Rotator-Cuff Muscle-Recruitment Strategies During Shoulder Rehabilitation Exercises

2011 ◽  
Vol 20 (4) ◽  
pp. 471-486 ◽  
Author(s):  
Kathleen A. Swanik ◽  
Kellie Huxel Bliven ◽  
Charles Buz Swanik
Keyword(s):  
Rotator Cuff ◽  
Muscle Activation ◽  
Glenohumeral Joint ◽  
Neuromuscular Control ◽  
Muscle Recruitment ◽  
Individual Muscle ◽  
Muscle Activation Patterns ◽  
Outcomes Measures ◽  
Rehabilitation Exercises ◽  
Teres Minor

Context:There are contradictory data on optimal muscle-activation strategies for restoring shoulder stability. Further investigation of neuromuscular-control strategies for glenohumeral-joint stability will guide clinicians in decisions regarding appropriate rehabilitation exercises.Objectives:To determine whether subscapularis, infraspinatus, and teres minor (anteroposterior force couple) muscle activation differ between 4 shoulder exercises and describe coactivation ratios and individual muscle-recruitment characteristics of rotator-cuff muscles throughout each shoulder exercise.Design:Crossover.Setting:Laboratory.Participants:healthy, physically active men, age 20.55 ± 2.0 y.Interventions:4 rehabilitation exercises: pitchback, PNF D2 pattern with tubing, push-up plus, and slide board.Main Outcomes Measures:Mean coactivation level, coactivation-ratio patterns, and level (area) of muscle-activation patterns of the subscapularis, infraspinatus, and teres minor throughout each exercise.Results:Coactivation levels varied throughout each exercise. Subscapularis activity was consistently higher than that of the infraspinatus and teres minor combined at the start of each exercise and in end ranges of motion. Individual muscle-recruitment levels in the subscapularis were also different between exercises.Conclusion:Results provide descriptive data for determining normative coactivation-ratio values for muscle recruitment for the functional exercises studied. Differences in subscapularis activation suggest a reliance to resist anteriorly directed forces.

scholarly journals Effects of Short-Term Training With Uncoupled Cranks in Trained Cyclists

2012 ◽  
Vol 7 (2) ◽  
pp. 113-120 ◽  
Author(s):  
Jack M. Burns ◽  
Jeremiah J. Peiffer ◽  
Chris R. Abbiss ◽  
Greig Watson ◽  
Angus Burnett ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Training Group ◽  
Recovery Phase ◽  
Muscle Recruitment ◽  
Short Term ◽  
Activation Patterns ◽  
Gross Efficiency ◽  
Muscle Activation Patterns

Purpose:Manufacturers of uncoupled cycling cranks claim that their use will increase economy of motion and gross efficiency. Purportedly, this occurs by altering the muscle-recruitment patterns contributing to the resistive forces occurring during the recovery phase of the pedal stroke. Uncoupled cranks use an independent-clutch design by which each leg cycles independently of the other (ie, the cranks are not fixed together). However, research examining the efficacy of training with uncoupled cranks is equivocal. The purpose of this study was to determine the effect of short-term training with uncoupled cranks on the performance-related variables economy of motion, gross efficiency, maximal oxygen uptake (VO2max), and muscle-activation patterns.Methods:Sixteen trained cyclists were matched-paired into either an uncoupled-crank or a normal-crank training group. Both groups performed 5 wk of training on their assigned cranks. Before and after training, participants completed a graded exercise test using normal cranks. Expired gases were collected to determine economy of motion, gross efficiency, and VO2max, while integrated electromyography (iEMG) was used to examine muscle-activation patterns of the vastus lateralis, biceps femoris, and gastrocnemius.Results:No significant changes between groups were observed for economy of motion, gross efficiency, VO2max, or iEMG in the uncoupled- or normal-crank group.Conclusions:Five weeks of training with uncoupled cycling cranks had no effect on economy of motion, gross efficiency, muscle recruitment, or VO2max compared with training on normal cranks.

scholarly journals Thoracic posture, shoulder muscle activation patterns and isokinetic strength of semi-professional rugby union players

2013 ◽  
Vol 25 (1) ◽  
pp. 12 ◽  
Author(s):  
G Bolton ◽  
SJ Moss ◽  
M Sparks ◽  
PC Venter
Keyword(s):  
Rotator Cuff ◽  
Muscle Strength ◽  
Muscle Activation ◽  
Rugby Union ◽  
Lateral View ◽  
Isokinetic Strength ◽  
Serratus Anterior ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Lower Trapezius

