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Glenohumeral Extension and the Dip: Considerations for the Strength and Conditioning Professional
Abstract
A significant number of resistance training injuries occur at the shoulder complex. However, there is a lack of research may increase the risk of these injuries. Certain exercises, such as those requiring the apprehension position (glenohumeral abduction with external rotation), have been investigated and found to be associated with shoulder pain and injury. However, there are additional exercises or positions that may also be associated with increased injury risk. The position of end-range glenohumeral extension, particularly as it pertains to a dip, is a vulnerable position that may have previously
been overlooked.
... Dips are completed some height above the ground and decreased movement control may increase fall risk, forcing the shoulder beyond the maximal range of motion, resulting in traumatic injury. Any potential increase in the risk of injury warrants investigation, particularly when considering that there are currently un-investigated practitioner concerns for a suspected high risk of injury to the shoulder when completing dip repetitions [22]. The effects of fatigue have previously been investigated in other upper body push exercises such as the bench press [13][14][15] and push-up [16,17] and have been shown to significantly alter repetition characteristics such as increasing the duration of the upwards phase of these movements [13,14,18,19] and decreasing movement control [14]. ...
... Dips are completed some height above the ground and decreased movement control may increase fall risk, forcing the shoulder beyond the maximal range of motion, resulting in traumatic injury. Any potential increase in the risk of injury warrants investigation, particularly when considering that there are currently un-investigated practitioner concerns for a suspected high risk of injury to the shoulder when completing dip repetitions [22]. ...
... One more important potential fatigue-related control issue is the end-range shoulder extension observable at the bottom position when completing the dip. It has been suggested that there is an increased risk of injury to the anterior shoulder capsule and PM when in this position under load [22][23][24][25], especially when fatigued. This line of thinking is related to the perceived decreased neuromuscular and coordination control when fatigued which may put performers of the dip in an injurious position. ...
The purpose of this study was to profile and compare the bar dip’s kinematics and muscle activation patterns in non-fatigued and fatigued conditions. Fifteen healthy males completed one set of bar dips to exhaustion. Upper limb and trunk kinematics, using 3D motion capture, and muscle activation intensities of nine muscles, using surface electromyography, were recorded. The average kinematics and muscle activations of repetitions 2–4 were considered the non-fatigued condition, and the average of the final three repetitions was considered the fatigued condition. Paired t-tests were used to compare kinematics and muscle activation between conditions. Fatigue caused a significant increase in repetition duration (p < 0.001) and shifted the bottom position to a significantly earlier percentage of the repetition (p < 0.001). There were no significant changes in the peak joint angles measured. However, there were significant changes in body position at the top of the movement. Fatigue also caused an increase in peak activation amplitude in two agonist muscles (pectoralis major [p < 0.001], triceps brachii [p < 0.001]), and three stabilizer muscles. For practitioners prescribing the bar dip, fatigue did not cause drastic alterations in movement technique and appears to target pectoralis major and triceps brachii effectively.
... Yet, the prescription of the dip in these various performance and rehabilitation programs is based on the practitioner's experience rather than empirical evidence. While other upper-body push exercises, that may have similar neuromechanical profiles, have previously been investigated, including the push-up [11][12][13], bench press [14], and shoulder press [15][16][17], such research has not been conducted In addition to the lack of evidence justifying the dips use in exercise programs, the dip has also been criticised as a potentially high-risk exercise for injury to the shoulder [2,7,18]. A potential mechanism of injury has been suggested by McKenzie, Crowley-McHattan [18] relating to injury of anterior shoulder and PM. ...
... While other upper-body push exercises, that may have similar neuromechanical profiles, have previously been investigated, including the push-up [11][12][13], bench press [14], and shoulder press [15][16][17], such research has not been conducted In addition to the lack of evidence justifying the dips use in exercise programs, the dip has also been criticised as a potentially high-risk exercise for injury to the shoulder [2,7,18]. A potential mechanism of injury has been suggested by McKenzie, Crowley-McHattan [18] relating to injury of anterior shoulder and PM. However, supporting evidence is limited, with only two case reports of PM ruptures caused by the bar dip [19,20], anecdotal examples of PM injury caused by the ring dip [21,22], and unsubstantiated claims of the ring dip being a high-risk exercise for shoulder injury [7]. ...
... The elongation of this ligament is likely to present as anterior shoulder instability [31]. This larger shoulder extension ROM may also excessively strain the PM when likely operating at a mechanical disadvantage [18,32]. However, the smaller load and low intensity of PM activation may mitigate PM injury risk. ...
The purpose of this study was to profile and compare the kinematics, using 3D motion capture, and muscle activation patterns, using surface electromyography (sEMG), of three common dip variations; the bench, bar, and ring dips. Thirteen experienced males performed four repetitions of each dip variation. For each participant, repetitions 2–4 were time-normalized and then averaged to produce a mean value for all kinematic and sEMG variables. The mean maximal joint angles and mean peak sEMG amplitudes were compared between each variation using a one-way ANOVA with repeated measures. Several significant differences (p < 0.05) between dip variations were observed in both kinematic and sEMG data. The bench dip predominantly targets the triceps brachii but requires greater shoulder extension range. The mean peak triceps brachii activation was 0.83 ± 0.34 mV on the bench, 1.04 ± 0.27 mV on the bar, and 1.05 ± 0.40 mV on the ring. The bar dip is an appropriate progression from the bench dip due to the higher peak muscle activations. The ring dip had similar peak activations to the bar dip, with three muscles increasing their activation intensities further. These findings have implications for practitioners prescribing the dip, particularly to exercisers with a history of shoulder pain and injury.
... Dip movement is performed as a closed kinetic chain and generally performed for triceps brachii and pectoral muscle group development. Despite the popularity of the dip exercise, it has been stated that it has not been studied in detail, especially in terms of kinematics (McKenzie, Crowley-McHattan, Meir, Whitting, & Volschenk, 2021). When the literature is reviewed, a study has been found that compares the triceps brachi and pectoralis major activation values during different dip exercises (Bagchi, 2015). ...
... In a study in which the glenohumeral joint was fixed, it was determined that the triceps muscle has a long moment arm and stabilizes the force in a wide range of motion (30°-120°) (Murray, Buchanan, & Delp, 2000). However, the dip movement is a rare exercise in which the glenohumeral joint is reached to the end range glenohumeral extension (McKenzie, Crowley-McHattan, Meir, Whitting, & Volschenk, 2021). ...
