scholarly journals Maximizing Acceleration and Change of Direction in Sport: A Case Series to Illustrate How the Force-Velocity Profile Provides Additional Information to That Derived from Linear Sprint Time

2021 ◽  
Vol 18 (11) ◽  
pp. 6140
Author(s):  
Andrés Baena-Raya ◽  
Manuel A. Rodríguez-Pérez ◽  
Pedro Jiménez-Reyes ◽  
Alberto Soriano-Maldonado
Keyword(s):  
Mechanical Properties ◽  
Case Series ◽  
Relevant Information ◽  
Maximal Power Output ◽  
Sprint Time ◽  
Change Of Direction ◽  
Training Interventions ◽  
Additional Information ◽  
Technical Report ◽  
Force Velocity

Sprint running and change of direction (COD) present similar mechanical demands, involving an acceleration phase in which athletes need to produce and apply substantial horizontal external force. Assessing the mechanical properties underpinning individual sprint acceleration might add relevant information about COD performance in addition to that obtained through sprint time alone. The present technical report uses a case series of three athletes with nearly identical 20 m sprint times but with different mechanical properties and COD performances. This makes it possible to illustrate, for the first time, a potential rationale for why the sprint force-velocity (FV) profile (i.e., theoretical maximal force (F0), velocity (V0), maximal power output (Pmax), ratio of effective horizontal component (RFpeak) and index of force application technique (DRF)) provides key information about COD performance (i.e., further to that derived from simple sprint time), which can be used to individualize training. This technical report provides practitioners with a justification to assess the FV profile in addition to sprint time when the aim is to enhance sprint acceleration and COD performance; practical interpretations and advice on how training interventions could be individualized based on the athletes’ differential sprint mechanical properties are also specified.

scholarly journals The Association Between Force-Velocity Relationship in Countermovement Jump and Sprint With Approach Jump, Linear Acceleration and Change of Direction Ability in Volleyball Players

2021 ◽  
Vol 12 ◽  
Author(s):  
Jernej Pleša ◽  
Žiga Kozinc ◽  
Nejc Šarabon
Keyword(s):  
Athletic Performance ◽  
Force Production ◽  
Young Male ◽  
Linear Acceleration ◽  
Maximal Power Output ◽  
Jump Performance ◽  
Change Of Direction ◽  
Volleyball Players ◽  
Force Velocity ◽  
The Individual

The force-velocity (FV) relationship allows the identification of the mechanical capabilities of musculoskeletal system to produce force, power and velocity. The aim of this study was to assess the associations of the mechanical variables derived from the FV relationship with approach jump, linear sprint and change of direction (CoD) ability in young male volleyball players. Thirty-seven participants performed countermovement jumps with incremental loads from bodyweight to 50–100 kg (depending on the individual capabilities), 25-m sprint with split times being recorded for the purpose of FV relationship calculation, two CoD tests (505 test and modified T-test) and approach jump. Results in this study show that approach jump performance seems to be influenced by maximal power output (r = 0.53) and horizontal force production (r = 0.51) in sprinting, as well as force capacity in jumping (r = 0.45). Only the FV variables obtained from sprinting alone contributed to explaining linear sprinting and CoD ability (r = 0.35–0.93). An interesting finding is that sprinting FV variables have similar and some even stronger correlation with approach jump performance than jumping FV variables, which needs to be considered for volleyball training optimization. Based on the results of this study it seems that parameters that refer to horizontal movement capacity are important for volleyball athletic performance. Further interventional studies are needed to check how to implement specific FV-profile-based training programs to improve specific mechanical capabilities that determine volleyball athletic performance and influence the specific physical performance of volleyball players.

scholarly journals The Influence of Sprint Mechanical Properties on Change of Direction in Female Futsal Players

