Effects of variations of speed and slope on locomotor system variability during running

Detalhes bibliográficos
Autor(a) principal: El Dash, Ingrid
Data de Publicação: 2019
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
Texto Completo: http://www.teses.usp.br/teses/disponiveis/41/41135/tde-14082019-100756/
Resumo: Running is achieved by cyclic execution of movements that ultimately allows a person to move. Each cycle is divided into two phases. The first phase is where power is absorbed as the body\'s center of mass is lowered and decelerated. The second being where power is generated and the center of mass is propelled upwards and forwards. Power absorption is primarily done by quadriceps muscles while plantar flexors generate most of the power during push-off phase. Variations in speed and slope are met by adjustments in the same direction of force produced by lower limb muscles and, due to changes in energy expenditure, of heart rate. In this context, analysis of variability offer a non-invasive way to measure how well-adjusted muscles are to cope with variations in demand. Thus, our aim was to investigate the relationship between the variability of contractions of muscles from the quadriceps and plantar flexors with changes in speed and slope and in heart rate. Secondarily, we sought to verify if the patterns observed in a restricted group of subjects could also be noted in a wider population. To answer these questions, we used electromyography to collect data of intervals between successive contractions of vasti and gastrocnemius muscles of seventeen runners across several target runs. These runs were chosen with several different speeds and slopes. Runners were divided into two experimental groups: Experiment 1 contained no restrictions regarding age and fitness level while Experiment 2 did control for these variables. Linear regressions and gradients showed that even though variability estimators correlated negatively to speed and/or slope, they could be better explained by changes in heart rate. Thus our main conclusion was that variability between contractions is inversely proportional to muscle activation, in relation to its maximum capacity. As a consequence, different combinations of speed and slope could result in the same variability despite differences in metabolic profile, as long as the power output remains constant. Due to methodological issues, we could not reach a decisive conclusion regarding the comparison between the more restricted and more heterogeneous groups of volunteers, although results suggest that the runners respond to changes of speed and slope in a similar way regardless of differences in age and fitness level
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spelling Effects of variations of speed and slope on locomotor system variability during runningEfeitos das variações de velocidade e inclinação na variabilidade do sistema locomotor durante a corridaEMGEMGForça muscularMuscle strengthRunning is achieved by cyclic execution of movements that ultimately allows a person to move. Each cycle is divided into two phases. The first phase is where power is absorbed as the body\'s center of mass is lowered and decelerated. The second being where power is generated and the center of mass is propelled upwards and forwards. Power absorption is primarily done by quadriceps muscles while plantar flexors generate most of the power during push-off phase. Variations in speed and slope are met by adjustments in the same direction of force produced by lower limb muscles and, due to changes in energy expenditure, of heart rate. In this context, analysis of variability offer a non-invasive way to measure how well-adjusted muscles are to cope with variations in demand. Thus, our aim was to investigate the relationship between the variability of contractions of muscles from the quadriceps and plantar flexors with changes in speed and slope and in heart rate. Secondarily, we sought to verify if the patterns observed in a restricted group of subjects could also be noted in a wider population. To answer these questions, we used electromyography to collect data of intervals between successive contractions of vasti and gastrocnemius muscles of seventeen runners across several target runs. These runs were chosen with several different speeds and slopes. Runners were divided into two experimental groups: Experiment 1 contained no restrictions regarding age and fitness level while Experiment 2 did control for these variables. Linear regressions and gradients showed that even though variability estimators correlated negatively to speed and/or slope, they could be better explained by changes in heart rate. Thus our main conclusion was that variability between contractions is inversely proportional to muscle activation, in relation to its maximum capacity. As a consequence, different combinations of speed and slope could result in the same variability despite differences in metabolic profile, as long as the power output remains constant. Due to methodological issues, we could not reach a decisive conclusion regarding the comparison between the more restricted and more heterogeneous groups of volunteers, although results suggest that the runners respond to changes of speed and slope in a similar way regardless of differences in age and fitness levelDurante a corrida, uma série de movimentos é realizada de forma cíclica que, em última análise, fazem com que o corpo se desloque. Cada ciclo é dividido em uma fase em que ocorre absorção de trabalho conforme o centro de massa é rebaixado e desacelerado e uma fase em que ocorre produção de trabalho, conforme o centro de massa é impulsionado para cima e para frente. Os músculos do quadríceps e flexores plantares são os principais responsáveis pela absorção e geração de trabalho, respectivamente. Variações na velocidade da corrida e na inclinação do terreno requerem ajustes da força muscular e, como consequência, da freqüência cardíaca. Neste contexto, análises de variabilidade oferecem uma maneira de medir a adequação do sistema muscular às variações na demanda. Assim, buscamos investigar a relação entre a variabilidade das contrações de músculos do quadríceps e flexores plantares com alterações na velocidade, inclinação e potência; bem como verificar se os padrões observados em um grupo restrito de indivíduos se aplicavam a uma amostra mais variada. Para isso, coletamos dados de intervalos entre contrações do vasto e gastrocnêmio de dezessete voluntários durante corridas realizadas em diferentes combinações de velocidade e inclinação da esteira. Os sujeitos foram divididos em dois grupos experimentais: no Experimento 1, não houve restrições quanto à idade e