical Therapy
2159-2896
NASMI Website: International Journal of Sports Physical Therapy

38576830
94604
10.26603/001c.94604
Original Research
Muscle Activations of the Upper Extremity and Core during Elevation and Rotational Movements in Overhead Throwing Athletes
Owens Liam P 1
Khaiyat Omid 1
Coyles Ginny 1
1 School of Health and Sport Sciences Liverpool Hope University https://ror.org/03ctjbj91
Corresponding Author: Liam P. Owens School of Health and Sport Sciences Liverpool Hope University Liverpool L16 9JD Email Contact: OWENSL2@HOPE.AC.UK Telephone: 00 44 151 291 3442
1 4 2024
2024
19 4 466476
17 10 2023
7 2 2024
© The Author(s)
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (4.0) which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.

Background

A strong body of literature has been published outlining muscle activity differences during sports performance in groups of overhead athletes. However, there are limited studies that have directly compared the muscle activity in overhead athletes with and without history of shoulder injury during functional everyday tasks.

Purpose

This study aimed to identify muscle activities across fourteen upper extremity and core muscles during three functional everyday movements in athletes with and without history of shoulder injury.

Study Design

Cross-Sectional Study

Methods

Thirty-two male overhead throwing athletes (fifteen healthy and seventeen injured) were recruited and completed three everyday functional movements of high elevation, low elevation, and rotation, using their dominant arm to move an object between two fixed positions. Electromyography (EMG) was recorded for fourteen muscles including: biceps brachii, deltoids (anterior, medial, and posterior), trapezius (upper and lower), pectoralis major, latissimus dorsi, serratus anterior, infraspinatus, external obliques, and gluteus maximus (all surface electrodes) and supraspinatus (fine wire electrode). Mixed model repeated measures ANOVA and post-hoc analysis assessed mean muscle activity (%MVC) between groups and each movement phase.

Results

Upper trapezius elicited higher mean activity in healthy athletes during both phases of the arm rotation task (p < 0.05). No differences between groups were evident for arm elevation tasks. Qualitative analysis of muscle patterns during functional tasks reflected a temporal shift in muscle activation timings and magnitudes between athlete groups, suggesting potential compensatory mechanisms in injured athletes.

Conclusion

Injured overhead athletes appear to utilize other upper limb and shoulder girdle muscles to compensate for lower upper trapezius activity during functional everyday tasks.

Level of Evidence

3

Overhead
EMG
Functional Task
Shoulder
Throwing
==== Body
pmcINTRODUCTION

Shoulder injury and pain are among the most prevalent musculoskeletal complaints, ranking third in reporting to primary care1 and a lifetime prevalence of 67%.2 Daily shoulder pain has been reported within 30% of the working population,3 with chronic shoulder pain occurring in approximately 50% of all cases.2 However, pain and injury prevalence has been reported to be much higher in overhead sports. Research has shown shoulder pain history in 44-75% of elite handball players,4 with injury occurrence recorded at 48% in tennis,5 23% in cricket6 and 31% in baseball.7 Shoulder injury occurrence in overhead athletes is usually as a result of breakdown(s) in the function of the upper extremity kinetic chain (KC) which causes mechanical adaptations and performance dysfunction.8 Injuries and adaptations have been reported to include acquired glenohumeral instability, Glenohumeral Internal Rotation Deficit (GIRD), scapular muscle imbalances, scapular dyskinesis, and rotator cuff disease.9–12

In order to assess diagnosis and management strategies in populations with shoulder injury, understanding of functional performance, impact on quality of life through measures of health and well-being, and greater appreciation of the ramifications of pain are required.13 Functional assessment of the shoulder can be categorized as either a self-report measure (SRM) or a physical performance measure (PPM),14 although little focus has been given to identifying similarities and differences between healthy and injured overhead athletes during functional movement. Several testing protocols are available to practitioners to assess the function of the injured limb, with the vast majority focusing on requiring the injured patient to complete an everyday movement or task. The Simple Shoulder Endurance Test,15 involves turning and twisting bolts but in a single position and although this is an endurance-based test, it does not consider the broader functional demands of the shoulder. The most recently published testing protocol is the Timed Functional Arm and Shoulder Test (TFAST),16 consisting of three main tasks, each assessing the endurance, ROM and strength of the injured shoulder and focused on reaching, circular upper extremity motion, and lifting related tasks. Another performance-based test of upper extremity function is the 9-Hole Peg Test, whereby patients pick up pegs and place them into specified holes.17

One of the most popular testing protocols for functionality is the FIT-HaNSA (Functional Impairment Test-Hand and Neck/Shoulder/Arm) which is a functional assessment designed to test the upper extremity across multiple levels with the aim of simulating daily activities.18 The protocol consists of a test battery of three tasks, each lasting up to five minutes or until the participant feels unable to continue any longer. The three tasks consisted of a “waist-up” movement, an “eyedown” movement and an “overhead work” movement. Kumta and colleagues19 correlated FIT-HaNSA scores with shoulder strength measurements and found positive correlations for flexion (r = 0.66) and abduction (r = 0.55). Research on symptomatic patients using the FIT-HaNSA protocol has produced important findings; firstly, patients with impingement had issues completing the “eye-down” task, averaging a total task performance time of 246s out of a maximum of 300s18; and secondly, when comparing healthy controls to a symptomatic group with sub-acromial impingement syndrome (SAIS) the latter group scored significantly lower overall (59.9% vs. 98.5%) as well as on each individual task.13 FIT-HaNSA has also been used to assess functionality in patients with a massive rotator cuff tears and were found to have increased rotator cuff and latissimus dorsi (LD) activity during the elevation phase of the “waist-up” protocol.20 This was attributed to the increased need to provide stability of the glenohumeral (GH) joint. Due to this being the only protocol with previously published muscle activity findings, although for only one movement, it may be the most effective protocol to assess muscle activities across different types of performers as it requires a controlled environment and relies little on skill to complete.

