his study investigated the lower limb biomechanics during downhill and uphill running in habitual forefoot strike and habitual rearfoot strike runners. Fifteen habitual forefoot strike and fifteen habitual rearfoot strike recreational male runners ran at 3 m/s ± 5% during level, uphill and downhill overground running on a ramp mounted at 6° and 9°. Results showed that hill running had similar impacts on joint angles in rearfoot strike and forefoot strike runners, causing a decrease in hip flexion at initial contact during downhill running, an increase in knee flexion angle at initial contact during uphill running and a decrease in peak hip flexion angle. In addition to differences in ankle joint angle due to landing pattern difference between rearfoot strike and forefoot strike runners, forefoot strike runners had a more flexed hip angle during downhill running. Forefoot strike runners had an absent impact peak in all running conditions, while the impact peaks only decreased during the uphill conditions in rearfoot strike runners. Active peaks decreased during the downhill conditions in forefoot strike runners while active loading rates increased during downhill conditions in rearfoot strike runners. Compared to the level condition, parallel braking peaks were larger during downhill conditions and parallel propulsive peaks were larger during uphill conditions. Peak hip flexion moment was significantly greater while peak knee flexion moment was significantly lower in both groups during the downhill 9° condition. Forefoot strike runners had larger peak plantar flexion moments and peak ankle power absorption compared to rearfoot strike runners during all conditions. Forefoot strike runners had decreased peak power absorption at the knee joint during downhill and level running conditions. Combined with previous biomechanics studies, our findings of no impact peak in forefoot strike runners suggests that this landing pattern may have potential in reducing overuse running injuries. Forefoot strike running reduces loading at the knee joint and can be used as an effective strategy to reduce stress at the knee joint experienced with rearfoot strike running.

Exoskeletons are wearable assistive devices made to be worn by users to enhance the function of the joint, reduce metabolic costs, and reduce required biological work. This thesis looks at several different types of knee exoskeletons and how they affect the user’s biomechanics and reduce the tibiofemoral force experienced by the user. Tibiofemoral forces are one of the joint contact forces experienced at the knee and are dependent on the level of activity from the surrounding muscles (DeMers et al., 2014). The knee is one of the largest joints in the human body, but is also prone to injury and degradation, with a global incidence of 203 per 10,000 people developing knee osteoarthritis (Cui et al., 2020). Everyone’s step-by-step biomechanics are going very slightly but summed together the muscle activity will be very similar (Ivanenko et al., 2004). This makes it easy to design an exoskeleton for the common man and make slight alterations as needed. Through this literature review, it will be shown that powered exoskeletons can be effective at reducing the tibiofemoral forces during a variety of conditions, and are best suited by targeting the knee extensor muscles.

The biomechanics and muscle activity of forward and backward slope walking was investigated in humans to gain additional insight into neural control strategies. An adjustable instrumented ramped walkway was constructed and validated. Kinematic, ground reaction force, and muscle activity data were collected from nine subjects walking at three grades (0%, 15%, and 39%) for each of four conditions (forward upslope and downslope and backward upslope and downslope). The changes observed in the data were generally progressive from 0% to 15% to 39% grade. During forward downslope walking the joint moment pattern at the knee changed significantly, power absorption increased, and changes in the muscle activity patterns corresponded directly to changes in joint mechanics. During forward upslope walking, the hip joint moment pattern changed significantly, power generation increased, and changes in the muscle activity pattern were not directly related to changes in the joint moments at all joints. The muscle activity pattern data suggest that modifications to the level walking control strategies were necessary during slope walking. Backward slope walking was used to further explore these findings. Backward upslope and forward downslope kinematics and kinetics were similar, as were those from backward downslope and forward upslope walking. However, power generation increased during upslope walking tasks and power absorption increased during downslope walking tasks, and the changes in muscle firing patterns were more similar for these tasks than for those with similar kinetics. Increased power generation required compensatory muscle activity at adjacent joints that was not directly related to the moments at those joints; increased power absorption did not require such compensatory activity, and muscle activity was directly related to the joint moments. Overall, these data suggest that changes in the control strategy and/or modifications of the level walking control strategy are strongly influenced by the power demands of a task. The characterization of forward and backward slope walking presented here is novel and has important implications for many patient populations; knowledge of the task mechanics may be used to develop or improve physical therapy and rehabilitation exercise programs as well as the design of replacement and/or assistive devices.

