This thesis evaluated energy levels, muscle activity, and upper limb kinematics during AVG play in children with cerebral palsy (CP). For context, a systematic review was conducted, which found that AVGs elicited light to moderate physical activity in typically developing children. In children with CP, moderate levels of physical activity were achieved for Dance Dance Revolution and Wii Boxing, while light levels of physical activity were achieved for Wii Bowling and Wii Tennis. Muscle activity was highest during Wii Boxing, but remained below the maximum voluntary effort for all games and muscles. Angular velocities and accelerations were significantly larger in the dominant limb compared to the hemiplegic limb. When children played against a real opponent, dominant arm activity increased, while hemiplegic arm activity decreased. The results of this thesis indicate that AVGs may be an enjoyable and relatively safe option for children with CP to attain moderate physical activity.

This thesis evaluated energy levels, muscle activity, and upper limb kinematics during AVG play in children with cerebral palsy (CP). For context, a systematic review was conducted, which found that AVGs elicited light to moderate physical activity in typically developing children. In children with CP, moderate levels of physical activity were achieved for Dance Dance Revolution and Wii Boxing, while light levels of physical activity were achieved for Wii Bowling and Wii Tennis. Muscle activity was highest during Wii Boxing, but remained below the maximum voluntary effort for all games and muscles. Angular velocities and accelerations were significantly larger in the dominant limb compared to the hemiplegic limb. When children played against a real opponent, dominant arm activity increased, while hemiplegic arm activity decreased. The results of this thesis indicate that AVGs may be an enjoyable and relatively safe option for children with CP to attain moderate physical activity.

Previous research investigating the stability of the ankle joint complex may be categorised into two methodological groups, employing either an actuator to perturb the limb, or a form of standing balance disturbance such as a tilting platform, both of which test the joint in single degree of freedom (DOF). The aim of this thesis was to investigate how we control foot position and stabilise the joint when there is potential for movement in three DOF. A secondary aim of the thesis was to model the intrinsic mechanical properties of the ankle joint complex in three dimensions when coupled movement of the tibio-talar and talo-calcaneal joints are possible. This thesis details (i) the development of a perturbation rig that allows foot movement in single- or three-DOF with associated real-time visual target-matching software, and (ii) the use of the rig to investigate the stabilisation of the ankle joint complex in single- and three-DOF. The experimental procedure used a common task performed in three experimental conditions. Subjects were required to maintain a neutral foot position while developing varying levels of plantar-flexion torque. A perturbation was applied to the foot if subjects were within specified tolerance for both foot position and torque, represented by the visual display. Performance of the task in the first condition required the subject to only match torque as the foot position was fixed, with the perturbation being applied in dorsi-flexion (ie, single-DOF). The second experimental condition allowed the foot to move in the sagittal plane, hence subjects were required to control both torque and foot position in single-DOF, with perturbation applied in dorsi-flexion. The third condition enabled movement in dorsi/plantar-flexion, inversion/eversion and adduction/abduction (three-DOF) in both task and perturbation. Subjects were required to maintain the neutral foot position and the necessary torque level. There were three areas of interest common to each experimental protocol. The muscle strategy used to complete the task was investigated using a combination of surface and fine-wire electromyography on lower leg and thigh muscles. The 500ms period prior to perturbation was investigated to determine if synergies were evident between muscles such as medial and lateral gastrocnemius, soleus and peroneus longus. Two classes of activation strategies for the three-DOF condition emerged from the subject population: differential activation of the triceps surae group, and co-contraction. The former strategy may take advantage of the distinct morphology of the lateral gastrocnemius and peroneus longus muscles to best perform the position-matching component of the 3D task. The results suggest that the ankle joint is mostly stabilised in 3D by the intrinsic mechanical actions of the muscles producing plantar flexion moments. The muscles stabilised the foot in inversion, but not in eversion where there was very little motion. However, the different activation strategies employed may have varied efficacy in contributing to joint stability. This form of active stabilisation means that the previous literature focus on reflexes to stabilise the joint may need to be reassessed. Likewise, it may be appropriate to use the perturbation rig to quantify active ankle joint stability in order to assess the probability of ankle injury, rather than the current clinical measures employed. The reflexive response due to the perturbation was examined in the 200ms following perturbation. Variation in the modulation of monosynaptic reflexes was observed between subjects in various muscles in the higher DOF tasks. This is likely due to the differing activation strategies used to perform the task, and the variability in the kinematic response to perturbation. An attempt was made to calculate the intrinsic mechanical properties of the joint in 3-D using the kinematic and kinetic data during the first 15 ms period of perturbation. The system was modelled as a spring-damper using a constrained non-linear least squares, with stiffness and viscous terms for each axis, and inertial tensor elements as variables in the routine. The effect of increased muscle activation on the displacement of the foot about each of the anatomical axes was to significantly lower the movement of the sub-talar joint.