Background. Shoulder injuries are the most severe injuries in rugby union players, accounting for almost 20% of injuries related to the sport and resulting in lost playing hours.Objective. To profile the thoracic posture, scapular muscle activation patterns and rotator cuff muscle isokinetic strength of semi-professionalrugby union players.Methods. Using the hand-behind-the-neck and -back methods, we manually tested the range of motion (ROM) of the shoulder joints of 91 uninjured semi-professional rugby union players who consented to participate in the study. Profiling and classification of thoracic posture was performed according to the New York Posture Test. Activation patterns of the upper and lower trapezius, serratus anterior and infraspinatus scapular muscles were determined by electromyography. The isokinetic muscle strength of the rotator cuff muscles was determined at 60°/sec by measuring the concentric and eccentric forces during internal rotation (IR) and external rotation (ER).Results. Participants presented with non-ideal or unsatisfactory internal (59%) and external (85%) rotators of the shoulder. A slightly abnormal or abnormal forward head posture was observed in 55% of participants, while 68% had an abnormal shoulder position in the lateral view. The muscle activation sequence of the rotator cuff muscles was: (i) serratus anterior, (ii) lower trapezius, (iii) infraspinatus, and (iv) upper trapezius. The isokinetic ER/IR muscle-strength ratio during concentric muscle contraction was 64% (standard deviation (SD) ±14) for the left shoulder and 54% (SD ±10) for the right shoulder. The ER/IR ratio for eccentric muscle contraction was 67% (SD ±12) and 61% (SD ±9) for the left and right shoulders, respectively.Conclusions. Non-ideal or unsatisfactory flexibility of the external rotators of the shoulder, a forward shoulder posture in the lateral view, and weakness of the external rotators did not result in an abnormal rotator cuff muscle activation pattern in this study. Postural deviations may, however, increase the risk of shoulder injury in rugby union players in the long term, and should be corrected.

scholarly journals Kinematic Differences between Two Types of Forward Elevations of the Shoulder Joint: Flexion and Reaching Elevation

2020 ◽  
Vol 14 (1) ◽  
pp. 15-25
Author(s):  
Ryo Sahara ◽  
Junichiro Hamada ◽  
Kunio Yoshizaki ◽  
Kazuhiro Endo ◽  
Daisuke Segawa ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Elbow Joint ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Three Dimensional ◽  
Coronal Plane ◽  
Shoulder Flexion ◽  
Joint Flexion ◽  
Motion Plane ◽  
Teres Minor

Background: Extension of the elbow joint is maintained during shoulder flexion. In contrast, the arm starts from the flexed position of the elbow joint and the joint gradually extends during reaching elevation. Objectives: This study aimed to compare the kinematic elements and electromyographic (EMG) activities of the rotator cuff muscles between flexion and reaching elevation. Methods: The study included 10 healthy young men. (average age, 21.5 ± 3.4 years), and measurements were performed on their dominant arms. A three-dimensional motion analyzer was used to record the following elements during shoulder flexion and reaching elevation: the angles of glenohumeral joint elevation and scapular upward rotation, scapulohumeral rhythm, external rotation of the humerus, and glenohumeral plane shifting from the coronal plane. The EMG activities in the supraspinatus, infraspinatus, subscapularis, and teres minor were recorded simultaneously. Results: The plane of reaching elevation was retained at 60° from the coronal plane. The glenohumeral planes (P < 0 .01) and the external rotation angles of the humerus below 90° of elevation (P < 0.05) were significantly different between both the motions. The EMG activities in the supraspinatus (P < .01), infraspinatus (P < 0.05), and teres minor (P < 0.01) were significantly lower while reaching elevation than those during flexion. Conclusion: The motion plane at 60° from the coronal plane, movement of the humeral external rotation, and EMG activities of the rotator cuff muscles were different during reaching elevation and shoulder flexion.

scholarly journals Stability of Measurement Outcomes for Voluntary Task Performance in Participants With Chronic Ankle Instability and Healthy Participants

2011 ◽  
Vol 46 (4) ◽  
pp. 366-375 ◽  
Author(s):  
Sara Van Deun ◽  
Karel Stappaerts ◽  
Oron Levin ◽  
Luc Janssens ◽  
Filip Staes
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Intervention Program ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Control Group ◽  
Muscle Recruitment ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Recruitment Order