A literatura refere que os estímulos produzidos pelos diferentes tipos de contração no sistema músculo-esquelético geram adaptações específicas. A locomoção em aclive e declive vem sendo utilizada como modelo de treinamento concêntrico e excêntrico para estudos dessas adaptações em animais. Sendo assim este estudo teve o objetivo de avaliar características mecânicas e histológicas do músculo sóleo de ratos submetidos a treinamento em aclive ou declive. Foram avaliados 36 ratos Wistar machos (90 dias de idade no início do treinamento) divididos igualmente em três grupos: aclive (A), declive (D) e controle (C). Os treinamentos foram realizados em uma esteira adaptada com raias individuais e inclinação de + 16° (aclive) ou – 16° (declive). Os animais passaram por um período de adaptação de uma semana na esteira com a inclinação específica e, em seguida, foram avaliados quanto à velocidade máxima suportada. Os treinamentos aconteceram com velocidade (relativa à máxima avaliada) e tempo progressivos ao longo de oito semanas (29 sessões). Dois dias após o último treino os animais foram anestesiados com Tiopental Sódico (± 5 ml), os músculos sóleos direitos e esquerdos foram removidos e os animais decapitados. Os músculos sóleos da pata direita (n = 7C, 8A, 9D) foram submetidos a ensaios de tração em uma máquina EMIC DL2000, com célula de carga de 50 N a velocidade de 1,66 m·s-1. Durante o ensaio, as amostras foram borrifadas com solução salina a cada um minuto. Os músculos sóleos esquerdos foram retirados para contagem de sarcômeros (n = 4A, 4C e 5D) e análise na proteína titina por Western Blot (n = 4 por grupo). Foi verificada a normalidade e homogeneidade dos dados e a confiabilidade das medidas foi avaliada pelo coeficiente Alpha de Cronbach. Comportamentos individuais foram analisados pelo Coeficiente de Correlação Intraclasse (ICC); ANOVA one way e post hoc de Bonferroni e teste não paramétrico Kruskal-Walls foram aplicados para identificação das diferenças entre os grupos. Dos 36 animais, três morreram antes do final do experimento. Os coeficientes Alpha de Cronbach indicaram confiabilidade das medidas com valores próximos a um para todas as variáveis. Os dados mecânicos dos animais que treinaram em declive apresentaram menores valores de ICC, mesmo assim significativos. As comparações entre os grupos indicaram aumento significativo da rigidez da curva tensão X deformação para os animais treinados em aclive e declive, e maior deformação da curva para os animais controle. Foi encontrado aumento da média da tensão passiva dos músculos dos animais treinados (57 ± 5 e 56 ± 11 para A e D; 51,6 ± 7,7 para C), contudo essa diferença não foi estatisticamente significativa, possivelmente devido a grande variabilidade dos dados mecânicos. Em relação ao número de sarcômeros em série os animais que treinaram em declive apresentaram menores comprimentos de sarcômero (2,806 ± 0,059 μm) e maior número de sarcômeros em série (8170 ± 510) quando comparados aos grupos controle (3,06 ± 0,054 μm e 7510 ± 240) e aclive (2,990 ± 0,023 μm e 7390 ± 270). As demais variáveis analisadas não apresentaram diferenças entre os grupos. É possível concluir com este estudo que adaptações estruturais nem sempre acontecem em paralelo às adaptações funcionais, que o treinamento em declive parece produzir resultados com maiores variações e que os diferentes estímulos provocam diferentes adaptações no músculo sóleo de ratos. / The literature states that the stimulus produced by different types of contraction in skeletal muscle generates specific adaptations. Downhill and uphill locomotion have been used as a model of concentric and eccentric training in studies that verify the different adaptations in animals. Therefore this study intended to evaluate mechanical and histological properties of rats’ soleus muscle submitted to uphill or downhill running. We evaluated 36 male Wistar rats (90 days old at the start of training). They were divided equally into three groups: uphill (A), downhill (D) and control (C). Training was performed on a treadmill adapted to individual lanes and +16º (uphill) or -16º (downhill) incline. The animals went through a one week adjustment period on the treadmill with the specific inclines, and then there were evaluated the maximal speeds they reached. The training took place with progressive speed (relative to the