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Master's Dissertation
DOI
10.11606/D.39.2014.tde-24062014-113328
Document
Author
Full name
Fabiano Aparecido Pinheiro
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2014
Supervisor
Committee
Pires, Flávio de Oliveira (President)
Fontes, Eduardo Bodnariuc
Santos, Tony Meireles dos
Title in Portuguese
Efeitos da privação de luz sobre o desempenho e as respostas fisiológicas e psicológicas durante exercício aberto e fechado
Keywords in Portuguese
Estratégia de prova
Percepção subjetiva de esforço
Regulação central.
Sistema visual
Tolerância ao esforço
Abstract in Portuguese
O sistema visual exerce importante papel para o reconhecimento do ambiente externo e para estabelecer relações entre objetos, tempo e espaço. Além disso, ele está relacionado com o controle e o desempenho motor. O objetivo deste estudo foi verificar se a privação de luz ambiente alteraria o desempenho e as respostas fisiológicas e psicológicas durante dois modelos de exercício, um fechado e um aberto. Onze ciclistas formaram o grupo de exercício fechado (GEF) e completaram um teste de 20 km, enquanto doze indivíduos ativos formaram o grupo de exercício aberto (GEA) e executaram um teste de potência constante até a exaustão (TWC). Após teste incremental máximo, GEF e GEA realizaram exercício na presença (controle) ou privação (experimental) de luz ambiente, em ordem balanceada. Respostas de desempenho, VE, VO2, VCO2 RER, FC, eletromiografia do músculo vato lateral (EMG), percepção subjetiva de esforço (PSE) e pensamento associado ao exercício (PAE) foram obtidas durante, e no ponto final do exercício, em ambas as condições. O tempo total de exercício indicou a resposta de desempenho em GEF e GEA. As respostas das variáveis fisiológicas e psicológicas foram analisadas durante a realização, ou no ponto final do exercício. A média das respostas geradas durante os 20 km no GEF, e as respostas obtidas no mesmo tempo absoluto do TWC no GEA, pareado pelo menor tempo de exaustão atingido no teste, indicaram as respostas durante a execução do exercício. As respostas obtidas nos 5 segundos finais de cada exercício indicaram as respostas do ponto final do GEF e GEA. A taxa de incremento na PSE foi calculada em GEF e GEA, e o erro de predição da distância real percorrida no teste de 20 km foi obtido no GEF. No GEF, não houve efeito da privação de luz sobre o tempo para completar o teste de 20 km, porém a privação de luz gerou menores respostas (P< 0,01) na VE, VO2, VCO2, EMG e PAE, quando comparada ao controle. No ponto final do exercício, nenhuma diferença foi verificada entre as condições. A privação de luz não alterou a taxa de elevação da PSE ou o erro de predição da distância percorrida. No GEA a privação de luz ambiente reduziu o tempo de exaustão (P< 0,05) no TWC e aumentou a resposta do VO2 e EMG (P< 0,05). Entretanto, não foi observado efeito da privação de luz na VE, VCO2 e FC. No ponto final do exercício observou-se menor EMG com a privação de luz (P< 0,03), mas nenhuma diferença nas demais variáveis foi observada. Maior taxa de elevação na PSE foi observada em ambiente privado de luz. Os resultados do presente estudo podem ser interpretados de acordo com a existência de um "relógio biológico interno" que calcula a duração tolerável do exercício de acordo com a aproximação ao ponto final do exercício, sugerindo que os efeitos da privação de luz sobre o desempenho possam depender da presença de um ponto final previamente conhecido
Title in English
Effects of light deprivation in performance and physiological and psychological responses during open and close loop exercise
Keywords in English
Exercise centrally-regulated
Exercise tolerance
Pacing strategy
Perceived exertion
Visual system
Abstract in English
The visual system plays an important role for the environment recognition as well as to set objects, time and space relationships. Furthermore, the visual system is related to the motor learning and performance. The aim of this study was to verify if light deprivation environment would alter performance, and physiological and psychological responses to different exercise modes, closed- and open-loop exercises. Eleven cyclists were the closed-loop exercise group (CLE) and performed a 20 km time trial, while twelve active individuals were the open-loop exercise group (OLE) and cycled to exhaustion during a constant workload exercise. After maximal incremental test CLE and OLE groups performed exercise in a control and experimental condition (i.e. under light deprivation), in a counterbalanced fashion. Performance responses and responses of VE, VO2, VCO2 RER, HR, eletromyography of the vastus lateralis muscle (EMG), ratings of perceived exertion (RPE) and associative thoughts to exercise (ATE) were obtained during exercise and at the exercise endpoint in both the conditions. Time of exercise indicated performance responses in CLE and OLE groups. Physiological and psychological responses were analyzed either during or at the exercise endpoint. Mean responses throughout the 20 km cycling time trial and responses obtained at absolute matched time of exercise, corresponding to the shortest time to exhaustion provided responses along the exercise in CLE and OLE groups, respectively. Responses obtained during the last 5 seconds of the exercises provided responses at the exercise endpoint in both CLE and OLE groups. The rate of increase in RPE was calculated in CLE and OLE groups, and the predictive error of the distance was calculated in the CLE group. In CLE group no effect of light deprivation was observed in the time to complete the 20 km, although the lower response (P< 0.01) of VE, VO2, VCO2, EMG e ATE when compared to control condition. Neither difference was observed in variables at the exercise endpoint. Light deprivation had effect in neither rate of increase in RPE or predictive error of distance. Regarding OLE group the light deprivation decreased the time to exhaustion (P< 0.05) and increased VO2 and EMG (P< 0.05) responses. However, there was no light deprivation effect in VE, VCO2 and HR. Lower EMG was observed at the exercise endpoint in light deprivation condition (P< 0.05) than in control, but no difference was observed in the others. Greater rate of increase in RPE was detected (P< 0.05) in the light deprivation condition than in control. Results of the present study were interpreted according to a "biological internal clock" that calculates the tolerable exercise duraton based on the exercise endpoint approximation, suggesting that light deprivation effects on performance may depend on the presence of an exercise endpoint previously known
 
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Publishing Date
2014-07-02
 
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