Neuromuscular control and active trunk stiffness during isometric flexion and extension

2005 ◽  
Author(s):  
Kevin Granata ◽  
Patrick Lee
Keyword(s):  
Neuromuscular Control ◽  
Flexion And Extension

scholarly journals Neuromuscular Control of the Knee during a Resisted Single-Limb Squat Exercise

2005 ◽  
Vol 33 (10) ◽  
pp. 1520-1526 ◽  
Author(s):  
Richard K. Shields ◽  
Sangeetha Madhavan ◽  
Emy Gregg ◽  
Jennifer Leitch ◽  
Ben Petersen ◽  
...  
Keyword(s):  
Body Weight ◽  
Knee Joint ◽  
Knee Flexion ◽  
Neuromuscular Control ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Isometric Contractions ◽  
Low Resistance ◽  
Squat Exercise ◽  
Flexion And Extension

Background Closed kinetic chain exercises such as single-limb squats are preferred for knee rehabilitation. A complete understanding of the neuromuscular control of the knee during the single-limb squat is essential to increase the efficiency of rehabilitation programs. Hypothesis Performing a controlled single-limb squat with resistance to knee flexion and extension will increase the coactivation of the hamstring muscle group, thus reducing the quadriceps/hamstrings ratio. Study Design Descriptive laboratory study. Methods A total of 15 healthy human subjects (7 women, 8 men) performed controlled single-limb squats in a custom mechanical device that provided resistance to both flexion and extension. Subjects performed the task at 3 levels of resistance, set as a percentage of body weight. Surface electromyographic recordings from 7 muscles (gluteus medius, rectus femoris, vastus medialis oblique, vastus lateralis, biceps femoris, semitendinosus, and medial gastrocnemius) were collected during the task. Results Biceps femoris activity during knee flexion increased from approximately 12% maximum voluntary isometric contractions during low resistance (0% body weight) to approximately 27% maximum voluntary isometric contractions during high resistance (8% body weight). Although the quadriceps had greater activity than the hamstrings at all levels of resistance, the quadriceps/hamstrings ratio declined significantly with resistance (F2,27 = 29.05; P=. 012) from 3.0 at low resistance to 2.32 at the highest resistance. Conclusions Performing controlled resisted single-limb squats may help to simultaneously strengthen the quadriceps and facilitate coactivation of the hamstrings, thus reducing anterior tibial shear forces. The coactivation may also increase the dynamic control of the knee joint. Clinical Relevance The typical single-limb squat exercise performed in the clinic does not usually control for bidirectional resistance and knee joint excursion. As seen in this study, controlled single-limb squats at increased levels of resistance help to increase the coactivation of the hamstring muscles, which is essential to optimize neuromuscular control of the knee.

Human Finger Independence: Limitations due to Passive Mechanical Coupling Versus Active Neuromuscular Control

2004 ◽  
Vol 92 (5) ◽  
pp. 2802-2810 ◽  
Author(s):  
Catherine E. Lang ◽  
Marc H. Schieber
Keyword(s):  
Neuromuscular Control ◽  
The Other ◽  
Passive Condition ◽  
Mechanical Coupling ◽  
Complete Independence ◽  
Active Condition ◽  
Middle Ring ◽  
Human Finger ◽  
Passive Movements ◽  
Flexion And Extension

We studied the extent to which mechanical coupling and neuromuscular control limit finger independence by studying passive and active individuated finger movements in healthy adults. For passive movements, subjects relaxed while each finger was rotated into flexion and extension by a custom-built device. For active movements, subjects moved each finger into flexion and extension while attempting to keep the other, noninstructed fingers still. Active movements were performed through approximately the same joint excursions and at approximately the same speeds as the passive movements. We quantified how mechanical coupling limited finger independence from the passive movements, and quantified how neuromuscular control limited finger independence using an analysis that subtracted the indices obtained in the passive condition from those obtained in the active condition. Finger independence was generally similar during passive and active movements, but showed a trend toward less independence in the middle, ring, and little fingers during active, large-arc movements. Mechanical coupling limited the independence of the index, middle, and ring fingers to the greatest degree, followed by the little finger, and placed only negligible limitations on the independence of the thumb. In contrast, neuromuscular control primarily limited the independence of the ring, and little fingers during large-arc movements, and had minimal effects on the other fingers, especially during small-arc movements. For the movement conditions tested here, mechanical coupling between the fingers appears to be a major factor limiting the complete independence of finger movement.

