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Previous issue date: 2013 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes) / Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG) / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Introdu??o: Recentemente, a vibra??o de todo o corpo (VTC) tem sido um m?todo de exerc?cio f?sico utilizado para aumentar o desempenho f?sico-funcional. No entanto, os mecanismos relacionados aos efeitos produzidos por essa modalidade de exerc?cio ainda n?o tem sido completamente investigados. Objetivos: Os objetivos desse estudo foram definir o protocolo de VTC capaz de aumentar o desempenho muscular em jovens fisicamente ativos (estudos 1 e 2) e investigar poss?veis mecanismos fisiol?gicos da VTC sobre o desempenho f?sico (estudos 3, 4 e 5). Metodologia: No estudo 1 foi avaliada a influ?ncia de diferentes ?ngulos de flex?o dos joelhos (60 e 90?) e da VTC na ativa??o muscular do vasto lateral (VL) e na transmissibilidade do est?mulo vibrat?rio para propor o melhor posicionamento corporal durante o exerc?cio. Nesse estudo, 34 jovens fisicamente ativos tiveram a atividade eletromiogr?fica (EMG) do m?sculo VL do membro dominante e a acelera??o nas articula??es dos joelhos e quadril avaliadas durante exerc?cio de agachamento (AG) a 60? e 90? de flex?o de joelhos associada ou n?o a VTC (30 Hz, 4 mm). No estudo 2 foi proposta a avalia??o da curva dose-resposta do est?mulo vibrat?rio (acelera??o) sobre o desempenho muscular dos membros inferiores e superiores. Para isto, nove homens fisicamente ativos foram submetidos a cinco condi??es experimentais: 1) AG sem VTC; 2) AG/VTC [20 Hz, 2 mm: 31,55 m.s-2]; 3) AG/VTC [45 Hz, 2 mm: 159,73 m.s-2]; 4) AG/VTC [45 Hz, 4 mm: 319,45 m.s-2]; e 5) AG/VTC [60 Hz, 4 mm: 567,91 m.s-2]. Antes e ap?s os procedimentos experimentais o desempenho muscular foi avaliado pelo teste do salto vertical (SV), for?a de preens?o palmar e desempenho anaer?bio pelo teste Wingate (TW). O objetivo do estudo 3 foi comparar os efeitos do aquecimento passivo (AP), da VTC e controle (C) sobre o desempenho de alta intensidade e curta dura??o (DAICD). Seis homens fisicamente ativos realizaram um teste de 30 segundos de sprint ap?s uma das tr?s condi??es experimentais: 1) VTC: que consistiu em 5 minutos de AG associados ? VTC (45 Hz, 2 mm), 2) AP: que consistiu de 30 minutos de AP usando uma manta t?rmica sobre as coxas e as pernas (35 W) e 3) C: que foi constitu?do por 30 minutos de repouso sem aquecimento. A excitabilidade muscular do VL, avaliada pela EMG, foi determinada em repouso e durante o DAICD. As concentra??es sangu?neas de lactato (LACT), avaliadas por espectroscopia, e a temperatura muscular (TM) da coxa, estimada indiretamente medindo a temperatura da pele, foram determinadas nos seguintes momentos: antes, imediatamente ap?s as condi??es experimentais e 3 minutos ap?s o sprint de 30 segundos. O estudo 4 foi desenhado para avaliar o efeito agudo de diferentes intensidades de VTC no desempenho muscular e relacion?-los com fatores intramusculares. Oito homens fisicamente ativos foram aleatoriamente submetidos a uma das tr?s condi??es experimentais: (1) VTC 2 mm [45 Hz e 2 mm], (2) VTC 4 mm [45 Hz e 4 mm] e (3) sem VTC. Para avaliar a PAP, o torque conc?ntrico dos flexores e extensores de joelho foi medido durante tr?s flexo-extens?es unilaterais de joelho a 60?.s-1 em um dinam?metro isocin?tico. A pot?ncia e a altura do SV tamb?m foram avaliadas. Estas medidas foram realizadas antes e ap?s as condi??es experimentais. O objetivo do estudo 5 foi determinar os efeitos da adi??o da VTC aos exerc?cios de AG na ativa??o cerebral, avaliada pelo eletroencefalografia (EEG). Sete homens fisicamente ativos foram submetidos de forma aleat?ria a uma das tr?s condi??es experimentais: a) exerc?cios de AG/VTC 45 Hz/2 mm; B) AG/VTC 45 Hz/4 mm e C) AG sem VTC. Para avaliar os efeitos da VTC na ativa??o EEG, os volunt?rios foram submetidos a um per?odo de oito minutos em estado de repouso (olhos fechados) antes e 3 minutos ap?s as condi??es experimentais. Resultados: Os principais achados do estudo 1 foram que (1) 90? de flex?o dos joelhos produziu maior atividade EMG que 60? (p <0,001), sem diferen?a na transmissibilidade acelera??o, (2) em ambos os ?ngulos de flex?o do joelho, a adi??o de VTC n?o produziu diferen?as significativas na EMG, mas com maiores valores de acelera??o em rela??o ao AG realizado sem a VTC (p <0,001). O estudo 2 demonstrou que h? uma faixa de acelera??o de VTC mais apropriada para promover melhor desempenho muscular dos membros inferiores [159,45 m.s-2 - 319,45 m.s-2]. No entanto, estes est?mulos aplicados sob os p?s n?o parecem melhorar a for?a de