The problems associated with the contamination of groundwater environments by non-aqueous phase liquids (NAPLs) such as chlorinated solvents, gasoline and manufacturing gas plant (MGP) residuals, including their distribution and persistence, are well accepted. The treatment of groundwater by in situ chemical oxidation (ISCO) relies on the oxidation potential of chemical reagents to destroy harmful organic compounds. The interaction of these oxidants with target and non-target compounds in the subsurface will help determine effectiveness and efficiency of an ISCO treatment system. Push-pull tests (PPTs) have the utility to estimate key properties in situ and allow for sampling a larger volume of aquifer to yield more representative estimates as compared to conventional bench-scale tests. The scale and cost-effectiveness of a PPT make it an ideal tool to collect valuable information on subsurface system behaviour so that uncertainties can be minimized. The use of PPTs to provide insight into treatment expectations or to support the design of an ISCO system requires a suitable interpretation tool. A multi-species numerical model (‘PPT-ISCO’) in a radial coordinate system was developed to simulate a PPT with the injection of a conservative tracer and oxidant (persulfate or permanganate) into the saturated zone of a porous medium environment. The pore space may contain variable amounts of immobile, multicomponent, residual NAPL. The aquifer material contains a natural organic matter (NOM) fraction and/or other oxidizable aquifer material (OAM) species. The model is capable of simulating mass transport for an arbitrary number of conservative and reactive tracers and NAPL constituents subjected to chemical reactions. The ability of PPTs to capture the in situ natural oxidant interaction (NOI) was tested with PPTISCO. Breakthrough curve (BTC) data collected from permanganate and persulfate PPTs conducted in the field were compared to simulated BTCs by assigning the same field operational parameters to the model and applying NOI kinetic information obtained from batch tests. These tests confirmed the usability of the model and PPTs to obtain the NOI kinetics from PPT BTCs. The sensitivity of PPT BTCs to variations in the field operating and NOI parameters were investigated. The results of varying the field operating parameters indicated that the oxidant BTCs could be scaled to match varying injection and extraction flow rates. Variations in NOI parameters revealed that the permanganate BTC is primarily controlled by the permanganate fast reaction rate coefficient and the quantity of OAM present in the aquifer. The spatial profiles of OAM across the test zone revealed that the majority of the OAM consumption is from the fast fraction and occurs in the vicinity of the well where the permanganate concentration is greatest. An estimate of the permanganate fast reaction rate coefficient can be obtained from a permanganate PPT BTC by employing the model to simulate the PPT with the operational parameters (used in the field) and literature estimates of the remaining NOI parameters. Calibration between the simulated and observed BTCs can be undertaken to adjust the permanganate fast reaction rate coefficient to fit the permanganate PPT BTC. Persulfate NOI sensitivity investigations revealed that persulfate PPT BTCs can be characterized by a concentration plateau at early times as a result of the increased ionic strength in the area around the injection well. The ionic strength is primarily controlled by the injected persulfate concentration, and as persulfate degrades into sulphate and acid, the ionic strength is enhanced. Graphical analysis of the BTC revealed that an underestimated value of the persulfate degradation rate coefficient can be obtained from the PPT BTC. A more representative estimate of the persulfate degradation rate coefficient can be achieved after fitting the field BTC to the simulated results, applying the underestimated value as a starting point. PPTs investigating ISCO treatability have the ability to provide insight into the effect of the NOI on the oxidation of target compounds, site-specific oxidant dosage requirements and NAPL treatment expectations. NAPL component BTCs from treatability PPTs are primarily controlled by the mass in the fast region, and the fast region mass transfer rate coefficient. Oxidation estimates extracted from NAPL component BTCs were shown to accurately approximate the mass of each NAPL component oxidized when compared to model calculations. The mass of NAPL oxidized for each of the components yields a site-specific oxidant dosage. This estimate exceeds what is prescribed by the stoichiometry between permanganate and the contaminant of concern due to the effect of the NOI. The utility of PPTs to study and quantify the interaction between injected oxidants and the aquifer material has been demonstrated with PPT-ISCO. In addition, PPT-ISCO has revealed that treatability PPTs can be tailored to investigate the dosage requirements and treatment expectations of residual NAPLs. Results from this effort will be used to support ongoing field research exploring the use of PPTs to assist in understanding the competing subsurface processes affecting ISCO applications.

