scholarly journals Shoulder External Rotation Fatigue and Scapular Muscle Activation and Kinematics in Overhead Athletes

2011 ◽  
Vol 46 (4) ◽  
pp. 349-357 ◽  
Author(s):  
Mithun Joshi ◽  
Charles A. Thigpen ◽  
Kevin Bunn ◽  
Spero G. Karas ◽  
Darin A. Padua
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activation ◽  
External Rotation ◽  
Shoulder Injuries ◽  
Serratus Anterior ◽  
Overhead Athletes ◽  
Scapular Kinematics ◽  
Fatigue Protocol ◽  
Upper Trapezius ◽  
Lower Trapezius

Context: Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. Objective: To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. Setting: Human performance research laboratory. Design: Descriptive laboratory study. Patients or Other Participants: Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. Intervention(s): We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. Main Outcome Measure(s): Surface electromyography was used to measure muscle activity for the upper trapezius, lower trapezius, serratus anterior, and infraspinatus. An electromyographic motion analysis system was used to assess 3-dimensional scapular kinematics. Repeated-measures analyses of variance (phase × condition) were used to test for differences. Results: We found a decrease in ascending-phase and descending-phase lower trapezius activity (F1,25 = 5.098, P = .03) and an increase in descending-phase infraspinatus activity (F1,25 = 5.534, P = .03) after the fatigue protocol. We also found an increase in scapular upward rotation (F1,24 = 3.7, P = .04) postfatigue. Conclusions: The GH ER muscle fatigue protocol used in this study caused decreased lower trapezius and increased infraspinatus activation concurrent with increased scapular upward rotation range of motion during the functional task. This highlights the interdependence of scapular and glenohumeral force couples. Fatigue-induced alterations in the lower trapezius might predispose the infraspinatus to injury through chronically increased activation.

scholarly journals Scapular Bracing and Alteration of Posture and Muscle Activity in Overhead Athletes With Poor Posture

2013 ◽  
Vol 48 (1) ◽  
pp. 12-24 ◽  
Author(s):  
Ashley K. Cole ◽  
Melanie L. McGrath ◽  
Shana E. Harrington ◽  
Darin A. Padua ◽  
Terri J. Rucinski ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Surface Emg ◽  
Lateral View ◽  
Controlled Clinical Trial ◽  
Serratus Anterior ◽  
Overhead Athletes ◽  
Forward Flexion ◽  
Upper Trapezius ◽  
Lower Trapezius

Context: Overhead athletes commonly have poor posture. Commercial braces are used to improve posture and function, but few researchers have examined the effects of shoulder or scapular bracing on posture and scapular muscle activity. Objective: To examine whether a scapular stabilization brace acutely alters posture and scapular muscle activity in healthy overhead athletes with forward-head, rounded-shoulder posture (FHRSP). Design: Randomized controlled clinical trial. Setting: Applied biomechanics laboratory. Patients or Other Participants: Thirty-eight healthy overhead athletes with FHRSP. Intervention(s): Participants were assigned randomly to 2 groups: compression shirt with no strap tension (S) and compression shirt with the straps fully tensioned (S + T). Posture was measured using lateral-view photography with retroreflective markers. Electromyography (EMG) of the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) in the dominant upper extremity was measured during 4 exercises (scapular punches, W's, Y's, T's) and 2 glenohumeral motions (forward flexion, shoulder extension). Posture and exercise EMG measurements were taken with and without the brace applied. Main Outcome Measure(s): Head and shoulder angles were measured from lateral-view digital photographs. Normalized surface EMG was used to assess mean muscle activation of the UT, MT, LT, and SA. Results: Application of the brace decreased forward shoulder angle in the S + T condition. Brace application also caused a small increase in LT EMG during forward flexion and Y's and a small decrease in UT and MT EMG during shoulder extension. Brace application in the S + T group decreased UT EMG during W's, whereas UT EMG increased during W's in the S group. Conclusions: Application of the scapular brace improved shoulder posture and scapular muscle activity, but EMG changes were highly variable. Use of a scapular brace might improve shoulder posture and muscle activity in overhead athletes with poor posture.

scholarly journals Single-Session Video and Electromyography Feedback in Overhead Athletes With Scapular Dyskinesis and Impingement Syndrome