Context: Acceptable measurement stability during data collection is critically important to research. To interpret differences in measurement outcomes among participants or changes within participants after an intervention program, we need to know whether the measurement is stable and consistent. Objective: To determine the within-session stability of muscle activation patterns for a voluntary postural-control task in a group of noninjured participants and a group of participants with chronic ankle instability (CAI). Design: Descriptive laboratory study. Setting: Musculoskeletal laboratory. Patients or Other Participants: Twenty control participants (8 men, 12 women; age = 21.8 ± 2.4 years, height = 164.3 ± 13.4 cm, mass = 68.4 ± 17.9 kg) and 20 participants with CAI (12 men, 8 women; age = 21.2 ± 2.1 years, height = 176 ± 10.2 cm, mass = 71.7 ± 11.3 kg). Intervention(s): Participants performed 4 barefoot standing trials, each of which included a 30-second double-legged stance followed by a 30-second single-legged stance in 3 conditions: with vision, without vision, and with vision on a balance pad. Main Outcome Measure(s): The activity of 7 muscles of the lower limb was measured for the stance task in the 3 different conditions for each trial. The onset of muscle activity and muscle recruitment order were determined and compared between the first and the fourth trials for both groups and for each condition. Results: We found no differences in the onset of muscle activity among trials for both groups or for each condition. The measurement error was 0.9 seconds at maximum for the control group and 0.12 seconds for the CAI group. In the control group, 70% to 80% of the participants used the same muscle recruitment order in both trials. In the CAI group, 75% to 90% used the same recruitment order. Conclusions: Within 1 session, measurement stability for this task was acceptable for use in further research. Furthermore, no differences were found in measurement stability across conditions in the control or CAI groups.

A Computational Model of Muscle Recruitment for Wrist Movements

2002 ◽  
Vol 88 (6) ◽  
pp. 3348-3358 ◽  
Author(s):  
Andrew H. Fagg ◽  
Ashvin Shah ◽  
Andrew G. Barto
Keyword(s):  
Motor System ◽  
Muscle Activation ◽  
Movement Direction ◽  
Joint Motion ◽  
Muscle Recruitment ◽  
Task Constraints ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Recruitment Behavior ◽  
Total Effort

To execute a movement, the CNS must appropriately select and activate the set of muscles that will produce the desired movement. This problem is particularly difficult because a variety of muscle subsets can usually be used to produce the same joint motion. The motor system is therefore faced with a motor redundancy problem that must be resolved to produce the movement. In this paper, we present a model of muscle recruitment in the wrist step-tracking task. Muscle activation levels for five muscles are selected so as to satisfy task constraints (moving to the designated target) while also minimizing a measure of the total effort in producing the movement. Imposing these constraints yields muscle activation patterns qualitatively similar to those observed experimentally. In particular, the model reproduces the observed cosine-like recruitment of muscles as a function of movement direction and also appropriately predicts that certain muscles will be recruited most strongly in movement directions that differ significantly from their direction of action. These results suggest that the observed recruitment behavior may not be an explicit strategy employed by the nervous system, but instead may result from a process of movement optimization.

scholarly journals Modularity speeds up motor learning by overcoming mechanical bias in musculoskeletal geometry

2018 ◽  
Vol 15 (147) ◽  
pp. 20180249 ◽  
Author(s):  
Shota Hagio ◽  
Motoki Kouzaki
Keyword(s):  
Cortical Neurons ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Neuromuscular Control ◽  
Muscle Synergies ◽  
Model Learning ◽  
Joint Torques ◽  
Muscle Activation Patterns ◽  
Wide Range ◽  
Simple Neural Network

We can easily learn and perform a variety of movements that fundamentally require complex neuromuscular control. Many empirical findings have demonstrated that a wide range of complex muscle activation patterns could be well captured by the combination of a few functional modules, the so-called muscle synergies. Modularity represented by muscle synergies would simplify the control of a redundant neuromuscular system. However, how the reduction of neuromuscular redundancy through a modular controller contributes to sensorimotor learning remains unclear. To clarify such roles, we constructed a simple neural network model of the motor control system that included three intermediate layers representing neurons in the primary motor cortex, spinal interneurons organized into modules and motoneurons controlling upper-arm muscles. After a model learning period to generate the desired shoulder and/or elbow joint torques, we compared the adaptation to a novel rotational perturbation between modular and non-modular models. A series of simulations demonstrated that the modules reduced the effect of the bias in the distribution of muscle pulling directions, as well as in the distribution of torques associated with individual cortical neurons, which led to a more rapid adaptation to multi-directional force generation. These results suggest that modularity is crucial not only for reducing musculoskeletal redundancy but also for overcoming mechanical bias due to the musculoskeletal geometry allowing for faster adaptation to certain external environments.

