scholarly journals Electromyographic Activity of Scapular Muscle Control in Free-Motion Exercise

2016 ◽  
Vol 51 (3) ◽  
pp. 195-204 ◽  
Author(s):  
Yukiko Nakamura ◽  
Masaaki Tsuruike ◽  
Todd S. Ellenbecker

The appropriate resistance intensity to prescribe for shoulder rehabilitative exercise is not completely known. Excessive activation of the deltoid and upper trapezius muscles could be counterproductive for scapulohumeral rhythm during humeral elevation.Context: To identify the effects of different exercise intensities on the scapular muscles during a free-motion “robbery” exercise performed in different degrees of shoulder abduction in seated and standing positions.Objective: Descriptive laboratory study.Design: Kinesiology Adapted Physical Education Laboratory.Setting: A total of 15 healthy male college students (age = 20.5 ± 2.2 years, height = 174.5 ± 5.3 cm, mass = 63.8 ± 6.0 kg).Patients or Other Participants: Participants performed 5 repetitions of a randomized exercise sequence of the robbery exercise in 2 body positions (seated, standing), 2 shoulder-abducted positions (W [20°], 90/90 [90°]) at 3 intensities (0%, 3%, and 7% body weight).Intervention(s): Electromyographic (EMG) activity of the upper trapezius, lower trapezius, serratus anterior, anterior deltoid, and infraspinatus muscles of the upper extremity was collected. All EMG activities were normalized by the maximal voluntary isometric contraction of each corresponding muscle (%).Main Outcome Measure(s): The serratus anterior, anterior deltoid, and infraspinatus EMG activities were greater at 7% body weight in the seated position compared with the standing position (P < .05). The EMG activities in all 5 muscles were greater in the 90/90 position than in the W position (P < .05).Results: Scapular muscle activity modulated relative to changes in body posture and resistance intensity. These findings will enable clinicians to prescribe the appropriate level of exercise intensity and positioning during shoulder rehabilitation.Conclusions:

2014 ◽  
Vol 44 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Rafael Soncin ◽  
Juliana Pennone ◽  
Thiago M. Guimarães ◽  
Bruno Mezêncio ◽  
Alberto C. Amadio ◽  
...  

Abstract The purpose of this study was to investigate the effects of exercise order on electromyographic activity in different muscle groups among youth men with experience in strength training. Three sets of 8 RM were performed of each exercise in two sequences order: (a) sequence A: bench press, chest fly, shoulder press, shoulder abduction, close grip bench press and lying triceps extension; (b) sequence B: the opposite order. The electromyographic activity was analyzed in the sternocostal head of the pectoralis major, anterior deltoid, and long head triceps brachii, normalized for maximal voluntary isometric contraction. The muscles activity of the sternocostal head of the pectoralis major, anterior deltoid, and long head triceps brachii showed significant interaction between sequence and exercise. The sternocostal head of the pectoralis major showed considerably higher activity in sequence A (100.13 ± 13.56%) than sequence B (81.47 ± 13.09%) for the chest fly. The anterior deltoid showed significantly higher electromyographic activity in sequence B (86.81 ± 40.43%) than sequence A (66.15 ± 22.02%) for the chest fly, whereas for the lying triceps extension, the electromyographic activity was significantly higher in sequence A (53.89 ± 27.09%) than sequence B (34.32 ± 23.70%). For the long head triceps brachii, only the shoulder press showed differences between sequences (A = 52.43 ± 14.64 vs. B = 38.53 ± 16.26). The present study showed that the exercise order could modify the training results even though there was no alteration in volume and intensity of the exercise. These changes may result in different training adaptations.


2019 ◽  
Vol 54 (11) ◽  
pp. 1156-1164 ◽  
Author(s):  
Fu-Jie Kang ◽  
Hsiang-Ling Ou ◽  
Kun-Ying Lin ◽  
Jiu-Jenq Lin