O objetivo do presente estudo foi analisar as respostas cinemáticas e neuromusculares de diferentes saltos da patinação artística sobre rodas, com e sem patins, as respostas cinéticas dos mesmos saltos sem patins, e as respostas cinéticas e cinemáticas do countermovement jump (CMJ), drop jump (DJ) e squat jump (SJ), em patinadores de elite. Foram avaliados quatro patinadores de elite do Rio Grande do Sul, sendo estes uma mulher e um homem da categoria Junior e uma mulher e um homem da categoria Sênior. Os sujeitos participaram de três sessões: a primeira foi destinada à coleta das medidas antropométricas e à realização da contração isométrica voluntária máxima para normalização da eletromiografia, a segunda foi destinada à coleta das variáveis cinéticas, cinemáticas e neuromusculares sem patins, no laboratório, e a terceira foi destinada à coleta das variáveis neuromusculares e cinemáticas durante os saltos realizados com patins, no ginásio. Foram avaliados quatro saltos da patinação artística: Axel simples, Axel duplo, Mapes duplo e Mapes triplo. Os sujeitos executaram três saltos de cada tipo e foi selecionado aquele que estava melhor localizado dentro da zona de filmagem e que apresentou a melhor qualidade de execução. De acordo com os resultados, os patinadores homens foram mais potentes do que as mulheres durante os saltos verticais CMJ, DJ e SJ. Nos saltos da patinação os quatro atletas apresentaram maior impulso, potência máxima, altura e velocidade rotacional durante os saltos com mais rotações do que durante os saltos com menos rotações, enquanto a velocidade horizontal no take-off foi menor nos saltos com mais rotações. Na comparação entre os saltos Axel e Mapes, os patinadores demonstraram maior duração da propulsão no salto Axel do que no Mapes. Quanto à análise eletromiográfica, os músculos gastrocnêmio lateral, reto femoral, vasto lateral, bíceps femoral e glúteo máximo, apresentaram maior ativação durante os saltos com mais rotações, principalmente nas fases de propulsão e voo. Sugere-se que os resultados obtidos no presente estudo sejam considerados no planejamento de um treinamento específico, já que podem ser importantes para o desenvolvimento dos patinadores de elite, provavelmente sendo úteis também para os patinadores de outros níveis que almejam alcançar o nível internacional e obter sucesso em competições. / The aim of the present study was to analyze the kinematic and neuromuscular responses of different roller figure skating jumps, with and without skates, the kinetic responses of the same jumps without skates and the kinetic and kinematic responses of the countermovement jump (CMJ), drop jump (DJ) and squat jump (SJ), in elite skaters. Four elite skaters from Rio Grande do Sul were evaluated, including one Junior female, one Junior male, one Senior female and one Senior male. Each one took part in three experimental sessions: the first one was to collect the anthropometric data and to perform the maximum voluntary isometric contraction for electromyography normalization, the second one was to collect the kinetic, kinematic and neuromuscular variables, without skates, at the laboratory, and the third one was to collect the neuromuscular and kinematic variables during the jumps executed with skates, at the rink. Four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. Subjects executed three jumps of each type and one was selected for analysis based on the best recording area and on the overall quality of the jump. According to the results, male skaters were more powerful than female skaters during the vertical jumps CMJ, DJ and SJ. During the roller figure skating jumps, the four skaters demonstrated higher impulse, maximal power, height and rotational velocity during jumps with more rotations than during jumps with less rotation, while the horizontal velocity at take-off was lower in the jumps with more rotations. Comparing the Axel and Mapes jumps, the skaters demonstrated more duration at the propulsion phase in the Axel jump than in the Mapes. In regard to the electromyographic response, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation in the jumps with more rotations and mainly in the propulsion and flight phases. It is suggested that the results obtained in this study are considered in planning a specific training, since they may be important for the development of elite skaters, probably being also useful for skaters of other levels that aim to achieve the international level and succeed in competitions.