The problems associated with the contamination of groundwater environments by non-aqueous phase liquids (NAPLs) such as chlorinated solvents, gasoline and manufacturing gas plant (MGP) residuals, including their distribution and persistence, are well accepted. The treatment of groundwater by in situ chemical oxidation (ISCO) relies on the oxidation potential of chemical reagents to destroy harmful organic compounds. The interaction of these oxidants with target and non-target compounds in the subsurface will help determine effectiveness and efficiency of an ISCO treatment system. Push-pull tests (PPTs) have the utility to estimate key properties in situ and allow for sampling a larger volume of aquifer to yield more representative estimates as compared to conventional bench-scale tests. The scale and cost-effectiveness of a PPT make it an ideal tool to collect valuable information on subsurface system behaviour so that uncertainties can be minimized. The use of PPTs to provide insight into treatment expectations or to support the design of an ISCO system requires a suitable interpretation tool. A multi-species numerical model (‘PPT-ISCO’) in a radial coordinate system was developed to simulate a PPT with the injection of a conservative tracer and oxidant (persulfate or permanganate) into the saturated zone of a porous medium environment. The pore space may contain variable amounts of immobile, multicomponent, residual NAPL. The aquifer material contains a natural organic matter (NOM) fraction and/or other oxidizable aquifer material (OAM) species. The model is capable of simulating mass transport for an arbitrary number of conservative and reactive tracers and NAPL constituents subjected to chemical reactions. The ability of PPTs to capture the in situ natural oxidant interaction (NOI) was tested with PPTISCO. Breakthrough curve (BTC) data collected from permanganate and persulfate PPTs conducted in the field were compared to simulated BTCs by assigning the same field operational parameters to the model and applying NOI kinetic information obtained from batch tests. These tests confirmed the usability of the model and PPTs to obtain the NOI kinetics from PPT BTCs. The sensitivity of PPT BTCs to variations in the field operating and NOI parameters were investigated. The results of varying the field operating parameters indicated that the oxidant BTCs could be scaled to match varying injection and extraction flow rates. Variations in NOI parameters revealed that the permanganate BTC is primarily controlled by the permanganate fast reaction rate coefficient and the quantity of OAM present in the aquifer. The spatial profiles of OAM across the test zone revealed that the majority of the OAM consumption is from the fast fraction and occurs in the vicinity of the well where the permanganate concentration is greatest. An estimate of the permanganate fast reaction rate coefficient can be obtained from a permanganate PPT BTC by employing the model to simulate the PPT with the operational parameters (used in the field) and literature estimates of the remaining NOI parameters. Calibration between the simulated and observed BTCs can be undertaken to adjust the permanganate fast reaction rate coefficient to fit the permanganate PPT BTC. Persulfate NOI sensitivity investigations revealed that persulfate PPT BTCs can be characterized by a concentration plateau at early times as a result of the increased ionic strength in the area around the injection well. The ionic strength is primarily controlled by the injected persulfate concentration, and as persulfate degrades into sulphate and acid, the ionic strength is enhanced. Graphical analysis of the BTC revealed that an underestimated value of the persulfate degradation rate coefficient can be obtained from the PPT BTC. A more representative estimate of the persulfate degradation rate coefficient can be achieved after fitting the field BTC to the simulated results, applying the underestimated value as a starting point. PPTs investigating ISCO treatability have the ability to provide insight into the effect of the NOI on the oxidation of target compounds, site-specific oxidant dosage requirements and NAPL treatment expectations. NAPL component BTCs from treatability PPTs are primarily controlled by the mass in the fast region, and the fast region mass transfer rate coefficient. Oxidation estimates extracted from NAPL component BTCs were shown to accurately approximate the mass of each NAPL component oxidized when compared to model calculations. The mass of NAPL oxidized for each of the components yields a site-specific oxidant dosage. This estimate exceeds what is prescribed by the stoichiometry between permanganate and the contaminant of concern due to the effect of the NOI. The utility of PPTs to study and quantify the interaction between injected oxidants and the aquifer material has been demonstrated with PPT-ISCO. In addition, PPT-ISCO has revealed that treatability PPTs can be tailored to investigate the dosage requirements and treatment expectations of residual NAPLs. Results from this effort will be used to support ongoing field research exploring the use of PPTs to assist in understanding the competing subsurface processes affecting ISCO applications.