Context Whereas the serratus anterior (SA) and the upper trapezius (UT) work as a force couple for scapular motion, weakness of the SA and overactivation of the UT are often present in overhead athletes with shoulder dysfunction. Therefore, researchers addressing an intramuscular imbalance between the SA and UT have focused on finding exercises that target the weak SA and minimally activate the UT. Objective To compare the effectiveness of push-up plus (PUP) exercise variants based on the electromyographic (EMG) activity of the SA and UT. Data Sources A systematic search of PubMed and Scopus between January 1, 2000, and March 31, 2008. Study Selection Studies of PUP exercises that involved EMG analysis. Data Extraction We assessed study quality using the Critical Appraisal Skills Program. For the systematic analysis, the following data were extracted: (1) author, year, and study design; (2) participant characteristics; (3) type of PUP intervention; (4) EMG outcome measures; and (5) main results. For the meta-analysis, the EMG data of the SA and UT were calculated using the mean difference of EMG activity with a 95% confidence interval. Data Synthesis Based on 19 studies with 356 participants, different hand positions (the distance between the hands, shoulder-flexion angle, and elbow-flexion angle) and different lower extremity positions variably affected the activation of the SA and UT during the PUP exercise. Also, when participants performed the PUP on an unstable surface compared with a stable surface, UT activity increased 2.74% (95% confidence interval = 0.07%, 5.41%). Conclusions The standard PUP exercise elicited high EMG activity of the SA. Participants generated higher SA and lower UT EMG activity when they performed the PUP exercise on a stable surface in full elbow extension, with the hands placed shoulder-width apart, shoulder-flexion angles of 110° or 120°, and the ipsilateral lower extremity lifted.


2000 ◽  
Vol 80 (3) ◽  
pp. 276-291 ◽  
Author(s):  
Paula M Ludewig ◽  
Thomas M Cook

AbstractBackground and Purpose. Treatment of patients with impingement symptoms commonly includes exercises intended to restore “normal” movement patterns. Evidence that indicates the existence of abnormal patterns in people with shoulder pain is limited. The purpose of this investigation was to analyze glenohumeral and scapulothoracic kinematics and associated scapulothoracic muscle activity in a group of subjects with symptoms of shoulder impingement relative to a group of subjects without symptoms of shoulder impingement matched for occupational exposure to overhead work. Subjects. Fifty-two subjects were recruited from a population of construction workers with routine exposure to overhead work. Methods. Surface electromyographic data were collected from the upper and lower parts of the trapezius muscle and from the serratus anterior muscle. Electromagnetic sensors simultaneously tracked 3-dimensional motion of the trunk, scapula, and humerus during humeral elevation in the scapular plane in 3 hand-held load conditions: (1) no load, (2) 2.3-kg load, and (3) 4.6-kg load. An analysis of variance model was used to test for group and load effects for 3 phases of motion (31°–60°, 61°–90°, and 91°–120°). Results. Relative to the group without impingement, the group with impingement showed decreased scapular upward rotation at the end of the first of the 3 phases of interest, increased anterior tipping at the end of the third phase of interest, and increased scapular medial rotation under the load conditions. At the same time, upper and lower trapezius muscle electromyographic activity increased in the group with impingement as compared with the group without impingement in the final 2 phases, although the upper trapezius muscle changes were apparent only during the 4.6-kg load condition. The serratus anterior muscle demonstrated decreased activity in the group with impingement across all loads and phases. Conclusion and Discussion. Scapular tipping (rotation about a medial to lateral axis) and serratus anterior muscle function are important to consider in the rehabilitation of patients with symptoms of shoulder impingement related to occupational exposure to overhead work.


2018 ◽  
Vol 53 (12) ◽  
pp. 1181-1189 ◽  
Author(s):  
Ramonica Scott ◽  
Hyung Suk Yang ◽  
C. Roger James ◽  
Steven F. Sawyer ◽  
Phillip S. Sizer

Context The abdominal-bracing maneuver, a volitional preemptive abdominal contraction (VPAC) strategy, is commonly used during resisted shoulder exercises. How VPAC affects shoulder-muscle function during resisted shoulder exercise is unknown. Objective To identify the effects of VPAC on selected parascapular and glenohumeral muscles during specific shoulder exercises with or without resistance. Design Cross-sectional study. Setting Clinical biomechanics research laboratory. Patients or Other Participants Twenty-two asymptomatic volunteers between 18 and 40 years of age. Intervention(s) Participants performed arm elevation in scaption and D1 shoulder-flexion (D1F) patterns with and without resistance and VPAC. Main Outcome Measure(s) Electromyography was used to test the muscle-contraction amplitudes and onset timing of the anterior deltoid, posterior deltoid, upper trapezius, lower trapezius, and serratus anterior. Muscle-response amplitudes were quantified using root mean square electromyography. Shoulder-muscle relative-onset timing was quantified in reference to kinematic elbow-movement initiation. Results The VPAC increased serratus anterior amplitude during D1F (P < .001) and scaption (P < .001) and upper trapezius amplitude (P < .001) in scaption. All muscle amplitudes increased with resistance. The VPAC decreased muscle-onset latencies for the anterior deltoid (P < .001), posterior deltoid (P = .008), upper trapezius (P = .001), lower trapezius (P = .006), and serratus anterior (P = .001) during D1F. In addition, the VPAC decreased muscle-onset latencies for the anterior deltoid (P < .001), posterior deltoid (P = .007), upper trapezius (P < .001), lower trapezius (P < .001), and serratus anterior (P < .001) during scaption. Conclusions The VPAC affected only the parascapular muscles that had the greatest scapular-stabilizing roles during the specific open chain movement we tested. It decreased latencies in all muscles. These neuromuscular changes may enhance the stability of the shoulder during D1F and scaption exercises.


