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No description available.

Gloved work has been shown to increase the effort required to perform manual tasks. In power grip tasks, these differences have been observed as reductions in strength and increases in muscular effort. Decreases in force output have been attributed to a number of factors, including loss of tactile sensitivity, glove flexibility or suppleness, thickness, changes in hand geometry, and friction at the glove-object interface. Glove research has rarely quantified glove attributes, and often compared gloves of varying material and physical properties. This research had the unique opportunity to control for a number of these properties by using three sets of identical gloves (powerline maintainers? insulating rubber gloves), differing only in thickness. <br /><br /> Administering the Von Frey Hair Test indicated that the gloves did indeed decrease tactile sensitivity. This research showed that increasing glove thickness led to large decreases in maximum power grip force. Small changes in hand geometry, such as increased interdigital space or grip span, affected force output. In the same hand posture, participants increased their grip force with increasing glove thickness for the object lifting task but were able to maintain a fixed submaximal force with visual feedback. The decrease in tactile sensitivity is a likely cause of this difference. <br /><br /> Muscular activity was affected by wearing the gloves while performing manual tasks. Inconsistent responses of muscular activation were seen in gloved maximum grip effort, while overall increases in electromyographic activity were recorded for tasks at submaximal levels when wearing gloves. <br /><br /> Interdigital spacing had different effects on maximal and submaximal tasks. For maximum effort power grip, interdigital spacing decreased force output by as much as 10%, with no significant changes in muscle activation. For submaximal tasks, no significant differences were seen in muscular activity or in force output. The overall force capability of the gloved user is hindered by changes in interdigital spacing at near maximal effort, but does not appear to be for tasks requiring lower grip force, such as the lifting task which required roughly 20%MVC. Overall, the effect of wearing these gloves on the users, the powerline maintainers, is a substantially increased effort to work. This research contributes to a greater understanding of why and how gloves inhibit performance.

Title: Stereognosis assessment in the hands area of physiotherapy students. Objectives of work: The main objective of this dissertation is an evaluation of stereognosis functions of hands and also the influence from the practise of palpation skills on the stereognosis at a group of thirty physiotherapy students from the first-year bachelor's degree during two measurements at an interval of six months. Next aim is to compare results of these measurements and to evaluate potential changes. Methods: This dissertation work was made by form of clinical study. The evaluation criterion was time and perfection in performed tests. For the assessment of hand stereognosis at the research group were used 4 simple tests without using sight: test by Petrie - sort the balls by size, to recognise a foam made letters and to determine the roughness of sandpaper. Results: The results show that during the study of physiotherapy at students there has been a slight development in the stereognosis functions. The influence of somatosensory learning during the six months period helped to reduce the number of errors which have been made by probands while taking the assigned tests. Results indicate that regular and careful practise of palpation ability has a particular influence for development and improvement of...

Orientador : José Carlos Plácido da Silva / Banca: José Antonio Galbiatti / Banca: Luis Carlos Paschoarelli / Resumo: O presente trabalho avaliou 60 indivíduos, sem patologias, 30 homens e 30 mulheres, entre 17 e 70 anos, totalizando 120 membros superiores. Elaborou-se um protocolo, a fim de se avaliar a força de preensão palmar plena, medida com o Dinamômetro JAMAR®, e a força de preensão pulpo-lateral, medida com o Medidor de Pinça B&L, correlacionando-as com o gênero, idade, posições dos membros superiores e medidas antropométricas da mão. Constatou-se que ambas as forças de preensão foram maiores no gênero masculino do que no gênero feminino, assim como, as medidas antropométricas das mãos. Levando-se em conta a correlação das forças com as posições dos membros superiores, nas quais foram avaliadas as forças não se encontrou correlação estatisticamente significativa em nenhuma das posições, porém, observou-se correlação com algumas medidas antropométricas das mãos, como largura da mão, comprimento do polegar e do dedo médio, assim como da mão. Portanto as medidas antropométricas devem ser consideradas em uma avaliação clínica e/ou ergonômica. / Abstract: The present research evaluated 60 people without any current pathologies, 30 male and 30 female whose age range went from 17 to 70 years old making up a total of 120 upper limbs. A protocol was created aiming to evaluate full grip strength, measured with JAMAR® Dynamometer, and lateral pulp grasp measured with B&L Pinch, relating them to gender, age, upper limbs positions and anthropometrical hand measurements. It has been noticed that both grip strengths were larger with males rather than females as well as the anthropometrical hand measurements. Taking into consideration the relation of the forces with the upper limbs positions in which the forces were evaluated, no meaningful statistical relation was found in any of the positions, however, a relation with some anthropometrical hand measurement were noticed such as hand width, thumb and middle finger length, as well as the hand’s. Therefore, the anthropometrical hand measurements shall be regarded towards a clinical and/or ergonomic evaluation. / Mestre

