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Explosive lower limb extension mechanics: An on-land vs. in-water exploratory comparison

Guignard, Brice ; Lauer, Jessy ; Samozino, Pierre ; Mourão, Luis ; Vilas-Boas, João Paulo ; Rouard, Annie Hélène

Journal of Biomechanics, December 2017, Vol.65, pp.106-114 [Periódico revisado por pares]

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  • Título:
    Explosive lower limb extension mechanics: An on-land vs. in-water exploratory comparison
  • Autor: Guignard, Brice ; Lauer, Jessy ; Samozino, Pierre ; Mourão, Luis ; Vilas-Boas, João Paulo ; Rouard, Annie Hélène
  • Assuntos: Physics ; Mechanics ; Mechanics of the Fluids ; Physics ; Mechanics ; Biomechanics ; Medicine ; Engineering ; Anatomy & Physiology ; Physics
  • É parte de: Journal of Biomechanics, December 2017, Vol.65, pp.106-114
  • Descrição: To access, purchase, authenticate, or subscribe to the full-text of this article, please visit this link: http://dx.doi.org/10.1016/j.jbiomech.2017.10.024 Byline: Brice Guignard [brice.guignard@neuf.fr] (a,b,*), Jessy Lauer (a,b), Pierre Samozino (a), Luis Mourao (b,c,d), Joao Paulo Vilas-Boas (b,c), Annie Helene Rouard (a) Keywords Mechanical power; Force-velocity relationship; Aquatic environment; CFD; Squat jump Abstract During a horizontal underwater push-off, performance is strongly limited by the presence of water, inducing resistances due to its dense and viscous nature. At the same time, aquatic environments offer a support to the swimmer with the hydrostatic buoyancy counteracting the effects of gravity. Squat jump is a vertical terrestrial push-off with a maximal lower limb extension limited by the gravity force, which attracts the body to the ground. Following this observation, we characterized the effects of environment (water vs. air) on the mechanical characteristics of the leg push-off. Underwater horizontal wall push-off and vertical on-land squat jumps of two local swimmers were evaluated with force plates, synchronized with a lateral camera. To better understand the resistances of the aquatic movement, a quasi-steady Computational Fluid Dynamics (CFD) analysis was performed. The force-, velocity- and power-time curves presented similarities in both environments corresponding to a proximo-distal joints organization. In water, swimmers developed a three-step explosive rise of force, which the first one mainly related to the initiation of body movement. Drag increase, which was observed from the beginning to the end of the push-off, related to the continuous increase of body velocity with high values of drag coefficient (C.sub.D) and frontal areas before take-off. Specifically, with velocity, frontal area was the main drag component to explain inter-individual differences, suggesting that the streamlined position of the lower limbs is decisive to perform an efficient push-off. This study motivates future CFD simulations under more ecological, unsteady conditions. Author Affiliation: (a) Inter-university Laboratory of Human Movement Science, Savoie Mont Blanc University, University Department SceM -- Technolac, 73376 Le Bourget-du-Lac, France (b) Porto Biomechanics Laboratory (LABIOMEP), University of Porto, Porto, Portugal (c) Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Portugal (d) Industrial and Management Studies Superior School, Porto Polytechnic Institute, Vila do Conde, Portugal * Corresponding author at: Inter-university Laboratory of Human Movement Science, Savoie Mont Blanc University, University Department SceM -- Technolac, 73376 Le Bourget-du-Lac, France. Article History: Accepted 15 October 2017
  • Idioma: Inglês

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