preens?o palmar. No estudo 3 observou-se que o pico de pot?ncia, a pot?ncia relativa, o trabalho relativo, o tempo para a pot?ncia pico e a cad?ncia no ciclismo foram significativamente mais elevados durante a VTC comparado com o C. A TM foi significativamente maior no AP comparado com a VTC e C antes do teste de desempenho. N?o foram observadas diferen?as significativas entre as condi??es experimentais para LACT imediatamente ap?s o sprint e na EMG durante o sprint. O estudo 4 demonstrou que a VTC aumentou o pico de torque para os m?sculos flexores de joelhos. Al?m disso, a pot?ncia e a altura do SV tamb?m foram aumentadas pela VTC. O estudo 5 demonstrou que houve uma diminui??o significativa da pot?ncia absoluta na banda Alfa durante a VTC com exerc?cios de AG (45 Hz/2 mm e 45 Hz/4 mm) em compara??o com a situa??o C nos seguintes eletrodos: F7 (p: 0,03, tamanho do efeito: 0,750, poder: 0,708) e F8 (p: 0,01, tamanho do efeito: 0,838, poder: 0,909). Conclus?es: Os resultados dos estudos supracitados indicam que o protocolo de VTC associado ao AG a 90? de flex?o dos joelhos, nos par?metros de VTC de 45 Hz/2-4 mm (159,45 - 319,45 m.s-2), aumentou a altura e a pot?ncia do SV, bem como o desempenho anaer?bio dos membros inferiores, sem altera??es na for?a de preens?o. Os poss?veis mecanismos relacionados com aumento no desempenho muscular dos membros inferiores seriam fatores intramusculares e envolvimento de componentes centrais (ativa??o eletroencefalogr?fica), sem modifica??es no metabolismo anaer?bio l?tico, na temperatura muscular e na atividade eletromiogr?fica. / Tese (Doutorado) ? Programa Multic?ntrico de P?s-Gradua??o em Ci?ncias Fisiol?gicas, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / ABSTRACT
Introduction: Recently, whole body vibration (WBV) has been an alternative method of exercise that is increasingly used to improve the physical performance of athletes. However, the mechanisms related to the effects produced by this training mode have not been fully elucidated in the literature. Objectives: The objectives of this study were to define the protocol of WBV able to increase muscle performance in athletes (Studies 1 and 2) and propose possible physiological mechanisms of WBV on physical performance (studies 3, 4 and 5). Methods: In study 1 was evaluated the influence of different angles of knee flexion and adittion of WBV in the vastus lateralis muscle activation and transmissibility of vibratory stimulus to propose the best body position for this exercise. In this study, 34 individuals had electromyography activity (EMG) of the vastus lateralis and the acceleration assessed while squatting with 60? and 90? of knee flexion either with or without whole-body vibration (WBV: 30 Hz, 4mm). In study 2 was proposed to evaluate the dose-response curve of vibratory stimulation on muscle performance of the lower and upper limb. Nine recreationally males were subjected to five experimental conditions: 1) Squat exercise (SE) without WBV; 2) SE/WBV [20 Hz, 2mm: 31.55 m.s-2]; 3) SE/WBV [45 Hz, 2mm: 159.73 m.s-2]; 4) SE/WBV [45 Hz, 4mm: 319.45 m.s-2] and 5) SE/WBV [567.91 m.s-2]. Before and after the experimental procedures, muscle performance was assessed by a vertical jump test, handgrip strength test and Wingate anaerobic test (WT). The purpose of the study 3 was to compare the effects of passive warm-up (PW), whole-body vibration (WBV) and control (C) on high-intensity performance during sprint cycle exercise. Six recreationally trained men performed a 30-seconds sprint cycle test after the three conditions: 1) The WBV consisted of 5 minutes of squats associated with WBV (45 Hz, 2 mm), 2) The PW consisted of 30 minutes of PW using a thermal blanket on the thighs and legs (35 W) and 3) The C consisted of 30 minutes of no warm-up with the subject lying down. Motor neuron excitability from the vastus lateralis muscle, evaluated by electromyography (EMG), was determined prior to exercise at rest and during sprint cycle exercise. Blood lactate levels (BL), evaluated by spectroscopy, and muscle temperature (MT) of the thigh, estimated indirectly by measuring skin temperature, were determined at following time points: prior to exercise at rest (before and after experimental conditions), immediately and 3 minutes after the 30-s sprint cycle test. The study 4 was designed to assess the acute effect of different intensities of WBV on post-activation potentiation (PAP). Eight recreationally trained males were randomly subjected to one of three experimental conditions: 1) WBV 2 mm [45 Hz and 2 mm], 2) WBV 4 mm [45 Hz and 4 mm] and 3) no WBV. To assess PAP, the peak concentric torque of knee flexors and extensors was