A osteoartrite é uma desordem articular comum nos idosos, sendo responsável por causar perda da funcionalidade destes indivíduos, quando comparada a outras doenças. Sua prevalência aumenta com a idade por ser uma doença irreversível. Esta condição musculoesquelética causa dor, incapacidade física e redução da qualidade de vida. A artroplastia total de joelho é o procedimento adequado para o tratamento da osteoartrite em seus graus mais avançados, e tem apresentado uma melhora funcional dos extensores do joelho (por meio da redução da inibição reflexa e possível aumento da capacidade de produção de força) e da qualidade de vida (pela redução da dor, aumento da mobilidade e retorno às atividades de vida diárias) nesses casos avançados da doença. No entanto, os efeitos da substituição do joelho osteoartrítico pela prótese não são totalmente conhecidos. Em função disso, o objetivo do presente estudo foi comparar a ativação muscular e a produção de força (torque) de indivíduos com osteoartrite (n=20) e indivíduos com artroplastia total de joelho (n=12). O pico de torque dos músculos extensores de joelho foi avaliado durante contrações isométricas voluntárias máximas nos ângulos de 30º, 60º, 75º e 90º. Nos mesmos ângulos articulares também foi avaliada a ativação elétrica dos músculos vasto lateral, vasto medial e reto femoral, através da eletromiografia de superfície. A qualidade de vida foi comparada entre os dois grupos através do questionário WOMAC. O grupo artroplastia obteve menores escores no questionário, o que indica melhora da qualidade de vida destes indivíduos ao serem comparados com o grupo osteoartrite. O comportamento dos dados tanto para a produção de torque como para a ativação muscular, apresentou-se semelhante nos dois grupos. A produção de torque não apresentou diferença significativa entre os grupos avaliados (p=0,775), sendo que a única diferença observada foi para o torque entre os ângulos testados (p=0,0001). Assim como para a produção de torque, a ativação muscular não apresentou diferença significativa entre os grupos osteoartrite e artroplastia total de joelho para os músculos VL, RF e VM (p>0,05). Somente para o menor ângulo (30º) e para o maior ângulo (90º) houve diferença significativa da ativação muscular em relação aos ângulos para os músculos vasto lateral (p=0,011) e vasto medial (p=0,014). Os resultados apresentados neste estudo suportam a hipótese de que a técnica cirúrgica de artroplastia total de joelho propicia uma redução da dor e uma melhora da qualidade de vida. No entanto, essa melhora na qualidade de vida parece não ser refletida em uma melhora funcional após a colocação da prótese, uma vez que não foi observado um aumento na ativação muscular com um correspondente aumento na capacidade de produção de força dos músculos extensores do joelho. / Osteoarthritis is a degenerative disease prevalent in the elderly population characterized by pain, disability and decrease of quality of life. Total knee replacement is indicated for the last stages of the disease, and shows a functional improvement of the knee extensor muscles (by a reduction of reflex inhibition and possibly by increasing muscle force production capacity) and improvement of quality of life (by the reduction in pain, increase in mobility and return to daily life activities) in these advanced stages of the disease. However, the functional effects of the joint replacement are not completely understood. Therefore, the purpose of this study was to compare both the muscle activation and the force production (torque) developed by patients with osteoarthritis (n=20) and patients which underwent total knee replacement (n=12). The knee extensor muscles peak torque was evaluated during maximal voluntary isometric contractions at the joint angles of 30º, 60º, 75º and 90º of knee extension. At the same joint angles the electrical activation was obtained, by surface electromyography from the vastus lateralis, the vastus medialis and the rectus femoris muscles. The WOMAC questionnaire was used to compare the quality of life between the two groups of the study. The arthroplasty group showed lower scores, indicating an improvement in the quality of life compare to the osteoarthritis group. Both groups showed a similar behavior in the torque production and in the muscle activation. Torque production was similar between the two groups (p=0,775), although there was a difference in the torque amongst the studied angles (p=0,0001). There was no difference between the osteoarthritis and the arthroplasty groups for muscle activation of the VL, RF and VM muscles (p>0,05). Nevertheless, activation was different when comparing the smallest and the largest angles studied (30º and 90º, respectively) of the vastus lateralis (p=0,011) and the vastus medialis (p=0,014) muscles in both groups. These results seem to support the hypothesis that the total knee replacement produces an improvement in the quality of life by a reduction in knee joint pain and an increase in the patients mobility and a return to the daily life activities. However, this surgical procedure did not produce a functional improvement in the knee extensor muscles, as there was no increase in muscle activation nor in the expected force produced by this muscle group.