While previous research studies have focussed on functional movements in injured populations,18,20 several more-recent studies have investigated the impact of fatigue in overhead athletes,21–23 during movement assessment of athletes with and without shoulder injury24 and preventative/ rehabilitative exercises.25–28 However, there is a lack of information relating to utilising functional tests to assess muscle activity during controlled, non-skilled everyday tasks. As a result, this study aimed to identify muscle activities across fourteen upper extremity and core muscles during three functional everyday movements in athletes with and without history of shoulder injury.

METHODS

Participants

A total of thirty-two male overhead throwing athletes participated in this study; fifteen were healthy (age: 25.1 ± 6.7 years) and seventeen were injured (age: 32.7 ± 10.7 years). All participants were overhead athletes recruited from local and regional baseball, cricket and handball sports clubs, and were allocated into two groups; healthy and injured. Inclusion criteria was based on shoulder injury history, with healthy defined as those who had no history of injury to their throwing shoulder or upper limb. Injured participants had a clinical history of shoulder injury (i.e. shoulder instability [n = 3] or rotator cuff disease [n = 14]) within the previous three years, as well as difficulty or pain during performance indicated in the Sports Module section of the quick Disability of the Arm, Shoulder and Hand (qDASH) questionnaire. Overhead athletes were excluded if they had no history of shoulder injury but registered difficulty or pain when completing the qDASH. The study received ethical approval from the national Research Ethics Committee. All participants were provided with a detailed information sheet at least 72 hours before their participation outlining the main details of the project and measurement procedures. All participants gave written consent before undertaking any data collection.

Functional Tasks

Three everyday functional movements using the dominant arm (high elevation, low elevation and rotation) were investigated (Figure 1). The high and low elevation tasks were adapted from the FIT-HaNSA protocol18 which requires participants to move a tin can (1kg) between two fixed positions at 25cm height increments. For the rotation task, participants moved the tin can between two fixed positions, 20cm apart, on a shelf positioned at waist height. Each movement was divided into two phases for data analysis purposes. For high elevation, Phase 1 was defined as the tin can moving from the top shelf to the bottom shelf and Phase 2 defined as bottom to top. For low elevation, Phase 1 was defined as the tin can moving from bottom shelf to top shelf and Phase 2 defined from top to bottom. For the rotation task, Phase 1 was defined as the tin can being moved medially across the shelf and the arm internally rotating and Phase 2 defined as the tin can being moved laterally across the shelf and the arm externally rotating.

198479 Figure 1. Functional Movement Tasks (a) High Elevation (b) Low Elevation (c) Rotation

Measurement Protocol

A 16-channel TeleMyo TDS System (Noraxon USA, Inc., Scottsdale, Arizona, USA) and associated MyoResearch software (version 3.8.6) were used for signal acquisition, processing, and analysis. Raw EMG signals were amplified (CMR: > 100 dB; input impedance: > 100 Mohm; and Base Gain: 200 dB), with signals collected at 1500 Hz and band-pass filtered at 20 to 250 Hz for surface electrodes and at 20 to 350 Hz for fine-wire electrodes.

Self-adhesive Ag/AgCL snap, surface dual electrodes (Noraxon USA, Inc) were placed parallel with the muscle fibers, with an inter-electrode distance of 20mm, to record EMG from muscles across KC segments. Surface EMG was collected for thirteen muscles; biceps brachii (BB), anterior, medial and posterior deltoids (AD, MD, PD), upper and lower trapezius (UT and LT), pectoralis major (PM), latissimus dorsi (LD), serratus anterior (SA), infraspinatus (ISP), contralateral and ipsilateral external bliques (contraEO and ipsilEO), and gluteus maximus (GM). Skin preparation included shaving the site and cleaning by an alcohol-free moist tissue (Kay’s Medical, UK). Fine-wire electrodes were used to record signals from the supraspinatus (SSP) using a disposable bi-polar hook intramuscular fine-wire electrode (size: 0.50x30mm (10cm wire)) (Spes Medica S.r.l., Genova, Italy) using a hypodermic needle.29

Raw EMG signals from twelve full cycles for each task (the first two and last two cycles omitted for consistency purposes) were smoothed (1500 sample/window), full-wave rectified (400 sample/window) and a root mean square (RMS) amplitude algorithm with a window size of 100ms applied. EMG from each muscle was recorded during Maximal Voluntary Contraction (MVC) for normalisation purposes. Manual muscle testing was performed by the lead investigator using procedures previously reported in functional exercise research.30–34 Two, five second efforts, with verbal encouragement, were recorded for each muscle, with the mean calculated for normalization during each functional task and reported as %MVC. A one-minute rest period was permitted between each MVC trial.