... The elbow flexion angle and the eccentric contraction rate of the pectoralis major muscle show a positive relationship. At the same time, with the anterior translation of the humeral head, the glenohumeral joint will be under pressure and may cause injuries (McKenzie, Crowley-McHattan, Meir, Whitting, & Volschenk, 2021). In this study, the greater activation obtained at an elbow angle of 75° can be used as a strategy for both muscular development and injury avoidance in terms of dip movement. ...
The parallel bar dip is one of the most commonly used calisthenic exercises. However, a recommended elbow angle in terms of activation patterns has not yet been studied. The aim of this study is to examine the activation values of the pectoralis major and triceps muscle groups during parallel bar dip at different elbow angles. Ten male volunteers (age: 25.1 ± 3.9 years) with regular exercise habits participated in the study. During the parallel bar dip, the pectoralis major, lateral triceps and long triceps muscles were examined at elbow angles of 75°, 85° and 95°. The movement was standardized using the metronome (60 beats.min-1) and evaluated in three phases (eccentric = 2 seconds, isometric = 1 seconds, concentric = 2 seconds). There was no statistically significant difference between the angles for pectoralis major (p>0.05). Significant differences were observed in triceps muscle groups, especially in favor of 75° in the isometric phase (p<0.05). The greatest activation in terms of phases was seen in concentric contraction for all muscles. This research has shown that the reduction of the elbow flexion angle has a positive effect on the activation of triceps muscle group. However, since there are some methodological limitations (such as biomechanical markers), it can be said that future research should improve these findings.
Objective:
Stress fractures are common in highly active people, such as athletes or those in the military. They occur frequently in the lower extremities but sternal stress fractures are rare injuries.
Methods:
We present a case of a young male who reported no pain and a 'click' sound from the front of the chest while training with parallel bar dips with a grip that was wider than shoulder-width apart.
Results:
In this case, radiological evaluation was the most helpful tool to diagnose manubrium sterni stress fracture. We advised him to rest but he started exercises immediately because he had to participate in a military camp after the injury. The patient was treated conservatively. The treatment consisted of activity modification and supplemental drugs.
Conclusion:
We report a case of manubrium stress fracture that developed in a young male military recruit.
The pectoralis major is a large, flat muscle of the pectoral girdle of the upper limb. It has a fan-shaped appearance with three heads or portions: the clavicular, the sternocostal and the abdominal head. The clavicular head originates from the medial two-thirds of the clavicle (collar bone). The muscle fibers of the clavicular head have a broad origin on the caudal-anterior and caudal-posterior surface of the clavicle covering approximately half to two-thirds of that surface and converting toward the humerus, resulting in a triangular shape [1]. The clavicular head is an independent portion of the pectoralis major (Figure 1). It is located more superficial and partially overlapping ventrally the sternocostal head. According to our observations, the clavicular portion has an autonomous tendon of approximately 3.0cm length. This distinct tendon enters in contact towards the insertion on the humerus with the tendon of the sternocostal and abdominal parts. The sternocostal head originates from the manubrium and the body of sternum, as well as from the cartilages of the first six ribs. This part is the largest, thickest and strongest portion of the pectoralis, usually well developed in athletes [2]. Detailed dissection revealed that the sternocostal portion includes about three muscular clusters with well-pronounced interstitial clefts (Figure 1C). The third element of the pectoralis major is the abdominal head. This part originates from the tendinous sheath of the rectus abdomen is [3] and/or superficial aponeurosis of external oblique [4]. The abdominal head has two layers of muscle fibers, which wind around each other towards its tendon, as well as around the caudal edge of sternocostal head (Figure1D). Tendon Anatomy The tendon of the pectoralis major has a "convoluted" appearance. According to the literature it consists of two layers [5,6]. The clavicular tendon constitutes the first layer. The second layer is the common tendon from the sternocostal and abdominal portions. The layers screw around each other and as a result the common sterno-costo-abdominal portion fixes more distally to the humerus compare to the clavicular portion which fixes a bit proximally [7,8]. In literature, the different layers are named as anterior and posterior layers (lamina). In cadaver dissection, we correspondingly observed complex organization of the pectoralis major tendon. The three muscular portions together forma broad, flat, strong tendon that extends along the crest of the major tubercle of the humerus, close to the bicipital groove (intertubercular sulcus), which varies in size between 3.0-5.0 cm (Figure 1E). However, the tendinous fibres of the three portions form three distinct layers that can be easily separated anatomically. The tendinous fibres of the three layers have different orientations in continuity of and according to the different orientation of the muscle fibres of the three heads, i.e. cranial-medial to caudal-lateral for the clavicular head, horizontal for the sternocostal head, caudal-medial to cranial-lateral for the abdominal head. This allows pulling on the proximal humerus in three different direction, i.e. proximal direction for the clavicular head, plain adduction for the sternocostal head and distal direction for the abdominal head. Together, they allow better stabilisation of the upper arm in the adduction position. The specific tendon architecture of the pectoralis major allows surgeons to use different portions as Abstract The pectoralis major is a muscle of the upper limb girdle. This muscle has a unique morphological architectonic and a high rate of clinical applications. However, there is lack of data regarding the morphological and functional interactions of the pectoralis major with other muscle and fascial compartments. According to the applied knowledge, the "Humero-pectoral" morpho-functional concept has been postulated. The purpose of this review was the dissectible investigation of the muscle anatomy and literature review of surgical applications.
Muscle strain injury and exercise‐induced muscle damage have been described as a continuum of injury whereby micro tears (muscle damage) lead to muscle strain injury. However, the clinical scenario is one of two mutually exclusive conditions that differ markedly in terms of site of injury, mechanism of injury, associated symptoms, repair process, and re‐injury rate. Muscle strain injury is a tearing of muscle fibers close to the muscle‐tendon junction during the application of a single tensile load, with sudden debilitating symptoms, and a subsequent repair process that is slow, and often incomplete, resulting in a high risk of recurrence. Exercise‐induced muscle damage is a disruption to myofibrils that occurs gradually during eccentrically biased exercise, resulting in delayed symptoms, that typically resolve uneventfully, with a repair process that makes the muscle resistant to a recurrence of damage. Thus muscle strain injury and exercise‐induced muscle damage should be viewed as mutually exclusive clinical entities.