maximum tested) and time over 8 weeks (29 sessions). Two days after the last training the animals were anesthetized with sodium thiopental (± 5 ml), the right and left soleus muscles were removed and the animals were decapitated. The right soleus muscles (n = 7C, 8A, 9D) were subjected to tensile tests on one machine EMIC DL2000, with a load cell of 50 N, speed of 1,66 m.s-1. During the test, the samples were sprayed with saline solution every one minute. The left soleus muscles were removed for counting of sarcomeres (n = 4A, 4C, 5D) and the titin Western blot analysis (n = 4 per group). Data normality and homogeneity were verified and reliability of the measures was assessed by Cronbach's Alpha coefficient. Individual behaviors were analyzed by Intraclass Correlation Coefficient (ICC); one-way ANOVA and post hoc Bonferroni test and nonparametric Kruskal-Wallis were applied to identify the differences between the groups. Three out of the 36 animals died before the end of the experiment. The Cronbach's Alpha coefficients indicated reliability of the measures with values close to one for all the analyzed variables. The mechanical data of downhill trained animals had significantly lower ICC, even though significant. Comparisons between groups showed increased rigidity of the muscles of trained animals and greater deformation of the muscles of control animals. It has been found greater passive tension mean for both training groups (57 ± 5 and 56 ± 11 for A and D; 51.6 ± 7.7 for C), but it was not statistically significant probably due to the high mechanical data variability. Regarding the number of sarcomeres in series the downhill trained animals showed smaller sarcomere lengths (2.806 ± 0.059 μm) and greater serial sarcomere number (8170 ± 510) when compared to control (3.06 ± 0.054 μm and 7510 ± 240) and uphill (2.990 ± 0.023 μm e 7390 ± 270) groups. The remaining variables did not differ between groups. It can be concluded from this study that structural adaptations do not happen in parallel with functional adaptations, downhill running appear to produce more variable results and that different stimuli generate different adaptations in rats’ soleus muscle.

A literatura refere que os estímulos produzidos pelos diferentes tipos de contração no sistema músculo-esquelético geram adaptações específicas. A locomoção em aclive e declive vem sendo utilizada como modelo de treinamento concêntrico e excêntrico para estudos dessas adaptações em animais. Sendo assim este estudo teve o objetivo de avaliar características mecânicas e histológicas do músculo sóleo de ratos submetidos a treinamento em aclive ou declive. Foram avaliados 36 ratos Wistar machos (90 dias de idade no início do treinamento) divididos igualmente em três grupos: aclive (A), declive (D) e controle (C). Os treinamentos foram realizados em uma esteira adaptada com raias individuais e inclinação de + 16° (aclive) ou – 16° (declive). Os animais passaram por um período de adaptação de uma semana na esteira com a inclinação específica e, em seguida, foram avaliados quanto à velocidade máxima suportada. Os treinamentos aconteceram com velocidade (relativa à máxima avaliada) e tempo progressivos ao longo de oito semanas (29 sessões). Dois dias após o último treino os animais foram anestesiados com Tiopental Sódico (± 5 ml), os músculos sóleos direitos e esquerdos foram removidos e os animais decapitados. Os músculos sóleos da pata direita (n = 7C, 8A, 9D) foram submetidos a ensaios de tração em uma máquina EMIC DL2000, com célula de carga de 50 N a velocidade de 1,66 m·s-1. Durante o ensaio, as amostras foram borrifadas com solução salina a cada um minuto. Os músculos sóleos esquerdos foram retirados para contagem de sarcômeros (n = 4A, 4C e 5D) e análise na proteína titina por Western Blot (n = 4 por grupo). Foi verificada a normalidade e homogeneidade dos dados e a confiabilidade das medidas foi avaliada pelo coeficiente Alpha de Cronbach. Comportamentos individuais foram analisados pelo Coeficiente de Correlação Intraclasse (ICC); ANOVA one way e post hoc de Bonferroni e teste não paramétrico Kruskal-Walls foram aplicados para identificação das diferenças entre os grupos. Dos 36 animais, três morreram antes do final do experimento. Os coeficientes Alpha de Cronbach indicaram confiabilidade das medidas com valores próximos a um para todas as variáveis. Os