2021 ◽  
Vol 79 (1) ◽  
pp. 221-228
Author(s):  
Andrés Baena-Raya ◽  
Dolores García-Ortega ◽  
Sergio Sánchez-López ◽  
Alberto Soriano-Maldonado ◽  
Pedro Jiménez- Reyes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Body Height ◽  
Force Production ◽  
Maximum Velocity ◽  
Test Results ◽  
Change Of Direction ◽  
Force Velocity ◽  
Relationship Of ◽  
The Relationship ◽  
Spearman’S Correlation

Abstract The aim of the present study was to analyze the association of the sprint force-velocity profile [Hzt FV profile] variables with change of direction [COD] performance in female futsal players. Twelve female futsal players (age: 19.83 ± 4.2 years; body height: 160.75 ± 8.37 cm; body mass: 57.64 ± 8.3 kg) volunteered to be evaluated in the following assessments: Hzt FV profile, 505 test, modified 505 test [M505test] and V-cut test. The Spearman’s correlation coefficient [rs] (p < 0.05) was used to determine the relationship of the mechanical variables of the sprint (maximum power output [Pmax], maximum horizontal force production [F0] and maximum velocity [V0]) with COD performance. V0 showed a very large significant association with the 505 test (rs = -0.767; 90% CI: (-0.92 to -0.43); p < 0.01) and a large association with the V-cut test (rs = -0.641; 90% CI: (-0.86 to -0.21); p < 0.05), whereas Pmax was strongly associated with results of the 505 test (rs = -0.821; 90% CI: (-0.94 to -0.55); p < 0.01) and largely associated with the V-cut test results (rs = -0.596; 90% CI: (-0.84 to -0.14); p < 0.05). In conclusion, maximal power and velocity output during sprinting are determinant factors to successful COD in 180º and 45º cuts, thus, the Hzt FV profile should be assessed in female futsal players to better understand the influence of sprint mechanical properties on COD performance and prescribe individualized training programs

Basic set of experiments for determination of mechanical properties of sand

2014 ◽  
Vol 62 (1) ◽  
pp. 129-137
Author(s):  
A. Sawicki ◽  
J. Mierczyński
Keyword(s):  
Mechanical Properties ◽  
Soil Mechanics ◽  
Physical And Mechanical Properties ◽  
Local Strain ◽  
Initial State ◽  
Laboratory Equipment ◽  
Additional Information ◽  
Basic Set ◽  
Initial Anisotropy

Abstract A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.

scholarly journals Greater Power but Not Strength Gains Using Flywheel Versus Equivolumed Traditional Strength Training in Junior Basketball Players

2021 ◽  
Vol 18 (3) ◽  
pp. 1181
Author(s):  
Marko D. M. Stojanović ◽  
Mladen Mikić ◽  
Patrik Drid ◽  
Julio Calleja-González ◽  
Nebojša Maksimović ◽  
...  
Keyword(s):  
Strength Training ◽  
Training Group ◽  
T Test ◽  
Control Group ◽  
Basketball Players ◽  
Significant Group ◽  
Sprint Time ◽  
Change Of Direction ◽  
Time Interaction ◽  
And Control