scholarly journals Asymptomatic Elite Adolescent Tennis Players' Signs of Tendinosis in Their Dominant Shoulder Compared With Their Nondominant Shoulder

2015 ◽  
Vol 50 (12) ◽  
pp. 1299-1305 ◽  
Author(s):  
Fredrik R. Johansson ◽  
Eva Skillgate ◽  
Anders Adolfsson ◽  
Göran Jenner ◽  
Edin DeBri ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Muscle Activation ◽  
External Rotation ◽  
Radiology Department ◽  
Mri Findings ◽  
Cross Sectional ◽  
Tennis Players ◽  
Muscle Activation Patterns ◽  
Normal Tendon ◽  
Mri Scans

Context Tennis is an asymmetric overhead sport with specific muscle-activation patterns, especially eccentrically in the rotator cuff. Magnetic resonance imaging (MRI) findings in asymptomatic adolescent elite tennis players have not previously been reported. Objective The first aim of the study was to describe MRI findings regarding adaptations or abnormalities, as well as muscle cross-sectional area (CSA), of the rotator cuff. The second aim of the study was to investigate the rotator cuff based on the interpretation of the MRI scans as normal versus abnormal, with the subdivision based on the grade of tendinosis, and its association with eccentric rotator cuff strength in the dominant arm (DA) of the asymptomatic elite adolescent tennis player. Setting Testing environment at the radiology department of Medicinsk Röntgen AB. Patients or Other Participants Thirty-five asymptomatic elite tennis players (age = 17.4 ± 2.7 years) were selected based on ranking and exposure time. Intervention(s) We assessed MRI scans and measured the CSA of the rotator cuff muscle. The non-DA (NDA) was used as a control. In addition, eccentric testing of the external rotators of the DA was performed with a handheld dynamometer. Results The DA and NDA displayed different frequencies of infraspinatus tendinosis (grade 1 changes) (P &lt; .05). Rotator cuff measurements revealed larger infraspinatus and teres minor CSA (P &lt; .05) in the DA than in the NDA. Mean eccentric external-rotation strength in the DA stratified by normal tendon and tendinosis was not different between groups (P = .723). Conclusions Asymptomatic adolescent elite tennis players demonstrated infraspinatus tendinosis more frequently in the DA than in the NDA. Clinicians must recognize these tendon changes in order to modify conditioning and performance programs appropriately.

scholarly journals GANGGUAN MANSET ROTATOR SENDI BAHU Suatu tinjauan anatomik

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
George N. Tanudjaja
Keyword(s):  
Rotator Cuff ◽  
Range Of Motion ◽  
Shoulder Pain ◽  
Glenohumeral Joint ◽  
Spontaneous Pain ◽  
Supraspinatus Muscle ◽  
Joint Structure ◽  
Wide Range ◽  
Teres Minor

Abstract: Rotator cuff of glenohumeral joint is a group of muscles and their tendons which surrounds and protects the wholeness of the glenohumeral joint and functions as a shoulder rotator. Shoulder pain is commonly found and is mostly caused by tendinitis of the rotator cuff or subacromial bursitis. There are four important muscles of this rotator cuff: supraspinatus, infraspinatus, teres minor, and subscapularis (SITS) muscles. Among them, the most troublesome is the tendon of supraspinatus muscle that functions as a sheet as well as the abductor of glenohumeral joint. Therefore, tendinitis of this muscle is associated with spontaneous pain and disturbance in lifting the superior extremity. This cuff structure shows that tendons of the SITS muscles together with the capsule of genohumeral joint and the joint structure itself enable a very wide range of motion with a consequence of being troubled easily.Keywords: glenohumeral, rotator cuf, tendon, jointAbstrak: Manset rotator sendi bahu adalah sekelompok otot dan tendonnya yang mengelilingi dan menjaga keutuhan articulatio genohumerale dengan fungsi lain sebagai rotator brachium. Nyeri bahu sering ditemukan dan umumnya disebabkan oleh tendinitis manset rotator atau bursitis subacromiale. Di antara keempat tendines, yang tersering mengalami gangguan yaitu tendon m. supraspinatus yang selain sebagai pembungkus juga berfungsi sebagai abduktor articulatio glenohumerale sehingga selain nyeri spontan juga ditemukan kesulitan mengangkat membrum superior. Struktur manset ini menunjukkan bahwa tendines keempat otot tersebut bergabung dengan capsula articularis genohumerale dengan struktur sendinya yang memungkinkan pergerakan bahu yang sangat luas tetapi dengan konsekuensi akan lebih mudah terjadi gangguan.Kata kunci: sendi bahu, manset rotator, tendon, articulatio

scholarly journals Thoracic posture, shoulder muscle activation patterns and isokinetic strength of semi-professional rugby union players