dados mecânicos dos animais que treinaram em declive apresentaram menores valores de ICC, mesmo assim significativos. As comparações entre os grupos indicaram aumento significativo da rigidez da curva tensão X deformação para os animais treinados em aclive e declive, e maior deformação da curva para os animais controle. Foi encontrado aumento da média da tensão passiva dos músculos dos animais treinados (57 ± 5 e 56 ± 11 para A e D; 51,6 ± 7,7 para C), contudo essa diferença não foi estatisticamente significativa, possivelmente devido a grande variabilidade dos dados mecânicos. Em relação ao número de sarcômeros em série os animais que treinaram em declive apresentaram menores comprimentos de sarcômero (2,806 ± 0,059 μm) e maior número de sarcômeros em série (8170 ± 510) quando comparados aos grupos controle (3,06 ± 0,054 μm e 7510 ± 240) e aclive (2,990 ± 0,023 μm e 7390 ± 270). As demais variáveis analisadas não apresentaram diferenças entre os grupos. É possível concluir com este estudo que adaptações estruturais nem sempre acontecem em paralelo às adaptações funcionais, que o treinamento em declive parece produzir resultados com maiores variações e que os diferentes estímulos provocam diferentes adaptações no músculo sóleo de ratos. / The literature states that the stimulus produced by different types of contraction in skeletal muscle generates specific adaptations. Downhill and uphill locomotion have been used as a model of concentric and eccentric training in studies that verify the different adaptations in animals. Therefore this study intended to evaluate mechanical and histological properties of rats’ soleus muscle submitted to uphill or downhill running. We evaluated 36 male Wistar rats (90 days old at the start of training). They were divided equally into three groups: uphill (A), downhill (D) and control (C). Training was performed on a treadmill adapted to individual lanes and +16º (uphill) or -16º (downhill) incline. The animals went through a one week adjustment period on the treadmill with the specific inclines, and then there were evaluated the maximal speeds they reached. The training took place with progressive speed (relative to the maximum tested) and time over 8 weeks (29 sessions). Two days after the last training the animals were anesthetized with sodium thiopental (± 5 ml), the right and left soleus muscles were removed and the animals were decapitated. The right soleus muscles (n = 7C, 8A, 9D) were subjected to tensile tests on one machine EMIC DL2000, with a load cell of 50 N, speed of 1,66 m.s-1. During the test, the samples were sprayed with saline solution every one minute. The left soleus muscles were removed for counting of sarcomeres (n = 4A, 4C, 5D) and the titin Western blot analysis (n = 4 per group). Data normality and homogeneity were verified and reliability of the measures was assessed by Cronbach's Alpha coefficient. Individual behaviors were analyzed by Intraclass Correlation Coefficient (ICC); one-way ANOVA and post hoc Bonferroni test and nonparametric Kruskal-Wallis were applied to identify the differences between the groups. Three out of the 36 animals died before the end of the experiment. The Cronbach's Alpha coefficients indicated reliability of the measures with values close to one for all the analyzed variables. The mechanical data of downhill trained animals had significantly lower ICC, even though significant. Comparisons between groups showed increased rigidity of the muscles of trained animals and greater deformation of the muscles of control animals. It has been found greater passive tension mean for both training groups (57 ± 5 and 56 ± 11 for A and D; 51.6 ± 7.7 for C), but it was not statistically significant probably due to the high mechanical data variability. Regarding the number of sarcomeres in series the downhill trained animals showed smaller sarcomere lengths (2.806 ± 0.059 μm) and greater serial sarcomere number (8170 ± 510) when compared to control (3.06 ± 0.054 μm and 7510 ± 240) and uphill (2.990 ± 0.023 μm e 7390 ± 270) groups. The remaining variables did not differ between groups. It can be concluded from this study that structural adaptations do not happen in parallel with functional adaptations, downhill running appear to produce more variable results and that different stimuli generate different adaptations in rats’ soleus muscle.