The friction of tyres on roads has been of practical importance for many years with nearly 80% of terrestrial traffic making use of rubber tyres. Tyres provide the grip required for vehicle acceleration, braking and cornering. In order for a tyre to grip on a snow covered surface friction mechanisms such as “ploughing”, (where sharp tread block edges dig into and break bonds between the snow grains) and fluid film lubrication must be considered. These are not present when a tyre interacts with tarmac. In addition metamorphism of the snow over time can result in variations of the structure and mechanical properties, this can occur rapidly especially when dealing with temperatures close to snows melting point. When full car-scale outdoor testing is carried out the snow conditions cannot be controlled and vary daily. This means the snow properties must be measured every day so that any observed variations in friction can be attributed to the tyres rather than the snow. At present the simple measurements being carried out on the snow tracks have not proved sufficient to pick up on the variations in the snow. This leads to inconsistent results: one tyre behaves differently on two different days, even though the snow was measured to be the same. This has resulted in the need for further study of the way snow variations influence the grip of winter tyres. The primary aim of this study is to identify which snow properties contribute to the friction of tyres on snow and be able to estimate the friction from measurements of snow properties. This work is the first comprehensive study to combine: multiple snow properties, microstructure characterisation, measurement of friction behaviour and different snow (both artificial and natural). In order to study the way snow affects the grip of winter tyres, methods of manufacturing artificial snow with consistent mechanical properties and microstructure are used. A method of blending ice chips (a solid state fracturing process) and compressing the resulting snow to form a test track was developed during a previous PhD carried out in our group. An alternate snow microstructure was created by using an established process of creating snow by vapour deposition. The process was simplified and downscaled, the resulting snow consisted of large dendritic grains, very different to the blended ice chips. Both snows were pressed in identical manners to create snow testing tracks. In addition, natural snow collected from the field was tested to compare with the artificial snow. In order to investigate how the variations in the snow affected the friction of tyres extensive testing was carried out in a cold room using a linear tribometer, using procedures established in previous studies. Two analytical rubber samples were used to investigate the friction, a rounded edge sample and a siped sample. Testing was carried out at -10°C at speeds of 0.01m/s, 0.1m/s and 1m/s. A significant part of this PhD involved the development of new methods and equipment which have not been used to study snow in this way before. In order to characterise mechanical properties, shear testing, compression testing and cohesion testing were carried out. To investigate snow microstructure, surface profilometry, microscopy and X-ray microtomography were used. Correlating the changes observed in snow characteristics with the changes recorded in the coefficient of friction has allowed the development of an empirical equation. This can be used to predict the coefficient of friction of a given snow based on three relatively simple snow measurements: a compression test to calculate the effective modulus, a roughness measurement to calculate the peak count density and a snow penetration test. For the first time this study allows us to use the empirical equation to estimate the relative contributions of the ploughing and surface friction mechanisms to the total friction. This allows the comparison of full car-scale test data as it is now possible to account for variations in the snow test tracks.

Healthy aging influences peripheral and central levels of the neuromotor system. These age-related changes contribute to the decline in dexterous manual behavior. Difficulty in performing activities of daily living increases reliance on external assistance. Understanding specific mechanisms leading to the decline in fine manual performance is crucial for their rehabilitation. In this thesis, we have attempted to increase our awareness of the causes underlying manual disability in old age. The first study investigated how old adults apply forces and moments on a freely-movable object using a precision grip (thumb and index finger) during functionally-relevant tasks. During the grasp-lift task old adults misaligned their thumb and finger contacts and produced greater grip force, greater external moments on the object around its roll axis, and oriented force vectors differently compared with young adults. During a precision-orientation task of inserting a slot on the object over a bar (`key-slot' task), old adults were more variable in digit-tip force directions and performed the key-slot task more slowly. With practice old adults aligned their digits, reduced their grip force, and minimized external moments on the object. We conclude that with old age comes with a reduced ability to control the forces and moments applied to objects during precision grasp and manipulation. This may contribute to the ubiquitous slowing and deteriorating manual dexterity in healthy aging. Another study investigated the effects of transcranial direct current stimulation (tDCS) to the contralateral M1 combined with motor training (MP) on changes in the forces applied to the object during grasp and manipulation. We also measured performances on functional tasks in healthy elderly individuals. Our results indicate that anodal tDCS+MP facilitates retention of learning on a skillful manual task in healthy old adults. Furthermore, improved retention on the pegboard test was associated with reduced force variability on the key-slot task that demanded similar precise control over the forces applied to the object. These findings suggest that the improvement in force steadiness is one of the potential mechanisms through which short-term anodal tDCS during motor training improved performance on a functional task that outlasted the intervention period. Furthermore, anodal tDCS over M1 in combination with motor practice also influenced motor response to tasks that critically depend on sensory signals in healthy old adults. Finally, we found that, in healthy elderly individuals, the memory representations scaling the lift force for the grip and lift task generalized, while the training-based learning on the ballistic task showed an incomplete transfer to the contralateral hand. These differences may indicate task-dependent interhemispheric transfer of learning in old age. Collectively, the work presented in this thesis demonstrates that the performance on dexterous manual tasks in healthy old adults may depend on how they configure their grasp, and control their finger forces (both linear and rotational) applied to the grasped object, specifically how smooth is the applied force.