The main aim of the present study was to compare the effects of flywheel strength training and traditional strength training on fitness attributes. Thirty-six well trained junior basketball players (n = 36; 17.58 ± 0.50 years) were recruited and randomly allocated into: Flywheel group (FST; n = 12), traditional strength training group (TST; n = 12) and control group (CON; n = 12). All groups attended 5 basketball practices and one official match a week during the study period. Experimental groups additionally participated in the eight-week, 1–2 d/w equivolume intervention conducted using a flywheel device (inertia = 0.075 kg·m−2) for FST or free weights (80%1 RM) for TST. Pre-to post changes in lower limb isometric strength (ISOMET), 5 and 20 m sprint time (SPR5m and SPR20m), countermovement jump height (CMJ) and change of direction ability (t-test) were assessed with analyses of variance (3 × 2 ANOVA). Significant group-by-time interaction was found for ISOMET (F = 6.40; p = 0.000), CMJ (F = 7.45; p = 0.001), SPR5m (F = 7.45; p = 0.010) and T test (F = 10.46; p = 0.000). The results showed a significantly higher improvement in CMJ (p = 0.006; 11.7% vs. 6.8%), SPR5m (p = 0.001; 10.3% vs. 5.9%) and t-test (p = 0.045; 2.4% vs. 1.5%) for FST compared to the TST group. Simultaneously, th FST group had higher improvement in ISOMET (p = 0.014; 18.7% vs. 2.9%), CMJ (p = 0.000; 11.7% vs. 0.3%), SPR5m (p = 0.000; 10.3% vs. 3.4%) and t-test (p = 0.000; 2.4% vs. 0.6%) compared to the CON group. Players from the TST group showed better results in CMJ (p = 0.006; 6.8% vs. 0.3%) and t-test (p = 0.018; 1.5% vs. 0.6%) compared to players from the CON group. No significant group-by-time interaction was found for sprint 20 m (F = 2.52; p = 0.088). Eight weeks of flywheel training (1–2 sessions per week) performed at maximum concentric intensity induces superior improvements in CMJ, 5 m sprint time and change of direction ability than equivolumed traditional weight training in well trained junior basketball players. Accordingly, coaches and trainers could be advised to use flywheel training for developing power related performance attributes in young basketball players.

scholarly journals First experience with augmented reality neuronavigation in endoscopic assisted midline skull base pathologies in children

2021 ◽  
Author(s):  
Valentina Pennacchietti ◽  
Katharina Stoelzel ◽  
Anna Tietze ◽  
Erwin Lankes ◽  
Andreas Schaumann ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Skull Base ◽  
Skull Base Surgery ◽  
Morphological Variability ◽  
Case Series ◽  
Relevant Information ◽  
Navigation Systems ◽  
Postoperative Mri ◽  
The Mean ◽  
Clinical Conditions

Abstract Introduction Endoscopic skull base approaches are broadly used in modern neurosurgery. The support of neuronavigation can help to effectively target the lesion avoiding complications. In children, endoscopic-assisted skull base surgery in combination with navigation systems becomes even more important because of the morphological variability and rare diseases affecting the sellar and parasellar regions. This paper aims to analyze our first experience on augmented reality navigation in endoscopic skull base surgery in a pediatric case series. Patients and methods A retrospective review identified seventeen endoscopic-assisted endonasal or transoral procedures performed in an interdisciplinary setting in a period between October 2011 and May 2020. In all the cases, the surgical target was a lesion in the sellar or parasellar region. Clinical conditions, MRI appearance, intraoperative conditions, postoperative MRI, possible complications, and outcomes were analyzed. Results The mean age of our patients was 14.5 ± 2.4 years. The diagnosis varied, but craniopharyngiomas (31.2%) were mostly represented. AR navigation was experienced to be very helpful for effectively targeting the lesion and defining the intraoperative extension of the pathology. In 65% of the oncologic cases, a radical removal was proven in postoperative MRI. The mean follow-up was 89 ± 79 months. There were no deaths in our series. No long-term complications were registered; two cerebrospinal fluid (CSF) fistulas and a secondary abscess required further surgery. Conclusion The implementation of augmented reality to endoscopic-assisted neuronavigated procedures within the skull base was feasible and did provide relevant information directly in the endoscopic field of view and was experienced to be useful in the pediatric cases, where anatomical variability and rarity of the pathologies make surgery more challenging.

scholarly journals When more is more: redundant modifiers can facilitate visual search

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Gwendolyn Rehrig ◽  
Reese A. Cullimore ◽  
John M. Henderson ◽  
Fernanda Ferreira
Keyword(s):  
Visual Search ◽  
Real World ◽  
Search Space ◽  
Relevant Information ◽  
Target Object ◽  
Search Performance ◽  
Redundant Information ◽  
Additional Information ◽  
Target Template ◽  
Template Specificity