2020 ◽  
Vol 55 (3) ◽  
pp. 265-273
Author(s):  
Wan-Yu Du ◽  
Tsun-Shun Huang ◽  
Yuan-Chun Chiu ◽  
Szu-Jieh Mao ◽  
Li-Wei Hung ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Training Group ◽  
Video Feedback ◽  
Emg Biofeedback ◽  
Scapular Dyskinesis ◽  
Serratus Anterior ◽  
Overhead Athletes ◽  
Feedback Training ◽  
Scapular Kinematics ◽  
Lower Trapezius

Context Subacromial impingement syndrome (SIS) is associated with scapular dyskinesis, or imbalanced scapular muscle activity. Evidence has shown that feedback can improve scapular control in patients with SIS. However, it is unknown whether real-time video feedback or electromyography (EMG) biofeedback is optimal for improving scapular kinematics and muscle activity during a functional task. Objective To compare the effects of video and EMG feedback sessions on absolute muscle activity (upper trapezius [UT], lower trapezius [LT], serratus anterior), muscle balance ratios (UT/LT, UT/serratus anterior), and scapular kinematics (anterior-posterior tilt, external-internal rotation, upward rotation) in SIS participants during arm elevation and lowering. Design Randomized controlled clinical trial. Setting Research laboratory. Patients or Other Participants Overhead athletes who were diagnosed with SIS and who also exhibited scapular dyskinesis (N = 41). Main Outcome Measure(s) Three-dimensional kinematics and EMG were recorded before and after feedback training. Results Lower trapezius muscle activity increased (4.2%–18%, P < .011) and UT/LT decreased (0.56–1.17, P < .013) in the EMG biofeedback training group as compared with those in the video feedback training group. Scapular upward rotation during arm elevation was higher in the video group than in the EMG group after feedback training (2.3°, P = .024). Conclusions The EMG biofeedback improved muscle control and video feedback improved the correction of scapular upward rotation in patients with SIS. Trial Registration Number ClinicalTrials.gov: NCT03252444.

Effects of Kinesiology Taping on Scapular Reposition Accuracy, Kinematics, and Muscle Activity in Athletes With Shoulder Impingement Syndrome: A Randomized Controlled Study

2018 ◽  
Vol 27 (6) ◽  
pp. 560-569 ◽  
Author(s):  
Yi-Fen Shih ◽  
Ya-Fang Lee ◽  
Wen-Yin Chen
Keyword(s):  
Muscle Activation ◽  
Position Sense ◽  
Joint Position Sense ◽  
Controlled Study ◽  
Shoulder Impingement ◽  
Scapular Kinematics ◽  
Randomized Controlled ◽  
Upper Trapezius ◽  
Posterior Tilt ◽  
Lower Trapezius

Context:Scapular proprioception is a key concern in managing shoulder impingement syndrome (SIS). However, no study has examined the effect of elastic taping on scapular proprioception performance.Objective:To investigate the immediate effect of kinesiology taping (KT) on scapular reposition accuracy, kinematics, and muscle activation in individuals with SIS.Design:Randomized controlled study.Setting:Musculoskeletal laboratory, National Yang-Ming University, Taiwan.Participants:Thirty overhead athletes with SIS.Interventions:KT or placebo taping over the upper and lower trapezius muscles.Main Outcome Measures:The primary outcome measures were scapular joint position sense, measured as the reposition errors, in the direction of scapular elevation and protraction. The secondary outcomes were scapular kinematics and muscle activity of the upper trapezius, lower trapezius, and serratus anterior during arm elevation in the scapular plane (scaption).Results:Compared with placebo taping, KT significantly decreased the reposition errors of upward/downward rotation (P = .04) and anterior/posterior tilt (P = .04) during scapular protraction. KT also improved scapular kinematics (significant group by taping effect for posterior tilt,P = .03) during scaption. Kinesiology and placebo tapings had a similar effect on upper trapezius muscle activation (significant taping effect,P = .003) during scaption.Conclusions:Our study identified the positive effects of KT on scapular joint position sense and movement control. Future studies with a longer period of follow-up and clinical measurement might help to clarify the clinical effect and mechanisms of elastic taping in individuals with SIS.

