Search results for "jump"

Acute and prolonged reduction in joint stiffness in humans after exhausting stretch-shortening cycle exercise.

2002

The purpose of the present study was to examine the acute and long-term fatigue effects of exhausting stretch-shortening cycle (SSC) exercise on the stiffness of ankle and knee joints. Five subjects were fatigued on a sledge apparatus by 100 maximal rebound jumps followed by continuous submaximal jumping until complete exhaustion. Neuromuscular fatigue ef- fects were examined in submaximal hopping (HOP) and in maximal drop jumps (DJ) from 35 (DJ35) and 55 cm (DJ55) heights on a force plate. Additional force and reflex measurements were made using an ankle ergom- eter. Jumping tests and ankle ergometer tests were car- ried out before, immediately after, 2 h (2H), 2 days and 7 days (7D) after…

The effects of assisted and resisted plyometric training on jump height and sprint performance among physically active females

2021

The aim of the present study was to compare the effects of assisted and resisted plyometric jump training on jump height, sprint performance (acceleration (0-20m), maximum speed (30-40m) and 40m sprint time) among physically active females. Fifty-six participants (age: 21.1 ± 1.7 years; body mass: 64.2 ± 7.0 kg; height: 168.0 ± 5.6 cm) were randomly allocated to either an assisted (n = 16) or resisted training group (n = 17), or a control group (n = 14). Nine participants dropped out during the intervention. The training sessions consisted of three different plyometric jump exercises over an eight-week period, while the control group continued their normal training routine. The results reve…

Aerodynamics of Ski Jumping

2016

Ski jumping is an exciting and primarily competitive sport involving both ballistic and aerodynamic factors. The ballistic factors are release velocity and release position of a ski jumper from the take-off table, whereas aerodynamic factors include the gliding properties of the jumper/ski system (velocity, suit design, surface area, posture of the jumper/ski system, resisting and lifting forces). Both ballistic and aerodynamic factors place special demands on the jumper so that he/she can, for example, optimally maximize the vertical lift and minimize the drag forces. Ski jumping has attracted spectators 200 years and it has undergone several notable steps in the development of performance…

2020

Abstract Background To examine longitudinal changes in physical performance during the menopausal transition and the role of physical activity (PA) in these changes. Methods Based on follicle-stimulating hormone levels and bleeding diaries, women (47–55 years) were classified as early (n = 89) and late perimenopausal (n = 143) and followed prospectively until postmenopausal status, with mean duration of 17.5 and 13.8 months, respectively. Physical performance was measured by handgrip force, knee extension torque, vertical jumping height, maximal walking speed, and 6-minute walking distance. Physical activity was self-reported and categorized as inactive, low, medium, and high. Longitudinal …

A Criterium for the Strict Positivity of the Density of the Law of a Poisson Process

2011

We translate in semigroup theory our result (Leandre, 1990) giving a necessary condition so that the law of a Markov process with jumps could have a strictly positive density. This result express, that we have to jump in a finite number of jumps in a "submersive" way from the starting point to the end point if the density of the jump process is strictly positive in . We use the Malliavin Calculus of Bismut type of (Leandre, (2008;2010)) translated in semi-group theory as a tool, and the interpretation in semi-group theory of some classical results of the stochastic analysis for Poisson process as, for instance, the formula giving the law of a compound Poisson process.

Lietojumprogrammatūra pasākumu organizēšanai

2018

Kvalifikācijas darbā ir izstrādāta Android lietotne pasākumu organizācijai. Lietotne sastāv no četrām daļām. Pirmajā (galvenajā) daļā «Pasākumi», lietotājs var apskatīt dažādes aktivitātes un var tām pievienoties. Pasākumi dalās 3 dažādos tipos: • «Publiskie (Public) pasākumi» – pasākumi, kuros ir piekļuve visiem lietotājiem, ar dalībnieku skaita ierobežojumu. • «Masu pasākumi» – pasākumi, kuros ir piekļuve visiem lietotājiem, bez dalībnieku skaita ierobežojuma. • «Slēgtie pasākumi» – pasākumi, kuriem ir ierobežots lietotāju loks. Otrajā daļā «Manas aktivitātes» lietotājs var izveidot jebkura tipa pasākumu, kontrolēt un rediģēt jau izveidotos pasākumus un apskatīt tekošos pasākumus, ar kuri…

Characteristics of the early flight phase in the Olympic ski jumping competition.

2004

Early flight phase (approximately 40 m) of the athletes participating in the final round of the individual large hill ski jumping competition in Salt Lake City Olympics was filmed with two high-speed pan & tilt video cameras. The results showed that jumpers' steady flight position was almost completed within 0.5s. The most significant correlation with the length of the jump was found in the angle between the skis and body (r=.714, p.001 at 1.1s after the take-off). This particular phase seemed to be important because the ski angle of attack was also related to the jumping distance at the same phase. Although the more upright ski position relative to flight path resulted in longer jumping di…

Change in take-off elevation angle after limb autotomy mitigates the reduction in jumping distance in rice grasshoppersOxya yezoensis

2013

Autotomy is the ability to spontaneously self-amputate a limb or other appendage, often as a reflexive action. This limb amputation typically occurs as a specialized defensive response to an attack from a predator and thereby enables the prey to escape from predation. Despite the benefits of escape, autotomized organisms lose the body part and its associated function. Here, we investigated the jumping behavior and performance of one-leg-autotomized and intact rice grasshoppers, Oxya yezoensis, to examine changes in jumping behavior after autotomy. The take-off elevation of autotomized grasshoppers was 7.8° lower than in intact grasshoppers, resulting in nearly a 45° angle of take-off, which…

Domain decomposition in the symmetric boundary element analysis

2002

Recent developments in the symmetric boundary element method (SBEM) have shown a clear superiority of this formulation over the collocation method. Its competitiveness has been tested in comparison to the finite element method (FEM) and is manifested in several engineering problems in which internal boundaries are present, i.e. those in which the body shows a jump in the physical characteristics of the material and in which an appropriate study of the response must be used. When we work in the ambit of the SBE formulation, the body is subdivided into macroelements characterized by some relations which link the interface boundary unknowns to the external actions. These relations, valid for e…

Quasi-elastic Neutron Scattering Investigation of the Hydrogen Surface Self-Diffusion on Polymer Electrolyte Membrane Fuel Cell Catalyst Support

2008

International audience; Quasi-elastic neutron scattering (QENS) measurements have been performed to investigate the surface selfdiffusion of hydrogen molecules. A monolayer of molecular hydrogen was adsorbed on a carbon material commonly used in polymer electrolyte membrane fuel cells, called XC-72. QENS spectra were recorded at the time-of-flight spectrometer IN5 at Institut Laue-Langevin (ILL) in Grenoble at 40, 50, 60, and 70 K. By using the Chudley & Elliott model for jump diffusion, we found the diffusion coefficient at each temperature. The logarithm of the diffusion coefficient was plotted versus the inverse of the temperature to give the coefficient in the Arrhenius equation. From t…