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drop jump

Karen-Helene Støverud, Hans Petter Langtangen, Geir Andre Ringstad, Per Kristian Eide, Kent-Andre Mardal
PURPOSE: Previous computational fluid dynamics (CFD) studies have demonstrated that the Chiari malformation is associated with abnormal cerebrospinal fluid (CSF) flow in the cervical part of the subarachnoid space (SAS), but the flow in the SAS of the posterior cranial fossa has received little attention. This study extends previous modelling efforts by including the cerebellomedullary cistern, pontine cistern, and 4th ventricle in addition to the cervical subarachnoid space. METHODS: The study included one healthy control, Con1, and two patients with Chiari I malformation, P1 and P2...
2016: PloS One
Sara L Arena, Kelsey McLaughlin, Anh-Dung Nguyen, James M Smoliga, Kevin R Ford
Athletic individuals may differ in body segment inertial parameter (BSIP) estimates due to differences in body composition, and this may influence calculation of joint kinetics. The purposes of this study were to 1) compare BSIPs predicted by the method introduced by de Leva(1) with DXA-derived BSIPs in collegiate female soccer players, and 2) examine the effects of these BSIPs estimation methods on joint moment and power calculations during a drop vertical jump (DVJ). Twenty female NCAA Division 1 soccer players were recruited...
October 5, 2016: Journal of Applied Biomechanics
Emilija Stojanović, Vladimir Ristić, Daniel Travis McMaster, Zoran Milanović
BACKGROUND: Plyometric training is an effective method to prevent knee injuries in female athletes; however, the effects of plyometric training on jump performance in female athletes is unclear. OBJECTIVE: The aim of this systematic review and meta-analysis was to determine the effectiveness of plyometric training on vertical jump (VJ) performance of amateur, collegiate and elite female athletes. METHODS: Six electronic databases were searched (PubMed, MEDLINE, ERIC, Google Scholar, SCIndex and ScienceDirect)...
October 4, 2016: Sports Medicine
Lee A Bridgeman, Michael R McGuigan, Nicholas D Gill, Deborah Dulson
The aims of this study were to (A) investigate the acute effects of different drop jump (DJ) accentuated eccentric loading (AEL) protocols and (B) to investigate the effect of these AEL DJ protocols on subsequent countermovement jump (CMJ) performance. The subjects were 12 strength-trained athletes, initially, baseline CMJ performance was assessed and individual optimal DJ drop height identified. In subsequent weeks subjects completed 1 set of 5 DJ's with no additional load or an AEL of 10, 20 or 30% of their individual body mass (BM) utilising dumbbells to provide the extra load...
September 16, 2016: Journal of Strength and Conditioning Research
Albertas Skurvydas, Gediminas Mamkus, Sigitas Kamandulis, Vilma Dudoniene, Dovile Valanciene, Håkan Westerblad
PURPOSE: Force production frequently remains depressed for several hours or even days after various types of strenuous physical exercise. We hypothesized that the pattern of force changes during the first hour after exercise can be used to reveal muscular mechanisms likely to underlie the decline in muscle performance during exercise as well as factors involved in the triggering the prolonged force depression after exercise. METHODS: Nine groups of recreationally active male volunteers performed one of the following types of exercise: single prolonged or repeated short maximum voluntary contractions (MVCs); single or repeated all-out cycling bouts; repeated drop jumps...
September 16, 2016: European Journal of Applied Physiology
Mari Leppänen, Kati Pasanen, Urho M Kujala, Tommi Vasankari, Pekka Kannus, Sami Äyrämö, Tron Krosshaug, Roald Bahr, Janne Avela, Jarmo Perttunen, Jari Parkkari
BACKGROUND: Few prospective studies have investigated the biomechanical risk factors of anterior cruciate ligament (ACL) injury. PURPOSE: To investigate the relationship between biomechanical characteristics of vertical drop jump (VDJ) performance and the risk of ACL injury in young female basketball and floorball players. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: At baseline, a total of 171 female basketball and floorball players (age range, 12-21 years) participated in a VDJ test using 3-dimensional motion analysis...
September 16, 2016: American Journal of Sports Medicine
Ram Haddas, Steven F Sawyer, Phillip S Sizer, Toby Brooks, Ming-Chien Chyu, C Roger James
INTRODUCTION: Recurrent LBP (rLBP) and neuromuscular fatigue are independently thought to increase the risk of lower extremity (LE) injury. Volitional preemptive abdominal contraction (VPAC) is thought to improve lumbar spine and pelvis control in individuals with rLBP. The effects of VPAC on fatigued landing performance in individuals with rLBP are unknown. OBJECTIVES: To determine the effects of VPAC and LE fatigue on landing performance in a rLBP population. DESIGN: Cross-sectional pretest-posttest cohort control design...
