共查询到11条相似文献,搜索用时 15 毫秒
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Praveen Bhardwaj Navin Bhardwaj 《Journal of brachial plexus and peripheral nerve injury》2009,4(1):1-3
We present a new surgical technique for a pedicled teres major muscle transfer to improve shoulder abduction and flexion in children with sequelae of obstetric brachial plexus palsy. In addition, we provide the clinical outcome in the first 17 operated children. 相似文献
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Ilona J. Pinter Maarten F. Bobbert A.J. “Knoek” van Soest Jeroen B.J. Smeets 《Journal of electromyography and kinesiology》2010,20(5):923-931
Maximal voluntary isometric torque–angle relationships of elbow extensors and flexors in the transverse plane (humerus elevation angle of 90°) were measured at two different horizontal adduction angles of the humerus compared to thorax: 20° and 45°. For both elbow flexors and extensors, the torque–angle relationship was insensitive to this 25° horizontal adduction of the humerus. The peak in torque–angle relationship of elbow extensors was found at 55° (0° is full extension). This is closer to full elbow extension than reported by researchers who investigated this relationship in the sagittal plane. Using actual elbow angles during contraction, as we did in this study, instead of angles set by the dynamometer, as others have done, can partly explain this difference.We also measured electromyographic activity of the biceps and triceps muscles with pairs of surface electrodes and found that electromyographic activity level of the agonistic muscles was correlated to measured net torque (elbow flexion torque: Pearson’s r = 0.21 and extension torque: Pearson’s r = 0.53). We conclude that the isometric torque–angle relationship of the elbow extensors found in this study provides a good representation of the force–length relationship and the moment arm–angle relationship of the elbow extensors, but angle dependency of neural input gives an overestimation of the steepness. 相似文献
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The present research investigates factors contributing to bradykinesia in the control of simple and complex voluntary limb
movement in Parkinson’s disease (PD) patients. The functional scheme of the basal ganglia (BG)–thalamocortical circuit was
described by a mathematical model based on the mean firing rates of BG nuclei. PD was simulated as a reduction in dopamine
levels, and a loss of functional segregation between two competing motor modules. In order to compare model simulations with
performed movements, flexion and extension at the elbow joint is taken as a test case. Results indicated that loss of segregation
contributed to bradykinesia due to interference between competing modules and a reduced ability to suppress unwanted movements.
Additionally, excessive neurotransmitter depletion is predicted as a possible mechanism for the increased difficulty in performing
complex movements. The simulation results showed that the model is in qualitative agreement with the results from movement
experiments on PD patients and healthy subjects. Furthermore, based on changes in the firing rate of BG nuclei, the model
demonstrated that the effective mechanism of Deep Brain Stimulation (DBS) in STN may result from stimulation induced inhibition
of STN, partial synaptic failure of efferent projections, or excitation of inhibitory afferent axons even though the underlying
methods of action may be quite different for the different mechanisms. 相似文献
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Youdas JW Amundson CL Cicero KS Hahn JJ Harezlak DT Hollman JH 《Journal of strength and conditioning research / National Strength & Conditioning Association》2010,24(12):3404-3414
This study compared a conventional pull-up and chin-up with a rotational exercise using Perfect·Pullup? twisting handles. Twenty-one men (24.9 ± 2.4 years) and 4 women (23.5 ± 1 years) volunteered to participate. Electromyographic (EMG) signals were collected with DE-3.1 double-differential surface electrodes at a sampling frequency of 1,000 Hz. The EMG signals were normalized to peak activity in the maximum voluntary isometric contraction (MVIC) trial and expressed as a percentage. Motion analysis data of the elbow were obtained using Vicon Nexus software. One-factor repeated measures analysis of variance examined the muscle activation patterns and kinematic differences between the 3 pull-up exercises. Average EMG muscle activation values (%MVIC) were as follows: latissimus dorsi (117-130%), biceps brachii (78-96%), infraspinatus (71-79%), lower trapezius (45-56%), pectoralis major (44-57%), erector spinae (39-41%), and external oblique (31-35%). The pectoralis major and biceps brachii had significantly higher EMG activation during the chin-up than during the pull-up, whereas the lower trapezius was significantly more active during the pull-up. No differences were detected between the Perfect·Pullup? with twisting handles and the conventional pull-up and chin-up exercises. The mean absolute elbow joint range of motion was 93.4 ± 14.6°, 100.6 ± 14.5°, and 99.8 ± 11.7° for the pull-up, chin-up, and rotational exercise using the Perfect·Pullup? twisting handles, respectively. For each exercise condition, the timing of peak muscle activation was expressed as a percentage of the complete pull-up cycle. A general pattern of sequential activation occurred suggesting that pull-ups and chin-ups were initiated by the lower trapezius and pectoralis major and completed with biceps brachii and latissimus dorsi recruitment. The Perfect·Pullup? rotational device does not appear to enhance muscular recruitment when compared to the conventional pull-up or chin-up. 相似文献
