BACKGROUND: Frequently, patients who are candidates for reverse shoulder arthroplasty have had prior surgery that may compromise the anterior deltoid muscle. There have been conflicting reports on the necessity of the anterior deltoid thus it is unclear whether a dysfunctional anterior deltoid muscle is a contraindication to reverse shoulder arthroplasty. ...

OBJECTIVE: The purpose of this study was to compare the behavior of the trapezius muscle in patients with chronic mechanical neck pain (MNP) and clinical signs of scapula dysfunction to healthy controls. METHODS: This is a cross-sectional, between-participant study of trapezius muscle behavior. Eighteen volunteers with chronic MNP and 20 ...

Introduction Full range of motion and powerful shoulder abduction can be performed without any deltoid muscle function by the supplemental action of the supraspinatus and biceps brachii muscles. For evaluation of deltoid muscle function, we need to negate these actions, which can be done with the "akimbo test," in which ...

Disordered reflex activity and alterations in the neural control of walking have been observed after stroke. In addition to impairments in leg movement which affect locomotor ability after stroke, significant impairments are also seen in the arms. Altered neural control in the upper limb can often lead to altered tone ...

Facioscapulohumeral muscular dystrophy (FSHD) is a neuromuscular disease, characterized by an autosomal dominant mode of inheritance, facial involvement, and selectivity and asymmetry of muscle involvement. In general, FSHD typically presents before age 20 years. Usually, FSHD muscle involvement starts in the face and then progresses to the shoulder girdle, the humeral ...

BACKGROUND: Fatty infiltration and muscle atrophy have been described as interrelated characteristic changes that occur within the muscles of the rotator cuff after cuff tears, and both are independently associated with poor outcomes after surgical repair. We hypothesize that fatty infiltration and muscle atrophy are two distinct processes independently associated ...

This study aimed at determining the upper limb muscles coordination during a power backward giant swing (PBGS) and the recruitment pattern of motor units (MU) of co-activated muscles. The wavelet transformation (WT) was applied to the surface electromyographic (EMG) signal of eight shoulder muscles. Total gymnast's body energy and wavelet ...

BACKGROUND: The purpose of this study was to describe the complex anatomy surrounding the teres minor muscle. METHODS: Thirty-one cadaveric human shoulders were dissected. Qualitative fascial and neurovascular anatomy were described. Location of motor nerves to teres minor were measured in reference to local anatomy. RESULTS: Fascial anatomy of the ...

Rotator cuff tears are the most common tendon injury seen in orthopaedic patients. Muscle atrophy and fatty infiltration in rotator cuff muscles are considered among the key factors responsible for the failure of attempted repair of a massive rotator cuff tear. However, the pathophysiology of rotator cuff muscle atrophy and ...

ABSTRACT: Youdas, JW, Arend, DB, Exstrom, JM, Helmus, TJ, Rozeboom, JD, and Hollman, JH. Comparison of muscle activation levels during arm abduction in the plane of the scapula vs. proprioceptive neuromuscular facilitation upper extremity patterns. J Strength Cond Res 26(4): 1058-1065, 2012-This study quantified activation of 8 muscles of the ...

Suprascapular neuropathy remains a rare, albeit increasingly recognized, diagnosis. Despite its relatively low prevalence, it must be kept in the shoulder surgeon's mind as a potential cause of shoulder pain, particularly in patients where the history, physical examination, and imaging studies do not adequately explain a patient's symptoms or disability. ...

BACKGROUND: The rotator cuff has been hypothesized as a dynamic stabilizer at the shoulder joint yet evidence supporting this role remains inconclusive. We aimed to investigate the activity levels and recruitment patterns between the rotator cuff and superficial shoulder muscles in response to external perturbations to provide insight into the ...

The act of throwing requires proper functioning and timing of the entire kinetic chain musculature to generate a coordinated movement pattern for ball delivery. The role of the shoulder complex is vital in the transmission of force from the lower extremities and trunk to the arm and hand. A review ...

Overhead activities require the shoulder to be exposed to and sustain repetitive loads. The segmental activation of the body's links, known as the kinetic chain, allows this to occur effectively. Proper muscle activation is achieved through generation of energy from the central segment or core, which then transfers the energy ...

Recent evidence suggests that active trigger points (TrPs) in neck and shoulder muscles contribute to tension-type headache. Active TrPs within the suboccipital, upper trapezius, sternocleidomastoid, temporalis, superior oblique and lateral rectus muscles have been associated with chronic and episodic tension-type headache forms. It seems that the pain profile of this ...

PURPOSE: This study reports the results of restoring the deltoid and triceps functions in patients with C5, 6, and 7 root avulsion injuries by simultaneously transferring 4 intercostal nerves to the anterior axillary nerve and the nerve to the long head of the triceps through the posterior approach. METHODS: Nine ...

Objective: To compare the shoulder load during handcycling and wheelchair propulsion under similar conditions of external power in persons with spinal cord injury. Design: Cross-sectional. Subjects: Eight men with spinal cord injury. Methods: Kinetics and kinematics were measured during handbike and wheelchair propulsion at 25, 35, 45 and 55 W ...