A osteoartrite é uma desordem articular comum nos idosos, sendo responsável por causar perda da funcionalidade destes indivíduos, quando comparada a outras doenças. Sua prevalência aumenta com a idade por ser uma doença irreversível. Esta condição musculoesquelética causa dor, incapacidade física e redução da qualidade de vida. A artroplastia total de joelho é o procedimento adequado para o tratamento da osteoartrite em seus graus mais avançados, e tem apresentado uma melhora funcional dos extensores do joelho (por meio da redução da inibição reflexa e possível aumento da capacidade de produção de força) e da qualidade de vida (pela redução da dor, aumento da mobilidade e retorno às atividades de vida diárias) nesses casos avançados da doença. No entanto, os efeitos da substituição do joelho osteoartrítico pela prótese não são totalmente conhecidos. Em função disso, o objetivo do presente estudo foi comparar a ativação muscular e a produção de força (torque) de indivíduos com osteoartrite (n=20) e indivíduos com artroplastia total de joelho (n=12). O pico de torque dos músculos extensores de joelho foi avaliado durante contrações isométricas voluntárias máximas nos ângulos de 30º, 60º, 75º e 90º. Nos mesmos ângulos articulares também foi avaliada a ativação elétrica dos músculos vasto lateral, vasto medial e reto femoral, através da eletromiografia de superfície. A qualidade de vida foi comparada entre os dois grupos através do questionário WOMAC. O grupo artroplastia obteve menores escores no questionário, o que indica melhora da qualidade de vida destes indivíduos ao serem comparados com o grupo osteoartrite. O comportamento dos dados tanto para a produção de torque como para a ativação muscular, apresentou-se semelhante nos dois grupos. A produção de torque não apresentou diferença significativa entre os grupos avaliados (p=0,775), sendo que a única diferença observada foi para o torque entre os ângulos testados (p=0,0001). Assim como para a produção de torque, a ativação muscular não apresentou diferença significativa entre os grupos osteoartrite e artroplastia total de joelho para os músculos VL, RF e VM (p>0,05). Somente para o menor ângulo (30º) e para o maior ângulo (90º) houve diferença significativa da ativação muscular em relação aos ângulos para os músculos vasto lateral (p=0,011) e vasto medial (p=0,014). Os resultados apresentados neste estudo suportam a hipótese de que a técnica cirúrgica de artroplastia total de joelho propicia uma redução da dor e uma melhora da qualidade de vida. No entanto, essa melhora na qualidade de vida parece não ser refletida em uma melhora funcional após a colocação da prótese, uma vez que não foi observado um aumento na ativação muscular com um correspondente aumento na capacidade de produção de força dos músculos extensores do joelho. / Osteoarthritis is a degenerative disease prevalent in the elderly population characterized by pain, disability and decrease of quality of life. Total knee replacement is indicated for the last stages of the disease, and shows a functional improvement of the knee extensor muscles (by a reduction of reflex inhibition and possibly by increasing muscle force production capacity) and improvement of quality of life (by the reduction in pain, increase in mobility and return to daily life activities) in these advanced stages of the disease. However, the functional effects of the joint replacement are not completely understood. Therefore, the purpose of this study was to compare both the muscle activation and the force production (torque) developed by patients with osteoarthritis (n=20) and patients which underwent total knee replacement (n=12). The knee extensor muscles peak torque was evaluated during maximal voluntary isometric contractions at the joint angles of 30º, 60º, 75º and 90º of knee extension. At the same joint angles the electrical activation was obtained, by surface electromyography from the vastus lateralis, the vastus medialis and the rectus femoris muscles. The WOMAC questionnaire was used to compare the quality of life between the two groups of the study. The arthroplasty group showed lower scores, indicating an improvement in the quality of life compare to the osteoarthritis group. Both groups showed a similar behavior in the torque production and in the muscle activation. Torque production was similar between the two groups (p=0,775), although there was a difference in the torque amongst the studied angles (p=0,0001). There was no difference between the osteoarthritis and the arthroplasty groups for muscle activation of the VL, RF and VM muscles (p>0,05). Nevertheless, activation was different when comparing the smallest and the largest angles studied (30º and 90º, respectively) of the vastus lateralis (p=0,011) and the vastus medialis (p=0,014) muscles in both groups. These results seem to support the hypothesis that the total knee replacement produces an improvement in the quality of life by a reduction in knee joint pain and an increase in the patients mobility and a return to the daily life activities. However, this surgical procedure did not produce a functional improvement in the knee extensor muscles, as there was no increase in muscle activation nor in the expected force produced by this muscle group.

O objetivo do presente estudo foi analisar as respostas cinemáticas e neuromusculares de diferentes saltos da patinação artística sobre rodas, com e sem patins, as respostas cinéticas dos mesmos saltos sem patins, e as respostas cinéticas e cinemáticas do countermovement jump (CMJ), drop jump (DJ) e squat jump (SJ), em patinadores de elite. Foram avaliados quatro patinadores de elite do Rio Grande do Sul, sendo estes uma mulher e um homem da categoria Junior e uma mulher e um homem da categoria Sênior. Os sujeitos participaram de três sessões: a primeira foi destinada à coleta das medidas antropométricas e à realização da contração isométrica voluntária máxima para normalização da eletromiografia, a segunda foi destinada à coleta das variáveis cinéticas, cinemáticas e neuromusculares sem patins, no laboratório, e a terceira foi destinada à coleta das variáveis neuromusculares e cinemáticas durante os saltos realizados com patins, no ginásio. Foram avaliados quatro saltos da patinação artística: Axel simples, Axel duplo, Mapes duplo e Mapes triplo. Os sujeitos executaram três saltos de cada tipo e foi selecionado aquele que estava melhor localizado dentro da zona de filmagem e que apresentou a melhor qualidade de execução. De acordo com os resultados, os patinadores homens foram mais potentes do que as mulheres durante os saltos verticais CMJ, DJ e SJ. Nos saltos da patinação os quatro atletas apresentaram maior impulso, potência máxima, altura e velocidade rotacional durante os saltos com mais rotações do que durante os saltos com menos rotações, enquanto a velocidade horizontal no take-off foi menor nos saltos com mais rotações. Na comparação entre os saltos Axel e Mapes, os patinadores demonstraram maior duração da propulsão no salto Axel do que no Mapes. Quanto à análise eletromiográfica, os músculos gastrocnêmio lateral, reto femoral, vasto lateral, bíceps femoral e glúteo máximo, apresentaram maior ativação durante os saltos com mais rotações, principalmente nas fases de propulsão e voo. Sugere-se que os resultados obtidos no presente estudo sejam considerados no planejamento de um treinamento específico, já que podem ser importantes para o desenvolvimento dos patinadores de elite, provavelmente sendo úteis também para os patinadores de outros níveis que almejam alcançar o nível internacional e obter sucesso em competições. / The aim of the present study was to analyze the kinematic and neuromuscular responses of different roller figure skating jumps, with and without skates, the kinetic responses of the same jumps without skates and the kinetic and kinematic responses of the countermovement jump (CMJ), drop jump (DJ) and squat jump (SJ), in elite skaters. Four elite skaters from Rio Grande do Sul were evaluated, including one Junior female, one Junior male, one Senior female and one Senior male. Each one took part in three experimental sessions: the first one was to collect the anthropometric data and to perform the maximum voluntary isometric contraction for electromyography normalization, the second one was to collect the kinetic, kinematic and neuromuscular variables, without skates, at the laboratory, and the third one was to collect the neuromuscular and kinematic variables during the jumps executed with skates, at the rink. Four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. Subjects executed three jumps of each type and one was selected for analysis based on the best recording area and on the overall quality of the jump. According to the results, male skaters were more powerful than female skaters during the vertical jumps CMJ, DJ and SJ. During the roller figure skating