Data Analysis

Descriptive statistics are reported as %MVC for each individual muscle (mean ± standard deviation [SD]) during each phase of functional everyday task. Mixed model repeated measures ANOVA tests were performed for each functional task to determine group effects, time (phase) effects and interaction between them. Mauchly’s Test of Sphericity was performed to assess the variance of within-subject conditions35 and on occurrences of violation (p < 0.05), the appropriate epsilon correction was chosen (> 0.75, a Huynh-Feldt correction was applied; < 0.75, a Greenhouse-Geisser correction was applied). Post-hoc independent t-tests were performed to assess the statistical differences between groups during each phase of each functional task for mean activity values. The level of statistical significance was set at p < 0.05. SPSS (Statistical Package for Social Sciences, version 25) was used for all data analysis procedures.

RESULTS

Table 1 summarizes the mean activation of muscles during each functional task.

198485 Table 1. Normalized Mean Activity (%MVC ± SD) during Phase 1 (P1) and Phase 2 (P2) of three functional everyday tasks

Muscle	Healthy	Injured	
High Elevation	Low Elevation	Rotation	High Elevation	Low Elevation	Rotation	
P1	P2	P1	P2	P1	P2	P1	P2	P1	P2	P1	P2	
BB	8.9 (± 5.8)	9.0 (± 4.5)	7.7 (± 4.1)	6.2 (± 4.0)	5.3 (± 3.3)	5.2 (± 3.3)	6.8 (± 3.3)	6.9 (± 3.5)	10.5 (± 11.3)	8.6 (± 8.7)	4.0 (± 1.8)	3.9 (± 1.6)	
AD	16.3 (± 6.6)	20.3 (± 9.1)	8.1 (± 5.3)	7.6 (± 5.0)	8.3 (± 4.4)	7.8 (± 3.9)	15.2 (± 7.9)	17.8 (± 10.3)	7.3 (± 3.9)	7.1 (± 3.7)	6.6 (± 4.1)	6.2 (± 3.5)	
MD	7.8 (± 3.6)	8.5 (± 4.1)	2.4 (± 1.8)	2.4 (± 1.9)	2.3 (± 1.8)	2.2 (± 1.6)	9.5 (± 8.0)	10.3 (± 8.5)	2.3 (± 2.3)	2.3 (± 2.6)	2.4 (± 4.7)	2.4 (± 4.5)	
PD	3.8 (± 2.6)	4.2 (± 2.9)	2.3 (± 1.7)	2.3 (± 1.8)	2.0 (± 1.5)	2.2 (± 1.7)	5.6 (± 3.9)	6.2 (± 4.2)	2.8 (± 1.9)	2.9 (± 2.0)	2.9 (± 1.9)	2.9 (± 1.9)	
UT	13.5 (± 4.2)	16.3 (± 5.6)	7.7 (± 6.3)	6.9 (± 5.6)	6.0 (± 5.3)*	6.1 (± 5.1)*	12.2 (± 5.7)	14.9 (± 6.4)	7.3 (± 7.6)	6.1 (± 6.3)	2.7 (± 2.1)	3.0 (± 2.5)	
LT	17.9 (± 6.3)	20.5 (± 6.7)	10.7 (± 4.7)	10.0 (± 4.0)	10.6 (± 7.1)	9.9 (± 4.1)	13.7 (± 8.2)	15.8 (± 10.7)	10.3 (± 6.0)	9.5 (± 5.3)	8.6 (± 5.1)	9.2 (± 5.7)	
PM	7.4 (± 3.2)	9.0 (± 4.1)	5.5 (± 2.8)	5.2 (± 2.7)	8.1 (± 3.8)	8.7 (± 3.9)	9.4 (± 7.8)	11.1 (± 9.3)	6.2 (± 4.4)	5.9 (± 4.4)	7.0 (± 3.7)	7.5 (± 3.7)	
LD	4.2 (± 3.1)	4.3 (± 3.0)	2.4 (± 1.2)	2.5 (± 1.3)	2.5 (± 1.3)	2.6 (± 1.4)	3.3 (± 2.5)	3.6 (± 2.6)	2.6 (± 1.9)	2.5 (± 1.9)	2.7 (± 1.7)	2.8 (± 1.7)	
SA	5.4 (± 4.8)	5.5 (± 5.0)	2.0 (± 1.2)	2.1 (± 1.3)	1.7 (± 1.0)	1.8 (± 1.0)	5.6 (± 3.8)	5.9 (± 3.7)	2.3 (± 1.4)	2.2 (± 1.3)	2.5 (± 1.9)	2.5 (± 1.7)	
SSP	14.7 (± 13.9)	18.2 (± 15.8)	8.2 (± 11.1)	7.3 (± 8.9)	5.9 (± 6.3)	6.5 (± 8.3)	20.2 (± 12.9)	23.4 (± 14.5)	11.7 (± 9.3)	11.6 (± 8.5)	7.9 (± 7.6)	8.1 (± 8.0)	
ISP	15.0 (± 3.8)	18.0 (± 4.7)	8.7 (± 3.6)	7.8 (± 3.0)	7.8 (± 3.5)	8.3 (± 3.2)	17.0 (± 12.6)	20.3 (± 14.0)	10.6 (± 7.4)	9.5 (± 6.9)	10.3 (± 10.6)	11.4 (± 10.9)	
GM	3.0 (± 2.7)	2.9 (± 2.6)	3.5 (± 4.2)	3.3 (± 3.8)	4.0 (± 4.8)	4.7 (± 5.6)	3.1 (± 3.0)	3.2 (± 3.1)	3.7 (± 3.3)	3.6 (± 3.1)	3.9 (± 3.5)	4.0 (± 3.7)	
ipsilEO	2.3 (± 1.3)	2.1 (± 0.9)	2.1 (± 1.1)	2.2 (± 1.0)	3.5 (± 2.4)	3.2 (± 2.4)	2.4 (± 3.0)	2.4 (± 3.1)	1.6 (± 0.1)	1.6 (± 0.1)	2.6 (± 0.9)	2.5 (± 0.6)	
contraEO	2.3 (± 0.8)	2.3 (± 0.8)	2.1 (± 0.9)	2.1 (± 0.9)	1.9 (± 0.7)	2.0 (± 0.7)	2.6 (± 2.1)	2.7 (± 2.3)	3.0 (± 3.3)	3.0 (± 3.2)	2.9 (± 2.8)	2.9 (± 2.7)	
BB – Biceps Brachii; AD – Anterior Deltoid; MD – Medial Deltoid; PD – Posterior Deltoid; UT – Upper Trapezius; LT – Lower Trapezius; PM – Pectoralis Major; LD – Latissimus Dorsi; SA – Serratus Anterior; SSP – Supraspinatus; ISP – Infraspinatus; contraEO – Contralateral External Oblique; GM – Gluteus Maximus; ispilEO – Ipsilateral External Oblique] [ipsilEO data was only collected for seven participants. Note: * denotes statistically significant difference (p < 0.05) between healthy and injured throwers during P1 or P2 for each task.

