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Concept: Gluteus medius muscle

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The gluteus medius muscle is essential for gait and hip stability. Changes that occur in the gluteus medius muscles in patients with developmental dysplasia of the hip (DDH) are not well understood. A better understanding of DDH related changes will have positive repercussions toward hip soft tissue reconstruction.

Concepts: Tissues, Gluteus medius muscle

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We investigated the neuromuscular contributions to kinematic variability and thus step to step adjustments in posture and foot placement across a range of walking speeds in response to optical flow perturbations of different amplitudes using a custom virtual environment. We found that perturbations significantly increased step width, decreased step length, and elicited larger trunk sway compared to normal walking. However, perturbation-induced effects on the corresponding variabilities of these measurements were much more profound. Consistent with our hypotheses, we found that: (1) perturbations increased EMG activity of the gluteus medius and postural control muscles during leg swing, and increased antagonist leg muscle coactivation during limb loading in early stance, and (2) changes in the magnitude of step to step adjustments in postural sway and lateral foot placement positively correlated with those of postural control and gluteus medius muscle activities, respectively, in response to perturbations. However, (3) interactions between walking speed and susceptibility to perturbations, when present, were more complex than anticipated. Our study provides important mechanistic neuromuscular insight into walking balance control and important reference values for the emergence of balance impairment.

Concepts: Locomotion, Leg, Length, Speed, Gluteal muscles, Electromyography, Foot, Gluteus medius muscle

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INTRODUCTION: Exercise programmes are used in the prevention and treatment of adductor-related groin injuries in soccer; however, there is a lack of knowledge concerning the intensity of frequently used exercises. OBJECTIVE: Primarily to investigate muscle activity of adductor longus during six traditional and two new hip adduction exercises. Additionally, to analyse muscle activation of gluteals and abdominals. MATERIALS AND METHODS: 40 healthy male elite soccer players, training >5 h a week, participated in the study. Muscle activity using surface electromyography (sEMG) was measured bilaterally for the adductor longus during eight hip adduction strengthening exercises and peak EMG was normalised (nEMG) using an isometric maximal voluntary contraction (MVC) as reference. Furthermore, muscle activation of the gluteus medius, rectus abdominis and the external abdominal obliques was analysed during the exercises. RESULTS: There were large differences in peak nEMG of the adductor longus between the exercises, with values ranging from 14% to 108% nEMG (p<0.0001). There was a significant difference between legs in three of the eight exercises (35-48%, p<0.0001). The peak nEMG results for the gluteals and the abdominals showed relatively low values (5-48% nEMG, p<0.001). CONCLUSIONS: Specific hip adduction exercises can be graded by exercise intensity providing athletes and therapists with the knowledge to select appropriate exercises during different phases of prevention and treatment of groin injuries. The Copenhagen Adduction and the hip adduction with an elastic band are dynamic high-intensity exercises, which can easily be performed at any training facility and could therefore be relevant to include in future prevention and treatment programmes.

Concepts: Strength training, Exercise physiology, Gluteus medius muscle, Exercise, Hip, Physical exercise, Muscle, Electromyography

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To determine how gluteus medius (Gmed) and maximus (Gmax) activate during closed-chain functional rehabilitative exercises in those with and without chronic ankle instability (CAI).

Concepts: Gluteal muscles, Gluteus medius muscle

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STUDY DESIGN: Controlled laboratory study, repeated measures design. OBJECTIVES: To compare hip abductor muscle activity during selected exercises using fine-wire electromyography (EMG), and determine which exercises are best for activating gluteus medius and the superior portion of gluteus maximus while minimizing activity of tensor fascia lata (TFL). BACKGROUND: Abnormal hip kinematics (i.e. excessive hip adduction and internal rotation) has been linked to certain musculoskeletal disorders. The TFL is a hip abductor but also internally rotates the hip. As such, it may be important to select exercises that activate the gluteal hip abductors while minimizing activation of TFL. METHODS: Twenty healthy persons participated. EMG signals were obtained from the gluteus medius, superior gluteus maximus, and TFL muscles using fine-wire electrodes as subjects performed 11 different exercises. Normalized EMG signal amplitude was compared among muscles for each exercise using multiple 1-way repeated measures analyses of variance (ANOVAs). A descriptive gluteal-to-TFL muscle activation (GTA) index was used to identify preferred exercises for recruiting the gluteal muscles while minimizing TFL activity. RESULTS: Both gluteal muscles were significantly (P<.05) more active than TFL in unilateral and bilateral bridging, quadruped hip extension (knee flexed and extending), the clam, side-stepping, and squatting. The GTA index ranged from 18 to 115, and was highest for the clam (115), side-step (64), unilateral bridge (59), and both quadruped exercises (50). CONCLUSION: If the goal of rehabilitation is to preferentially activate the gluteal muscles while minimizing TFL activation, then the clam, side-step, unilateral bridge, and both quadruped hip extension exercises would appear to be most appropriate.J Orthop Sports Phys Ther, Epub 16 November 2012. doi:10.2519/jospt.2013.4116.