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Purpose of review:
The purpose of this review is to outline the natural history and best clinical practices for nonoperative management of anterior shoulder instability.
Recent findings:
Recent studies continue to demonstrate a role for nonoperative treatment in the successful long-term management of anterior glenohumeral instability. The success of different positions of shoulder immobilization is reviewed as well. There are specific patients who may be best treated with nonoperative means after anterior glenohumeral instability. There are also patients who are not good nonoperative candidates based on a number of factors that are outlined in this review. There continues to be no definitive literature regarding the return to play of in-season athletes. Successful management requires a thorough understanding of the epidemiology, pathoanatomy, history, physical examination, diagnostic imaging modalities, and natural history of operative and nonoperative treatment.
The purpose of this manuscript is to review the knowledge of scapular positioning at rest and scapular movement in different anatomic planes in asymptomatic subjects and patients with shoulder impingement syndrome (SIS) and glenohumeral shoulder instability. We reviewed the literature for all biomechanical and kinematic studies using keywords for impingement syndrome, shoulder instability, and scapular movement published in peer reviewed journal. Based on the predefined inclusion and exclusion criteria, 30 articles were selected for inclusion in the review. The literature is inconsistent regarding the scapular resting position. At rest, the scapula is positioned approximately horizontal, 35° of internal rotation and 10° anterior tilt. During shoulder elevation, most researchers agree that the scapula tilts posteriorly and rotates both upward and externally. It appears that during shoulder elevation, patients with SIS demonstrate a decreased upward scapular rotation, a decreased posterior tilt, and a decrease in external rotation. In patients with glenohumeral shoulder instability, a decreased scapular upward rotation and increased internal rotation is seen. This literature overview provides clinicians with insight into scapular kinematics in unimpaired shoulders and shoulders with impingement syndrome and instability.
Injuries to the pectoralis major muscle are relatively infrequent but result in pain, weakness, and deformity of the upper extremity. The usual injury mechanism is during eccentric shortening of the pectoralis major under heavy load, such as when performing a bench press exercise. The ability to detect and treat a pectoralis major rupture is important for both the clinician and the patient and is aided with knowledge of the anatomy, the clinical findings, and results of nonoperative and operative care. It is important to understand the physical demands and desires of the patient as well as to understand the outcomes of both nonoperative and operative care to make an informed decision regarding optimal treatment. This article highlights the importance of the clinical examination in identifying the injury, examines various surgical techniques to repair the rupture, and reports on potential complication and reinjury rates.
Both structural and non-structural components can contribute to shoulder instability. Classification and therefore management must recognise these factors to achieve functional stability. This paper discusses a classification system proposing three types of shoulder instability recognising the structural and non-structural components and that a continuum exists between pathologies. Structural causes can be addressed with surgical intervention, but non-structural causes such as altered neuromuscular control within the rotator cuff should be addressed conservatively. The purpose of this article is to describe the types of instability and guide appropriate management, helping to avoid surgery in inappropriate cases and ensure that effective rehabilitation has been achieved.
A systematic review of the scientific literature was conducted to identify the optimal ranges of motion for preventing injury in the main joints of the body during resistance exercise performance. These ranges of motion are independent of the type in which the resistance exercises could be applied (ie, adults, elderly, athletes, recreational exercisers), and the regions examined include the shoulder, spine, and knee, which are injured most often. It can be concluded that during the performance of any resistance exercise, it is possible to put anatomical structures at risk with certain body positions; therefore, it is necessary to understand these movements so injury can be avoided.
The purpose of this study was to determine the relationship between non-invasive laboratory measures of 'muscle power' and swim performance over sprint (50 m) and middle-distance (400 m) events. Twenty-two swimmers performed an upper and lower body Wingate Anaerobic Test (WAT) and a maximal sustained power output test (MPO) for the upper body. Peak power (PP) and mean power (MP) were determined for the WAT, while peak sustained workload (WLpeak) was determined for the MPO. Timed swims over 50 m and 400 m were undertaken by all swimmers during which the number of arm strokes per length was recorded. Highly significant relationships were found between sprint-swim speed (S50) and mean power of the arms (MP(arms)) (r = 0.63, P less than 0.01), between S50 and mean power of the legs (MP(legs)) (r = 0.76, P less than 0.001) and between S50 and the distance covered with each arm stroke (DS) (r = 0.91, P less than 0.001). Multiple regression analyses revealed that WAT power indices for the legs did not significantly increase explained variance in S50 above that of the arms. The relationship between WL(peak) and S400 was highly significant (r = 0.70, P less than 0.001) and indicates the importance of arm power in the longer distance swim events.
Unlabelled:
The static restraints of the scapulohumeral joint provide stability for the humeral head in the glenoid cavity, limit extremes of motion of the glenohumeral joint, and guide positioning of the humerus during normal shoulder movement. Eleven fresh-frozen cadaver shoulders of unknown age were attached to a shoulder motion device that allowed measurement of motion in three planes with an accuracy to 0.5 degrees. Four shoulders underwent motion analysis and seven were used for strain gauge analysis of the static scapulohumeral ligamentous restraints. The results of the motion analysis demonstrated that any attempt at simple motion (flexion, extension, abduction, internal or external rotation) resulted in coupled motion in two additional planes. The strain gauge data, expressed as a percent of total tension for each ligament tested, demonstrated a reciprocal tension-sharing relationship among all ligament components and a transference of tension among these components when original and new joint positions were compared. These data provide an in vitro model of shoulder restraint function to explain primary restraint, tension sharing, and transference of tension functions in the in vivo scapulohumeral joint.
Clinical relevance:
These principles of shoulder function have application in the treatment of instability and frozen shoulder syndrome, and provide an in vitro model to better understand static restraint function in the throwing mechanism.