In today’s technological society, there are increasingly less physical demands on the locomotor system. However, despite that notion strength and function in the hand’s complex biomechanical system are in fact both needed to cope with daily life. The grip function is a main function in the hand and is used in many examples of scientific research, for instance when assessing physical health and predicting the probabilities of premature mortality. A newly developed tool for assessing grip strength is Grip-it which today lacks support for the arm which would offer a standardized measured position for the upper extremity. The objective of this project was to design and evaluate a support for the arm that positions the upper extremity for maximum power capacity when assessing the amount of grip strength. A dynamic product development based on anthropometrical data has been applied to design a support for the arm with focus on the user. Literature surveys, preliminary studies and an evaluation of clinical personnel have provided the basis for a functional prototype, developed in close contact with the industry, and is now ready for user tests. The group of the project is of the opinion that there are good possibilities of developing a finished product, which would enable a standardized positioning when assessing the amount of grip strength with Grip-it. With new technology, Grip-it expands possibilities of analyzing grip strength assessments and can lead to an expanded research and understanding of these assessments, subsequently applicable to rehabilitation, various sports and evaluations of certain actions taken, such as surgical ones. / I dagens tekniska samhälle ställs allt mindre fysiska krav på rörelseapparaten. Trots det så krävs styrka och funktion i handens komplexa biomekaniska system för att klara av det dagliga livet. Gripfunktionen är en huvudfunktion i handen och används i flertalet forskningssyften, exempelvis vid bedömning av fysisk hälsa och att förutspå tidig dödlighet. Ett nyutvecklat mätinstrument för gripstyrka är Grip-it som idag saknar avlastningsarmstöd som möjliggör standardiserade mätpositioner för övre extremitet. Projektets syfte var att designa och utvärdera ett avlastningsarmstöd som positionerar övre extremitet för maximal kraftutveckling vid gripstyrkemätningar. För att designa ett avlastningsarmstöd, med användaren i centrum, har dynamisk produktutveckling utifrån antropometriska data tillämpats. Litteraturstudier, genomförd förstudie och utvärdering av klinisk personal har legat till grund för en funktionell prototyp som tagits fram i nära kontakt med näringslivet och nu är redo för användartester. Projektgruppen anser att det finns goda möjligheter för utveckling till färdig produkt, vilket skulle möjliggöra standardiserad positionering vid mätning av gripstyrka med Grip-it. Med ny teknik utökar Grip-it möjligheterna att analysera gripstyrkemätningar och kan leda till en utökad forskning och förståelse som sedan är applicerbar inom rehabilitering, olika sporter samt utvärdering av ingripanden, såsom kirurgiska ingrepp.

Gloved work has been shown to increase the effort required to perform manual tasks. In power grip tasks, these differences have been observed as reductions in strength and increases in muscular effort. Decreases in force output have been attributed to a number of factors, including loss of tactile sensitivity, glove flexibility or suppleness, thickness, changes in hand geometry, and friction at the glove-object interface. Glove research has rarely quantified glove attributes, and often compared gloves of varying material and physical properties. This research had the unique opportunity to control for a number of these properties by using three sets of identical gloves (powerline maintainers? insulating rubber gloves), differing only in thickness. <br /><br /> Administering the Von Frey Hair Test indicated that the gloves did indeed decrease tactile sensitivity. This research showed that increasing glove thickness led to large decreases in maximum power grip force. Small changes in hand geometry, such as increased interdigital space or grip span, affected force output. In the same hand posture, participants increased their grip force with increasing glove thickness for the object lifting task but were able to maintain a fixed submaximal force with visual feedback. The decrease in tactile sensitivity is a likely cause of this difference. <br /><br /> Muscular activity was affected by wearing the gloves while performing manual tasks. Inconsistent responses of muscular activation were seen in gloved maximum grip effort, while overall increases in electromyographic activity were recorded for tasks at submaximal levels when wearing gloves. <br /><br /> Interdigital spacing had different effects on maximal and submaximal tasks. For maximum effort power grip, interdigital spacing decreased force output by as much as 10%, with no significant changes in muscle activation. For submaximal tasks, no significant differences were seen in muscular activity or in force output. The overall force capability of the gloved user is hindered by changes in interdigital spacing at near maximal effort, but does not appear to be for tasks requiring lower grip force, such as the lifting task which required roughly 20%MVC. Overall, the effect of wearing these gloves on the users, the powerline maintainers, is a substantially increased effort to work. This research contributes to a greater understanding of why and how gloves inhibit performance.

No description available.