High Elevation

Significant time effects were evident for PM (p = 0.000), LD (p = 0.003), all deltoid (AD: p = 0.000; MD: p = 0.041; PD: p = 0.000), trapezius (UT: p = 0.000; LT: p = 0.000) and rotator cuff musculature (SSP: p = 0.024; ISP: p = 0.000). However, post-hoc tests found no differences in mean activity between groups during downward (Phase 1) or upward (Phase 2) movements.

198977 Figure 2. Upper Trapezius and Rotator Cuff muscle activity during High Elevation functional task [H – Healthy, I – Injured; Upper Trapezius (UT), Supraspinatus (SSP), Infraspinatus (ISP)]

Low Elevation

Significant time effects were evident for BB (p = 0.001), trapezius muscles (UT: p = 0.001; LT: p = 0.002), ISP (p = 0.000) and GM (p = 0.049). Post-hoc tests determined no differences in mean activity between groups upward (Phase 1) or downward (Phase 2) movements.

198979 Figure 3. Key muscle activity during Low Elevation functional task [H – Healthy, I – Injured; Biceps Brachii (BB), Anterior Deltoid (AD), Upper Trapezius (UT), Supraspinatus (SSP), Infraspinatus (ISP)]

Rotation

A significant group effect was evident for UT (p = 0.038) only. Significant time effects were evident for the AD (p = 0.033 and PM (p = 0.034). Post-hoc tests revealed significant differences in mean UT activity between groups during both medial movement (Phase 1: p = 0.038) and lateral movement (p = 0.048). In both phases, mean UT activity was higher in healthy overhead athletes compared to injured (Phase 1: 6.0 %MVC (± 5.3) compared to 2.7 %MVC (± 2.1); Phase 2: 6.1 %MVC (± 5.1) compared to 3.0 %MVC (± 2.5)).

198980 Figure 4. Key muscle activity during a Rotational functional task [H – Healthy, I – Injured; Upper Trapezius (UT), Supraspinatus (SSP).

DISCUSSION

This research study investigated differences in muscle activities of fourteen muscles across upper extremity and core segments during three everyday tasks in overhead athletes with and without shoulder injury. Across elevation and rotational functional tasks, only significant differences in mean UT activity during both phases of the rotational task were evident, with greater UT activity recorded in healthy overhead athletes. However, potential compensatory mechanisms between key scapula and rotator cuff muscles may be evident in injured throwers to assist in humeral elevation and internal rotation of the arm.

In addition to the higher mean UT activity, differences in UT activity patterns were also evident throughout the rotational functional task movement cycle, with three distinct peaks identified for healthy overhead athletes that were not evident in injured overhead athletes (Figure 4). The healthy group appear to activate the UT to assist with raising the tin can, most notably around as the arm internally rotates over mid-shelf during Phase 1 and again at the start of Phase 2 as the tin can was lifted back off the shelf at the start of the external rotation phase. In addition, UT activity increases for a third time as the arm is lowered back to the start point. Actions of the UT encompass both scapular control and clavicle elevation36 and the activity profiles identified in this research study could be a method employed by the healthy group to assist in glenohumeral joint stability but also in elevating the clavicle to assist in clearance and initial elevation. In contrast, injured throwers elicited more SSP activity when lifting the tin can off the shelf and internally rotating across mid-shelf. This suggests SSP activity is needed during humeral elevation as previously proposed by Otis and colleagues37 and to counteract the reduction in UT activity at these points of the movement cycle which may increase the risk of impingement.