Concepts: Extension, Adduction, Hip, Muscle, Gluteus maximus muscle, Gluteal muscles, Gluteus medius muscle, Electromyography

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The purpose of this study was to determine the relationship between gluteal muscle activation and pelvis and trunk kinematics when catchers throw to second base. Forty-two baseball and softball catchers (14.74 ± 4.07 years; 161.85 ± 15.24 cm; 63.38 ± 19.98 kg) participated. Muscle activity of the bilateral gluteus maximus and medius were analyzed as well as pelvis and trunk kinematics throughout the throwing motion. It was discovered that at foot contact there were two significant inverse relationships between stride leg gluteus maximus activity and pelvis axial rotation (r = -0.31, r = 0.10, p = 0.05); and between trunk axial rotation and pelvis lateral flexion (r = -0.34, r = 0.12, p = 0.03). In addition, at foot contact, a significant positive relationship between the drive leg [throwing arm side] and trunk flexion (r = 0.33, r = 0.11, p = 0.04) was present. The results of this study provide evidence of gluteal activation both concentrically and eccentrically, in attempt to control the pelvis and trunk during the throwing motion of catchers. The gluteal muscles play a direct role in maintaining the stability of the pelvis and catchers should incorporate strengthening of the entire lumbo-pelvic hip complex into their training regimen. Incorporating concentric and eccentric gluteal exercises will help to improve musculoskeletal core stability thereby assisting in upper extremity injury prevention.

Concepts: Deadlift, Squat, Gluteus maximus muscle, Gluteus medius muscle, Gluteal muscles

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Previous electromyographic (EMG) studies of gluteus medius (GMed) have not accurately quantified the function of the three proposed structurally and functionally unique segments (anterior, middle and posterior). Therefore this study used anatomically verified locations for intramuscular electrode recordings in three segments of GMed to determine whether the segments are functionally independent. Bipolar fine wire electrodes were inserted into each segment of GMed in 15 healthy individuals. Participants completed a series of four walking trials, followed by maximum voluntary isometric contractions (MVICs) in five different positions. Temporal and amplitude variables for each segment were compared across the gait cycle using ANOVA. The relative contributions of each segment to the MVIC trials were compared with non-parametric tests. All segments showed a biphasic response during the stance phase of gait. There were no differences in amplitude variables (% MVIC) between segments, but the anterior segment had a later peak during both the first and second bursts.For the MVIC trials, there were significant differences in amplitude between segments in four of the five test positions. These data indicate that GMed is composed of three functionally independent segments. This study contributes to the theoretical understanding of the role of GMed.

Concepts: Gluteal muscles, Electromyography, Electroencephalography, Isometric exercise, Non-parametric statistics, Electrode, Segment, Gluteus medius muscle

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Background and purpose - There are no international guidelines to define adverse reaction to metal debris (ARMD). Muscle fatty atrophy has been reported to be common in patients with failing metal-on-metal (MoM) hip replacements. We assessed whether gluteal muscle fatty atrophy is associated with elevated blood metal ion levels and pseudotumors. Patients and methods - 263 consecutive patients with unilateral ASR XL total hip replacement using a posterior approach and with an unoperated contralateral hip were included in the study. All patients had undergone a standard screening program at our institution, including MRI and blood metal ion measurement. Muscle fatty atrophy was graded as being absent, mild, moderate, or severe in each of the gluteal muscles. Results - The prevalance of moderate-to-severe gluteal muscle atrophy was low (12% for gluteus minimus, 10% for gluteus medius, and 2% for gluteus maximus). Muscle atrophy was neither associated with elevated blood metal ion levels (> 5 ppb) nor with the presence of a clear (solid- or mixed-type) pseudotumor seen in MRI. A combination of moderate-to-severe atrophy in MRI, elevated blood metal ion levels, and MRI-confirmed mixed or solid pseudotumor was rare. Multivariable regression revealed that “preoperative diagnosis other than osteoarthrosis” was the strongest predictor of the presence of fatty atrophy. Interpretation - Gluteal muscle atrophy may be a clinically significant finding with influence on hip muscle strength in patients with MoM hip replacement. However, our results suggest that gluteal muscle atrophy seen in MRI is not associated with either the presence or severity of ARMD, at least not in patients who have been operated on using the posterior approach.

Concepts: Hip replacement, Squat, Solid, Gluteus maximus muscle, Gluteus minimus muscle, Muscle, Gluteus medius muscle, Gluteal muscles

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The purpose of this study was to compare the neuromotor control of the Gluteus Medius (GMED) and Gluteus Maximus (GMAX) muscles in runners with Achilles tendinopathy to that of healthy controls.

Concepts: Squat, Gluteus maximus muscle, Gluteus medius muscle, Gluteal muscles

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Clinical observation suggests that hip abductor weakness is common in patients with low back pain (LBP). The purpose of this study is to describe and compare the prevalence of hip abductor weakness in a clinical population with chronic non-specific LBP and a matched sample without LBP.

Concepts: Back pain, Gluteus medius muscle, Low back pain