condicionamento, enquanto que no Experimento 2 essas variáveis foram controladas. Regressões lineares e gradientes mostraram que, embora os estimadores de variabilidade correlacionem negativamente com velocidade e inclinação, eles são melhor explicados por mudanças no consumo energético (i.e.,frequência cardíaca). Assim, concluímos que a variabilidade é inversamente proporcional à força muscular, em relação à sua capacidade máxima. Como conseqüência, diferentes combinações de velocidade e inclinação podem resultar na mesma variabilidade, apesar das diferenças no perfil metabólico. Devido a complicações metodológicas, não pudemos chegar a uma conclusão definitiva em relação a comparação entre voluntários dos Experimentos 1 e 2, embora os resultados sugiram que corredores respondam a mudanças de velocidade e inclinação de maneira semelhante, independentemente de diferenças de idade e nível de condicionamentoBiblioteca Digitais de Teses e Dissertações da USPBerlinck, José Guilherme de Souza Chaui MattosEl Dash, Ingrid 2019-05-03info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://www.teses.usp.br/teses/disponiveis/41/41135/tde-14082019-100756/reponame:Biblioteca Digital de Teses e Dissertações da USPinstname:Universidade de São Paulo (USP)instacron:USPLiberar o conteúdo para acesso público.info:eu-repo/semantics/openAccesseng2019-11-08T22:06:27Zoai:teses.usp.br:tde-14082019-100756Biblioteca Digital de Teses e Dissertaçõeshttp://www.teses.usp.br/PUBhttp://www.teses.usp.br/cgi-bin/mtd2br.plvirginia@if.usp.br|| atendimento@aguia.usp.br||virginia@if.usp.bropendoar:27212019-11-08T22:06:27Biblioteca Digital de Teses e Dissertações da USP - Universidade de São Paulo (USP)false
dc.title.none.fl_str_mv Effects of variations of speed and slope on locomotor system variability during running
Efeitos das variações de velocidade e inclinação na variabilidade do sistema locomotor durante a corrida
title Effects of variations of speed and slope on locomotor system variability during running
spellingShingle Effects of variations of speed and slope on locomotor system variability during running
El Dash, Ingrid
EMG
EMG
Força muscular
Muscle strength
title_short Effects of variations of speed and slope on locomotor system variability during running
title_full Effects of variations of speed and slope on locomotor system variability during running
title_fullStr Effects of variations of speed and slope on locomotor system variability during running
title_full_unstemmed Effects of variations of speed and slope on locomotor system variability during running
title_sort Effects of variations of speed and slope on locomotor system variability during running
author El Dash, Ingrid
author_facet El Dash, Ingrid
author_role author
dc.contributor.none.fl_str_mv Berlinck, José Guilherme de Souza Chaui Mattos
dc.contributor.author.fl_str_mv El Dash, Ingrid
dc.subject.por.fl_str_mv EMG
EMG
Força muscular
Muscle strength
topic EMG
EMG
Força muscular
Muscle strength
description Running is achieved by cyclic execution of movements that ultimately allows a person to move. Each cycle is divided into two phases. The first phase is where power is absorbed as the body\'s center of mass is lowered and decelerated. The second being where power is generated and the center of mass is propelled upwards and forwards. Power absorption is primarily done by quadriceps muscles while plantar flexors generate most of the power during push-off phase. Variations in speed and slope are met by adjustments in the same direction of force produced by lower limb muscles and, due to changes in energy expenditure, of heart rate. In this context, analysis of variability offer a non-invasive way to measure how well-adjusted muscles are to cope with variations in demand. Thus, our aim was to investigate the relationship between the variability of contractions of muscles from the quadriceps and plantar flexors with changes in speed and slope and in heart rate. Secondarily, we sought to verify if the patterns observed in a restricted group of subjects could also be noted in a wider population. To answer these questions, we used electromyography to collect data of intervals between successive contractions of vasti and gastrocnemius muscles of seventeen runners across several target runs. These runs were chosen with several different speeds and slopes. Runners were divided into two experimental groups: Experiment 1 contained no restrictions regarding age and fitness level while Experiment 2 did control for these variables. Linear regressions and gradients showed that even though variability estimators correlated negatively to speed and/or slope, they could be better explained by changes in heart rate. Thus our main conclusion was that variability between contractions is inversely proportional to muscle activation, in relation to its maximum capacity. As a consequence, different combinations of speed and slope could result in the same variability despite differences in metabolic profile, as long as the power output remains constant. Due to methodological issues, we could not reach a decisive conclusion regarding the comparison between the more restricted and more heterogeneous groups of volunteers, although results suggest that the runners respond to changes of speed and slope in a similar way regardless of differences in age and fitness level
publishDate 2019
dc.date.none.fl_str_mv 2019-05-03
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/masterThesis
format masterThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://www.teses.usp.br/teses/disponiveis/41/41135/tde-14082019-100756/
url http://www.teses.usp.br/teses/disponiveis/41/41135/tde-14082019-100756/
dc.language.iso.fl_str_mv eng
language eng
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dc.rights.driver.fl_str_mv Liberar o conteúdo para acesso público.
info:eu-repo/semantics/openAccess
rights_invalid_str_mv Liberar o conteúdo para acesso público.
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
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dc.publisher.none.fl_str_mv Biblioteca Digitais de Teses e Dissertações da USP
publisher.none.fl_str_mv Biblioteca Digitais de Teses e Dissertações da USP
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reponame:Biblioteca Digital de Teses e Dissertações da USP
instname:Universidade de São Paulo (USP)
instacron:USP
instname_str Universidade de São Paulo (USP)
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reponame_str Biblioteca Digital de Teses e Dissertações da USP
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repository.name.fl_str_mv Biblioteca Digital de Teses e Dissertações da USP - Universidade de São Paulo (USP)
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