STRENGTHENING AND STABILIZATION EXERCISES IN PREVENTION OF SHOULDER INJURIES

sportlogia ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 149-160
Author(s):  
Bernarda Letnar ◽  
Keyword(s):  
Training Program ◽  
Internal Rotation ◽  
Shoulder Joint ◽  
External Rotation ◽  
Shoulder Injuries ◽  
Serratus Anterior ◽  
Warm Up ◽  
Overhead Athletes ◽  
Daily Training ◽  
Stretching Exercises

The shoulder joint is the most flexible joint in the human body which experiences high loads during certain sport activities involving overhead motion. Overhead athletes experience rapid shoulder elevation, abduction and external rotation during the movement and rapid deceleration after the movement, making them susceptible to shoulder injuries. Due to the extreme ranges of motion, overhead athletes tend to develop increased external rotation, combined with decreased range of internal rotation, emphasizing the need for balanced shoulder care program in the training process to prevent such occurrences. The aim of the research paper was to develop training regimen for injury prevention and shoulder maintenance that can be incorporated in daily training activities of the athletes in order to decrease the occurrence of injuries. Three part training program was designed consisting of specific warm up, strengthening and stabilization exercises and stretching exercises. The aim of the specific warm up was to prepare the shoulder for the training loads, mimicking the overhead movements and stimulating the stabilization in the joint. Strengthening and stabilization exercises aimed to strengthen external rotators in the shoulder and improve the stabilization of the shoulder joint by targeting specific muscles such as serratus anterior. The focus of stretching exercises was to stretch internal rotation muscles, which experience high loads in the overhead athlete's training. An effective training program that can be performed with minimal equipment and in a short time frame was designed to enable its simple incorporation into the daily training of overhead athletes.

Rehabilitation of Scapular Muscle Balance

2007 ◽  
Vol 35 (10) ◽  
pp. 1744-1751 ◽  
Author(s):  
Ann M. Cools ◽  
Vincent Dewitte ◽  
Frederick Lanszweert ◽  
Dries Notebaert ◽  
Arne Roets ◽  
...  
Keyword(s):  
External Rotation ◽  
Trapezius Muscle ◽  
Electromyographic Activity ◽  
Shoulder Injury ◽  
Serratus Anterior ◽  
Upper Trapezius ◽  
Strengthening Exercises ◽  
Muscle Balance ◽  
Lower Trapezius ◽  
Balance Rehabilitation

Background Strengthening exercises for the scapular muscles are used in the treatment of scapulothoracic dysfunction related to shoulder injury. In view of the intermuscular and intramuscular imbalances often established in these patients, exercises promoting lower trapezius (LT), middle trapezius (MT), and serratus anterior (SA) activation with minimal activity in the upper trapezius (UT) are recommended. Hypothesis Of 12 commonly used trapezius strengthening exercises, a selection can be performed for muscle balance rehabilitation, based on a low UT/LT, UT/MT, or UT/SA muscle ratio. Study Design Controlled laboratory study. Methods Electromyographic activity of the 3 trapezius parts and the SA was measured in 45 healthy subjects performing 12 commonly described scapular exercises, using surface electromyography. Results For each intramuscular trapezius ratio (UT/LT, UT/MT), 3 exercises were selected for restoration of muscle balance. The exercises side-lying external rotation, side-lying forward flexion, prone horizontal abduction with external rotation, and prone extension were found to be the most appropriate for intramuscular trapezius muscle balance rehabilitation. For the UT/SA ratio, none of the exercises met the criteria for optimal intermuscular balance restoration. Conclusion In cases of trapezius muscle imbalance, some exercises are preferable over others because of their low UT/LT and UT/MT ratios. Clinical Relevance In the selection of rehabilitation exercises, the clinician should have a preference for exercises with high activation of the LT and MT and low activity of the UT.

Shoulder Muscle Activation Levels During Exercises With Axial and Rotational Load on Stable and Unstable Surfaces

2017 ◽  
Vol 33 (2) ◽  
pp. 118-123 ◽  
Author(s):  
Vinícius Yan Santos Nascimento ◽  
Rafaela Joyce Barbosa Torres ◽  
Natália Barros Beltrão ◽  
Priscila Soares dos Santos ◽  
André Luiz Torres Pirauá ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Bench Press ◽  
Biceps Brachii ◽  
Emg Activity ◽  
Triceps Brachii ◽  
Serratus Anterior ◽  
Upper Trapezius ◽  
Unstable Surface ◽  
Lower Trapezius ◽  
Rotational Load