Abstract According to the Gricean Maxim of Quantity, speakers provide the amount of information listeners require to correctly interpret an utterance, and no more (Grice in Logic and conversation, 1975). However, speakers do tend to violate the Maxim of Quantity often, especially when the redundant information improves reference precision (Degen et al. in Psychol Rev 127(4):591–621, 2020). Redundant (non-contrastive) information may facilitate real-world search if it narrows the spatial scope under consideration, or improves target template specificity. The current study investigated whether non-contrastive modifiers that improve reference precision facilitate visual search in real-world scenes. In two visual search experiments, we compared search performance when perceptually relevant, but non-contrastive modifiers were included in the search instruction. Participants (NExp. 1 = 48, NExp. 2 = 48) searched for a unique target object following a search instruction that contained either no modifier, a location modifier (Experiment 1: on the top left, Experiment 2: on the shelf), or a color modifier (the black lamp). In Experiment 1 only, the target was located faster when the verbal instruction included either modifier, and there was an overall benefit of color modifiers in a combined analysis for scenes and conditions common to both experiments. The results suggest that violations of the Maxim of Quantity can facilitate search when the violations include task-relevant information that either augments the target template or constrains the search space, and when at least one modifier provides a highly reliable cue. Consistent with Degen et al. (2020), we conclude that listeners benefit from non-contrastive information that improves reference precision, and engage in rational reference comprehension. Significance statement This study investigated whether providing more information than someone needs to find an object in a photograph helps them to find that object more easily, even though it means they need to interpret a more complicated sentence. Before searching a scene, participants were either given information about where the object would be located in the scene, what color the object was, or were only told what object to search for. The results showed that providing additional information helped participants locate an object in an image more easily only when at least one piece of information communicated what part of the scene the object was in, which suggests that more information can be beneficial as long as that information is specific and helps the recipient achieve a goal. We conclude that people will pay attention to redundant information when it supports their task. In practice, our results suggest that instructions in other contexts (e.g., real-world navigation, using a smartphone app, prescription instructions, etc.) can benefit from the inclusion of what appears to be redundant information.

TECHNOLOGY ADOPTION AND ADAPTATION TO CLIMATE CHANGE — A CASE-BASED APPROACH

2012 ◽  
Vol 03 (02) ◽  
pp. 1250007 ◽  
Author(s):  
JÜRGEN EICHBERGER ◽  
ANI GUERDJIKOVA
Keyword(s):  
New Technologies ◽  
New Technology ◽  
Relevant Information ◽  
Adaptation To Climate Change ◽  
Climate Conditions ◽  
Technology Learning ◽  
The Public ◽  
Additional Information ◽  
Technological Adaptation ◽  
Long Run

We present a model of technological adaptation in response to a change in climate conditions. The main feature of the model is that new technologies are not just risky, but also ambiguous. Pessimistic agents are thus averse to adopting a new technology. Learning is induced by optimists, who are willing to try out technologies about which there is little evidence available. We show that both optimists and pessimists are crucial for a successful adaptation. While optimists provide the public good of information which gives pessimists an incentive to innovate, pessimists choose the new technology persistently in the long-run which increases the average returns for the society. Hence, the optimal share of optimists in the society is strictly positive. When the share of optimists in the society is too low, innovation is slow and the obtained steady-state is inefficient. We discuss two policies which can potentially alleviate this inefficiency: Subsidies and provision of additional information. We show that if precise and relevant information is available, pessimists would be willing to pay for it and consequently adopt the new technology. Hence, providing information might be a more efficient policy, which is both self-financing and results in better social outcomes.

scholarly journals COMBINE Archive Specification Version 1

2015 ◽  
Vol 12 (2) ◽  
pp. 104-118 ◽  
Author(s):  
Frank T. Bergmann ◽  
Nicolas Rodriguez ◽  
Nicolas Le Novère
Keyword(s):  
Modeling And Simulation ◽  
Relevant Information ◽  
Essential Information ◽  
Media Type ◽  
Additional Information ◽  
Internet Media ◽  
Metadata File ◽  
Description Framework ◽  
Audit Trails ◽  
Resource Description