August 24, 2016: Journal of Sport Rehabilitation
Simeng Chen, Volfango Bertola
When a droplet of water impacts a heated surface, the drop may be observed to bounce. Recently is has been found that small quantities (∼100 ppm) of polymer additives such as polyethylene oxide can significantly increase the maximum bouncing height of drops. This effect has been explained in terms of the reduction of energy dissipation caused by polymer additives during the drop retraction and rebound, resulting in higher mechanical energy available for bouncing. Here we demonstrate, by comparing three types of fluids (Newtonian, shear-thinning, and viscoelastic), that the total kinetic energy carried by low-viscosity Newtonian drops during retraction is partly transformed into rotational kinetic energy rather than dissipated when compared with high-viscosity or non-Newtonian drops...
August 2016: Physical Review. E
Gwang-Pil Jung, Kyu-Jin Cho
To improve the maneuverability and agility of jumping robots, several researchers have studied steerable jumping mechanisms. This steering ability enables robots to reach a particular target by controlling their jumping direction. To this end, we propose a novel direction-changing concept for miniature jumping robots. The proposed concept allows robots to be steerable while exerting minimal effects on jumping performance. The key design principles were adopted from the froghopper's power-producing hind legs and the moment cancellation accomplished by synchronized leg operation...
2016: Bioinspiration & Biomimetics
Kris Beattie, Brian P Carson, Mark Lyons, Ian C Kenny
Maximum- and reactive-strength qualities both have important roles in athletic movements and sporting performance. Very little research has investigated the relationship between maximum-strength and reactive-strength. The aim of this study was to investigate the relationship between maximum-strength (isometric mid-thigh pull peak force; IMTP PF) and reactive-strength (drop-jump reactive-strength index; DJ-RSI) variables at 0.3 m, 0.4 m, 0.5 m and 0.6 m box heights. A secondary aim investigated the between- and within-group differences in reactive-strength characteristics between relatively 'strong' and 'weak' athletes...
September 6, 2016: International Journal of Sports Physiology and Performance
Duncan P Fransz, Arnold Huurnink, Vosse A de Boode, Idsart Kingma, Jaap H van Dieën
The single leg drop jump landing test may assess dynamic and static balance abilities in different phases of the landing. However objective definitions of different phases following landing and associated reliability are lacking. Therefore, we determined the existence of possible distinct phases of single leg drop jump landing on a force plate in 82 elite youth soccer players. Three outcome measures were calculated over moving windows of five sizes: center of pressure (COP) speed, COP sway and horizontal ground reaction force (GRF)...
September 4, 2016: Gait & Posture
I Loturco, Ccc Abad, F Y Nakamura, S P Ramos, R Kobal, S Gil, L A Pereira, Fhp Burini, H Roschel, C Ugrinowitsch, V Tricoli
The aim was to investigate the effects of far infrared (FIR) ray emitting clothes on indirect markers of exercise-induced muscle damage and physical performance recovery after a plyometric bout applied to soccer players. Twenty-one male players (18.9±0.6 years; 70.8±5.01 kg; 178.3±0.06 cm) performed 100 drop-jumps. Six hours after the bout, athletes put on FIR clothes (FIR) (density of 225 g·m(-2), 88% far infrared rays emitting polyamide 66 Emana yarn (PA66) fibre, 12% Spandex, emissivity of 0.88 and power emitted of 341 W/m2µm at 37°C in the 5-20 µm wavelength range, patent WO 2009/077834 A2) (N = 10) or placebo clothes (PLA) (N = 11)...
September 2016: Biology of Sport
Madison J Marquez, Paul W Kline, Mary Lloyd Ireland, Darren Johnson, Brian Noehren
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
A Vieira, A F Siqueira, J B Ferreira-Junior, J do Carmo, J L Q Durigan, A Blazevich, M Bottaro
This study investigated the effects of 5 and 15°C cold-water immersion on recovery from exercise resulting in exercise-induced muscle damage. 42 college-aged men performed 5×20 drop-jumps and were randomly allocated into one of 3 groups: (1) 5°C; (2) 15°C; or (3) control. After exercise, individuals from the cold-water immersion groups had their lower limbs immerged in iced water for 20 min. Isometric knee extensor torque, countermovement jump, muscle soreness, and creatine kinase were measured before, immediately after, 24, 48, 72, 96 and 168 h post-exercise...