We have demonstrated that certain passive motions of the glenohumeral joint are reproducibly accompanied by translation of the head of the humerus on the glenoid. We investigated the relationship of these translations to the position of the glenohumeral joint and to applied torques and forces in seven isolated glenohumeral joints from fresh cadavera, using a six-degrees-of-freedom position sensor and a six-axis force and torque transducer. Reproducible and significant translation occurred in an anterior direction with glenohumeral flexion and in a posterior direction with extension. We also observed translation with cross-body movement. The translation occurring with flexion was obligate in that it could not be prevented by the application of an oppositely directed force of thirty to forty newtons. Operative tightening of the posterior portion of the capsule increased the anterior translation on flexion and cross-body movement and caused it to occur earlier in the arc of motion compared with the intact glenohumeral joint. Operative tightening of the posterior part of the capsule also resulted in significant superior translation with flexion of the glenohumeral joint.
We investigated the stabilizing mechanism of the glenohumeral joint that prevents anterior dislocation by anatomical dissections of the subscapularis, the shoulder capsule, and the superior, middle, and inferior glenohumeral ligaments in thirty-six shoulders of embalmed cadavera. We also performed roentgenographic studies of ten unembalmed cadaver shoulders in which radiopaque markers were used to demonstrate the position, tightness, and laxity of the subscapularis muscle and of the middle and inferior glenohumeral ligaments during external rotation of the shoulder at zero, 45, and 90 degrees of abduction. The subscapularis muscle and the three glenohumeral ligaments were cut in different sequences to determine their relative contributions to stability (limitation of external rotation). The conclusions from these experiments were that at zero degrees of abduction, the subscapularis muscle stabilizes the joint to a large extent; at 45 degrees of abduction, the subscapularis, middle glenohumeral ligament, and anterosuperior fibers of the inferior glenohumeral ligament provide the stability; and as the shoulder approaches 90 degrees of abduction, the inferior glenohumeral ligament prevents dislocation during external rotation.
Shoulder dislocation and subluxation occurs frequently in athletes with peaks in the second and sixth decades. The majority (98%) of traumatic dislocations are in the anterior direction. The most frequent complication of shoulder dislocation is recurrence, a complication that occurs much more frequently in the adolescent population. The static (predominantly capsuloligamentous and labral) and dynamic (neuromuscular) restraints to shoulder instability are now well defined. Rehabilitation aims to enhance the dynamic muscular and proprioceptive restraints to shoulder instability. This paper reviews the nonoperative treatment and the postoperative management of patients with various classifications of shoulder instability.
Much is known about the physiological impairments that can cause muscle fatigue. It is known that fatigue can be caused by many different mechanisms, ranging from the accumulation of metabolites within muscle fibres to the generation of an inadequate motor command in the motor cortex, and that there is no global mechanism responsible for muscle fatigue. Rather, the mechanisms that cause fatigue are specific to the task being performed. The development of muscle fatigue is typically quantified as a decline in the maximal force or power capacity of muscle, which means that submaximal contractions can be sustained after the onset of muscle fatigue. There is even evidence that the duration of some sustained tasks is not limited by fatigue of the principal muscles. Here we review experimental approaches that focus on identifying the mechanisms that limit task failure rather than those that cause muscle fatigue. Selected comparisons of tasks, groups of individuals and interventions with the task-failure approach can provide insight into the rate-limiting adjustments that constrain muscle function during fatiguing contractions.
Context
Throwing injuries.
Objective
To study the effects of posterior capsule tightness on humeral head position in late cocking simulation.
Design
Eight fresh frozen shoulders were placed in position of “late cocking,” 90 degrees abduction, and 10 degrees adduction and maximal external rotation. 3D measurements of humeral head relationship to the glenoid were taken with an infrared motion sensor, both before and after suture plication of the posterior capsule. Plications of 20% posterior/inferior capsule and 20% entire posterior capsule were performed, followed by plications of 40% of the posterior/inferior capsule and 40% entire posterior capsule.
Setting
Cadaver Lab.
Intervention
Posterior capsular placation.
Main Outcome Measures
Humeral head position.
Results
40%, but not 20%, posterior/inferior and posterior plications demonstrated a trend to increased posterior-superior humeral head translation relative to controls.
Conclusion
Surgically created posterior capsular tightness of the glenohumeral joint demonstrated a nonsignificant trend to increased posterior/superior humeral head translation in the late cocking position of throwing.
Using water in shoulder rehabilitation increases the effectiveness and transition to full participation in sport. Using water as resistance improves muscle strength and endurance by increasing the force of the movements and the ability to perform repetitive movements. The hydrodynamic principles applied to shoulder rehabilitation can be employed for any joint injury in conjunction with traditional rehabilitation techniques. Having to overcome the resistance of the water while training specific joint movements adds a separate, and very advantageous, component to any traditional rehabilitation program. The benefits of water exercise can also be used to maintain conditioning and flexibility while transitioning to, and after, return to play.
Weightlifting is considered as a dynamic strengthen exercise and power sport in which the athletes lifts a maximum weight with one repetition. The weightlifting as other sports has common musculoskeletal injuries in different body location corresponding to the sports beneficial. However, identifying the injuries incidence and the etiology is a first two-step in the model of the injury prevention in order to introduce preventive measures for sports. Therefore, this literature review is aimed to focus on the incidence and the etiology related to injuries of the weightlifting. However, the incidence injuries studies revealed that the children have more injuries related to accident than the adults. Whereas, the adults have more injuries related to strain and sprain. The most common injured locations are shoulder, lumbar spine, knee, elbow, hand, and wrist in the weightlifters. The percentage of the injuries according to location is the shoulder (36%), lumbar spine (24%), elbow (11%), and the knee (9%). In the other hand, the rule and regulation in the weightlifting had been changed since 1972 in which the clean and press lift eliminated from the competition due to the risk of this lift. Finally, weightlifting considered as safe sport if it is compared with other sports.
Background:
Anterior shoulder dislocation causes injury to the inferior gleno-humeral ligament (IGHL) and capsule. Clinical manoeuvres currently used to evaluate the IGHL test for, and may induce, apprehension. We developed the hyper extension-internal rotation (HERI) test to assess the IGHL and inferior capsule without causing apprehension or inducing a risk of gleno-humeral dislocation.
Hypothesis:
The HERI test is easy to perform and reproducible, induces no risk of gleno-humeral dislocation during the manoeuvre, and causes no apprehension in the patients.