Summary Several standard formats have been proposed that can be used to describe models, simulations, data or other essential information in a consistent fashion. These constitute various separate components required to reproduce a given published scientific result.The Open Modeling EXchange format (OMEX) supports the exchange of all the information necessary for a modeling and simulation experiment in biology. An OMEX file is a ZIP container that includes a manifest file, an optional metadata file, and the files describing the model. The manifest is an XML file listing all files included in the archive and their type. The metadata file provides additional information about the archive and its content. Although any format can be used, we recommend an XML serialization of the Resource Description Framework.Together with the other standard formats from the Computational Modeling in Biology Network (COMBINE), OMEX is the basis of the COMBINE Archive. The content of a COMBINE Archive consists of files encoded in COMBINE standards whenever possible, but may include additional files defined by an Internet Media Type. The COMBINE Archive facilitates the reproduction of modeling and simulation experiments in biology by embedding all the relevant information in one file. Having all the information stored and exchanged at once also helps in building activity logs and audit trails.

scholarly journals Noncontrast vestibular schwannoma surveillance imaging including an MR cisternographic sequence: is there a need for postcontrast imaging?

2019 ◽  
Vol 131 (2) ◽  
pp. 549-554 ◽  
Author(s):  
Karen Buch ◽  
Amy Juliano ◽  
Konstantina M. Stankovic ◽  
Hugh D. Curtin ◽  
Mary Beth Cunnane
Keyword(s):  
Vestibular Schwannoma ◽  
Relevant Information ◽  
Vestibular Schwannomas ◽  
Mr Images ◽  
Gadolinium Contrast ◽  
Additional Information ◽  
Significant Difference ◽  
T1 Hyperintensity ◽  
Temporal Bones ◽  
Mr Sequences

OBJECTIVEThe purpose of this study was to evaluate the use of a noncontrast MRI protocol that includes a cisternographic sequence (CISS/FIESTA/3D DRIVE) compared to a protocol that includes a gadolinium-enhanced sequence in order to determine whether a noncontrast approach could be utilized to follow vestibular schwannomas.METHODSA total of 251 patients with vestibular schwannomas who underwent MRI of the temporal bones that included both cisternographic sequence and postcontrast T1 imaging between January 2000 and January 2016 for surveillance were included in this retrospective study. The size of the vestibular schwannomas was independently assessed on a noncontrast MR cisternographic sequence and compared to size measurements on a postcontrast sequence. The evaluation of intralesional cystic components (identified as T2 signal hyperintensity) and hemorrhagic components (identified with intrinsic T1 hyperintensity) on noncontrast MR sequences was compared to evaluation on postcontrast MR sequences to determine whether additional information could be derived from the postcontrast sequences. Additionally, any potentially clinically significant, incidentally detected findings on the postcontrast T1 sequences were documented and compared with the detection of these findings on the precontrast images.RESULTSNo significant difference in vestibular schwannoma size was found when comparing measurements made on the images obtained with the MR cisternographic sequence and those made on images obtained with the postcontrast sequence (p = 0.99). Noncontrast MR images were better (detection rate of 87%) than postcontrast images for detection of cystic components. Noncontrast MR images were also better for identifying hemorrhagic components. No additional clinically relevant information regarding the tumors was identified on the postcontrast sequences.CONCLUSIONSBased on the results of this study, a noncontrast MR protocol that includes a cisternographic sequence would be sufficient for the accurate characterization of size and signal characteristics of vestibular schwannomas, obviating the need for gadolinium contrast administration for the routine surveillance of these lesions.

Gender-Specific Association of the Sprint Mechanical Properties With Change of Direction Performance in Basketball

2021 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Andrés Baena-Raya ◽  
Pedro Jiménez-Reyes ◽  
Enrique Salinas Romea ◽  
Alberto Soriano-Maldonado ◽  
Manuel A. Rodríguez-Pérez
Keyword(s):  
Mechanical Properties ◽  
Change Of Direction ◽  
Specific Association ◽  
Gender Specific
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