Author(s):  
Andréia C. O. Silva, PT, MSc ◽  
Claudia S. Oliveira, PT, PhD ◽  
Daniela A. Biasotto-Gonzalez, PT, PhD ◽  
Marco A. Fumagalli, Eng, PhD ◽  
Fabiano Politti, PT, PhD

Background and Purpose: The lack of clear knowledge about the etiology of nonspecific neck pain (NS-NP) strengthens the need for other mech-anisms, still poorly described in the literature, to be investigated. Therefore, a quantitative analysis of two cases of NS-NP in subjects with functiona dyspepsia was conducted in order to verify the immediate and seven-day postintervention effects of visceral manipulation (VM) to the stomach and liver on neck pain, cervical range of motion (ROM), and electromyographic (EMG) activity of the upper trapezius muscle. Case Description: Case A was an 18-year-old female with a complaint of nonspecific neck pain for one year, with reported pain on waking, momentary intermittent pain, and occasional symptoms of paresthesia in the upper limbs. Case B was a 25-year-old female with a complaint of cervical pain for one year, accompanied by pain in the unilateral temporomandibular joint, and medial thoracic region. Both cases presented functional dyspepsia.Outcomes: The results demonstrated (sub-jects A and B, respectively) a general increase in cervical ROM (range: 12.5% to 44.44%) and amplitude of the EMG signal (immediately postintervention: 57.62 and 20.78; post seven days: 53.54% and 18.83%), and an increase in muscle fiber conduction velocity immediately postintervention (4.44% and 7.44%) and a de-crease seven days postintervention (25.25% and 21.18%). For pain, a decrease was observed immediately postintervention (23.07% and 76.92%) and seven days postintervention (100% for both subjects). Discussion: A single VM provided important clinical improvement in neck pain, cervical spine range of motion, and EMG activity of the upper trapezius muscle, immediately and seven days postintervention in two NS-NP subjects with func-tional dyspepsia.


2017 ◽  
Vol 26 (4) ◽  
pp. 281-286 ◽  
Author(s):  
Rafaela J.B. Torres ◽  
André L.T. Pirauá ◽  
Vinícius Y.S. Nascimento ◽  
Priscila S. dos Santos ◽  
Natália B. Beltrão ◽  
...  

The aim of this study was to evaluate the acute effect of the use of stable and unstable surfaces on electromyography (EMG) activity and coactivation of the scapular and upper-limb muscles during the push-up plus (with full protraction of the scapula). Muscle activation of anterior deltoid (AD), posterior deltoid (PD), pectoralis major, biceps brachii (BB), triceps brachii (TB), upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) levels and coactivation index were determined by surface EMG in 20 young men during push-up plus performed on a stable and unstable condition (2 unstable devices applied to hands and feet). The paired t test and Cohen d were used for statistical analysis. The results showed that during the execution of the push-up plus on the unstable surface an increased EMG activity of the scapular stabilizing muscles (SA, MT, and LT) was observed, while AD and PD muscles showed a decrease. During exercise execution on the unstable surface there was a higher index of coactivation of the scapular muscles (SA–MT and UT–LT pairs). No significant differences were observed in TB–BB and AD–PD pairs. These results suggest that the push-up-plus exercise associated with unstable surfaces produced greater EMG activity levels and coactivation index of the scapular stabilizing muscle. On the other hand, the use of an unstable surface does not promote the same effect for the shoulder muscles.