Material and methods:
We studied 14 fresh cadaver shoulders. Each specimen was positioned supine with the lateral edge of the scapula on the table and the upper limb hanging down beside the table under the effect of gravity. This position produced hyperextension and internal rotation of the gleno-humeral joint. For each shoulder, the range of extension (°) was measured before and after isolated IGHL section. Then, we performed the HEIR test in 50 patients with chronic unilateral anterior gleno-humeral instability and we compared the range of extension between the normal and abnormal sides.
Results:
In the cadaver study, isolated IGHL section increased the angle of extension by a mean of 14.5° (11°-18°) compared to the pre-injury values. In the clinical study, the mean difference in extension angles between the normal and abnormal sides was 14.5°. The patients reported no apprehension during the HERI test.
Conclusion:
The angle of extension increases after section or injury of the IGHL in cadaver specimens and patients, respectively. When the inferior capsule and IGHL are damaged, the angle of extension increases compared to the normal side. Lesions to these structures can be evaluated clinically by performing the HERI test.
Level of evidence:
III.
Shoulder instability is a phenomenon, which has a variety of clinical presentations. Its complex nature has until recently been poorly understood. Inadequate understanding of the pathology of instability has been confounded by confusion over definitions and inadequate classification systems. As a result treatment failures have been observed in many of the specific pathologies. We propose a classification system, which challenges previous systems by being all inclusive and recognises that more than one pathology can occur in an individual shoulder. The system takes the form of a triangle with polar groups at each corner and specific subgroups mapped along each axis. It provides a usable framework for clinicians in the management of what can be complex problems.
Despite case reports implicating anterior instability (AI) as an etiological source of shoulder pain among weight-training (WT) participants, a paucity of case-controlled evidence exists to support this premise. The purpose of this study was to determine if WT participants have clinical characteristics of AI and hyperlaxity. Additionally, we investigated the role of exercise selection. One hundred and fifty-nine healthy male participants (mean age 28) were recruited and included 123 individuals who engaged in WT a minimum of 2 days per week; and 36 controls with no history of WT participation. Prior to testing, participants completed a questionnaire summarizing their training patterns. Upon completing the questionnaire, three reliable and valid tests used to identify clinical characteristics of AI were performed on both groups and included the load & shift, apprehension, and relocation maneuvers. Load & shift test results identified significantly greater anterior GH joint hyperlaxity in the WT group compared to controls (p=.004). The presence of positive apprehension (p < .001) and relocation (p< .001) tests were also significantly greater in the WT group. A significant association existed between performance of exercises that require the "high-five" position (behind the neck latissimus pull-downs and military press) and clinical characteristics of AI. Conversely, an inverse association between performance of external rotator strengthening and clinical characteristics of AI existed. Findings from this study suggest that individuals participating in WT may be predisposed to AI and hyperlaxity. Modification of exercises requiring the high-five position; as well as efforts to strengthen the external rotators may serve as a useful means to mitigate characteristics associated with AI and hyperlaxity. Future intervention based trials are needed to investigate a causative effect of exercises.
The mechanical response of the inferior glenohumeral ligament to varying subfailure cyclic strains was studied in 33 fresh frozen human cadaver shoulders. The specimens were tested as bone-ligament-bone preparations representing the 3 regions of the inferior glenohumeral ligament (superior band and anterior and posterior axillary pouches) through use of uniaxial tensile cycles. After mechanical preconditioning, each specimen was subjected to 7 test segments, consisting of a baseline strain level L1 (400 cycles) alternating with either 1 (group A, 10 shoulders), 10 (group B, 13 shoulders), or 100 (group C, 10 shoulders) cycles at increasing levels (L2, L3, L4) of subfailure strain. Cycling to higher levels of subfailure strain (L2, L3, L4) produced dramatic declines in the peak load response of the inferior glenohumeral ligament for all specimens. The group of ligaments subjected to 100 cycles of higher subfailure strains demonstrated a significantly greater decrease in load response than the other 2 groups. Ligament elongation occurred with cyclic testing at subfailure strains for all 3 groups, averaging 4.6% ± 2.0% for group A 6.5% ± 2.6% for group B, and 7.1% ± 3.2% for group C. Recovery of length after an additional time of nearly 1 hour was minimal. The results from this study demonstrate that repetitive loading of the inferior glenohumeral ligament induces laxity in the ligament, as manifested in the peak load response and measured elongations. The mechanical response of the ligament is affected by both the magnitude of the cyclic strain and the frequency of loading at the higher strain levels. The residual length increase was observed in all of the specimens and appeared to be largely unrecoverable. This length increase may result from accumulated microdamage within the ligament substance, caused by the repetitively applied subfailure strains. The clinical relevance of the study is that this mechanism may contribute to the development of acquired glenohumeral instability, which is commonly seen in the shoulders of young athletes who participate in repetitive overhead sports activities.
Rupture of the pectoralis major muscle is an uncommon athletic injury that can result in both functional and cosmetic deficiency. To date, most ruptures occurring in athletes have occurred while performing bench press or overhead lifting maneuvers. We describe a case of a pectoralis major rupture occurring while performing weighted parallel bar dips. Despite the popularity of this exercise, injuries associated with this exercise are infrequently reported. This injury can be easily detected by having the patient perform specific maneuvers on physical examination to accentuate any defect that may be present. In most cases, this injury is surgically repaired, although conservative treatment can be a successful option. Treatment options are discussed and recommendations given. A partial or complete tear of the pectoralis major muscle is a rare event and is often not easily detected on physical examination. Surgical repair is currently recommended to restore previous levels of strength and to correct the resulting cosmetic defect. Repair is rarely necessary to perform the normal activities of daily living.
A recent study has shown that posterior rotator cuff (RC) muscles are recruited at significantly higher levels than the anterior RC during shoulder flexion. It was proposed that the mechanism whereby the posterior RC muscles were providing shoulder stability during flexion was to counterbalance potential anterior humeral head translation caused by flexion torque producing muscles. This hypothesis implies that anterior RC activity should be higher than posterior RC activity during extension to prevent posterior humeral head translation. As the normal recruitment pattern of the RC during extension has not been established, the purpose of this study was to examine this hypothesis by comparing shoulder muscle activation levels and recruitment patterns during flexion and extension exercises. Electromyographic (EMG) activity was recorded from 9 shoulder muscles in 15 volunteers. Flexion and extension exercises were performed in prone at 20%, 50%, and 70% of each participant's maximal load. A repeated measures ANOVA was used to determine differences between exercises, muscles and loads, while Pearson's correlation analysis was used to relate mean EMG patterns. During extension subscapularis and latissimus dorsi were activated at higher levels than during flexion; during flexion, supraspinatus, infraspinatus, deltoid, trapezius, and serratus anterior were more highly activated than during extension. In addition, the pattern of activity in each muscle did not vary with load. These results support the hypothesis that during flexion and extension the RC muscles are recruited in a direction specific manner to prevent potential antero-posterior humeral head translation caused by torque producing muscles.