Co-Contraction Recruitment and Spinal Load during Isometric Pushing Tasks

2005 ◽  
Vol 49 (14) ◽  
pp. 1330-1333 ◽  
Author(s):  
Kevin Granata ◽  
Patrick Lee ◽  
Tim Franklin
Keyword(s):  
Biomechanical Model ◽  
Neuromuscular Control ◽  
Surface Emg ◽  
Trunk Flexion ◽  
Materials Handling ◽  
Manual Materials Handling ◽  
Muscle Groups ◽  
Spinal Load ◽  
Theoretical Analyses ◽  
Flexion And Extension

Pushing and pulling tasks account for 20% of occupational low-back injury claims but few studies have investigated the neuromuscular control of the spine during these tasks. Primary torso muscle groups recruited during pushing tasks include the rectus abdominis and external obliques. However, theoretical analyses suggest that co-contraction of the paraspinal muscles is necessary to stabilize the spine during flexion exertions. A biomechanical model was implemented to estimate co-contraction and spinal load from measured surface EMG and trunk moment data recorded during trunk flexion and extension exertions. Results demonstrate that co-contraction during flexion exertions was approximately twice the value of co-contraction during extension. Co-contraction accounted for up to 47% of the total spinal load during flexion exertions and spinal load attributed to co-contraction was nearly 50% greater during flexion than during extension exertions despite similar levels of trunk moment. Results underscore the need to consider neuromuscular recruitment when evaluating biomechanical risks. Keywords: Spine; Co-contraction; Push; Manual Materials Handling; Biomechanics

The postcranial skeletons of the Triassic mammals Eozostrodon, Megazostrodon and Erythrotherium

1976 ◽  
Vol 273 (926) ◽  
pp. 387-431 ◽  
Keyword(s):  
Cervical Vertebrae ◽  
Neuromuscular Control ◽  
Shoulder Girdle ◽  
Large Size ◽  
Spinous Processes ◽  
Flexion Extension ◽  
Atlanto Axial Joint ◽  
Occipital Condyles ◽  
First Time ◽  
Flexion And Extension

Abundant but dissociated postcranial materials assignable to Eozostrodon (from Pont Alun quarry, Glamorgan, Wales) are described together with the associated, partial skeletons of Megazostrodon rudnerae and Erythrotherium parringtoni (from the Red Beds of southern Africa). The postcranial skeletons of these Triassic triconodonts are evaluated in both comparative and functional terms. Triassic triconodonts inherited from cynodonts specializations in the atlas-axis complex (e.g. double occipital condyles, a dens, reduction of the atlanto-axial zygapophyses) which permitted extensive cranial flexion-extension at the atlanto-occipital joint and rotation at the atlanto-axial joint. Marked differentiation of the major vertebral regions appears for the first time among mammals. In Megazostrodon , post-axis cervical vertebrae bear relatively narrow laminae and pedicles, broadly spaced zygapophyses, and rod-like, posteriorly recurved spinous processes; this pattern appears to be basic to mammals, and is retained among many later, generalized groups. The structure of the cervical vertebrae reveals that a cervico-thoracic flexure and an ascending posture of the neck were present. The large size of cervical vertebral foramina is evidence of a marked enlargement of the spinal cord at levels corresponding to the origin of the brachial plexus; this relationship may be interpreted as evidence of a greater neuromuscular control of the forelimb and a freedom of neck movement typical of mammals. An ‘anticlinal’ region in the thoracolumbar vertebral series has been identified in Eozostrodon ; this musculoskeletal specialization is related to axial flexion and extension characteristic of the posture and locomotor movements in mammals. The sacrum consists of at least two (and possibly three) vertebrae. The tail is moderately long and incorporates approximately twelve vertebrae. The shoulder girdle of Eozostrodon is little modified from the basic cynodont pattern; a T-shaped interclavicle, the lack of a supraspinous fossa, and the presence of both coracoids are features retained by monotremes. Both the coracoid and the scapula participate in the narrow, semi-lunar glenoid. The humero-ulnar joint is condylar, rather than trochlear, a condition retained by monotremes and other non-therian groups. The pelvic girdle represents a fully mammalian grade of organization; there is no evidence of epipubic bones. The limb skeleton, and particularly the joints, show various features consistent with an interpretation of well-developed mobility. The claw structure is suggestive of prehensility and an ability to climb. The hallux, at least, was probably somewhat divergent, and its joint structures indicate that abduction and extension (independent of the other digits) were possible. Triassic mammals as now known were all small, insectivorous forms; Megazostrodon was approximately 10 cm in head-body length, probably weighed between 20 and 30 g, and was proportioned similarly to medium-sized shrews (e.g. Suncus murinus, Blarina blarina ). A skeletal reconstruction of a Triassic triconodont is depicted, and an interpretation of their habits is presented.