2017 ◽  
Vol 26 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Ui-jae Hwang ◽  
Oh-yun Kwon ◽  
In-cheol Jeon ◽  
Si-hyun Kim ◽  
Jong-hyuck Weon

Context:The push-up-plus (PP) exercise has been recommended for strengthening of the serratus anterior (SA). Previous studies have investigated the effect of different stability properties of the base of support to adjust the difficulty level of SA muscle-strengthening exercises in the PP position. However, the optimal humeral-elevation angle (HEA) for selective activation and maximum contraction of the SA during PP has not been investigated.Objectives:To assess the effects of HEA during PP on electromyographic (EMG) activity in the SA, upper trapezius (UT), and pectoralis major (PM) and on the UT:SA and PM:SA activity ratios.Design:Comparative, repeated-measures design.Setting:University research laboratory.Participants:29 healthy men.Main Outcome Measures:The subjects performed PP at 3 different HEAs (60°, 90°, and 120°); EMG activity in the SA, UT, and PM was measured, and the UT:SA and PM:SA activity ratios were calculated. Differences in muscle activity and ratios between the 60°, 90°, and 120° HEAs were assessed using 1-way repeated-measures analysis of variance; the Bonferroni correction was applied.Results:SA muscle activity was significantly increased, in order of magnitude, at the 120°, 90°, and 60° HEAs. UT:SA and PM:SA activity ratios were significantly greater during performance of the PP at an HEA of 60° than at HEAs of 120° and 90°.Conclusion:The results suggest that an HEA of 120° should be used during performance of the PP because it produces greater SA activation than HEAs of 60° and 90°.


2007 ◽  
Vol 35 (10) ◽  
pp. 1744-1751 ◽  
Author(s):  
Ann M. Cools ◽  
Vincent Dewitte ◽  
Frederick Lanszweert ◽  
Dries Notebaert ◽  
Arne Roets ◽  
...  

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.


2019 ◽  
Vol 28 (3) ◽  
pp. 272-277 ◽  
Author(s):  
Jun-Seok Kim ◽  
Moon-Hwan Kim ◽  
Duk-Hyun Ahn ◽  
Jae-Seop Oh

Context:A winged scapula (WS) is associated with faulty posture caused by weakness of the serratus anterior (SA), which mainly acts as a scapular stabilizer muscle. It is important to accurately assess and train the SA muscle with a focus on scapula stabilizers during musculoskeletal rehabilitation of individuals with a WS.Objective:The authors examined muscle activity in the SA and pectoralis major (PM), upper trapezius (UT), and anterior deltoid (AD) as well as shoulder protraction strength during isometric shoulder protraction in individuals with and without a WS.Design:Cross-sectional study.Setting:A clinical biomechanics laboratory.Participants:In total, 27 males with no shoulder, neck, or upper-extremity pain participated.Main Outcome Measures:Isometric shoulder protraction strength was collected and surface electromyography used to measure the activity of the SA, PM, UT, and AD muscles and selective SA activity ratio to other shoulder muscles.Results:Electromyography activity of the SA muscle and shoulder protraction strength were significantly lower in individuals with a WS compared with the non-WS group (P < .05). In contrast, PM muscle activity and the PM-to-SA, UT-to-SA, and AD-to-SA ratios were significantly greater in individuals with a WS than in individuals without winging (P < .05).Conclusions:Isometric shoulder protraction for measuring SA strength in individuals with a WS should focus on isolated muscle activity of the SA, and SA strengthening exercises are important for individuals with a WS.


Author(s):  
David Rodríguez-Ridao ◽  
José A. Antequera-Vique ◽  
Isabel Martín-Fuentes ◽  
José M. Muyor

The bench press exercise is one of the most used for training and for evaluating upper-body strength. The aim of the current study was to evaluate the electromyographic (EMG) activity levels of the pectoralis major (PM) in its three portions (upper portion, PMUP, middle portion, PMMP, and lower portion, PMLP), the anterior deltoid (AD), and the triceps brachii (TB) medial head during the bench press exercise at five bench angles (0°, 15°, 30°, 45°, and 60°). Thirty trained adults participated in the study. The EMG activity of the muscles was recorded at the aforementioned inclinations at 60% of one-repetition maximum (1RM). The results showed that the maximal EMG activity for PMUP occurred at a bench inclination of 30°. PMMP and PMLP showed higher EMG activity at a 0° bench inclination. AD had the highest EMG activity at 60°. TB showed similar EMG activities at all bench inclinations. In conclusion, the horizontal bench press produces similar electromyographic activities for the pectoralis major and the anterior deltoid. An inclination of 30° produces greater activation of the upper portion of the pectoralis major. Inclinations greater than 45° produce significantly higher activation of the anterior deltoid and decrease the muscular performance of the pectoralis major.


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