Shoulder disorders attributed to weight training are well documented in the literature, with prevalence rates exceeding that of the general population. Although researchers have identified both intrinsic and extrinsic risk factors among men who participate in weight training, a paucity of evidence-based research exists to describe risk factors inherent to participation among women. The purpose of this study was to investigate shoulder joint and muscle characteristics among healthy female recreational weight training (RWT) participants to determine specific risk-related adaptations that may occur from training. Eighty-eight women aged 18-55 (mean 26.8), including 57 who participated in upper extremity RWT and 31 controls with no record of RWT participation were recruited. Active range of motion (AROM), posterior shoulder tightness (PST), glenohumeral (GH) joint laxity, body weight-adjusted strength and strength ratios of force couples were compared between the RWT and control groups. Statistical analysis identified significant differences (p ≤ 0.004) between groups when analyzing shoulder internal rotation AROM, PST, and joint laxity. The RWT participants had decreased internal rotation AROM, greater PST, and anterior GH joint hyperlaxity when compared to the control group. No differences in strength ratios between groups were identified (p ≥ 0.109) implying the absence of weight training-induced muscle imbalances. The findings of this investigation suggest that female RWT participants are predisposed to mobility imbalances as a result of training. The imbalances identified in this investigation have been associated with shoulder disorders in both the general and athletic population thus may place weight training participants at risk for injury. Clinicians and strength and conditioning professionals should consider the biomechanical stresses and adaptations associated with RWT when prescribing exercises. Exercise prescription that mitigates mobility imbalances may serve to prevent injury in this population.
The popularity of resistance training (RT) is evident by the more than 45 million Americans who engage in strength training regularly. Although the health and fitness benefits ascribed to RT are generally agreed upon, participation is not without risk. Acute and chronic injuries attributed to RT have been cited in the epidemiological literature among both competitive and recreational participants. The shoulder complex in particular has been alluded to as one of the most prevalent regions of injury. The purpose of this manuscript is to present an overview of documented shoulder injuries among the RT population and where possible discern mechanisms of injury and risk factors. A literature search was conducted in the PUBMED, CINAHL, SPORTDiscus, and OVID databases to identify relevant articles for inclusion using combinations of key words: resistance training, shoulder, bodybuilding, weightlifting, shoulder injury, and shoulder disorder. The results of the review indicated that up to 36% of documented RT-related injuries and disorders occur at the shoulder complex. Trends that increased the likelihood of injury were identified and inclusive of intrinsic risk factors such as joint and muscle imbalances and extrinsic risk factors, namely, that of improper attention to exercise technique. A majority of the available research was retrospective in nature, consisting of surveys and descriptive epidemiological reports. A paucity of research was available to identify predictive variables leading to injury, suggesting the need for future prospective-based investigations.
The aim of this study was to investigate differences in muscle stiffness between subjects with stiff shoulders and controls, and to determine the correlation between posterior shoulder muscle stiffness and range of motion of rotation.
Prospective, cross-sectional study.
Twenty subjects with stiff shoulder and 20 healthy subjects.
Range of motion of rotation, and stiffness in 4 muscles (posterior deltoid, infraspinatus, teres minor and teres major), were measured in affected shoulders and control shoulders using a goniometer and a Myotonometer, respectively.
Patients with stiff shoulder had greater muscle stiffness than controls. Except for the teres major, significant correlations were found between internal rotation and stiffness of 3 muscles (r = 0.57-0.72). Among these 3 muscles, posterior deltoid muscle stiffness accounted for 51% of the variance in shoulder internal rotation beyond stiffness from the infraspinatus and teres minor muscles.
These findings support that muscle stiffness is related to shoulder range of motion. It is important to consider the posterior deltoid, infraspinatus, and teres minor muscles in the rehabilitation of patients with restricted internal rotation of the shoulder.
Unlabelled:
Congenital instability of the shoulder is a form of multidirectional instability not caused by a traumatic event. It is believed that excess laxity may be responsible for an overly elastic capsule and, therefore, can contribute to multidirectional instability. Minor microtraumatic events can progressively lead to the development of pain and lead to instability. The current preferred treatment is largely nonoperative with extensive rehabilitation of the dynamic restraints of the shoulder complex. In recalcitrant cases, operative intervention to restore stability may be necessary. It is of paramount importance to notice the directions of instability and to address each of them. Surgical procedures include open capsular shift, as well as arthroscopic capsular plication. Because multidirectional instability can be difficult to diagnose, this article will attempt to provide the clinician with a better understanding of the pathophysiology involved in this condition, the necessary steps for diagnosis, and considerations for treatment. A comprehensive guide to both nonoperative and operative treatment is reviewed in this article, as well as the surgical techniques used to decrease the capsular volume.
Level of evidence:
Level 5.
Shoulder disorders attributed to weight training are well documented in the literature; however, a paucity of evidence-based research exists to describe risk factors inherent to participation. Shoulder joint and muscle characteristics in the recreational weight training (RWT) population were investigated to determine specific risk-related adaptations that may occur from participation. Ninety participants, men between the ages of 19 and 47 (mean age 28.9), including 60 individuals who participated in upper-extremity RWT and 30 controls with no record of RWT participation, were recruited. Active range of motion (AROM), posterior shoulder tightness (PST), body weight-adjusted strength values, and agonist/antagonist strength ratios were compared between the RWT participants and the control group. Statistical analysis identified significant differences (p < 0.001) between the groups when analyzing shoulder mobility. The RWT participants had decreased mobility when compared with the control group for all AROM measurements except external rotation, which was greater. Strength ratios were significantly greater in the RWT group when compared with the control group (p <or= 0.001), implying agonist/antagonist muscle imbalances. The findings of this investigation suggest that RWT participants are predisposed to strength and mobility imbalances as a result of training. The imbalances identified have been associated with shoulder disorders in the general and athletic population; thus, these imbalances may place RWT participants at risk for injury. Common training patterns are biased toward large muscle groups such as the pectorals and deltoids but neglect muscles responsible for stabilization such as the external rotators and lower trapezius. Exercise selection that mitigates strength and mobility imbalances may serve to prevent injury in this population. Clinicians and strength and conditioning professionals should consider the biomechanical stresses and adaptations associated with RWT when prescribing upper-extremity exercises.