Introdução: Com o aumento da idade, estudos demonstram que a população experimenta um declínio de sistemas fisiológicos participantes no controle da estabilidade postural. Dentre os métodos de avaliação descritos na literatura, encontra-se o Pull Test (PT), que é amplamente utilizado em escala mundial para avaliação do equilíbrio em indivíduos com doença de Parkinson. O teste examina a resposta do corpo a um deslocamento corporal posterior, oferecendo um identificador útil da estabilidade postural do indivíduo. O padrão de ativação muscular durante a realização do PT não foi ainda estudado. Objetivo: analisar o padrão da atividade eletromiográfica durante a realização do PT, em indivíduos hígidos acima de 40 anos de idade. Métodos: Vinte e três indivíduos hígidos realizaram o estudo eletromiográfico (EMG) de superfície dos músculos tibial anterior, gastrocnêmio medial e bíceps femoral durante a realização do PT. O PT e registros eletromiográficos foram realizados sucessivamente por 10 vezes em cada indivíduo. Os indivíduos foram também avaliados pelo Montreal Cognitive Assessment (MoCA). Resultados: O registro EMG mostrou que a atividade muscular inicia pelo tibial anterior, sendo seguida sucessivamente pelo gastrocnêmio medial e bíceps femoral. A frequência do número de passos para a manutenção da estabilidade postural foi de 93,9% para 1 ou 2 passos e 6,1% para 3 passos ou mais. A latência para ativação muscular foi relacionada com o desempenho cognitivo no MoCA. Pacientes com escores no MoCA inferior a 26 apresentavam maior latência do tibial anterior (p=0,03) e do bíceps femoral (p=0,02). Além disso, a amplitude do gastrocnêmio medial relacionou-se inversamente com o índice de massa corporal (IMC) (p=0,01). Conclusão: Constatou-se que o declínio da função executiva e o sobrepeso estão relacionados com mudanças nas respostas 12 neurofisiológicas durante a realização do PT. Os mesmos podem contribuir para prejuízos da estabilidade postural nestes indivíduos. / Background: Physiologic systems that participate of the postural stability control are impaired with aging. Pull Test (PT) is an assessment method widely worldwide utilized for evaluating the balance in individuals with Parkinson’s disease. The test examines the body’s response to a posterior bodily displacement, offering a useful identifier of the individual’s postural stability. The pattern of muscle activation during the PT has not yet been studied. Objective: the objective of this study was to analyze the pattern of electromyographic activity during the PT, in healthy individuals, over 40 years of age. Methods: Twenty three healthy individuals have carried out an electromyographic (EMG) study of the tibialis anterior, gastrocnemius medialis and biceps femoris muscles during the PT. The PT and the electromyographic recordings have been taken successively for 10 times in each individual. The individuals cognition have been assessed by the Montreal Cognitive Assessment (MoCA). Results: The EMG recording has showed that the muscle activity begins by the tibialis anterior, being successively followed by the gastrocnemius medialis and by the biceps femoris. The rate of the number of steps for keeping the postural stability was 93.9% for 1 or 2 steps, and 6.1% for 3 or more steps. The latency for muscle activation was related to the cognitive performance in the MoCA. Patients with MoCA scores lower than 26 have presented a larger latency in the tibialis anterior (p=0.03), and in the biceps femoris (p=0.02). Furthermore, the amplitude of the gastrocnemius medialis has been inversely related to the body mass index (BMI) (p=0.01). Conclusion: It has been found out that the decline in the executive function and overweight related to changes in the neurophysiologic 14 response during the taking of the PT. These may contribute for the losses of postural stability in such individuals.