BACKGROUND: Osteotomy of the lesser tuberosity in shoulder arthroplasty allows bony healing of the subscapularis tendon but does not prevent fatty degeneration in its muscle. Occurrence or increase in fatty degeneration may depend on the surgical technique. QUESTIONS/PURPOSES: We (1) assessed fatty degeneration in the subscapularis muscle and its cross-sectional ...

PURPOSE: Unfavorable psychosocial working conditions are hypothesized to lead to perceived stress, which, in turn, can be related to an increased risk of development of neck/shoulder symptoms through increased and sustained muscle activation. The aim of the present study was to test this hypothesized process model among medical secretaries, a ...

Histochemical and morphometric analyses were performed to characterize the fibre-type composition of two forelimb muscles of the South American subterranean rodent Ctenomys talarum. The studied muscles were the triceps lateralis, an extensor of the elbow, and the teres major, a flexor of the shoulder. It was found that these muscles ...

Although historically considered a diagnosis of exclusion, suprascapular neuropathy may be more common than once believed, as more recent reports are describing the condition as a cause of substantial pain and weakness in patients with and without concomitant shoulder pathology. The etiology is traction or compression of the suprascapular nerve. ...

The present study, a part of the PROOF (PRedicting Occupational biomechanics in OFfice workers) study, aimed to determine whether trapezius muscle effort was different across computer activities in a field study of computer workers, and also investigated whether head and shoulder postures were different across computer activities. One hundred twenty ...

The aim was to analyze the relationship between periods with uninterrupted neck muscle activity for ≥4 min and neck and shoulder pain. The trapezius muscle activity was recorded bilaterally on 40 young workers and students during a full shift. Neck and shoulder pain, mechanical work load and decision control were ...

Mental demands have been associated with increased risk of injuries; however, its influence on muscle fatigability remains unclear. The aim of this study was to investigate the interaction of mental workload and physical workload on muscle fatigability during repetitive shoulder work. Twelve young participants, balanced by gender, performed shoulder abduction ...

Unexpected sudden (un)loading of the trunk may induce inadequate responses of trunk muscles and uncontrolled trunk motion. These unexpected perturbations may occur in pushing tasks, when the cart suddenly starts moving (unloading) or is blocked by an obstacle (loading). In pushing, handle height affects the user's working posture, which may ...

To compare the therapeutic efficacy of acupuncture, massage, and Tachibana-Ryojutsu (one of Japanese traditional body balance therapy techniques (SEITAI)), on stiff shoulders, the subjects' muscle firmness, blood pressure, pulse, VAS, and body temperature were measured before and after the treatment. Forty-seven volunteer subjects gave written informed consent to participate in ...

Handheld dynamometry (HHD) is considered an objective method of measuring strength, but the reliability of the procedure can be compromised by inadequate tester strength and insufficient stabilization of the dynamometer especially, for the scapular muscles. Primarily, to determine the intrarater reliability of HHD when testing shoulder and scapular muscle strength, ...

Work-related musculoskeletal disorders (WMSDs) have high prevalence in sewing machine operators employed in the garment industry. Long work duration, sustained low level work and precise hand work are the main risk factors of neck-shoulder disorders for sewing machine operators. Surface electromyogram (sEMG) offers a valuable tool to determine muscle activity ...

Three ghrelin gene-derived peptides, acyl ghrelin, des-acyl ghrelin and obestatin, are implicated in the regulation of feeding, adipogenesis and glucose metabolism, as well as gut motility. The effects of ghrelin gene-derived peptides on lower esophageal sphincter motility, however, were unknown. We investigated the influence of acyl ghrelin, des-acyl ghrelin and ...

Ghrelin is a growth hormone (GH) secretagogue secreted mainly from the stomach that functions in controlling muscle volume and energy homeostasis. We here studied the effects of ghrelin on unloading-induced muscle atrophy using a mouse model of hindlimb suspension (HS). Ghrelin administration during 2-week HS alleviated reductions of muscle mass ...

Recently, detecting upper-limb motion intention for prosthetic control purpose attracted growing research attention. In most of the studies, recordings of forearm muscle activities were used as the signal sources, from which the intention of wrist and hand motions were detected using pattern recognition technology. However, most daily-life upper limb activities ...

This paper introduces a 4-DOFs exoskeletal meal assistance system (EMAS II) for progressive muscle dystrophy patient. It is generally better for the patient to use his/her hands by himself in daily life because active works maintain level of residual functions, health and initiative of him/her. The EMAS II that has ...

This study utilized a novel robotic device, the ACT-4D, to investigate the relationship between the flexion synergy and stretch reflexes in individuals with chronic hemiparetic stroke. Because the flexion synergy influences the amount of elbow flexor muscle activation present in the paretic limb during tasks requiring shoulder abduction loading, it ...