A literatura refere que os estímulos produzidos pelos diferentes tipos de contração no sistema músculo-esquelético geram adaptações específicas. A locomoção em aclive e declive vem sendo utilizada como modelo de treinamento concêntrico e excêntrico para estudos dessas adaptações em animais. Sendo assim este estudo teve o objetivo de avaliar características mecânicas e histológicas do músculo sóleo de ratos submetidos a treinamento em aclive ou declive. Foram avaliados 36 ratos Wistar machos (90 dias de idade no início do treinamento) divididos igualmente em três grupos: aclive (A), declive (D) e controle (C). Os treinamentos foram realizados em uma esteira adaptada com raias individuais e inclinação de + 16° (aclive) ou – 16° (declive). Os animais passaram por um período de adaptação de uma semana na esteira com a inclinação específica e, em seguida, foram avaliados quanto à velocidade máxima suportada. Os treinamentos aconteceram com velocidade (relativa à máxima avaliada) e tempo progressivos ao longo de oito semanas (29 sessões). Dois dias após o último treino os animais foram anestesiados com Tiopental Sódico (± 5 ml), os músculos sóleos direitos e esquerdos foram removidos e os animais decapitados. Os músculos sóleos da pata direita (n = 7C, 8A, 9D) foram submetidos a ensaios de tração em uma máquina EMIC DL2000, com célula de carga de 50 N a velocidade de 1,66 m·s-1. Durante o ensaio, as amostras foram borrifadas com solução salina a cada um minuto. Os músculos sóleos esquerdos foram retirados para contagem de sarcômeros (n = 4A, 4C e 5D) e análise na proteína titina por Western Blot (n = 4 por grupo). Foi verificada a normalidade e homogeneidade dos dados e a confiabilidade das medidas foi avaliada pelo coeficiente Alpha de Cronbach. Comportamentos individuais foram analisados pelo Coeficiente de Correlação Intraclasse (ICC); ANOVA one way e post hoc de Bonferroni e teste não paramétrico Kruskal-Walls foram aplicados para identificação das diferenças entre os grupos. Dos 36 animais, três morreram antes do final do experimento. Os coeficientes Alpha de Cronbach indicaram confiabilidade das medidas com valores próximos a um para todas as variáveis. Os dados mecânicos dos animais que treinaram em declive apresentaram menores valores de ICC, mesmo assim significativos. As comparações entre os grupos indicaram aumento significativo da rigidez da curva tensão X deformação para os animais treinados em aclive e declive, e maior deformação da curva para os animais controle. Foi encontrado aumento da média da tensão passiva dos músculos dos animais treinados (57 ± 5 e 56 ± 11 para A e D; 51,6 ± 7,7 para C), contudo essa diferença não foi estatisticamente significativa, possivelmente devido a grande variabilidade dos dados mecânicos. Em relação ao número de sarcômeros em série os animais que treinaram em declive apresentaram menores comprimentos de sarcômero (2,806 ± 0,059 μm) e maior número de sarcômeros em série (8170 ± 510) quando comparados aos grupos controle (3,06 ± 0,054 μm e 7510 ± 240) e aclive (2,990 ± 0,023 μm e 7390 ± 270). As demais variáveis analisadas não apresentaram diferenças entre os grupos. É possível concluir com este estudo que adaptações estruturais nem sempre acontecem em paralelo às adaptações funcionais, que o treinamento em declive parece produzir resultados com maiores variações e que os diferentes estímulos provocam diferentes adaptações no músculo sóleo de ratos. / The literature states that the stimulus produced by different types of contraction in skeletal muscle generates specific adaptations. Downhill and uphill locomotion have been used as a model of concentric and eccentric training in studies that verify the different adaptations in animals. Therefore this study intended to evaluate mechanical and histological properties of rats’ soleus muscle submitted to uphill or downhill running. We evaluated 36 male Wistar rats (90 days old at the start of training). They were divided equally into three groups: uphill (A), downhill (D) and control (C). Training was performed on a treadmill adapted to individual lanes and +16º (uphill) or -16º (downhill) incline. The animals went through a one week adjustment period on the treadmill with the specific inclines, and then there were evaluated the maximal speeds they reached. The training took place with progressive speed (relative to the maximum tested) and time over 8 weeks (29 sessions). Two days after the last training the animals were anesthetized with sodium thiopental (± 5 ml), the right and left soleus muscles were removed and the animals were decapitated. The right soleus muscles (n = 7C, 8A, 9D) were subjected to tensile tests on one machine EMIC DL2000, with a load cell of 50 N, speed of 1,66 m.s-1. During the