Introdução: A Doença de Parkinson (DP) é uma desordem neurodegenerativa, progressiva, patologicamente caracterizada pela perda neuronal de dopamina na via nigro-estriatal e pela presença de inclusões intraneuronais de corpos de Lewy. De etiologia desconhecida é consensualmente aceita como uma doença multifatorial com determinantes genéticos, ambientais e relacionados ao envelhecimento. Constitui-se na segunda doença neurodegenerativa mais comum em idosos. Caracteriza-se clinicamente pela tríade tremor, rigidez e bradicinesia. Juntam-se a esses sinais clássicos as alterações posturais, que levam a DP a ser considerada fator de risco independente para quedas. Apesar disso, a avaliação da estabilidade postural na DP ainda permanece imprecisa e com tratamento difícil. Objetivos e métodos: O principal foco desta dissertação é a compreensão dos mecanismos envolvidos nas alterações do equilíbrio na DP. Neste sentido realizamos uma avaliação da atividade elétrica muscular através da Eletromiografia (EMG) de superfície durante a realização do Pull Test (PT), em português teste de retropulsão. Padrões de latência e amplitude de ativação dos músculos tibial anterior, gastrocnêmio e bíceps femoral foram comparados durante a realização do PT entre pacientes com DP e indivíduos hígidos. Os padrões neurofisiológicos dos pacientes com DP foram comparados com escores no PT, tendência a quedas e administração de levodopa (períodos on e off). Resultados e conclusões: Foram encontradas diferenças significantes na atividade muscular entre DP e controles durante PT. Pacientes com DP apresentaram uma menor latência de ativação muscular. Além disso, após uma repetição em sequência de 10 PT, indivíduos controles apresentaram aumento progressivo das latências, sugerindo habituação. Já os pacientes com DP mantiveram uma latência de ativação constante, ou seja não apresentaram habituação. Não foram observadas diferenças relevantes de atividade muscular entre os DPs com PT positivo e negativo, entre caidores e não caidores e após a ingestão de Levodopa o que sugere a interferência de outros fatores relacionados à estabilidade postural, que levam a quedas na DP, em virtude da natureza heterogênea desses eventos. / Background: Parkinson's disease (PD) is a neurodegenerative disorder, progressive, pathologically characterized by neuronal loss of dopamine in the nigrostriatal pathway and the presence of intraneuronal inclusions of Lewy bodies. Of unknown etiology is widely accepted as a multifactorial disease with genetical, environmental and aging determinants. It constitutes the second most common neurodegenerative disease in the elderly. It is clinically characterized by a triad of tremor, rigidity and bradykinesia. Besides these classic signs we can add postural changes, leading PD to be considered an independent risk factor to falls. Despite this, the assessment of postural stability in PD remains unclear and difficult to treat. Objective and Methods: The main focus of this dissertation is understanding the mechanisms involved in balance disorders in PD. We undertook an assessment of muscle electrical activity through surface electromyography (EMG) while performing a Pull Test (PT). Patterns of latency and amplitude of muscle activation of the tibialis anterior, gastrocnemius and biceps femoris muscles were compared during the course of PT between PD patients and healthy individuals. Neurophysiological patterns of PD patients were compared with scores on the PT, the tendency to fall and administration of levodopa (on and off periods). Results and Conclusion: Significant differences were found in muscle activity between PD and controls during PT. PD patients had a lower latency of muscle activation. Furthermore, after a repetition in sequence of 10 PT, control subjects showed a progressive increase in latency, suggesting habituation. Patients with PD a latency of activation remained constant or showed no habituation. However, there were no significant differences in muscle activity between the PDs with positive and negative PT, between fallers and non fallers and after administration of L-dopa suggesting the influence of other factors related to postural stability, leading to falls in PD, due to the heterogeneous nature of these events.

