Zoekresultaten

Responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects

PURPOSE: To compare the responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects.SCOPE: Nine healthy participants were subjected to perturbed walking on a split-belt treadmill. Four perturbation types were applied, each at five intensities. The activations of seven muscles surrounding the knee were measured using surface EMG. The responses in muscle activation were expressed by calculating mean, peak, co-contraction (CCI) and perturbation responses (PR) values. PR captures the responses relative to unperturbed gait. Statistical parametric mapping analysis was used to compare the muscle activation patterns between conditions.RESULTS: Perturbations evoked only small responses in muscle activation, though higher perturbation intensities yielded a higher mean activation in five muscles, as well as higher PR. Different types of perturbation led to different responses in the rectus femoris, medial gastrocnemius and lateral gastrocnemius. The participants had lower CCI just before perturbation compared to the same phase of unperturbed gait.CONCLUSIONS: Healthy participants respond to different perturbations during gait with small adaptations in their knee joint muscle activation patterns. This study provides insights in how the muscles are activated to stabilize the knee when challenged. Furthermore it could guide future studies in determining aberrant muscle activation in patients with knee disorders.

The Wrist Joint! Functional Analysis and Experimental Approach

The wrist allows the hand to combine dorsopalmar flexion and radioulnar deviation, a unique combination of functions that is made possible by a highly complex system of joints. The morphologic features of the carpal bones and of the radiocarpal and intercarpal contacts can be functionally interpreted by the mechanism that underlies the movements of the hand to the forearm. Displacements of the carpals take place in longitudinal articulation chains, with the proximal carpals having the position of an intercalated bone. The three articulation chains, radial, central, and ulnar, have interdependent movements at the radiocarpal and midcarpal levels. The linkage of movements in the longitudinal direction is associated to a transverse linkage by mutual joint contacts and by specific ligamentous interconnections. Kinematic analyses of the carpal joint motions have provided convincing evidence that each motion of the hand to the forearm demonstrates a specific motion pattern of the carpal bones. The stability of the carpus essentially depends on the integrity of the ligamentous system which consists of interwoven fiber bundles that differ in length, direction, and mechanical properties. Distinct separations into morphologic entities are difficult to make. From a functional point of view, the ligamentous interconnections can be regarded as a system that passively restricts movements of the carpals on one another and on the radius, but in a very differentiated way. The ligamentous system controls the linkage of the movements of the carpals, with the geometries of the bones and of the joint surfaces being, first of all, responsible for the kinematic behavior of the carpal joint.

The functional consequences of Generalized Joint Hypermobility

BACKGROUND: Generalized Joint Hypermobility (GJH) has been found to be associated with musculoskeletal complaints and disability. For others GJH is seen as a prerequisite in order to excel in certain sports like dance. However, it remains unclear what the role is of GJH in human performance. Therefore, the purpose of the study was to establish the association between GJH and functional status and to explore the contribution of physical fitness and musculoskeletal complaints to this association.METHODS: A total of 72 female participants (mean age (SD; range): 19.6 (2.2; 17-24)) were recruited among students from the Amsterdam School of Health Professions (ASHP) (n = 36) and the Amsterdam School of Arts (ASA), Academy for dance and theater (n = 36) in Amsterdam, The Netherlands. From each participant the following data was collected: Functional status performance (self-reported Physical activity level) and capacity (walking distance and jumping capacity: side hop (SH) and square hop (SQH)), presence of GJH (Beighton score ≥4), muscle strength, musculoskeletal complaints (pain and fatigue) and demographic characteristics (age and BMI).RESULTS: GJH was negatively associated with all capacity measures of functional status. Subjects with GJH had a reduced walking distance (B(SE):-75.5(10.5), p = <.0001) and jumping capacity (SH: B(SE):-10.10(5.0), p = .048, and SQH: B(SE):-11.2(5.1), p = .024) in comparison to subjects without GJH, when controlling for confounding: age, BMI and musculoskeletal complaints. In participants with GJH, functional status was not associated with performance measures.CONCLUSION: GJH was independently associated with lower walking and jumping capacity, potentially due to the compromised structural integrity of connective tissue. However, pain, fatigue and muscle strength were also important contributors to functional status.

A qualitative meta-analysis of performance measures and factors affecting international joint venture performance

A great deal of research has been undertaken to identify the factors affecting the success, failure, performance and stability of international equity joint ventures (EJVs) (see, for example, Beamish and Killing, 1996 for a review). Most of these studies, however, are static in nature. Although some scholars advocate a more dynamic approach to EJV research (for example, Parkhe, 1993; Stafford, 1995), to date only limited work has been done in this direction (Ring and van de Ven, 1994; Madhok, 1995a; Spekman et al., 1996; Ariño and de la Torre, 1996).

Children with Generalised Joint Hypermobility and Musculoskeletal Complaints: State of the Art on Diagnostics, Clinical Characteristics, and Treatment

INTRODUCTION: To provide a state of the art on diagnostics, clinical characteristics, and treatment of paediatric generalised joint hypermobility (GJH) and joint hypermobility syndrome (JHS).METHOD: A narrative review was performed regarding diagnostics and clinical characteristics. Effectiveness of treatment was evaluated by systematic review. Searches of Medline and Central were performed and included nonsymptomatic and symptomatic forms of GJH (JHS, collagen diseases).RESULTS: In the last decade, scientific research has accumulated on all domains of the ICF. GJH/JHS can be considered as a clinical entity, which can have serious effects during all stages of life. However research regarding the pathological mechanism has resulted in new potential opportunities for treatment. When regarding the effectiveness of current treatments, the search identified 1318 studies, from which three were included (JHS: n = 2, Osteogenesis Imperfecta: n = 1). According to the best evidence synthesis, there was strong evidence that enhancing physical fitness is an effective treatment for children with JHS. However this was based on only two studies.CONCLUSION: Based on the sparsely available knowledge on intervention studies, future longitudinal studies should focus on the effect of physical activity, fitness, and joint stabilisation. In JHS and chronic pain, the effectiveness of a multidisciplinary approach should be investigated.

Developing trust in international joint ventures