test, the samples were sprayed with saline solution every one minute. The left soleus muscles were removed for counting of sarcomeres (n = 4A, 4C, 5D) and the titin Western blot analysis (n = 4 per group). Data normality and homogeneity were verified and reliability of the measures was assessed by Cronbach's Alpha coefficient. Individual behaviors were analyzed by Intraclass Correlation Coefficient (ICC); one-way ANOVA and post hoc Bonferroni test and nonparametric Kruskal-Wallis were applied to identify the differences between the groups. Three out of the 36 animals died before the end of the experiment. The Cronbach's Alpha coefficients indicated reliability of the measures with values close to one for all the analyzed variables. The mechanical data of downhill trained animals had significantly lower ICC, even though significant. Comparisons between groups showed increased rigidity of the muscles of trained animals and greater deformation of the muscles of control animals. It has been found greater passive tension mean for both training groups (57 ± 5 and 56 ± 11 for A and D; 51.6 ± 7.7 for C), but it was not statistically significant probably due to the high mechanical data variability. Regarding the number of sarcomeres in series the downhill trained animals showed smaller sarcomere lengths (2.806 ± 0.059 μm) and greater serial sarcomere number (8170 ± 510) when compared to control (3.06 ± 0.054 μm and 7510 ± 240) and uphill (2.990 ± 0.023 μm e 7390 ± 270) groups. The remaining variables did not differ between groups. It can be concluded from this study that structural adaptations do not happen in parallel with functional adaptations, downhill running appear to produce more variable results and that different stimuli generate different adaptations in rats’ soleus muscle.

L'excitation et la propagation des ondes de cisaillement dans les dispositifs à ondes acoustiques de surface SAW à base de nitrure d'aluminium, en milieux liquides, nécessitent l'inclinaison de l'axe c dans la structure hexagonale. Le but de cette étude était de déposer des couches minces d'AlN à axe c incliné par la technique de pulvérisation magnétron sans aucune modification du dispositif de pulvérisation, le substrat et la cible n'ayant subi ni inclinaison ni décalage. Il a été possible, par une approche basée seulement sur la variation des paramètres de croissance, de déposer des couches minces piézoélectriques avec un angle d'inclinaison de 13°±2° dans des conditions de haute pression (0.8 Pa) et basse température (300°C). Une couche de SiO2 a été également déposée afin de favoriser la croissance inclinée des grains et par conséquent de celle des colonnes. Les couches déposées présentent une grande homogénéité de l'épaisseur sur 75% d'un substrat de silicium de 3 pouces. Après la détermination des paramètres optimaux de « croissance inclinée », nous avons réalisé un dispositif à onde acoustique de surface fonctionnant en mode de cisaillement avec lequel nous avons démontré la possibilité d'exciter les ondes de cisaillement dans un dispositif de type AlN/Si02/Si à 486.2 MHz avec une vitesse de propagation d'environ 5835m/s et un facteur de couplage électromécanique de 0.014%. La réponse électrique est fort intéressante si on tient compte du faible couplage électromécanique dû au substrat utilisé. / The excitation and propagation, in liquid media, of shear waves in surface acoustic wave (SAW) devices based aluminum nitride (AlN) require the inclination of the c axis in the hexagonal structure. The purpose of this study was to deposit tilted c-axis AlN thin films by magnetron sputtering technique without any modification of the deposition system. The search approach was based only on the optimisation of deposition parameters. Substrate and the target were not inclined or shifted. It has been possible through an approach based solely on changes in growth parameters, to deposit thin piezoelectric layers with an inclination angle of 13 ° ± 2 ° under conditions of high pressure (0.8 Pa) and low temperature ( 300 ° C). A thin layer of SiO2 was also introduced to enhance the growth of tilted grains and therefore the columns. The deposited layers have a homogeneous thickness of 75% of a silicon substrate of 3 inches. After determining the optimal parameters leading to growth AlN film with tilted c-axis, we achieved a SAW device and hence demonstrate the ability to excite shear waves in AlN/Si02 /Si SAW structure. The performed device operate at 486.2 MHz corresponding to an acoustic velocity of about 5835m/s and an electromechanical coupling coefficient of 0.014%. The obtained electrical response is very interesting if we take into account the low electromechanical coupling of the structure due to the used substrate.