We evaluated 12 patients with 14 ruptures of the pectoralis major muscle to compare surgical and con servative management of this injury. Because 9 of the injuries occurred while weight lifting, we performed an anatomic study on human hemithorax specimens dur ing a simulated bench press to determine the mecha nism of this rare occurrence.
Excursion of individual pectoralis muscle fibers was measured at seven points along the broad muscle origin by the use of fine wires connected to the humeral insertion and to dial gauges on the study apparatus. Excursions in the concentric and eccentric phases of the lift were expressed as a percentage of resting fiber length. The short, inferior fibers of the muscle length ened disproportionately during the final 30° of humeral extension. We concluded that the inferior fibers have a mechanical disadvantage in the final portion of the eccentric phase of the lift, and application of high loads to these maximally stretched fibers produces rupture.
We repaired five acute and two chronic ruptures, and measured peak torque and work production against the contralateral side using Cybex isokinetic testing. Surgically treated patients showed comparable torque and work measurements, while conservatively treated individuals demonstrated a marked deficit in both peak torque and work/repetition. We recommend repair of complete pectoralis muscle ruptures in active patients who require maximum strength in vocational or avoca tional activities.
There are two distinct pathological categories of shoulder injury. In the older population, shoulder injury is generally a result of the degenerative aging process. In the younger population, it is commonly a result of the repetitiousness of an overhead sport. In the latter group, instability is typically the core problem, leading to the continuum of subluxation, impingement, and rotator cuff tear. A classification scheme, proposing four definitive types of shoulder injury, assists in directing an effective management program. Once diagnosed (the first step of treatment) a conservative rehabilitation program that emphasizes strengthening of the glenohumeral protectors, scapulohumeral pivotors, humeral positioners, and power drivers is advised. The surgery of choice, for the small minority who fail to respond to the rehabilitation program, is the anterior capsulolabral reconstruction. A sports medicine team working together with the athlete is instrumental in his/her return to sport.
Occult instability is recognized as a major cause of shoulder dysfunction in throwing athletes. Few studies have characterized the findings of occult instability in nonthrowers. The purpose of this study was to examine shoulder instability in a group of weight lifters. The symptoms, physical findings, and results of treatment for 23 shoulders in 20 athletes are presented. All athletes presented with a complaint of progressive inability to perform exercises with the upper extremity in the abducted, externally rotated position (the "at-risk" position) because of pain. One hundred percent of the athletes experienced posterior shoulder pain when the shoulder was placed in forced abduction and external rotation. Thirteen shoulders in 10 patients responded to conservative management including aggressive rehabilitation and modification of technique to avoid the at-risk position. The other 10 shoulders, which did not respond to conservative treatment, required surgical treatment to alleviate the symptoms. All 20 patients have successfully returned to their previous weight lifting activities.
In the young throwing athlete with shoulder pain, it is essential to recognize that glenohumeral joint instability (occult subluxation, rather than impingement) is the primary underlying pathology. Fortunately, conservative management is effective in most chronic overuse injuries. For those athletes with continued symptoms, surgical intervention may become necessary. The anterior capsulolabral reconstruction addresses the problem of glenohumeral joint instability by correcting the capsular redundancy, labrum damage, or both. The authors believe this most recent surgical technique and postoperative rehabilitation program has resulted in a significant improvement in our ability to more predictably and successfully return these athletes to prior competitive levels.
The shoulder is the most commonly dislocated joint in the body. The primary restraint to anterior instability is the anterior band of the inferior glenohumeral ligament, where lesions are found after dislocation. The amount of surgical plication required to eliminate instability and maintain full range of shoulder motion remains unclear. We performed tensile testing with the shoulder in abduction and external rotation in 11 human, fresh-frozen, cadaveric glenohumeral joints to improve understanding of the glenoid origin of the anterior band of the inferior glenohumeral ligament and to quantify midsubstance irrecoverable elongation. After measuring the length, width, and thickness of the anterior bands with digital micrometry, biomechanical properties were obtained on bone-ligament-labrum-bone (b-l-l-b) complexes. The complexes were aligned for tensile testing with the humerus abducted 60 degrees and externally rotated. The b-l-l-b complexes were then loaded to failure at a strain rate of 100%/sec. Seven of the complexes failed at the glenoid insertion site (representing the Bankart lesion), 2 at the humeral insertion site, and 2 at the anterior band midsubstance. The ultimate load for the b-l-l-b complexes was 353+/-32 N (mean+/-SE), and tensile stress at failure of the glenoid insertion site averaged 9.6+/-2.1 MPa. When the complex failed at the glenoid insertion site, total elongation of the b-l-l-b complex was 9.1+/-0.5 mm, and the ligament midsubstance strain was 13.0%+/-1.8%. Irrecoverable elongation was only 0.8 mm when failure occurred at the glenoid insertion site. Our results indicate patients with initial anterior glenohumeral instability have small irrecoverable capsuloligamentous elongation so that meaningful plication in addition to repair of the Bankart lesion may be unnecessary.
The anatomy of the glenohumeral ligaments has been shown to be complex and variable and their function is highly dependent on the position of the humerus with respect to the glenoid. The superior glenohumeral ligament with the coracohumeral ligament was shown to be an important stabilizer in the inferior direction, even though the coracohumeral ligament is much more robust than the superior glenohumeral ligament. The middle glenohumeral ligament provides anterior stability at 45 degrees and 60 degrees abduction whereas the inferior glenohumeral ligament complex is the most important stabilizer against anteroinferior shoulder dislocation. Therefore, this component of the capsule is the most frequently injured structure. An appropriate surgical procedure to repair the inferior glenohumeral ligament complex after shoulder dislocation must be considered. In addition, a detached labrum can lead to recurrent anterior instability and a compromised inferior glenohumeral ligament complex. However, additional capsular injury usually is necessary to allow anterior dislocation.