Force Sense of the Knee Not Affected by Fatiguing the Knee Extensors and Flexors

2016 ◽  
Vol 25 (2) ◽  
pp. 155-163 ◽  
Author(s):  
Katelyn F. Allison ◽  
Timothy C. Sell ◽  
Anne Benjaminse ◽  
Scott M. Lephart
Keyword(s):  
Outcome Measures ◽  
Knee Flexion ◽  
Knee Injuries ◽  
Neuromuscular Control ◽  
Peak Torque ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Median Frequency ◽  
Force Sense ◽  
Flexion And Extension

Context:Knee injuries commonly occur in later stages of competition, indicating that fatigue may influence dynamic knee stability. Force sense (FS) is a submodality of proprioception influenced by muscle mechanoreceptors, which, if negatively affected by fatigue, may result in less-effective neuromuscular control.Objectives:To determine the effects of peripheral fatigue on FS of the quadriceps and hamstrings.Design:Quasi-experimental study design.Participants:20 healthy and physically active women and men (age 23.4 ± 2.7 y, mass 69.5 ± 10.9 kg, height 169.7 ± 9.4 cm).Interventions:Fatigue was induced during a protocol with 2 sets of 40 repetitions, and the last set was truncated at 90 repetitions or stopped if torque production dropped below 25% of peak torque.Main Outcome Measures:FS of the hamstrings and quadriceps was tested on separate days before and after 3 sets of isokinetic knee flexion and extension to fatigue by examining the ability to produce a target isometric torque (15% MVIC) with and without visual feedback (FS error). Electromyographic data of the tested musculature were collected to calculate and determine median frequency shift. T tests and Wilcoxon signed-rank tests were conducted to examine prefatigue and postfatigue FS error for flexion and extension.Results:Despite verification of fatigue via torque-production decrement and shift in median frequency, no significant differences were observed in FS error for either knee flexion (pre 0.54 ± 2.28 N•m, post 0.47 ± 1.62 N•m) or extension (pre –0.28 ± 2.69 N•m, post –0.21 ± 1.78 N•m) prefatigue compared with the postfatigue condition.Conclusions:Although previous research has demonstrated that peripheral fatigue negatively affects threshold to detect passive motion (TTDPM), it did not affect FS as measured in this study. The peripheral-fatigue protocol may have a greater effect on the mechanoreceptors responsible for TTDPM than those responsible for FS. Further investigation into the effects of fatigue across various modes of proprioception is warranted.

Neuromuscular Control and Active Trunk Stiffness during Isometric Flexion and Extension

2005 ◽  
Vol 49 (14) ◽  
pp. 1334-1338
Author(s):  
Kevin Granata ◽  
Patrick Lee
Keyword(s):  
Neuromuscular Control ◽  
Random Force ◽  
Muscle Stiffness ◽  
Spinal Stability ◽  
Trunk Flexion ◽  
Trunk Motion ◽  
Materials Handling ◽  
Motion Data ◽  
Trunk Movements ◽  
Flexion And Extension

Pushing and pulling tasks account for 20% of low-back injury claims. Torso flexion necessary for pushing exertions requires different muscle recruitment than for extension exertions typical of lifting tasks. These differences in recruitment and control may influence spinal stability and associated risk of injury. Active muscle stiffness is considered the primary stabilizing mechanism for spinal stability. Therefore, active trunk stiffness was recorded while subjects generated upright isometric trunk flexion and extension exertions against an isotonic preload. Small pseudo-random force disturbances were superimposed on the preloads causing small amplitude trunk movements. Trunk stiffness was computed from systems identification of the measured force and trunk motion data. Results demonstrated significantly greater stiffness during flexion exertions as compared to extension exertions. EMG data suggest this difference was due to increased co-contraction during the flexion exertions. These behaviours were attributed to the need to augment neuromuscular control of spinal stability during pushing tasks. Keywords: Spine; Co-contraction; Push; Manual Materials Handling; Biomechanics

Functional Anatomy Underlying Pharyngeal Swallowing Mechanics and Swallowing Performance Goals

2019 ◽  
Vol 4 (4) ◽  
pp. 648-655
Author(s):  
William G. Pearson ◽  
Jacline V. Griffeth ◽  
Alexis M. Ennis
Keyword(s):  
Functional Anatomy ◽  
Neuromuscular Control ◽  
Upper Esophageal Sphincter ◽  
Performance Goals ◽  
Laryngeal Elevation ◽  
Port Closure ◽  
Swallowing Dysfunction ◽  
Hyoid Movement ◽  
Pharyngeal Swallowing ◽  
Pharyngeal Constriction