The High Elevation protocol required participants to move a tin can from a shelf positioned at eye level to another 25cm below before returning it to the higher shelf. The findings of this study identified no differences between healthy and injured groups for mean muscle activation either during or between phases for this protocol, although differences in muscle activity patterns were evident. Activity patterns for the AD, UT and rotator cuff musculature exhibited some variation between healthy and injured throwers, agreeing with findings in previous research studies investigating shoulder elevation tasks.13,38 At mid-elevation, AD and UT activity increased as rotator cuff activity increased, with higher SSP and ISP activity evident in injured throwers (Figure 2). This supports the previous findings of Hawkes and colleagues,20 who attributed increased rotator cuff activity as a mechanism to ensure glenohumeral joint stability during arm elevation movements. In addition, patients with anterior shoulder instability exhibited higher peak ISP, UT and PD activity, but lower SSP activity when compared to healthy controls during elevation tasks.38 They deemed activity differences were significant around mid-elevation and determined that the early onset of ISP and SSP resulted in delayed onset of UT activity. This is in slight contrast to the findings of the present study, as although ISP and SSP activity were higher in injured throwers during mid-elevation, UT activity was lower when compared to healthy throwers. This suggests that injured throwers utilize rotator cuff musculature to compensate for reduced UT activity as the arm is elevated. During the mid-elevation range through to the end of Phase 2 as the arm is raised to its highest point, healthy throwers exhibited higher AD, UT and LT activity whereas injured throwers exhibited higher ISP, SSP, MD and PD activity. The increased eccentric activities of both the SSP and PD could be strategies to counteract AD activity as it contracts to flex the shoulder joint and in turn, aid repositioning of the humeral head during upward movement39 to support humeral elevation37 similar to the previously proposed mechanism during the rotation task.

Similar to the High Elevation protocol, no mean muscle activity differences were evident between groups during or between phases for the Low Elevation protocol. However, differences in activity patterns were evident around mid-elevation in both upward and downward phases for the same muscles as previously highlighted. Therefore, it is suggested that similar compensatory mechanisms should be applied towards this protocol. However, differences in BB activity patterns were noted for this protocol. The BB plays an important role during initial arm elevation, and when the arm is elevated to 30o, the BB provides stability to the glenohumeral joint as it moves through the range.40 In the present study, BB activity increased in both groups approaching mid-elevation during the upward phase, although activity was higher in injured throwers. This activity could be as a result of increased elbow flexion mid-elevation, although it is possible that the higher BB activity exhibited in injured throwers was required to assist in providing additional stability to the shoulder joint during the upward movement. Landin and colleagues41 reported that continued BB activity was evident when the arm was further elevated past 30o and this activity is in combination with increased AD activity as the shoulder continues to be flexed.42 This is consistent with the findings of the present study, with peak AD activity being exhibited in both groups after peak BB activity, approaching the end of the upward phase (Figure 3). Healthy throwers also exhibited a greater peak activity of AD compared to BB which contrasts the activity magnitudes of injured throwers. Peak BB activity during the downward phase was less than peak activity during the upward phase for both groups. This could suggest that muscle activity needs to be increased in the upward phase due to working against gravity (as proposed by Hawkes and colleagues),20 but also as a result of the need to enhance glenohumeral joint stability and reduce the anterior translation of the humeral head.43 BB activity patterns identified in this present study are comparable to those previously reported in similar studies,20 which detailed a gradual reduction in BB activity until around 70% of the movement cycle, where re-activation is evident.

Future studies should focus attention towards increasing the weight of the object being manipulated during functional everyday tasks, or increase the time permitted to complete the task. The fatiguability of key muscles could be investigated alongside postural movement during each trial. Due to the ballistic movement associated with overhead throwing, functional movements at greater speeds could be investigated to assess muscle activities across the upper extremity and core, and identify differences between healthy and injured throwers. This may provide further insights to those provided by Castillo-Lozano and colleagues44 who investigated the muscle activity of healthy participants during arm elevation through different planes and at different speeds. This may provide an intermediate test condition between controlled functional and throwing-related movements. Finally, for overhead throwing athletes, more complex functional tasks could be designed that reflect similar movements to an overhead throwing task where participants move through various planes of movement in succession.

CONCLUSION

The results of this study present the activity of selected upper extremity and core muscle in healthy and injured overhead throwing athletes during three functional everyday tasks (high elevation, low elevation, and rotation). While both groups recorded similar mean activities for high and low elevation movements, healthy throwers elicited higher UT activity during both phases of the rotational movement. Qualitative examination of muscle activity patterns presented temporal shifts in muscle activation timings and magnitudes which could relate to potential compensatory mechanisms in order to achieve task completion.