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Tennis elbow defines a condition of pain and tenderness over the lateral epicondyle of the humerus. The exact aetiology of the injury is not yet fully understood. The major constituent of tendons is type 1 collagen which is encoded by COL1A1 gene. The aim of the study was to determine whether Sp1 binding site polymorphism (SNP rs1800012; 1546G/T) within the intronic region of COL1A1 gene is associated with tennis elbow. One hundred and three tennis elbow patients and one hundred and three healthy subjects without any history of previous ligament or tendon injuries were recruited for this genetic association study. All participants were genotyped for the COL1A1 Sp1 binding site polymorphism by using PCR–RFLP method. There were no observed statistical differences in the genotype (p = 0.17) or allele (p = 0.11) distributions between the groups. G allele frequency in patients and controls was 82.5% and 76.21%, and T allele frequency was 17.5% and 23.79% respectively. This study has shown that there is no association between this polymorphism and tennis elbow within the population studied. 相似文献
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《Journal of Biomedical Engineering》1979,1(1):55-57
The subjective impression of many patients using ‘swing through’ gait, in which the body is swung over the crutches with both feet clear of the ground, is that elbow crutches are less stable and more difficult to use than conventional underarm crutches (known as axillary crutches). A study was undertaken on ten normal subjects to see if objective measurements of speed and relative energy expenditure by means of heart rate monitoring via radio telemetry could confirm these impressions when both types of crutch were compared to normal walking. The results unexpectedly showed that heart rates were higher for axillary crutches, even though all subjects considered them easier to use than elbow crutches. The increase in heart rate using axillary crutches requires further study, but it was considered that it might in part be due to pressure on the thoracic cage. Because of this, Canadian crutches, which are a compromise between the two former types and do not bear on the thorax, were similarly monitored. Results from this third trial showed a marked decrease in heart rate with a marginal increase in speed over both axillary and elbow crutches. Because of this a recommendation is made for Canadian crutches to be used more frequently. 相似文献
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R. T. Raikova D. A. Gabriel H. Ts. Aladjov 《Computer methods in biomechanics and biomedical engineering》2013,16(4):211-219
Experimental investigation of practicing a dynamic, goal-directed movement reveals significant changes in kinematics. Modeling can provide insight into the alterations in muscle activity, associated with the kinematic adaptations, and reveal the potential motor unit (MU) firing patterns that underlie those changes. In this paper, a previously developed muscle model and software (Raikova and Aladjov, Journal of Biomechanics, 35, 2002) have been used to investigate changes in MU control, while practicing fast elbow flexion to a target in the horizontal plane. The first trial (before practice) and the last trial (after extensive practice) of two subjects have been simulated. The inputs for the simulation were the calculated external moments at the elbow joint. The external moments were countered by the action of three flexor muscles and two extensor ones. The muscles have been modeled as a mixture of MUs of different types. The software has chosen the MU firing times necessary to accomplish the movement. The muscle forces and MUs firing statistics were then calculated. Three hypotheses were tested and confirmed: (1) peak muscle forces and antagonist co-contraction increase during training; (2) there is an increase in the firing frequency and the synchronization between MUs; and (3) the recruitment of fast-twitch MUs dominates the action. 相似文献
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Claes Krogh-Lund Kurt J?rgensen 《European journal of applied physiology and occupational physiology》1992,64(4):359-370
Isometric flexion of the right elbow at 15% of the maximal voluntary contraction (MVC) was maintained to the limit of endurance (elbow angle 135°). The surface electromyogram (EMG) of the brachioradialis (BR) and biceps brachii (BB) muscles was recorded for calculation of conduction velocity (CV) by the cross-correlation method, and determination of median frequency (fm) and root mean square (rms) amplitude. Perceived exertion was rated for both muscles, and heart rate and blood pressure were measured. The EMG of ten brief 15% MVC contractions distributed over a 30-min recovery period was also recorded. Eleven males in their twenties volunteered for the investigation. The average endurance time was 906 (SD 419) s. Mean CV for the unfatigued muscles was 4.2 (SD 0.41) m·s–1 (BR), and 4.3 (SD 0.29) m·s–1 (BB). The contraction caused a significant decrease in CV of BR (12%,P<0.001) whereas CV variation of BB remained insignificant. Concurrently the meanf
m of both muscles dropped to approximately 66% of their initial values and their average rms amplitudes grew by approximately 380% (BR and BB:P<0.001, both parameters). The 1st min of recovery lowered the rms amplitudes by approximately 60% (BR and BB:P<0.01), while thef
m increased to approximately 88% of the initial recording (BR,P<0.01; BB,P<0.05). The accompanying small increases in CV were beyond the level of significance. Over the next 29 min a significant parallel restitution inf
m and CV took place; changes inf
m evidenced a simple one to one reflection of relative CV variation. A similar uncomplicated linear causality between relative changes in CV andf
m was hypothesized for the endurance contraction. Consequently, the 12% CV decrease of the BR accounted for only one-third of the fatigue inducedf
m reduction of 33%, while two-thirds were assumed to be attributable to centrally mediated regulatory interventions in motor unit (MU) performance. Independent of contributions from the virtually unchanged CV, thef
m of the BB muscle decreased by 35%; from one subject exhibiting a remarkably manifest burst-type pattern of MU activity it is argued that synchronization/grouping of MU firing predominantly determined the power redistribution in the BB spectrum. 相似文献