2013 ◽  
Vol 25 (1) ◽  
pp. 12 ◽  
Author(s):  
G Bolton ◽  
SJ Moss ◽  
M Sparks ◽  
PC Venter
Keyword(s):  
Rotator Cuff ◽  
Muscle Strength ◽  
Muscle Activation ◽  
Rugby Union ◽  
Lateral View ◽  
Isokinetic Strength ◽  
Serratus Anterior ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Lower Trapezius

Background. Shoulder injuries are the most severe injuries in rugby union players, accounting for almost 20% of injuries related to the sport and resulting in lost playing hours.Objective. To profile the thoracic posture, scapular muscle activation patterns and rotator cuff muscle isokinetic strength of semi-professionalrugby union players.Methods. Using the hand-behind-the-neck and -back methods, we manually tested the range of motion (ROM) of the shoulder joints of 91 uninjured semi-professional rugby union players who consented to participate in the study. Profiling and classification of thoracic posture was performed according to the New York Posture Test. Activation patterns of the upper and lower trapezius, serratus anterior and infraspinatus scapular muscles were determined by electromyography. The isokinetic muscle strength of the rotator cuff muscles was determined at 60°/sec by measuring the concentric and eccentric forces during internal rotation (IR) and external rotation (ER).Results. Participants presented with non-ideal or unsatisfactory internal (59%) and external (85%) rotators of the shoulder. A slightly abnormal or abnormal forward head posture was observed in 55% of participants, while 68% had an abnormal shoulder position in the lateral view. The muscle activation sequence of the rotator cuff muscles was: (i) serratus anterior, (ii) lower trapezius, (iii) infraspinatus, and (iv) upper trapezius. The isokinetic ER/IR muscle-strength ratio during concentric muscle contraction was 64% (standard deviation (SD) ±14) for the left shoulder and 54% (SD ±10) for the right shoulder. The ER/IR ratio for eccentric muscle contraction was 67% (SD ±12) and 61% (SD ±9) for the left and right shoulders, respectively.Conclusions. Non-ideal or unsatisfactory flexibility of the external rotators of the shoulder, a forward shoulder posture in the lateral view, and weakness of the external rotators did not result in an abnormal rotator cuff muscle activation pattern in this study. Postural deviations may, however, increase the risk of shoulder injury in rugby union players in the long term, and should be corrected.

scholarly journals Position of the rotator cuff footprint in relation to the centre of rotation of the humeral head

2018 ◽  
Vol 11 (1_suppl) ◽  
pp. 26-29
Author(s):  
Ethan Caruana ◽  
Carlos Wigderowitz ◽  
Fraser Harrold
Keyword(s):  
Rotator Cuff ◽  
Humeral Head ◽  
Glenohumeral Joint ◽  
Articular Surface ◽  
Laser Scanner ◽  
Perpendicular Line ◽  
Moment Arms ◽  
Surface Laser ◽  
Centre Of Rotation ◽  
Teres Minor

Background The objective of the present study was to determine the size and position of the rotator cuff moment arms constructed from the cuff footprints, incident on the line of force acting through the humeral head. Methods Five humeri were dissected, leaving the footprints of the rotator cuff intact. Each of the rotator cuff footprints and the cartilage/calcar interface were digitized and the articular surface was scanned using a high precision surface laser scanner. All of the data were merged into the same coordinate system. The centroid of each cuff footprint, centroid of the articular surface of the humerus (G) and the centroid of the articular surface of the glenoid (P) were calculated. Moment arms were measured as the intersection of a perpendicular line of force from each footprint centroid onto the resultant line of force to the centroid of the Glenoid (P). Results The mean moment arms of the supraspinatus, infraspinatus and subscapularis muscles were incident close to the centroid (G), whereas teres minor was lateral to the centroid, consistently. Conclusions The teres minor moment arm aligned distal to the centroid of the sphere, consistently. The results may provide an understanding of the function of each muscle as a mobilizer or stabilizer of the glenohumeral joint. Further investigation is necessary.

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