jumps, the four skaters demonstrated higher impulse, maximal power, height and rotational velocity during jumps with more rotations than during jumps with less rotation, while the horizontal velocity at take-off was lower in the jumps with more rotations. Comparing the Axel and Mapes jumps, the skaters demonstrated more duration at the propulsion phase in the Axel jump than in the Mapes. In regard to the electromyographic response, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation in the jumps with more rotations and mainly in the propulsion and flight phases. It is suggested that the results obtained in this study are considered in planning a specific training, since they may be important for the development of elite skaters, probably being also useful for skaters of other levels that aim to achieve the international level and succeed in competitions.

O objetivo do presente estudo foi analisar as respostas cinemáticas e neuromusculares de diferentes saltos da patinação artística sobre rodas, com e sem patins, as respostas cinéticas dos mesmos saltos sem patins, e as respostas cinéticas e cinemáticas do countermovement jump (CMJ), drop jump (DJ) e squat jump (SJ), em patinadores de elite. Foram avaliados quatro patinadores de elite do Rio Grande do Sul, sendo estes uma mulher e um homem da categoria Junior e uma mulher e um homem da categoria Sênior. Os sujeitos participaram de três sessões: a primeira foi destinada à coleta das medidas antropométricas e à realização da contração isométrica voluntária máxima para normalização da eletromiografia, a segunda foi destinada à coleta das variáveis cinéticas, cinemáticas e neuromusculares sem patins, no laboratório, e a terceira foi destinada à coleta das variáveis neuromusculares e cinemáticas durante os saltos realizados com patins, no ginásio. Foram avaliados quatro saltos da patinação artística: Axel simples, Axel duplo, Mapes duplo e Mapes triplo. Os sujeitos executaram três saltos de cada tipo e foi selecionado aquele que estava melhor localizado dentro da zona de filmagem e que apresentou a melhor qualidade de execução. De acordo com os resultados, os patinadores homens foram mais potentes do que as mulheres durante os saltos verticais CMJ, DJ e SJ. Nos saltos da patinação os quatro atletas apresentaram maior impulso, potência máxima, altura e velocidade rotacional durante os saltos com mais rotações do que durante os saltos com menos rotações, enquanto a velocidade horizontal no take-off foi menor nos saltos com mais rotações. Na comparação entre os saltos Axel e Mapes, os patinadores demonstraram maior duração da propulsão no salto Axel do que no Mapes. Quanto à análise eletromiográfica, os músculos gastrocnêmio lateral, reto femoral, vasto lateral, bíceps femoral e glúteo máximo, apresentaram maior ativação durante os saltos com mais rotações, principalmente nas fases de propulsão e voo. Sugere-se que os resultados obtidos no presente estudo sejam considerados no planejamento de um treinamento específico, já que podem ser importantes para o desenvolvimento dos patinadores de elite, provavelmente sendo úteis também para os patinadores de outros níveis que almejam alcançar o nível internacional e obter sucesso em competições. / The aim of the present study was to analyze the kinematic and neuromuscular responses of different roller figure skating jumps, with and without skates, the kinetic responses of the same jumps without skates and the kinetic and kinematic responses of the countermovement jump (CMJ), drop jump (DJ) and squat jump (SJ), in elite skaters. Four elite skaters from Rio Grande do Sul were evaluated, including one Junior female, one Junior male, one Senior female and one Senior male. Each one took part in three experimental sessions: the first one was to collect the anthropometric data and to perform the maximum voluntary isometric contraction for electromyography normalization, the second one was to collect the kinetic, kinematic and neuromuscular variables, without skates, at the laboratory, and the third one was to collect the neuromuscular and kinematic variables during the jumps executed with skates, at the rink. Four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. Subjects executed three jumps of each type and one was selected for analysis based on the best recording area and on the overall quality of the jump. According to the results, male skaters were more powerful than female skaters during the vertical