Introdução: Com o aumento da idade, estudos demonstram que a população experimenta um declínio de sistemas fisiológicos participantes no controle da estabilidade postural. Dentre os métodos de avaliação descritos na literatura, encontra-se o Pull Test (PT), que é amplamente utilizado em escala mundial para avaliação do equilíbrio em indivíduos com doença de Parkinson. O teste examina a resposta do corpo a um deslocamento corporal posterior, oferecendo um identificador útil da estabilidade postural do indivíduo. O padrão de ativação muscular durante a realização do PT não foi ainda estudado. Objetivo: analisar o padrão da atividade eletromiográfica durante a realização do PT, em indivíduos hígidos acima de 40 anos de idade. Métodos: Vinte e três indivíduos hígidos realizaram o estudo eletromiográfico (EMG) de superfície dos músculos tibial anterior, gastrocnêmio medial e bíceps femoral durante a realização do PT. O PT e registros eletromiográficos foram realizados sucessivamente por 10 vezes em cada indivíduo. Os indivíduos foram também avaliados pelo Montreal Cognitive Assessment (MoCA). Resultados: O registro EMG mostrou que a atividade muscular inicia pelo tibial anterior, sendo seguida sucessivamente pelo gastrocnêmio medial e bíceps femoral. A frequência do número de passos para a manutenção da estabilidade postural foi de 93,9% para 1 ou 2 passos e 6,1% para 3 passos ou mais. A latência para ativação muscular foi relacionada com o desempenho cognitivo no MoCA. Pacientes com escores no MoCA inferior a 26 apresentavam maior latência do tibial anterior (p=0,03) e do bíceps femoral (p=0,02). Além disso, a amplitude do gastrocnêmio medial relacionou-se inversamente com o índice de massa corporal (IMC) (p=0,01). Conclusão: Constatou-se que o declínio da função executiva e o sobrepeso estão relacionados com mudanças nas respostas 12 neurofisiológicas durante a realização do PT. Os mesmos podem contribuir para prejuízos da estabilidade postural nestes indivíduos. / Background: Physiologic systems that participate of the postural stability control are impaired with aging. Pull Test (PT) is an assessment method widely worldwide utilized for evaluating the balance in individuals with Parkinson’s disease. The test examines the body’s response to a posterior bodily displacement, offering a useful identifier of the individual’s postural stability. The pattern of muscle activation during the PT has not yet been studied. Objective: the objective of this study was to analyze the pattern of electromyographic activity during the PT, in healthy individuals, over 40 years of age. Methods: Twenty three healthy individuals have carried out an electromyographic (EMG) study of the tibialis anterior, gastrocnemius medialis and biceps femoris muscles during the PT. The PT and the electromyographic recordings have been taken successively for 10 times in each individual. The individuals cognition have been assessed by the Montreal Cognitive Assessment (MoCA). Results: The EMG recording has showed that the muscle activity begins by the tibialis anterior, being successively followed by the gastrocnemius medialis and by the biceps femoris. The rate of the number of steps for keeping the postural stability was 93.9% for 1 or 2 steps, and 6.1% for 3 or more steps. The latency for muscle activation was related to the cognitive performance in the MoCA. Patients with MoCA scores lower than 26 have presented a larger latency in the tibialis anterior (p=0.03), and in the biceps femoris (p=0.02). Furthermore, the amplitude of the gastrocnemius medialis has been inversely related to the body mass index (BMI) (p=0.01). Conclusion: It has been found out that the decline in the executive function and overweight related to changes in the neurophysiologic 14 response during the taking of the PT. These may contribute for the losses of postural stability in such individuals.