The functional movements were designed to allow the participants to complete tasks without any inhibitory or adaptations in technique, controlling the intensity of action demanded on an injured limb. While the results may be useful to evaluate the impact of injury on completing every day functional tasks, caution should be taken when attempting to apply findings to overhead throwing performance. Overhead throwing is reliant on the interaction of muscles through the KC, and the functional tasks investigated do not engage the core musculature or reflect the intensity of a maximal throwing motion.
==== Refs
The incidence and management of shoulder complaints in general practice: a retrospective cohort study Family Practice van Doorn Pieter F de Schepper Evelien I T Rozendaal Rianne M Ottenheijm Ramon P G van der Lei Johan Bindels Patrick J Schiphof Dieuwke Oxford University Press (OUP) 16 4 2021
38 5 582 588 1460-2229 10.1093/fampra/cmab022 10.1093/fampra/cmab022 33860787
Prevalence and incidence of shoulder pain in the general population; a systematic review Scandinavian Journal of Rheumatology Luime J J Koes B W Hendriksen I J M Burdorf A Verhagen A P Miedema H S Verhaar J A N Informa UK Limited 3 2004
33 2 73 81 0300-9742 10.1080/03009740310004667 10.1080/03009740310004667 15163107
Epidemiologic surveillance of upper-extremity musculoskeletal disorders in the working population Arthritis Care & Research Roquelaure Yves Ha Catherine Leclerc Annette Touranchet Annie Sauteron Marine Melchior Maria Imbernon Ellen Goldberg Marcel Wiley 29 9 2006
55 5 765 778 0893-7524 10.1002/art.22222 10.1002/art.22222
Preventing overuse shoulder injuries among throwing athletes: a cluster-randomised controlled trial in 660 elite handball players British Journal of Sports Medicine Andersson Stig Haugsboe Bahr Roald Clarsen Benjamin Myklebust Grethe BMJ 2017
51 14 1073 1080 0306-3674 10.1136/bjsports-2016-096226 10.1136/bjsports-2016-096226 27313171
Shoulder to shoulder: stabilising instability, re-establishing rhythm, and rescuing the rotators! Br J Sports Med Pluim B.M. van Cingel R.E.H. Kibler W.B. 2006
44 5 299
Shoulder injury in professional cricketers Physical Therapy in Sport Ranson Craig Gregory Peter L. Elsevier BV 2 2008
9 1 34 39 1466-853X 10.1016/j.ptsp.2007.08.001 10.1016/j.ptsp.2007.08.001
Shoulder injuries in the overhead-throwing athlete: epidemiology, mechanisms of injury, and imaging findings Radiology Lin Dana J. Wong Tony T. Kazam Jonathan K. Radiological Society of North America (RSNA) 2 2018
286 2 370 387 0033-8419 10.1148/radiol.2017170481 10.1148/radiol.2017170481
Pathomechanics of the throwing shoulder Sports Medicine and Arthroscopy Review Kibler W. Ben Thomas Stephen J. Ovid Technologies (Wolters Kluwer Health) 3 2012
20 1 22 29 1062-8592 10.1097/jsa.0b013e3182432cf2 10.1097/jsa.0b013e3182432cf2 22311289
The disabled throwing shoulder: spectrum of pathology Part I: Pathoanatomy and biomechanics Arthroscopy: The Journal of Arthroscopic & Related Surgery Burkhart Stephen S. Morgan Craig D. Kibler W.Ben Elsevier BV 4 2003
19 4 404 420 0749-8063 10.1053/jars.2003.50128 10.1053/jars.2003.50128 12671624
Scapular dyskinesis and its relation to shoulder pain Journal of the American Academy of Orthopaedic Surgeons Kibler Ben W. McMullen John Ovid Technologies (Wolters Kluwer Health) 3 2003
11 2 142 151 1067-151X 10.5435/00124635-200303000-00008 10.5435/00124635-200303000-00008 12670140
The strength characteristics of internal and external rotator muscles in professional baseball pitchers The American Journal of Sports Medicine Wilk Kevin E. Andrews James R. Arrigo Christopher A. Keirns Michael A. Erber Donna J. SAGE Publications 1 1993
21 1 61 66 0363-5465 10.1177/036354659302100111 10.1177/036354659302100111
The advanced Throwers Ten Exercise Programme: A new exercise series for enhanced dynamic shoulder control in the overhead throwing athlete The Physician and Sportsmedicine Wilk Kevin E. Yenchak A. J. Arrigo Christopher A. Andrews James R. Informa UK Limited 11 2011
39 4 90 97 0091-3847 10.3810/psm.2011.11.1943 10.3810/psm.2011.11.1943
Pain, functional disability, psychological status, and health-related quality of life in patients with subacromial impingement syndrome Cogent Medicine Alizadehkhaiyat Omid Roebuck Margaret M. Makki Ahmed T. Frostick Simon P. Informa UK Limited 1 1 2017
4 1 1 14 2331-205X 10.1080/2331205x.2017.1406631 10.1080/2331205x.2017.1406631
The best combination of physical performance and self-report measures to capture function in three patient groups Physical Therapy Reviews Hegedus Eric J. Vidt Meghan E. Tarara Daniel T. Informa UK Limited 2014
19 3 196 203 1083-3196 10.1179/1743288x13y.0000000121 10.1179/1743288x13y.0000000121
Reliability of a simple shoulder endurance test Journal of Musculoskeletal Research Hughes Richard E. Johnson Marjorie E. Skow Anne An Kai-Nan O'Driscoll Shawn W. World Scientific Pub Co Pte Ltd 9 1999
3 3 195 200 0218-9577 10.1142/s0218957799000208 10.1142/s0218957799000208
Early development and reliability of the Timed Functional Arm and Shoulder Test Journal of Orthopaedic & Sports Physical Therapy Shah Kshamata M. Baker Timothy Dingle Abigail Hansmeier Thomas Jimenez Matthew Lopez Sarah Marks Dylan Safford Daniel Sternberg Amanda Turner Jeffrey McClure Philip W. Journal of Orthopaedic & Sports Physical Therapy (JOSPT) 6 2017
47 6 420 431 0190-6011 10.2519/jospt.2017.7136 10.2519/jospt.2017.7136 28257615
Hand strength and dexterity Am J Occup Ther Kellor M. Frost J. Silberberg N. Iversen I. Cummings R. 1971
25 77 83 5551515
Validation of a new test that assesses functional performance of the upper extremity and neck (FIT-HaNSA) in patients with shoulder pathology BMC Musculoskeletal Disorders MacDermid Joy C Ghobrial Myriam Quirion Karine Badra St-Amour Mélanie Tsui Tanya Humphreys Dave McCluskie John Shewayhat Eddy Galea Vickie Springer Science and Business Media LLC 17 5 2007
8 1 42 52 1471-2474 10.1186/1471-2474-8-42 10.1186/1471-2474-8-42 17509150
The FIT-HaNSA demonstrates reliability and convergent validity of functional performance in patients with shoulder disorders Journal of Orthopaedic & Sports Physical Therapy Kumta Prajyot MacDermid Joy C. Mehta Saurabh P. Stratford Paul W. Journal of Orthopaedic & Sports Physical Therapy (JOSPT) 5 2012
42 5 455 464 0190-6011 10.2519/jospt.2012.3796 10.2519/jospt.2012.3796 22281818
Shoulder muscle activation and coordination in patients with a massive rotator cuff tear: An electromyographic study Journal of Orthopaedic Research Hawkes David H. Alizadehkhaiyat Omid Kemp Graham J. Fisher Anthony C. Roebuck Margaret M. Frostick Simon P. Wiley 2012
30 7 1140 1146 0736-0266 10.1002/jor.22051 10.1002/jor.22051 22213234
Electromyographic evaluation of the shoulder muscle after a fatiguing isokinetic protocol in recreational overhead athletes International Journal of Environmental Research and Public Health Klich Sebastian Kawczyński Adam Pietraszewski Bogdan Zago Matteo Chen Aiguo Smoter Małgorzata Hassanlouei Hamidollah Lovecchio Nicola MDPI AG 3 3 2021
18 5 2516 1660-4601 10.3390/ijerph18052516 10.3390/ijerph18052516 33802582
The evaluation of shoulder muscle fatigue in volleyball players Journal of Novel Physiotherapies Oleksy Lukasz Czarny Wojciech Bajorek Wojciech Krol Paweł Mika Anna Kielnar Renata OMICS Publishing Group 2018
8 2 388 2165-7025 10.4172/2165-7025.1000388 10.4172/2165-7025.1000388
Shoulder external rotation fatigue and scapular muscle activation and kinematics in overhead athletes J Athl. Train Joshi M. Thigpen C.A. Bunn K. Karas S.G. Padua D.A. 2011
46 4 349 357 21944066
Comparison of shoulder range of motion, strength, and upper quarter dynamic balance between NCAA division I overhead athletes with and without a history of shoulder injury Physical Therapy in Sport Kim Youngwook Lee Jung-Min Wellsandt Elizabeth Rosen Adam B. Elsevier BV 3 2020
42 53 60 1466-853X 10.1016/j.ptsp.2019.12.007 10.1016/j.ptsp.2019.12.007 31887553
Incorporation of the kinetic chain Into shoulder elevation exercises: Does it affect scapular muscle activity? Journal of Athletic Training Borms Dorien Maenhout Annelies Cools Ann M Journal of Athletic Training/NATA 1 4 2020
55 4 343 349 1062-6050 10.4085/1062-6050-136-19 10.4085/1062-6050-136-19 32160060
Muscle recruitment during plyometric exercises in overhead athletes with and without shoulder pain Physical Therapy in Sport Werin Maria Maenhout Annelies Smet Stephanie Van Holder Laura Cools Ann Elsevier BV 5 2020
43 19 26 1466-853X 10.1016/j.ptsp.2020.01.015 10.1016/j.ptsp.2020.01.015 32058922
Electromyographic analysis of traditional and kinetic chain exercises for dynamic shoulder movements Journal of Strength and Conditioning Research Oliver Gretchen D. Plummer Hillary A. Gascon Sarah S. Ovid Technologies (Wolters Kluwer Health) 11 2016
30 11 3146 3154 1064-8011 10.1519/jsc.0000000000001389 10.1519/jsc.0000000000001389
Gluteus medius and scapula muscle activations in youth baseball pitchers Journal of Strength and Conditioning Research Oliver Gretchen D. Weimar Wendi H. Plummer Hillary A. Ovid Technologies (Wolters Kluwer Health) 6 2015
29 6 1494 1499 1064-8011 10.1519/jsc.0000000000000797 10.1519/jsc.0000000000000797 25546449
Surface Anatomy for Clinical Needle Electromyography Lee H.J. DeLisa J.A. Demos Medical (New York) 2000