jumps CMJ, DJ and SJ. During the roller figure skating jumps, the four skaters demonstrated higher impulse, maximal power, height and rotational velocity during jumps with more rotations than during jumps with less rotation, while the horizontal velocity at take-off was lower in the jumps with more rotations. Comparing the Axel and Mapes jumps, the skaters demonstrated more duration at the propulsion phase in the Axel jump than in the Mapes. In regard to the electromyographic response, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation in the jumps with more rotations and mainly in the propulsion and flight phases. It is suggested that the results obtained in this study are considered in planning a specific training, since they may be important for the development of elite skaters, probably being also useful for skaters of other levels that aim to achieve the international level and succeed in competitions.

A osteoartrite é uma desordem articular comum nos idosos, sendo responsável por causar perda da funcionalidade destes indivíduos, quando comparada a outras doenças. Sua prevalência aumenta com a idade por ser uma doença irreversível. Esta condição musculoesquelética causa dor, incapacidade física e redução da qualidade de vida. A artroplastia total de joelho é o procedimento adequado para o tratamento da osteoartrite em seus graus mais avançados, e tem apresentado uma melhora funcional dos extensores do joelho (por meio da redução da inibição reflexa e possível aumento da capacidade de produção de força) e da qualidade de vida (pela redução da dor, aumento da mobilidade e retorno às atividades de vida diárias) nesses casos avançados da doença. No entanto, os efeitos da substituição do joelho osteoartrítico pela prótese não são totalmente conhecidos. Em função disso, o objetivo do presente estudo foi comparar a ativação muscular e a produção de força (torque) de indivíduos com osteoartrite (n=20) e indivíduos com artroplastia total de joelho (n=12). O pico de torque dos músculos extensores de joelho foi avaliado durante contrações isométricas voluntárias máximas nos ângulos de 30º, 60º, 75º e 90º. Nos mesmos ângulos articulares também foi avaliada a ativação elétrica dos músculos vasto lateral, vasto medial e reto femoral, através da eletromiografia de superfície. A qualidade de vida foi comparada entre os dois grupos através do questionário WOMAC. O grupo artroplastia obteve menores escores no questionário, o que indica melhora da qualidade de vida destes indivíduos ao serem comparados com o grupo osteoartrite. O comportamento dos dados tanto para a produção de torque como para a ativação muscular, apresentou-se semelhante nos dois grupos. A produção de torque não apresentou diferença significativa entre os grupos avaliados (p=0,775), sendo que a única diferença observada foi para o torque entre os ângulos testados (p=0,0001). Assim como para a produção de torque, a ativação muscular não apresentou diferença significativa entre os grupos osteoartrite e artroplastia total de joelho para os músculos VL, RF e VM (p>0,05). Somente para o menor ângulo (30º) e para o maior ângulo (90º) houve diferença significativa da ativação muscular em relação aos ângulos para os músculos vasto lateral (p=0,011) e vasto medial (p=0,014). Os resultados apresentados neste estudo suportam a hipótese de que a técnica cirúrgica de artroplastia total de joelho propicia uma redução da dor e uma melhora da qualidade de vida. No entanto, essa melhora na qualidade de vida parece não ser refletida em uma melhora funcional após a colocação da prótese, uma vez que não foi observado um aumento na ativação muscular com um correspondente aumento na capacidade de produção de força dos músculos extensores do joelho. / Osteoarthritis is a degenerative disease prevalent in the elderly population characterized by pain, disability and decrease of quality of life. Total knee replacement is indicated for the last stages of the disease, and shows a functional improvement of the knee extensor muscles (by a reduction of reflex inhibition and possibly by increasing muscle force production capacity) and improvement of quality of life (by the reduction in pain, increase in mobility and return to daily life activities) in these advanced stages of the disease. However, the functional effects of the joint replacement are not completely understood. Therefore, the purpose of this study was to compare both the muscle activation and the