August 24, 2016: International Journal of Sports Medicine
F Rosas, R Ramirez-Campillo, D Diaz, F Abad-Colil, C Martinez-Salazar, A Caniuqueo, R Cañas-Jamet, I Loturco, F Y Nakamura, C McKenzie, J Gonzalez-Rivera, J Sanchez-Sanchez, M Izquierdo
The aim of this study was to compare the effects of a jump training program, with or without haltere type handheld loading, on maximal intensity exercise performance. Youth soccer players (12.1±2.2 y) were assigned to either a jump training group (JG, n=21), a jump training group plus haltere type handheld loading (LJG, n=21), or a control group following only soccer training (CG, n=21). Athletes were evaluated for maximal-intensity performance measures before and after 6 weeks of training, during an in-season training period...
August 24, 2016: International Journal of Sports Medicine
Ronaldo Kobal, Irineu Loturco, Renato Barroso, Saulo Gil, Rogério Cuniyochi, Carlos Ugrinowitsch, Hamilton Roschel, Valmor Tricoli
The combination of strength (ST) and plyometric training (PT) has been shown to be effective for improving sport specific performance. However, there is no consensus about the most effective way to combine these methods in the same training session, in order to produce greater improvements in neuromuscular performance of soccer players. Thus, the purpose of this study was to compare the effects of different combinations of ST and PT sequences on strength, jump, speed, and agility capacities of elite young soccer players...
August 18, 2016: Journal of Strength and Conditioning Research
Guilherme S Nunes, Marcos de Noronha, Bruna Wageck, Juliana Bonetti Scirea, Alessandro Haupenthal, Stella Maris Michaelsen
There is some evidence showing that people with functional ankle instability (FAI) can present changes in postural control during the landing phase of a jump. These studies also show preliminary results indicating possible changes during phases prior to landing. Therefore, the objective of this study was to investigate whether movement adjustments prior to a jump are different between people with and without FAI. Sixty participants with (n=30) and without (n=30) FAI participated in this study. The main outcome measures were the variability of range of motion in ankle inversion/eversion and dorsiflexion/plantarflexion; and variability of center of pressure for the directions anterior-posterior and medio-lateral during the pre-jump period for drop jump, vertical jump and during single-leg stance...
October 2016: Human Movement Science
C W Extrand
An experimental study on the underlying mechanisms of structured super-hydrophobic surfaces was recently published [ Butt, H.-J.; et al. How Water Advances on Superhydrophobic Surfaces. Phys. Rev. Lett. 2016, 116, 096101 . DOI: 10.1103/PhysRevLett.116.096101 ]. After depositing small drops of water, Butt's group inclined their surfaces to initiate movement. They examined the contact between the water and structured surfaces with confocal microscopy. They observed that drops were suspended atop the protruding features and movement of water was different at the advancing and receding edges...
August 30, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
H Monteillet, J M Kleijn, J Sprakel, F A M Leermakers
The Scheutjens-Fleer self-consistent field (SF-SCF) theory is used to study complexation between two oppositely charged polyelectrolytes across an interface formed by two solvents, here called oil and water. The focus is on the composition and the lateral stability of such interfacial coacervate. One polyelectrolyte is chosen to be oil soluble and the other one prefers water, whereas the counter and salt ions are taken to distribute ideally over all phases. There exists an electrostatic associative driving force for the formation of the coacervate phase which increases with decreasing ionic strength and may be assisted by some specific affinity between the associating units and an effective poor solvency for the coacervate...
August 4, 2016: Advances in Colloid and Interface Science
Clément N Gambelli, Daniel Theisen, Patrick A Willems, Bénédicte Schepens
Landing on the ground on one's feet implies that the energy gained during the fall be dissipated. The aim of this study is to assess human motor control of landing in different conditions of fall initiation, simulated gravity and sensory neural input. Six participants performed drop-landings using a trap-door system and landings from self-initiated counter-movement jumps in microgravity conditions, simulated in a weightlessness environment by different pull-down forces, of 1-, 0.6-, 0.4- and 0.2 g. External forces applied to the body, orientation of the lower limb segments and muscular activity of 6 lower limb muscles were recorded synchronously...
August 11, 2016: Journal of Applied Physiology
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