Scapular muscle activity in a variety of plyometric exercises Journal of Electromyography and Kinesiology Maenhout Annelies Benzoor Maya Werin Maria Cools Ann Elsevier BV 4 2016
27 39 45 1050-6411 10.1016/j.jelekin.2016.01.003 10.1016/j.jelekin.2016.01.003 26894494
The effects of surface condition on abdominal muscle activity during single-legged hold exercise Journal of Electromyography and Kinesiology Ha Sungmin Oh Jaeseop Jeon Incheol Kwon Ohyun Elsevier BV 2 2015
25 1 28 33 1050-6411 10.1016/j.jelekin.2014.07.001 10.1016/j.jelekin.2014.07.001
Electromyographic analysis of shoulder muscles during press-up variations and progressions Journal of Electromyography and Kinesiology Herrington Lee Waterman Rosemary Smith Laura Elsevier BV 2 2015
25 1 100 106 1050-6411 10.1016/j.jelekin.2014.10.002 10.1016/j.jelekin.2014.10.002
The manual muscle examination for shoulder rotator cuff strength. An electromyographic investigation The American Journal of Sports Medicine Kelly Bryan T. Kadrmas Warren R. Speer Kevin P. SAGE Publications 9 1996
24 5 581 588 0363-5465 10.1177/036354659602400504 10.1177/036354659602400504 8883676
Electromyographic activity of the lower limb muscles during salat and specific exercises Journal of Physical Therapy Science Safee Mohd Khairuddin Mohd Abas Wan Abu Bakar Wan Ibrahim Fatimah Osman Noor Azuan Abu Salahuddin Mohd Helmi Rizal Society of Physical Therapy Science 2012
24 6 549 552 0915-5287 10.1589/jpts.24.549 10.1589/jpts.24.549
Discovering Statistics using SPSS Field A. Sage Publications Ltd 2009