Rupture of the pectoralis major is being reported with increasing frequency1. Historically, injuries typically have resulted from accidental trauma, whereas recent injuries have occurred as a result of athletic competition or weight-lifting. During the last three decades, treatment trends have progressed toward more aggressive, early surgical repair for most injuries2-8. We report the case of a patient who sustained simultaneous bilateral rupture of the pectoralis major tendon. To our knowledge, this condition has not been previously reported in the English-language literature. Our patient was informed that data concerning the case would be submitted for publication. The patient agreed and, additionally, voluntarily supplied us with the initial post-injury photograph (Fig. 1).
Fig. 1
Photograph of the patient two days following injury, demonstrating severe ecchymoses over the anterior aspect of both arms.
Aforty-year-old man with no history of any serious medical conditions was performing dips on wide-grip parallel bars. While attempting to lower himself maximally from this wide-gripped position, he felt simultaneous painful and audible “pops” in both axillae and fell to the ground. He noticed the immediate onset of pain with subsequent swelling and ecchymosis in the axillae, and he had markedly diminished strength in adduction and internal rotation of both arms. The morning after the injury, the patient noticed the development of ecchymoses on the anterior surface of the arms (Fig. 1). As a result of military travel, the patient's presentation for medical attention was delayed by several weeks. During this time, the ecchymoses and pain largely resolved; however, there was continued, substantial bilateral weakness of arm adduction and internal rotation. The patient reported no history of complicating systemic medical illness or the use of fluoroquinolone or anabolic steroids.
On physical examination, the patient …
Shoulder muscles contribute to both mobility and stability of the glenohumeral joint. To improve treatments for shoulder instability, we focused on the contribution of the shoulder muscles to glenohumeral joint stability in clinically relevant positions. Both computational and experimental models were used. A computational model of the glenohumeral joint quantified stability provided by active muscle forces in both mid-range and end-range glenohumeral joint positions. Compared with mid-range positions, the resultant joint force at end-range positions was more anteriorly directed, indicating that its contribution to glenohumeral joint stability was diminished. In end-range positions, simulated increases in rotator cuff muscle forces tended to improve stability whereas increases in deltoid or pectoralis major muscle forces tended to further decrease stability. To validate these results, a cadaveric model, simulating relevant shoulder muscles, was used to quantify glenohumeral joint stability. When infraspinatus muscle activity was decreased, compressive forces decreased. When pectoralis major muscle activity was increased, anteriorly directed forces increased. If anteriorly directed forces increase or compressive forces decrease, stability of the glenohumeral joint decreases. This cadaveric model was then used to evaluate the effect of placing the joint in the apprehension position of abduction, external rotation, and horizontal abduction. Consistent with the results of our computational model, apprehension positioning increased anteriorly directed forces. Knowledge gained from these models was then used to develop a cadaveric model of glenohumeral joint dislocation. Dislocation resulted from the mechanism of forcible apprehension positioning when the appropriate shoulder muscles were simulated and a passive pectoralis major muscle was included. Capsulolabral lesions resulted that were similar to those observed in vivo. Shoulder muscle forces are usually powerful stabilizers of the glenohumeral joint, especially in mid-range positions when the passive stabilizers are lax. However, muscle forces can contribute to instability as well. Certain muscle forces decrease glenohumeral joint stability in end-range positions. We found this to be the case with both active and passive pectoralis major forces. Improved understanding of the contribution of muscle forces not only toward stability but also toward instability will improve rehabilitation protocols for the shoulder and prove useful in the treatment of joint instability throughout the body.
Posterior capsular contracture is a common cause of shoulder pain in which the patient presents with restricted internal rotation and reproduction of pain. Increased anterosuperior translation of the humeral head occurs with forward flexion and can mimic the pain reported with impingement syndrome; however, the patient with impingement syndrome presents with normal range of motion. Initial management of posterior capsular contracture should be nonsurgical, emphasizing range-of-motion stretching with the goal of restoring normal motion. For patients who fail nonsurgical management, arthroscopic posterior capsule release can result in improved motion and pain relief. In the throwing athlete, repetitive forces on the posteroinferior capsule may cause posteroinferior capsular hypertrophy and limited internal rotation. This may be the initial pathologic event in the so-called dead arm syndrome, leading to a superior labrum anteroposterior lesion and, possibly, rotator cuff tear. Management involves regaining internal rotation such that the loss of internal rotation is not greater than the increase in external rotation. In the athlete who fails nonsurgical management, a selective posteroinferior capsulotomy can improve motion, reduce pain, and prevent further shoulder injury.
The literature provides little information detailing the incidence of traumatic shoulder instability in young, healthy athletes.
Shoulder instability is common in young athletes.
Descriptive epidemiologic study.
We prospectively captured all traumatic shoulder instability events at the United States Military Academy between September 1, 2004, and May 31, 2005. Throughout this period, all new traumatic shoulder instability events were evaluated with physical examination, plain radiographs, and magnetic resonance imaging. Instability events were classified according to direction, chronicity, and type (subluxation or dislocation). Subject demographics, mechanism of injury, and sport were evaluated.
Among 4141 students, 117 experienced new traumatic shoulder instability events during the study period; 11 experienced multiple events. The mean age of these 117 subjects was 20.0 years; 101 students were men (86.3%), and 16 were women (13.7%). The 1-year incidence proportion was 2.8%. The male incidence proportion was 2.9% and the female incidence proportion was 2.5%. Eighteen events were dislocations (15.4%), and 99 were subluxations (84.6%). Of the 99 subluxations, 45 (45.5%) were primary events, while 54 (54.5%) were recurrent. Of the 18 dislocations, 12 (66.7%) were primary events, while 6 (33.3%) were recurrent. The majority of the 117 events were anterior in nature (80.3%), while 12 (10.3%) were posterior, and 11 (9.4%) were multidirectional. Forty-four percent (43.6%) of the instability events experienced were as a result of contact injuries, while 41.0% were a result of noncontact injuries, including 9 subluxations caused by missed punches during boxing; information was unavailable for the remaining 15%.
Glenohumeral instability is a common injury in this population, with subluxations comprising 85% of instability events.