Detta examensarbete utförs tillsammans med Ålö AB som tillverkar frontlastare under varumärket Quike och ämnar utvärdera olika möjliga lösningar för ett system som beräknar inklinationen på fordon. Systemet ska utformas med låg kostnad som prioritet och skall klara hårdvaruklassificeringar för elektronik tillämpat på fordon (AEC-Q100). Arbetet behandlar i huvudsak bestämmande- och motivation av komponentval, teori kring den signalbehandling som behövs i miljöer där en stor mängd brus förekommer samt implementationen av detta.   I arbetet valdes två sensorer som ansågs lämpliga för utvärdering. Den första var en 3-axlad accelerometer till vilken en proprietär 2D-positioneringsalgoritm används för att bestämma inklination. Den andra sensorn som valdes är en 6-axlad sensor som kombinerar accelerometer och gyroskop vilken implementeras med sensorfusion och Kalman-filter genom användning av ett mjukvarubibliotek. Systemet implementerades hårdvarumässigt i form av ett kretskort som huserar båda sensorerna.   Systemet testades och utvärderades stationärt och på fordon tillsammans med en referenssensor för att ge en bild av hur de respektive sensorerna och algoritmerna presterade i både ideala och verkliga förhållanden. Vid de stationära testerna uppvisar båda lösningarna goda egenskaper och ger inklination nära verklig vinkel. Traktortesternas tillförlitlighet kan höjas och håller inte nog hög kvalitet för att kunna leda till slutsats, vilket leder till en rekommendation om fortsatt utvecklingsarbete. / This student thesis is carried out togheter with Ålö AB which manufactures front loaders under the Quicke brand and intents to evaluate a system that calculates vehicle incline. The system should prioritize low cost and must use electronics that is classified for vehicle use (AEC-Q100). This thesis deals with selecting components, sensors and motivations of the selected components, theory of sensor signal conditioning in noisy environments and its implementation.   Two sensors where selected that was deemed suitable for evaluation. The first was a 3-axis accelerometer for which a proprietary 2D-positioning algorithm was used to calculate incline. The second sensor that was chosen was a 6-axis IMU that was implemented using sensor fusion with a Kalman filter which was realized with an available software library. The system hardware was implemented with a custom PCB.   The system was tested and evaluated stationary and, on a vehicle, along with a reference sensor to give an indication of how the sensors and their respective algorithms performed in both ideal and a real conditions. The stationary tests showed that both solutions perform well regarding outputting incline close to the actual angle. The reliability of the vehicle tests can be improved and as the results they yielded are not of high enough quality to draw conclusions from them. This leads to a recommendation of further testing and evaluation of both solutions.

In this study, we examined how hill running affects the Achilles tendon, which is a common location for injuries in runners. Twenty females ran for 10 min on three randomly selected grades (-6%, 0%, +6%). Achilles tendon (AT) cross-sectional area (CSA) was imaged using Doppler ultrasound and peak vertical forces were analyzed using high-speed (240 Hz) videography. A metabolic cart and gas analyzer ensured a similar metabolic cost across grades. Data were analyzed using a forward selection regression. Results showed a decrease in AT CSA from pre-run to post-run (p = .0001). Peak vertical forces were different across grades (p = .0001) with the largest occurring during downhill running and smallest during uphill running. The results suggest that the Achilles tendon is affected by running and a decrease in CSA appears to be a normal response. The AT CSA does not differ between grade conditions when metabolic cost of running is matched, suggesting an adaptive effect of the AT. Coaches and athletes can use this knowledge to develop workout protocols that transition runners to downhill running and allow them to adapt to these greater forces.

