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Master's Dissertation
DOI
10.11606/D.39.2019.tde-24042018-103453
Document
Author
Full name
Rafael de Almeida Azevedo
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2017
Supervisor
Committee
Bertuzzi, Rômulo Cássio de Moraes (President)
Lima, Jorge Roberto Perrout de
Silva, Adriano Eduardo Lima da
Zagatto, Alessandro Moura
Title in Portuguese
Contribuições dos sistemas nervoso central e muscular no estabelecimento da estratégia de prova durante uma prova contrarrelógio de 4 km de ciclismo
Keywords in Portuguese
Fadiga central
Fadiga periférica
Pacing strategy
Perfil metabolômico
Abstract in Portuguese
A presente dissertação procurou determinar as fases do pacing strategy em "U" e analisar o desenvolvimento da fadiga neuromuscular e o perfil metabolômico em um teste contrarrelógio de 4 km no ciclismo (4 km CT). No estudo 1, foi proposto dois modelos (visual e matemático) para determinar as três fases do pacing strategy em "U" durante um 4 km CT. Foram recrutados 15 ciclistas para realizar dois testes 4 km CT em dias separados. Para o modelo visual, quatro avaliadores experientes analisaram o pacing strategy duas vezes, sete dias de diferença. O modelo matemático foi composto pela média da potência durante a fase 2 (1 até 3 km) mais dois desvios padrões, identificando o ponto de mudança (PM) da fase 2 entre fase 1 (PM1) e 3 (PM2). O PM1 ocorreu em 419 ± 186 e 415 ± 178 m e PM2 ocorreu em 3646 ± 228 e 3809 ± 213 m para o modelo visual e matemático. Não houve diferença entre os modelos para ambos PM (p > 0,05). A reprodutibilidade intra avaliadores no modelo visual para PM1 e PM2 foi ICC >= 0,87 e >= 0,96 (p < 0,05), e entre avaliadores foi ICC >= 0,89 (p < 0,05). Gráficos de Bland-Altman mostraram boa concordância entre modelos, maioria da diferença ficou abaixo de 5%. O estudo 1 sugere que ambos modelos são reprodutíveis e produzem valores similares para determinar as fases do pacing strategy em "U". No estudo 2, 11 ciclistas visitaram o laboratório em seis ocasiões, sendo familiarizados três vezes com 4 km CT e técnica de estimulação elétrica no nervo femoral. Nas últimas três visitas, o mesmo pacing strategy da familiarização foi reproduzido, porém foram interrompidos ao final da fase 1 (F1FINAL), fase 2 (F2FINAL) e fase 3 (F3FINAL), randomizado. Antes e logo após o exercício, os ciclistas realizaram a técnica de estimulação elétrica e amostras sanguíneas foram coletadas para determinar o perfil metabolômico. A F1 teve duração de 68 ± 14 s (83,1% acima do ponto de compensação respiratória (PCR), em relação ao tempo total da F1), a F2 durou 287 ± 17 s (24,9% acima do PCR, tempo total da F2) e F3 durou 33 ± 7 s (74,5% acima do PCR, tempo total da F3). Houve apenas efeito principal de tempo para maioria das variáveis neuromusculares (p < 0,05) e não houve efeito principal de condição (p > 0,05). Apenas 5 metabólitos tiveram diferença estatística. Valores menores de 2-oxoisocarporate e dimatilamina para F1FINAL comparado com F2FINAL (p < 0,05). Valores menores de succinato para F1FINAL comparado com F3FINAL (p < 0,05). Asparagina e lactato apresentaram valores menores para F1FINAL em comparação à F2FINAL e F3FINAL (p < 0,05). Esses achados sugerem que, ao longo de um teste 4 km CT, o nível de fadiga neuromuscular é estabelecido logo no início e mantido até o final da tarefa. Não obstante, o perfil metabolômico parece estar associado com metabólitos da via oxidativa e outros marcadores relevantes para o SNC controlar a intensidade do exercício
Title in English
Contribution of central nervous and muscular systems in 4 km pacing time trial.
Keywords in English
Central fatigue
Metabolimic profile
Pacing strategy
Peripheral fatigue
Abstract in English
The present dissertation aimed to determine the distinct phases of "U" pacing strategy and the development of neuromuscular fatigue and metabolomic profile during a 4 km cycling time trial (4 km TT). The study 1 developed two models (visual and mathematical) to determine the three different phases of "U" pacing strategy during a 4 km TT. Fifteen cyclists were recruited to perform two 4 km TT at different days. For the visual model, four experienced evaluators analysed the pacing twice, seven days apart. The mathematical model was composed by the mean of power output during phase 2 (1 until 3 km) plus two standard deviation, which was the criteria to distinguish the change point (CP) of phase 2 among phase 1 (CP1) and 3 (CP2). CP1 occurred at 419 ± 186 and 415 ± 178 m and CP2 occurred at 3646 ± 228 and 3809 ± 213 m for the visual and mathematical models. There was no difference between models for both CP (p > 0.05). The intra-evaluator reliability of visual model for CP1 and CP2 were ICC >= 0.87 and >= 0.96 (p < 0.05), and the betweenevaluator was ICC >= 0.89 (p < 0.05). The Bland-Altman plots showed great agreement between models, with most values lower than 5% of difference. In conclusion, both models were reliable and produced similar values to distinguish the phases during "U" pacing strategy. At study 2, 11 cyclists visited the lab on six occasions, where they were familiarized three times with the 4 km TT and the femoral nerve stimulation technique. On the last three visits, the same pacing strategy from the familiarization was performed, but the cyclists were interrupted at the end of phase 1 (P1END), end of phase 2 (P2END) and end of phase 3 (P3END), randomized. Before and immediately after the exercise, the cyclists performed the stimulation technique and blood samples were collected to determine the metabolimic profile. The P1 had duration of 68 ± 14 s (83.1% above the respiratory compensation point (RCP), in relation with total time of P1), P2 lasted 287 ± 17 s (24.9% above RCP, from total time at P2) and P3 lasted 33 ± 7 s (74.5% above RCP, from total time at P3). Most of neuromuscular variables showed main effect of time (p < 0.05) but no main effect of condition (p > 0.05). Only five metabolites were statistically different among conditions. 2- oxoisocarporate and dimethylamine were lower for P1END compared with P2END. Succinate was lower for P1END compared with P3END. Asparagine and lactate were lower for P1END compared with P2 END and P3END. Those findings suggest that during a 4 km TT, the level of neuromuscular fatigue is established at P1END and maintained until the end of the exercise task. Moreover, the metabolimic profile might be associated with oxidative metabolites and other relevant markers for central nervous system, which may act as feedback to control the exercise intensity
 
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Publishing Date
2019-02-18
 
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