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Previous issue date: 2016-08-26 / Introduction: Previous studies have found that cerebral cooling is effective to decrease the elevation in core temperature during exercises performed in hot environment. Furthermore, other have shown that the rate of increase in core temperature may vary according to the exercise mode under consideration; in contrast to self-paced exercise, controled-pace exercise requires greater muscle recruitment, thereby inducing higher increase in core temperature. The aim of this study was to examine the acute effects of cranial-cervical cooling in the rate of increase of core temperature, and physiological and psychological responses during controlled-pace and self-paced exercises performed in hot environment. Methods: Ten cyclists took part in the study, they underwent 3 preliminary sessions under ~21 ??C and 4 experimental sessions in hyperthermia (~33 ??C), that is: self-paced exercise with or without central cooling (ESP33 e ESP33C); and controlled-pace exercise with or without central cooling (ECP33 e ECP33C). In both the exercise modes they completed 20km cycling trial either in a self-paced manner anchored in ratings of perceived exertion (RPE = 16), or in a controlled-pace manner with intensity set at the mean power output recorded during preliminary self-paced exercise session under ~21 ??C. Core and peripheral temperature, cardiopulmonary and perceptive measures were obtained during exercises, while maximal voluntary muscle torque, body mass and urine density were obtained prior and post exercises. Mean responses, as well as the rate of increase in core temperature and RPE along the exercises with or without cooling were compared. Results: The control trials showed that ESP e ECP were submaximal, and affected by the elevation in environment temperature (21 ??C vs 33??C). Regarding the responses to the cranial-cervical cooling, there were cooling main effects due to reduction in exercise time, increases in power output, reduction in mean core temperature and its rate of increase. Additionally, there was lower RPE and thermal sensation. Only the oxygen uptake showed exercise mode main effects, with greater values in ECP. No exercise mode by cooling interaction effects was observed. Conclusion: The central cooling was effective to increase the motor performance, likely due to the attenuated increase in core temperature and RPE. However, the exercise mode did not determine to these responses. / Introdu????o: Estudos anteriores observaram que o resfriamento central ?? efetivo para atenuar a taxa de eleva????o da temperatura central ao longo do exerc??cio realizado em hipertermia. Demonstram tamb??m, que a taxa de eleva????o da temperatura central pode depender do modelo de exerc??cio praticado; exerc??cios com ritmo controlado, ao contr??rio de exerc??cios com ritmo auto-ajustado, requerem maior recrutamento muscular e, consequentemente, apresentam maior eleva????o da temperatura central. O objetivo deste estudo foi examinar os efeitos agudos do resfriamento cr??nio-cervical sobre a taxa de eleva????o da temperatura central, respostas fisiol??gicas e perceptivas associadas, durante exerc??cios de ritmo auto-ajustado e ritmo controlado, realizados em ambiente quente. M??todos: Participaram do estudo dez ciclistas experientes e aclimatados ao calor, os quais foram submetidos a 4 sess??es preliminares em 21 ??C e 4 sess??es experimentais em hipertermia (33 ??C), a saber: exerc??cio com ritmo auto-ajustado sem e com resfriamento cr??nio-cervical (EAA33 e EAA33R); e exerc??cio com ritmo controlado sem e com resfriamento cr??nio-cervical (ECON33 e ECON33R). Em ambos os modelos, os participantes completaram 20 km; ou com ritmo auto-ajustado, controlado pela percep????o subjetiva de esfor??o (PSE = 16), ou ritmo controlado, em intensidade fixa, correspondente ?? intensidade m??dia gerada na sess??o preliminar de exerc??cio com ritmo auto-ajustado em 21 ??C. Medidas de temperatura central e perif??rica, cardiopulmonares e psicol??gicas foram obtidas durante a realiza????o dos exerc??cios, enquanto medidas do torque muscular volunt??rio m??ximo, massa corp??rea e densidade da urina, foram realizadas antes e ap??s os exerc??cios. Respostas m??dias e a taxa de modifica????o da temperatura retal (TR) e percep????o subjetiva de esfor??o (PSE) ao longo dos diferentes modelos de exerc??cio, sem e com resfriamento, foram comparadas. Resultados: Os testes controle evidenciaram que o EAA e ECON foram de intensidade subm??xima, e foram influenciados pelo aumento da temperatura ambiente (21 ??C vs 33??C). Quanto as respostas frente ao resfriamento cr??nio-cervical, foram verificados efeitos principais, em fun????o da redu????o do tempo total, eleva????o da pot??ncia mec??nica produzida, atenua????o da TR e de sua taxa de eleva????o; al??m da menor PSE (geral e local) e sensa????o t??rmica. Com rela????o aos efeitos principais do modelo de exerc??cio, somente o consumo de oxig??ncio foi modificado com maiores valores em ECON. Efeitos do resfriamento foram detectados sobre a TR e sua taxa de eleva????o, pois foram reduzidas em ambos os modelos de exerc??cio. Nenhum efeito de intera????o foi observado nas vari??veis medidas. Conclus??o: O resfriamento central foi efetivo na eleva????o do desempenho motor, possivelmente mediado por uma atenua????o da eleva????o da temperatura central e altera????o na PSE. Entretanto, o modelo de exerc??cio n??o foi determinante para a observa????o destas respostas.
| Identifer | oai:union.ndltd.org:IBICT/oai:bdtd.ucb.br:tede/2068 |
| Date | 26 August 2016 |
| Creators | Silva, Renato Andr?? Sousa da |
| Contributors | Pires, Fl??vio de Oliveira |
| Publisher | Universidade Cat??lica de Bras??lia, Programa Strictu Sensu em Educa????o F??sica, UCB, Brasil, Escola de Sa??de e Medicina |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UCB, instname:Universidade Católica de Brasília, instacron:UCB |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 6095716513072507778, 500, 500, 600, 3870802503144686128, 5178284805913411594 |
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