Anatomy and actions of the trapezius muscle Clinical Biomechanics Johnson G. Bogduk N. Nowitzke A. House D. Elsevier BV 1 1994
9 1 44 50 0268-0033 10.1016/0268-0033(94)90057-4 10.1016/0268-0033(94)90057-4
Changes in the moment arms of the rotator cuff and deltoid muscles with abduction and rotation. The Journal of Bone & Joint Surgery Otis J C Jiang C C Wickiewicz T L Peterson M G Warren R F Santner T J Ovid Technologies (Wolters Kluwer Health) 5 1994
76 5 667 676 0021-9355 10.2106/00004623-199405000-00007 10.2106/00004623-199405000-00007 8175814
Control strategies to re-establish glenohumeral stability after shoulder injury Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology Rajaratnam Bala S Goh James C H Kumar Prem V Springer Science and Business Media LLC 12 2013
5 26 1 9 1758-2555 10.1186/2052-1847-5-26 10.1186/2052-1847-5-26 24314049
Scapular muscle recruitment patterns: trapezius muscle latency with and without impingement symptoms The American Journal of Sports Medicine Cools Ann M. Witvrouw Erik E. Declercq Geert A. Danneels Lieven A. Cambier Dirk C. SAGE Publications 7 2003
31 4 542 549 0363-5465 10.1177/03635465030310041101 10.1177/03635465030310041101 12860542
The role of the biceps brachii in shoulder elevation Journal of Electromyography and Kinesiology Landin Dennis Myers Joseph Thompson Melissa Castle Ray Porter Jared Elsevier BV 4 2008
18 2 270 275 1050-6411 10.1016/j.jelekin.2006.09.012 10.1016/j.jelekin.2006.09.012 17196396
Actions of the Biceps Brachii at the Shoulder: A Review Journal of Clinical Medicine Research Landin Dennis Thompson Melissa Jackson Meghan R. Elmer Press, Inc. 2017
9 8 667 670 1918-3003 10.14740/jocmr2901w 10.14740/jocmr2901w 28725314
Roles of deltoid and rotator cuff muscles in shoulder elevation Clinical Biomechanics Liu J Hughes R E Smutz W P Niebur G Nan-An K Elsevier BV 1 1997
12 1 32 38 0268-0033 10.1016/s0268-0033(96)00047-2 10.1016/s0268-0033(96)00047-2
Bulk effect of rotator cuff on inferior glenohumeral stability as function of scapular inclination angle: a cadaver study The Tohoku Journal of Experimental Medicine Itoi EIJI Motzkin NEIL E. Morrey BERNARD F. An KAI-NAN Tohoku University Medical Press 1993
171 4 267 276 0040-8727 10.1620/tjem.171.267 10.1620/tjem.171.267 8184401
Analysis of arm elevation muscle activity through different movement planes and speeds during in-water and dry-land exercise Journal of Shoulder and Elbow Surgery Castillo-Lozano Romualdo Cuesta-Vargas Antonio Gabel Charles Philip Elsevier BV 2 2014
23 2 159 165 1058-2746 10.1016/j.jse.2013.04.010 10.1016/j.jse.2013.04.010