Cross-country (c.c.) skiing is a complex sport discipline from both physiological and biomechanical perspectives, with varying course topographies that require different proportions of the involved sub-techniques to be utilised. A relatively new event in c.c. skiing is the sprint race, involving four separate heats, each lasting 2-4 min, with diverse demands from distance races associated with longer durations. Therefore, the overall aim of the current thesis has been to examine the biomechanical and physiological factors associated with sprint c.c. skiing performance through novel measurements conducted both in the field (Studies I-III) and the laboratory (Studies IV and V). In Study I sprint skiing velocities and sub-techniques were analysed with a differential global navigation satellite system in combination with video recording. In Studies II and III the effects of an increasing velocity (moderate, high and maximal) on the biomechanics of uphill classical skiing with the diagonal stride (DS) (Study II) and herringbone (HB) (Study III) sub-techniques were examined. In Study I the skiers completed the 1,425 m (2 x 712 m) sprint time trial (STT) in 207 s, at an average velocity of 24.8 km/h, with multiple technique transitions (range: 21-34) between skiing techniques (i.e., the different gears [G2-7]). A pacing strategy involving a fast start followed by a gradual slowing down (i.e., positive pacing) was employed as indicated by the 2.9% faster first than second lap. The slower second lap was primarily related to a slower (12.9%) uphill velocity with a shift from G3 towards a greater use of G2. The maximal oxygen uptake ( O2max) was related to the ability to maintain uphill skiing velocity and the fastest skiers used G3 to a greater extent than G2. In addition, maximal speed over short distances (50 and 20 m) with the G3 and double poling (DP) sub-techniques exerted an important impact on STT performance. Study II demonstrated that during uphill skiing (7.5°) with DS, skiers increased cycle rate and cycle length from moderate to high velocity, while cycle rate increased and cycle length decreased at maximal velocity. Absolute poling, gliding and kick times became gradually shorter with an elevated velocity. The rate of pole and leg force development increased with elevated velocity and the development of leg force in the normal direction was substantially faster during skiing on snow than previous findings for roller skiing, although the peak force was similar in both cases. The fastest skiers applied greater peak leg forces over shorter durations. Study III revealed that when employing the HB technique on a steep uphill slope (15°), the skiers positioned their skis laterally (“V” between 25 to 30°) and planted their poles at a slight lateral angle (8 to 12°), with most of the propulsive force being exerted on the inside forefoot. Of the total propulsive force, 77% was generated by the legs. The cycle rate increased across all three velocities (from 1.20 to 1.60 Hz), while cycle length only increased from moderate to high velocity (from 2.0 to 2.3 m). Finally, the magnitude and rate of leg force generation are important determinants of both DS and HB skiing performance, although the rate is more important in connection with DS, since this sub-technique involves gliding. In Studies IV and V skiers performed pre-tests for determination of gross efficiency (GE), O2max, and Vmax on a treadmill. The main performance test involved four self-paced STTs on a treadmill over a 1,300-m simulated course including three flat (1°) DP sections interspersed with two uphill (7°) DS sections. The modified GE method for estimating anaerobic energy production during skiing on varying terrain employed in Study IV revealed that the relative aerobic and anaerobic energy contributions were 82% and 18%, respectively, during the 232 s of skiing, with an accumulated oxygen (O2) deficit of 45 mL/kg. The STT performance time was largely explained by the GE (53%), followed by O2 (30%) and O2 deficit (15%). Therefore, training strategies designed to reduce energetic cost and improve GE should be examined in greater detail. In Study V metabolic responses and pacing strategies during the four successive STTs were investigated. The first and the last trials were the fastest (both 228 s) and were associated with both a substantially larger and a more rapid anaerobic energy supply, while the average O2 during all four STTs was similar. The individual variation in STT performance was explained primarily (69%) by the variation in O2 deficit. Furthermore, positive pacing was employed throughout all the STTs, but the pacing strategy became more even after the first trial. In addition, considerably higher (~ 30%) metabolic rates were generated on the uphill than on the flat sections of the course, reflecting an irregular production of anaerobic energy. Altogether, a fast start appears important for STT performance and high work rates during uphill skiing may exert a more pronounced impact on skiing performance outdoors, due to the reduction in velocity fluctuations and thereby overall air-drag. / <p>Vid tidpunkten för disputationen var följande delarbeten opublicerade: delarbete 5 inskickat</p><p>At the time of the doctoral defence the following papers were unpublished: paper 5 submitted</p>