This study evaluated the effects of instability on the EMG activity of scapular stabilizing and upper limb muscles during exercises with axial and rotational load. Twenty male volunteers (20.9 ± 1.8 years, 174.1 ± 0.04 cm, 73.17 ± 8.77 kg) experienced in strength training participated in a crossover design. Muscle activation of anterior deltoid (AD), posterior deltoid (PD), pectoralis major (PM), biceps brachii (BB), triceps brachii (TB), upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) were determined on both conditions. Participants performed a single series of 10 repetitions of bench press and fly exercises on stable (bench) and unstable (proprioceptive disc) conditions at 60% of 1-RM. The Friedman test and post hoc Dunn’s indicated that the unstable condition showed greater EMG activity for AD (P = .001) and BB (P = .002) on the fly exercise, SA (P = .001) and LT (P = .048) on the bench press, and PM (P ≤ .002) on both exercises. These results show that using an unstable surface in exercises with rotational load provides superior EMG activity of the agonist muscles, while in exercise with axial load, the instability favors EMG activity of the scapular stabilizing muscles.

Effects of Push-Up Exercise Phase and Surface Stability on Activation of the Scapulothoracic Musculature

2013 ◽  
Vol 18 (4) ◽  
pp. 34-38 ◽  
Author(s):  
Se-yeon Park ◽  
Won-gyu Yoo
Keyword(s):  
Muscle Activation ◽  
Support Surface ◽  
Triceps Brachii ◽  
Serratus Anterior ◽  
Surface Stability ◽  
Upper Trapezius ◽  
Unstable Support ◽  
Support Surfaces ◽  
Lower Trapezius ◽  
Push Up

Objective:The purpose of this study was to measure muscle activation during ascending and descending phases of the push-up exercise on both stable and unstable support surfaces.Participants:Fourteen asymptomatic male amateur badminton players. During push-up exercises on stable and unstable bases, muscle activation measurements were collected with phase divisions (ascending and descending phase).Methods:Electromyography (EMG) was utilized to measure activation of the upper trapezius (UT) and lower trapezius (LT), middle serratus anterior (MSA) and lower serratus anterior (LSA), pectoralis major (PM), and triceps brachii (TB) muscles.Results:An unstable support surface produced significantly greater activation of the UT, LT, LSA, and PM muscles than a stable support surface (p < 0.05). The MSA, LSA, TB, and PM muscles demonstrated greater activation during the ascending phase than the descending phase of the push-up exercise (p < 0.05).Conclusions:The unstable support surface appeared to produce relatively greater activation of the LSA than that of the MSA. The descending phase of the push-up did not demonstrate a higher level of activation for any of the muscles tested.

Serratus Anterior Fatigue Reduces Scapular Posterior Tilt and External Rotation During Arm Elevation

2021 ◽  
pp. 1-7
Author(s):  
Nathan Harrison ◽  
W. Zach Garrett ◽  
Mark K. Timmons
Keyword(s):  
Internal Rotation ◽  
Repeated Measures ◽  
External Rotation ◽  
Elevation Angle ◽  
Serratus Anterior ◽  
Scapular Kinematics ◽  
Fatigue Protocol ◽  
Posterior Tilt ◽  
Arm Elevation ◽  
Arm Motion

Context: Fatigue of the scapular stabilizing muscles resulting from repeated arm motion has been reported to alter scapular kinematics, which could result in shoulder pathology, especially impingement. Objective: This study aimed to examine the effects of fatigue of the serratus anterior muscle on scapular kinematics, specifically, decrease scapular posterior tilt and upward scapular rotation during arm elevation. Design: Repeated measures. Setting: Laboratory. Participants: Thirty participants were included in the investigation. Interventions: Scapular kinematics and shoulder strength were measured before and immediately following a serratus anterior fatigue protocol. Main Outcome: Scapular 3-dimensional position during arm elevation. Results: No difference in upward rotation of the scapula between prefatigue and postfatigue conditions (ascending: P = .188; descending: P = .798). Scapular posterior tilt decreased during arm elevation following the fatigue protocol between 60° and 90° and 90° and 120° of arm elevation during the ascent (P = .004) and the descent (P = .013). Fatigue by arm elevation angle interaction was found for clavicular elevation during the ascent (P = .050) between 90° and 120° of arm elevation. Scapular internal rotation increased during the ascent (P = .027). There was no difference in clavicular protraction between the prefatigue and postfatigue conditions (ascending: P ≤ .001; descending: P ≤ .001). Conclusion: Fatigue of the serratus anterior decreases posterior scapular tilt and greater clavicular elevation and scapular internal rotation at higher arm elevation angles. These findings are consistent with the scapular kinematic patterns associated with shoulder pain. Improving serratus anterior endurance might delay the changes in scapular kinematics associated with repeated arm motion and shoulder injury mechanisms.

