scholarly journals Effects of knowing the task duration on players’ pacing patterns during soccer small-sided games

2017 ◽  
Vol 36 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Ricardo Ferraz ◽  
Bruno Gonçalves ◽  
Roland Van Den Tillaar ◽  
Sergio Jiménez Sáiz ◽  
Jaime Sampaio ◽  
...  
Keyword(s):  
Author(s):  
Moshe M. H. Aharoni ◽  
Anat V. Lubetzky ◽  
Liraz Arie ◽  
Tal Krasovsky

Abstract Background Persistent postural-perceptual dizziness (PPPD) is a condition characterized by chronic subjective dizziness and exacerbated by visual stimuli or upright movement. Typical balance tests do not replicate the environments known to increase symptoms in people with PPPD—crowded places with moving objects. Using a virtual reality system, we quantified dynamic balance in people with PPPD and healthy controls in diverse visual conditions. Methods Twenty-two individuals with PPPD and 29 controls performed a square-shaped fast walking task (Four-Square Step Test Virtual Reality—FSST-VR) using a head-mounted-display (HTC Vive) under 3 visual conditions (empty train platform; people moving; people and trains moving). Head kinematics was used to measure task duration, movement smoothness and anterior–posterior (AP) and medio-lateral (ML) ranges of movement (ROM). Heart rate (HR) was monitored using a chest-band. Participants also completed a functional mobility test (Timed-Up-and-Go; TUG) and questionnaires measuring anxiety (State-Trait Anxiety Inventory; STAI), balance confidence (Activities-Specific Balance Confidence; ABC), perceived disability (Dizziness Handicap Inventory) and simulator sickness (Simulator Sickness Questionnaire). Main effects of visual load and group and associations between performance, functional and self-reported outcomes were examined. Results State anxiety and simulator sickness did not increase following testing. AP-ROM and HR increased with high visual load in both groups (p < 0.05). There were no significant between-group differences in head kinematics. In the high visual load conditions, high trait anxiety and longer TUG duration were moderately associated with reduced AP and ML-ROM in the PPPD group and low ABC and  high perceived disability were associated with reduced AP-ROM (|r| =  0.47 to 0.53; p < 0.05). In contrast, in controls high STAI-trait, low ABC and longer TUG duration were associated with increased AP-ROM (|r| = 0.38 to 0.46; p < 0.05) and longer TUG duration was associated with increased ML-ROM (r = 0.53, p < 0.01). Conclusions FSST-VR may shed light on movement strategies in PPPD beyond task duration. While no main effect of group was observed, the distinct associations with self-reported and functional outcomes, identified using spatial head kinematics, suggest that some people with PPPD reduce head degrees of freedom when performing a dynamic balance task. This supports a potential link between spatial perception and PPPD symptomatology.


Author(s):  
James L. Szalma ◽  
Joel S. Warm ◽  
Gerald Matthews ◽  
William N. Dember ◽  
Ernest M. Weiler ◽  
...  

2008 ◽  
Vol 44-46 ◽  
pp. 595-600
Author(s):  
Xiao Ming Qian ◽  
Dun Bing Tang

In this paper a simulation algorithm for concurrent product development process (CPDP) is presented based on Design Structure Matrix (DSM). An aggregate DSM is used to model the CPDP. To simulate the influence on the process of the time limit and the resource competition, the schedule and resource model are established. A method is also advanced to handle task delay. At last a case is used to validate the simulation algorithm and to show the influence on the process of task duration and resource.


1980 ◽  
Vol 2 (3) ◽  
pp. 227-236 ◽  
Author(s):  
Walter J. Rejeski ◽  
Paul M. Ribisl

The purpose of this study was to examine the effects of anticipated task duration on ratings of perceived exertion during treadmill running. Male subjects.(N = 15) completed two separate runs on a motor-driven treadmill at 85% V02 max. During one trial, subjects ran for a period of 20 minutes, while for a second trial, subjects were led to believe that they would be running for 30 minutes. In each case, the trials were terminated at the 20-minute mark. Ratings of perceived exertion, heart rates, respiratory rates, and ventilatory minute volumes were collected across each trial. Results supported the supposition that the anticipation of continued performance mediated ratings of effort expenditure. This effect was obtained only during moderate work levels and was in contrast to research examining mental fatigue.


2019 ◽  
Vol 4 (1) ◽  
pp. 6
Author(s):  
Britton W. Brewer ◽  
Lawrence O. Schwartz ◽  
Allen E. Cornelius ◽  
Judy L. Van Raalte ◽  
Edmundo L. Urbina ◽  
...  

Background: Task duration is a fundamental aspect of exercise, but little is known about how completed bouts of physical activity are perceived. Consequently, the purpose of the five experiments conducted for this investigation was to examine the effects of engaging in physical tasks on retrospective duration estimates with college student participants. Methods: Across the five experiments, participants were 113 college students (82 women, 31 men). In Experiments 1 and 2, participants provided duration estimates of a period spent engaging in physical activity or rest. In Experiments 3, 4, and 5, participants provided duration estimates of periods spent engaged in physical tasks of high intensity and low intensity. Results: In Experiments 1, 2, and 3, participants engaged in physical activity tended to perceive durations as shorter than participants at rest. When completing less familiar tasks (Experiments 4 and 5), however, participants recalled a high intensity bout of physical activity as lasting longer than a low intensity bout of physical activity of comparable duration. Cohen’s d values for physical activity effects on duration estimates ranged from 0.40 to 1.60. Conclusion: The findings, which partially support a contextual-change interpretation, suggest that factors, such as perceived exertion and task familiarity, affect retrospective duration estimates.


Author(s):  
Terry Judd

<p>Detailed logs of students’ computer use, during independent study sessions, were captured in an open-access computer laboratory. Each log consisted of a chronological sequence of tasks representing either the application or the Internet domain displayed in the workstation’s active window. Each task was classified using a three-tier schema according to its likely context of use: The top-level categories being <em>Academic</em>, <em>Communication</em>, <em>Information</em>, <em>Recreation</em> and <em>Applications</em>. Students switched tasks frequently – median task duration was only 31 seconds. Approximately 30% of all tasks were <em>Academic</em> with the majority of these involving the university’s learning management system. <em>Communication</em> and <em>Recreation</em> tasks accounted for 18% and 9% of tasks respectively. Up to one half of all tasks were not related to study. Multitasking was very common during independent study sessions, particularly when <em>Communication</em> tasks were active. This study confirms that students are likely to regularly switch tasks, attend to distracting tasks, and multitask during independent study. Each one of these behaviours has the potential to negatively impact on students’ learning, and when combined they indicate that students are relatively inefficient at managing competing tasks and their time when studying.</p>


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