force production (torque) developed by patients with osteoarthritis (n=20) and patients which underwent total knee replacement (n=12). The knee extensor muscles peak torque was evaluated during maximal voluntary isometric contractions at the joint angles of 30º, 60º, 75º and 90º of knee extension. At the same joint angles the electrical activation was obtained, by surface electromyography from the vastus lateralis, the vastus medialis and the rectus femoris muscles. The WOMAC questionnaire was used to compare the quality of life between the two groups of the study. The arthroplasty group showed lower scores, indicating an improvement in the quality of life compare to the osteoarthritis group. Both groups showed a similar behavior in the torque production and in the muscle activation. Torque production was similar between the two groups (p=0,775), although there was a difference in the torque amongst the studied angles (p=0,0001). There was no difference between the osteoarthritis and the arthroplasty groups for muscle activation of the VL, RF and VM muscles (p>0,05). Nevertheless, activation was different when comparing the smallest and the largest angles studied (30º and 90º, respectively) of the vastus lateralis (p=0,011) and the vastus medialis (p=0,014) muscles in both groups. These results seem to support the hypothesis that the total knee replacement produces an improvement in the quality of life by a reduction in knee joint pain and an increase in the patients mobility and a return to the daily life activities. However, this surgical procedure did not produce a functional improvement in the knee extensor muscles, as there was no increase in muscle activation nor in the expected force produced by this muscle group.

Background. Climbing is growing as a recreational sport worldwide. Climbing is a physically demanding sport requiring well developed strength and endurance. Plenty of studies have been made in the area of climbing in order to understand how the body adapts, which muscles are being used and how to prevent injury. A lot of these studies uses electromyography (EMG), a tool that measures electrical currents in muscles to detect muscle activity, as measurement method in order to do findings within the area. Aim. The aim was to study differences in muscle activation in arm and leg muscles in climbers before and after 40 repeated attempts over two weeks on a boulder problem. Furthermore, correlation between climbing level and change in total measured muscle activation after repeated attempts was assessed. Methods. 15 participants (five women and ten men) participated in this study. Standardized electrode placements and maximal voluntary isometric contractions (MVIC) were made for muscles; Flexor Carpi Radialis (FCR), Bicep Brachii (BB), Rectus Femoris (RF) and Gastrocnemius Lateralis (GL) before each measurement in order to maintain good reliability. Participants repeated a specific climbing route, adapted to the participants climbing ability, 40 times, divided into four sessions over two weeks. Before the first measured attempt the participant got to practice the route twice to get familiar with the moves. Average muscle activation was calculated by dividing the total muscle activation from each muscle with the time it took to complete the climbing route. Peak muscle values were calculated by dividing the highest muscle activation value with the MVIC values to get a %MVIC value. Results. A decrease in average muscle activation for FCR and BB were found (p=0.038, 0.023) whereas an increase in average activation for GL was found (p=0.027). Peak muscle activation showed significant decreases regarding upper extremities FCR and BB (p=0.008, p=0.011) but no significant changes to lower extremities RF and GL. Total average muscular activation regarding all muscles combined showed a general decreased activation (p=0.001). Moderate correlation was found between red-point level and decrease in total average muscle activation (r=0.53). Conclusion. When repeating a climbing route, the climbers muscle activation differs in upper and lower extremities, with a decrease in upper extremities peak and average muscle values, and an increase in GL average muscle values. Repetitions improves technique and muscle memory which could be the reason for the overall decrease in total muscle activation. Hopefully, this study could enrich the climbing world with further knowledge in how to train for climbing.