Purpose Rehabilitation of pharyngeal swallowing dysfunction requires a thorough understanding of the functional anatomy underlying the performance goals of pharyngeal swallowing. These goals include the safe and efficient transfer of a bolus through the hypopharynx into the esophagus. Penetration or aspiration of a bolus threatens swallowing safety. Bolus residue indicates swallowing inefficiency. Several primary mechanics, or elements of the swallowing mechanism, underlie these performance goals, with some elements contributing to both goals. These primary mechanics include velopharyngeal port closure, hyoid movement, laryngeal elevation, pharyngeal shortening, tongue base retraction, and pharyngeal constriction. Each element of the swallowing mechanism is under neuromuscular control and is therefore, in principle, a potential target for rehabilitation. Secondary mechanics of pharyngeal swallowing, those movements dependent on primary mechanics, include opening the upper esophageal sphincter and epiglottic inversion. Conclusion Understanding the functional anatomy of pharyngeal swallowing underlying swallowing performance goals will facilitate anatomically informed critical thinking in the rehabilitation of pharyngeal swallowing dysfunction.

Motion Analysis of the Cervical Spine

2004 ◽  
Vol 9 (5) ◽  
pp. 1-11
Author(s):  
Patrick R. Luers
Keyword(s):  
Cervical Spine ◽  
Intervertebral Disk ◽  
Radiographic Evaluation ◽  
Ligamentous Injury ◽  
Pattern Of Injury ◽  
Motion Segment ◽  
Single Pattern ◽  
Compensatory Motion ◽  
Loss Of Motion ◽  
Flexion And Extension

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, defines a motion segment as “two adjacent vertebrae, the intervertebral disk, the apophyseal or facet joints, and ligamentous structures between the vertebrae.” The range of motion from segment to segment varies, and loss of motion segment integrity is defined as “an anteroposterior motion of one vertebra over another that is greater than 3.5 mm in the cervical spine, greater than 2.5 mm in the thoracic spine, and greater than 4.5 mm in the lumbar spine.” Multiple etiologies are associated with increased motion in the cervical spine; some are physiologic or compensatory and others are pathologic. The standard radiographic evaluation of instability and ligamentous injury in the cervical spine consists of lateral flexion and extension x-ray views, but no single pattern of injury is identified in whiplash injuries. Fluoroscopy or cineradiographic techniques may be more sensitive than other methods for evaluating subtle abnormal motion in the cervical spine. The increased motion thus detected then must be evaluated to determine whether it represents normal physiologic motion, normal compensatory motion, motion related to underlying degenerative disk and/or facet disease, or increased motion related to ligamentous injury. Imaging studies should be performed and interpreted as instructed in the AMA Guides.

Safety And Preliminary Efficacy of Magnetic Stimulation of Pelvic Floor with Hifem Technology in Urinary Incontinence

2018 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Urinary Incontinence ◽  
Pelvic Floor ◽  
Magnetic Stimulation ◽  
Muscle Tone ◽  
Pelvic Floor Muscle ◽  
Neuromuscular Control ◽  
Ultrasound Elastography ◽  
Functional Evaluation ◽  
Muscle Injuries ◽  
Stimulation Of

Introduction: BTL EMSELLA™ utilizes High-Intensity Focused Electromagnetic technology (HIFEM) to cause deep pelvic floor muscles stimulation and restoration of the neuromuscular control. Key effectiveness is based on focused electromagnetic energy, in-depth penetration and stimulation of the entire pelvic floor area. A single BTL EMSELLA™ session brings thousands of supramaximal pelvic floor muscle contractions, which are extremely important in muscle reeducation of incontinent patients. Objective: Prospective study to evaluate the safety and preliminary effectiveness of the use of BTL EMSELLA magnetic stimulation in urinary incontinence. Method: Thirty-two patients with light and moderate urinary incontinence were recruited to perform 6 sessions of BTL EMSELLA during three weeks of initial treatment. Follow-up after three months. The patients received sessions lasting 28 minutes, completing the different treatment protocols. Initially the patients underwent a quality of life test before and after treatment, evaluation with advanced ultrasound using elastography to measure the initial tissue's elasticity and be able to compare after treatment, clinical functional evaluation and urodynamic test. Results: No adverse reactions were observed. All the patients finished the treatment sessions. Two patients reported increased pain after treatment in the first session corresponding to a VAS scale greater than 5 with duration greater than three hours. The treatment was highly satisfactory in 84,4% of the patients. After the first three months the improvement was maintained in 77% of the patients. No muscle injuries were observed. Elastographic changes and improvement of muscle tone were detected by advanced ultrasound (elastography) in 100% of patients. Conclusions: BTL EMSELLA is safe, well tolerated and effective for the treatment of mild and moderate urinary incontinence. The observed elastographic changes demonstrate the improvement of pelvic floor muscle tone after treatment. A reduction in the symptoms of urinary incontinence was demonstrated. Recommendations: Continue increasing the number of cases for research and increase the variables that we have decided to incorporate in the next research section such as MRI and pressure calculation.

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