Scapulothoracic Muscle Activation on Stable and Unstable Support Surfaces

2013 ◽  
Vol 18 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Se-yeon Park ◽  
Won-gyu Yoo ◽  
Hun Kwon ◽  
Dong-hyun Kim ◽  
Si-eun Lee ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Center Of Pressure ◽  
Support Surface ◽  
Triceps Brachii ◽  
Serratus Anterior ◽  
Upper Trapezius ◽  
Unstable Support ◽  
Support Surfaces ◽  
Lower Trapezius ◽  
Push Up

Activation of the upper trapezius, lower trapezius, serratus anterior, and triceps brachii muscles was measured, while center of pressure excursion beneath the hands was simultaneously monitored, during the performance of a push-up exercise on both a stable and an unstable base of support. The activation levels of all muscles were significantly greater for the unstable support surface when compared to those for a stable support surface (p < 0.05). A negative correlation was found between activation of the serriatus anterior muscle and center of pressure excursion (r = -0.64, p < 0.05). Performance of the push-up exercise on an unstable support surface appears to elicit greater muscle activation than a standard push-up exercise performed on a stable support surface.

Shoulder-Muscle Activation in Individuals With Previous Shoulder Injuries

2015 ◽  
Vol 24 (3) ◽  
pp. 278-285 ◽  
Author(s):  
Alyssa Muething ◽  
Shellie Acocello ◽  
Kimberly A. Pritchard ◽  
Stephen F. Brockmeier ◽  
Susan A. Saliba ◽  
...  
Keyword(s):  
Shoulder Pain ◽  
Outcome Measures ◽  
Muscle Activation ◽  
Treatment Plan ◽  
Isometric Contractions ◽  
Shoulder Injuries ◽  
Upper Trapezius ◽  
History Of ◽  
Anterior Deltoid ◽  
Lower Trapezius

Context:Understanding how muscles activate in a population with a previous glenohumeral-joint (GH) injury may help clinicians understand how to build a conservative treatment plan to strengthen or activate the specific muscles in an attempt to reduce recurrent shoulder injury and development of GH laxity.Objective:To investigate muscle-activation differences between the previously injured limb of individuals with a history of GH-joint injury and healthy matched controls during functional isometric contractions.Design:Case control.Setting:University research laboratory.Participants:17 individuals (8 women, 9 men; age 22.3 ± 2.6 y, height 172.4 ± 8.8 cm, mass 75.4 ± 16.5 kg) with previous unilateral shoulder pain and 17 (8 women, 9 men; age 22.9 ± 3.9 y, height 170.9 ± 11.3 cm, mass 73.6 ± 22.9 kg) with no history of shoulder pain or injury.Intervention(s):Diagnostic ultrasound measurements of the supraspinatus were completed in both resting and contracted states to assess changes in muscle thickness. Manual muscle tests (anterior deltoid, upper trapezius, infraspinatus, lower trapezius, serratus anterior) and functional isometric contractions (forward flexion, scaption, abduction) were measured using electromyography.Main Outcome Measures:Peak, normalized activation of each muscle and supraspinatus thickness activation ratio were compared between groups and bilaterally within groups using separate ANOVAs.Results:The anterior deltoid was significantly less activated during all functional isometric tasks in previously injured subjects than in healthy subjects (P = .024). In previously injured subjects, the involved limb-lower trapezius was significantly less activated during scaption and abduction tasks than the contralateral side (P = .022 and P = .031, respectively).Conclusions:There were decreases in muscle activation in the anterior deltoid between previously injured and healthy people, as well as in the lower trapezius, in previously injured subjects. Understanding the source of muscle-activation deficits can help clinicians focus rehabilitation exercises on specific muscles.

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