measured during a set of 3 unilateral knee flexor-extensions at 600.s-1 in an isokinetic dynamometer. The power output and height during vertical jumps were also evaluated. These measurements were performed both before and after the experimental conditions and then compared. The objective of the study 5 was to determine the effects of adding whole body vibration (WBV) to squat exercises on brain activation, evaluated by electroencephalography (EEG). Seven recreationally trained males were randomly subjected to one of three experimental conditions: A) squat exercises (SE) - WBV 45 Hz/ 2 mm; B) SE - WBV 45 Hz/ 4 mm; and C) SE without WBV. The experimental sessions occurred on different days, at least 7 days after the preliminary session, with randomized intervals of 24 hours among the experimental conditions. To evaluate the effects of WBV on the EEGs, the vol?unteers were subjected to an eight-minute resting EEG (eyes closed) before and 3 minutes after the experimental conditions. Results: The main findings of the study 1 were (1) the larger the angle of knee flexion, the greater the EMG (p < 0.001), with no difference on acceleration transmissibility; (2) for both angles of knee flexion, the addition of WBV produced no significant difference in EMG and higher acceleration compared to without WBV (p < 0.001). The results of the study 2 suggest that lower limb muscular performance is dose-related to WBV acceleration. Given our results, there could be a WBV acceleration range that is suitable for improving lower limb muscular performance [159.45 m.s-2 to 319.45 m.s-2] during SE. However, these stimuli do not seem capable of improving upper limb strength. In the study 3 was noted that the peak power, relative power, relative work, time of peak power, and pedaling cadence were significantly higher in the WBV compared to C. The MT was significantly greater in PW compared to WBV and C prior to exercise and no significant differences were observed between the experimental conditions for BL immediately after sprint cycle exercise and in EMG during sprint cycle exercise. The study 4 proposes that WBV potentiated the peak torque of flexors of knee. In addition, the power output and vertical height of jump were also potentiated by WBV. However, increasing the vibratory stimulus did not further potentiate the results. The study 5 demonstrated that there was a significant decrease in the Alpha absolute power during WBV with squat exercises (45 Hz/2 mm and 45 Hz/4 mm) compared with that of the control at the following electrodes: F7 (p: 0.03, effect size: 0.750, power: 0.708) and F8 (p: 0.01, effect size: 0.838, power: 0.909). Conclusions: The results of the above-cited studies indicate that the protocol of WBV associated with squat at 90? in parameters of WBV 45Hz/2-4mm are capable of increasing the power and height in jump performance and anaerobic lower limbs, with no change in grip strength. The possible mechanism related to the increase in lower limbs anaerobic performance could be post-activation potentiation and cerebral activation, since it was not observed metabolic changes (no difference in lactate levels), MT and EMG. However, more studies should be conducted to check other physiological mechanisms related to improved physical performance caused by the WBV.
| Identifer | oai:union.ndltd.org:IBICT/oai:acervo.ufvjm.edu.br/jspui:1/283 |
| Date | 15 July 2013 |
| Creators | Avelar, N?bia Carelli Pereira de |
| Contributors | Garcia, Emerson Silami, Francischi, Janetti Nogueira, Batista, Mauro Alexandre Benites, Amorim, Fabiano Trigueiro, Coimbra, C?ndido Celso, Universidade Fedaral dos Vales do Jequitinhonha e Mucuri (UFVJM), Lacerda, Ana Cristina Rodrigues |
| Publisher | UFVJM |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | Portuguese |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFVJM, instname:Universidade Federal dos Vales do Jequitinhonha e Mucuri, instacron:UFVJM |
| Rights | A concess?o da licen?a deste item refere-se ao ? termo de autoriza??o impresso assinado pelo autor, assim como na licen?a Creative Commons, com as seguintes condi??es: Na qualidade de titular dos direitos de autor da publica??o, autorizo a Universidade Federal dos Vales do Jequitinhonha e Mucuri e o IBICT a disponibilizar por meio de seus reposit?rios, sem ressarcimento dos direitos autorais, de acordo com a Lei n? 9610/98, o texto integral da obra disponibilizada, conforme permiss?es assinaladas, para fins de leitura, impress?o e/ou download, a t?tulo de divulga??o da produ??o cient?fica brasileira, e preserva??o, a partir desta data., info:eu-repo/semantics/openAccess |
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