Introdução: A Doença de Parkinson (DP) é uma desordem neurodegenerativa, progressiva, patologicamente caracterizada pela perda neuronal de dopamina na via nigro-estriatal e pela presença de inclusões intraneuronais de corpos de Lewy. De etiologia desconhecida é consensualmente aceita como uma doença multifatorial com determinantes genéticos, ambientais e relacionados ao envelhecimento. Constitui-se na segunda doença neurodegenerativa mais comum em idosos. Caracteriza-se clinicamente pela tríade tremor, rigidez e bradicinesia. Juntam-se a esses sinais clássicos as alterações posturais, que levam a DP a ser considerada fator de risco independente para quedas. Apesar disso, a avaliação da estabilidade postural na DP ainda permanece imprecisa e com tratamento difícil. Objetivos e métodos: O principal foco desta dissertação é a compreensão dos mecanismos envolvidos nas alterações do equilíbrio na DP. Neste sentido realizamos uma avaliação da atividade elétrica muscular através da Eletromiografia (EMG) de superfície durante a realização do Pull Test (PT), em português teste de retropulsão. Padrões de latência e amplitude de ativação dos músculos tibial anterior, gastrocnêmio e bíceps femoral foram comparados durante a realização do PT entre pacientes com DP e indivíduos hígidos. Os padrões neurofisiológicos dos pacientes com DP foram comparados com escores no PT, tendência a quedas e administração de levodopa (períodos on e off). Resultados e conclusões: Foram encontradas diferenças significantes na atividade muscular entre DP e controles durante PT. Pacientes com DP apresentaram uma menor latência de ativação muscular. Além disso, após uma repetição em sequência de 10 PT, indivíduos controles apresentaram aumento progressivo das latências, sugerindo habituação. Já os pacientes com DP mantiveram uma latência de ativação constante, ou seja não apresentaram habituação. Não foram observadas diferenças relevantes de atividade muscular entre os DPs com PT positivo e negativo, entre caidores e não caidores e após a ingestão de Levodopa o que sugere a interferência de outros fatores relacionados à estabilidade postural, que levam a quedas na DP, em virtude da natureza heterogênea desses eventos. / Background: Parkinson's disease (PD) is a neurodegenerative disorder, progressive, pathologically characterized by neuronal loss of dopamine in the nigrostriatal pathway and the presence of intraneuronal inclusions of Lewy bodies. Of unknown etiology is widely accepted as a multifactorial disease with genetical, environmental and aging determinants. It constitutes the second most common neurodegenerative disease in the elderly. It is clinically characterized by a triad of tremor, rigidity and bradykinesia. Besides these classic signs we can add postural changes, leading PD to be considered an independent risk factor to falls. Despite this, the assessment of postural stability in PD remains unclear and difficult to treat. Objective and Methods: The main focus of this dissertation is understanding the mechanisms involved in balance disorders in PD. We undertook an assessment of muscle electrical activity through surface electromyography (EMG) while performing a Pull Test (PT). Patterns of latency and amplitude of muscle activation of the tibialis anterior, gastrocnemius and biceps femoris muscles were compared during the course of PT between PD patients and healthy individuals. Neurophysiological patterns of PD patients were compared with scores on the PT, the tendency to fall and administration of levodopa (on and off periods). Results and Conclusion: Significant differences were found in muscle activity between PD and controls during PT. PD patients had a lower latency of muscle activation. Furthermore, after a repetition in sequence of 10 PT, control subjects showed a progressive increase in latency, suggesting habituation. Patients with PD a latency of activation remained constant or showed no habituation. However, there were no significant differences in muscle activity between the PDs with positive and negative PT, between fallers and non fallers and after administration of L-dopa suggesting the influence of other factors related to postural stability, leading to falls in PD, due to the heterogeneous nature of these events.