The influence of RFLP-BsrI polymorphisms at the ghrelin gene locus on carcass, meat quality parameters and muscle fiber characteristics of longissimus lumborum was studied in 168 barrows of the Polish Landrace breed. Analysis revealed a high frequency of the 1 allele (0.60) with the frequencies of the 11, 12 and ...

An accessory muscle adjacent to the extensor hallucis longus muscle (EHL) was observed between the EHL and the extensor digitorum longus muscle (EDL) in the anterior side of both legs of the cadaver of a 72-year-old male, during educational dissection, and it was observed that the tendon of this muscle ...

The aim of this study was to evaluate whether electrical muscle stimulation (EMS) on dominant wrist flexors causes an increase in the muscle strength of the contralateral wrist extensors. Twenty-three healthy, young, adult men were included in this prospective, double-blind, controlled study. Participants were randomly allocated to the EMS group ...

Surface electromyograms(EMG) during test contractions (TCs) were studied to assess the muscle strain in simulated mushroom picking. Additionally, the duration of the TC for the effective assessment was investigated. Nine female subjects performed standardized shoulder abduction and a stooped posture for one minute as TCs. Each experiment consisted of a ...

When an active muscle is stretched, the force increases due to strain of contractile and noncontractile proteins. We examined this force enhancement in rat extensor digitorum longus (EDL) and soleus muscles, which differ in their composition of these proteins, and their susceptibility to damage. Small stretches were applied at different ...

The purpose of this investigation was to determine which stretching technique, static or ballistic, is most effective for increasing hamstring muscle length when delivered at the same stretching dose over a 4-week training program. A single-blind, randomized controlled trial design was used in this investigation. Thirty-two participants (16 women and ...

Mechanical loading of muscles by intrinsic muscle activity or passive stretch leads to an increase in the production of reactive oxygen species. The NAD-dependent protein deacetylase SIRT1 is involved in the protection against oxidative stress by enhancing FOXO-driven Sod2 transcription. In this report, we unravel a mechanism triggered by mechanical ...

Our understanding the neurophysiologic characteristics of the human paraspinal muscles has historically been hindered by the lack of experimental techniques to examine these muscles function in vivo. In this article we describe a paired-pulse transcranial magnetic stimulation (TMS) protocol to quantify intracortical facilitation (ICF) and short-interval intracortical inhibition (SICI) of ...

Acute passive stretching has been shown to alter muscle-tendon unit (MTU) stiffness and to reduce peak tetanic force (pF). MTU mechanical properties and electro-mechanical delay (EMD) are closely related. Thus, EMD changes would be expected after stretching. The aim of the study was to assess the stretching-induced changes in both ...

Stretch increases the force and decreases energy consumption in skeletal muscles. Cardiac muscle response to stretch has been scarcely investigated, and the underlying mechanisms remain elusive. We hypothesized that stretch increases the force by modulating the cross-bridge (XB) cycling rate. Trabeculae (n=10) were isolated from rat right ventricles. Sarcomere length ...

The purpose of the present study was to examine the acute effects of passives stretching versus prolonged vibration on the active and passive properties of voluntary and evoked muscle actions of the plantar flexors. Eleven healthy men performed the isometric maximal voluntary contractions (MVCs) and passive range of motion (PROM) ...

Among the three main factors of motor impairment that emerge in chronological order following a lesion to central motor pathways, the last two antagonize movement: 1) stretch-sensitive paresis, a reduction of agonist motor unit recruitment upon voluntary command, worsened by antagonist stretch; 2) soft tissue contracture, and 3) muscle overactivity. ...

The purpose of this study was to determine failure stresses and failure lengths of actively and passively stretched myofibrils. As expected, myofibrils failed at average sarcomere lengths (about 6-7μm) that vastly exceeded sarcomere lengths at which actin-myosin filament overlap ceases to exist (4μm) and thus actin-myosin-based cross-bridge forces are zero ...

When activated muscle fibers are stretched at low speeds [≤ 2 optimal length (L(o))/s], force increases in two phases, marked by a change in slope [critical force (P(c))] that happens at a critical sarcomere length extension (L(c)). Some studies attribute P(c) to the number of attached cross bridges before stretch, ...

The sensory circuit of the stretch reflex arc, composed of specialized intrafusal muscle fibers and type Ia proprioceptive sensory neurons, converts mechanical information regarding muscle length and stretch to electrical action potentials and relays them to the central nervous system. Utilizing a non-biological substrate, surface patterning photolithography and a serum-free ...

Electromyography (EMG) of the shoulder girdle is commonly performed; however, EMG spectral properties of shoulder muscles have not been clearly defined. The purpose of this study was to determine the maximum power frequency, Nyquist rate, and minimum sampling rate for indwelling and surface EMG of the normal shoulder girdle musculature. ...

The purpose of this study was to determine the effect of acute static stretching on torque and electromyography (EMG) in female athletes (ATHs) and nonathletes (NONATHs) using both normalized (NORM) and nonnormalized (NONNORM) data. Fifteen ATHs recruited from women's National Collegiate Athletic Association Division II varsity basketball and volleyball teams ...