Introdução: Com o aumento da idade, estudos demonstram que a população experimenta um declínio de sistemas fisiológicos participantes no controle da estabilidade postural. Dentre os métodos de avaliação descritos na literatura, encontra-se o Pull Test (PT), que é amplamente utilizado em escala mundial para avaliação do equilíbrio em indivíduos com doença de Parkinson. O teste examina a resposta do corpo a um deslocamento corporal posterior, oferecendo um identificador útil da estabilidade postural do indivíduo. O padrão de ativação muscular durante a realização do PT não foi ainda estudado. Objetivo: analisar o padrão da atividade eletromiográfica durante a realização do PT, em indivíduos hígidos acima de 40 anos de idade. Métodos: Vinte e três indivíduos hígidos realizaram o estudo eletromiográfico (EMG) de superfície dos músculos tibial anterior, gastrocnêmio medial e bíceps femoral durante a realização do PT. O PT e registros eletromiográficos foram realizados sucessivamente por 10 vezes em cada indivíduo. Os indivíduos foram também avaliados pelo Montreal Cognitive Assessment (MoCA). Resultados: O registro EMG mostrou que a atividade muscular inicia pelo tibial anterior, sendo seguida sucessivamente pelo gastrocnêmio medial e bíceps femoral. A frequência do número de passos para a manutenção da estabilidade postural foi de 93,9% para 1 ou 2 passos e 6,1% para 3 passos ou mais. A latência para ativação muscular foi relacionada com o desempenho cognitivo no MoCA. Pacientes com escores no MoCA inferior a 26 apresentavam maior latência do tibial anterior (p=0,03) e do bíceps femoral (p=0,02). Além disso, a amplitude do gastrocnêmio medial relacionou-se inversamente com o índice de massa corporal (IMC) (p=0,01). Conclusão: Constatou-se que o declínio da função executiva e o sobrepeso estão relacionados com mudanças nas respostas 12 neurofisiológicas durante a realização do PT. Os mesmos podem contribuir para prejuízos da estabilidade postural nestes indivíduos. / Background: Physiologic systems that participate of the postural stability control are impaired with aging. Pull Test (PT) is an assessment method widely worldwide utilized for evaluating the balance in individuals with Parkinson’s disease. The test examines the body’s response to a posterior bodily displacement, offering a useful identifier of the individual’s postural stability. The pattern of muscle activation during the PT has not yet been studied. Objective: the objective of this study was to analyze the pattern of electromyographic activity during the PT, in healthy individuals, over 40 years of age. Methods: Twenty three healthy individuals have carried out an electromyographic (EMG) study of the tibialis anterior, gastrocnemius medialis and biceps femoris muscles during the PT. The PT and the electromyographic recordings have been taken successively for 10 times in each individual. The individuals cognition have been assessed by the Montreal Cognitive Assessment (MoCA). Results: The EMG recording has showed that the muscle activity begins by the tibialis anterior, being successively followed by the gastrocnemius medialis and by the biceps femoris. The rate of the number of steps for keeping the postural stability was 93.9% for 1 or 2 steps, and 6.1% for 3 or more steps. The latency for muscle activation was related to the cognitive performance in the MoCA. Patients with MoCA scores lower than 26 have presented a larger latency in the tibialis anterior (p=0.03), and in the biceps femoris (p=0.02). Furthermore, the amplitude of the gastrocnemius medialis has been inversely related to the body mass index (BMI) (p=0.01). Conclusion: It has been found out that the decline in the executive function and overweight related to changes in the neurophysiologic 14 response during the taking of the PT. These may contribute for the losses of postural stability in such individuals.

Introdução: A Doença de Parkinson (DP) é uma desordem neurodegenerativa, progressiva, patologicamente caracterizada pela perda neuronal de dopamina na via nigro-estriatal e pela presença de inclusões intraneuronais de corpos de Lewy. De etiologia desconhecida é consensualmente aceita como uma doença multifatorial com determinantes genéticos, ambientais e relacionados ao envelhecimento. Constitui-se na segunda doença neurodegenerativa mais comum em idosos. Caracteriza-se clinicamente pela tríade tremor, rigidez e bradicinesia. Juntam-se a esses sinais clássicos as alterações posturais, que levam a DP a ser considerada fator de risco independente para quedas. Apesar disso, a avaliação da estabilidade postural na DP ainda permanece imprecisa e com tratamento difícil. Objetivos e métodos: O principal foco desta dissertação é a compreensão dos mecanismos envolvidos nas alterações do equilíbrio na DP. Neste sentido realizamos uma avaliação da atividade elétrica muscular através da Eletromiografia (EMG) de superfície durante a realização do Pull Test (PT), em português teste de retropulsão. Padrões de latência e amplitude de ativação dos músculos tibial anterior, gastrocnêmio e bíceps femoral foram comparados durante a realização do PT entre pacientes com DP e indivíduos hígidos. Os padrões neurofisiológicos dos pacientes com DP foram comparados com escores no PT, tendência a quedas e administração de levodopa (períodos on e off). Resultados e conclusões: Foram encontradas diferenças significantes na atividade muscular entre DP e controles durante PT. Pacientes com DP apresentaram uma menor latência de ativação muscular. Além disso, após uma repetição em sequência de 10 PT, indivíduos controles apresentaram aumento progressivo das latências, sugerindo habituação. Já os pacientes com DP mantiveram uma latência de ativação constante, ou seja não apresentaram habituação. Não foram observadas diferenças relevantes de atividade muscular entre os DPs com PT positivo e negativo, entre caidores e não caidores e após a ingestão de Levodopa o que sugere a interferência de outros fatores relacionados à estabilidade postural, que levam a quedas na DP, em virtude da natureza heterogênea desses eventos. / Background: Parkinson's disease (PD) is a neurodegenerative disorder, progressive, pathologically characterized by neuronal loss of dopamine in the nigrostriatal pathway and the presence of intraneuronal inclusions of Lewy bodies. Of unknown etiology is widely accepted as a multifactorial disease with genetical, environmental and aging determinants. It constitutes the second most common neurodegenerative disease in the elderly. It is clinically characterized by a triad of tremor, rigidity and bradykinesia. Besides these classic signs we can add postural changes, leading PD to be considered an independent risk factor to falls. Despite this, the assessment of postural stability in PD remains unclear and difficult to treat. Objective and Methods: The main focus of this dissertation is understanding the mechanisms involved in balance disorders in PD. We undertook an assessment of muscle electrical activity through surface electromyography (EMG) while performing a Pull Test (PT). Patterns of latency and amplitude of muscle activation of the tibialis anterior, gastrocnemius and biceps femoris muscles were compared during the course of PT between PD patients and healthy individuals. Neurophysiological patterns of PD patients were compared with scores on the PT, the tendency to fall and administration of levodopa (on and off periods). Results and Conclusion: Significant differences were found in muscle activity between PD and controls during PT. PD patients had a lower latency of muscle activation. Furthermore, after a repetition in sequence of 10 PT, control subjects showed a progressive increase in latency, suggesting habituation. Patients with PD a latency of activation remained constant or showed no habituation. However, there were no significant differences in muscle activity between the PDs with positive and negative PT, between fallers and non fallers and after administration of L-dopa suggesting the influence of other factors related to postural stability, leading to falls in PD, due to the heterogeneous nature of these events.

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This dissertation aimed to explore the usefulness of using force derivatives for onset detection in the isometric mid-thigh pull test. First, we examined applications of three differential calculus principles, first and second derivative, and curvature using visual detection as a reference under different baseline conditions. Second, we compared the best derivative method to a threshold-based method using visual detection as a reference. Results of our first investigation showed trivial differences between many differential calculus methods and visual detection. However, statistical differences exceeding a trivial effect was observed when instantaneous force and rate of force develop were examined. Through the first investigation, first and second derivative emerged as possible viable methods for baseline with a countermovement and for all other baseline conditions, respectively. Results of the second investigation showed similarities to the first investigation with respect to onset time. However, examination of instantaneous force and rate of force development indicated that a threshold-based method tended to overestimate compared to visual detection and a first and second derivative combined method. In fact, the difference between visual detection and the first and second derivative combined method ranged from trivial to moderate under all baseline conditions while the threshold-based method often reached a large difference. Overestimation by the threshold-method was more pronounced for rate of force development. In conclusion, while not perfect, the first and second derivative 3 combined method appears to hold possible practical potential and may be used as an assistant method for entry-level sport scientist plus using visual detection for obvious erroneous values.