18 research outputs found
When Something Is at Stake: Differences in Soccer Performance in 11 vs. 11 During Official Matches and Training Games
No full textOlthof, SBH, Frencken, WGP, and Lemmink, KAPM. When something is at stake: Differences in soccer performance in 11 vs. 11 during official matches and training games. J Strength Cond Res 33(1): 167-173, 2019-11 vs. 11 training games are used to mimic the official match, but differ in playing duration and a consequence of winning or losing. Anxiety levels, crowd pressure, and the intention to win are examples of constraints present in the match, but absent or less prevalent in training. The aim is, therefore, to compare soccer performance in official matches with 11 vs. 11 training games. Six elite youth soccer teams played 5 official matches and 15 training games. Soccer performance, defined as a combination of game characteristics (game duration, transitions, and ball possession duration) and physical (distance covered, high-intensity distance, and sprints), technical (passing), and team tactical performance (inter-team and intra-team distances) and corresponding interaction patterns, was determined with video footage and positional data (local position measurement system). Soccer performance in official matches differed from similar training games, in a way that players covered more distance, sprinted more often, but game pace was lower and players made more mistakes. In addition, team width was smaller and length-per-width ratio larger and teams were tighter coupled in official matches. 11 vs. 11 training games can be used to mimic the match, in particular the team tactical performance. Coaches could increase physical and technical representativeness of training games by raising the stakes and increasing the consequence of winning or losing
Exploring potential implications of automated inland shipping on the Dutch waterway infrastructure: A scenario analysis
No full textAutomated shipping is a technology which is highly anticipated by many actors in the inland shipping sector. Rijkswaterstaat, as the manager of the main inland waterways in the Netherlands, wants to be prepared for this technology. As the technology is still very immature, this research has attempted to reduce the amount of uncertainty in the effects and implications of this technology using a scenario analysis approach. As a result, the main research question is as follows: “What are the potential physical and digital implications for the waterway infrastructure of Rijkswaterstaat due to automated inland shipping in the Netherlands by 2050?”. As little research has been done regarding this topic, this research used literature regarding the diffusion and implementation of high-tech technologies and applied the insights from theory into a scenario analysis. This research used the intuitive logics approach for scenario analysis to develop four scenarios based on drivers, factors, and trends as found during nine expert interviews. Nine interviews were conducted to assess the uncertain trends in the development of automated inland shipping. As a result, technological development and niche development were found as the main trends that highly influence the technology and are both very uncertain. The resulting scenarios were called “Into the roots”, “Fairway bound”, “Business as Usual”, and “Market segmentation”. When the development of the scenarios was finished, an implication analysis was performed to answer the main research question. This was done by conducting an expert workshop. Six experts from Rijkswaterstaat, in the field of waterway management, and infrastructural design were present during the workshop. The scenarios were validated by the experts, and an open discussion was held to assess the implications per scenario. The results of the workshop were afterwards documented and analysed.Management of Technology (MoT
Converting car parking to bicycle parking: A GIS-Based Method Using a Location-Allocation Model
No full textIn the Netherlands, many cities aim to promote cycling as a solution for sustainable mobility. However, the bicycle parking shortage is common. The popularity of ‘car-free city’ concept provides the opportunity to solve the problem by replacing car parking spaces to bicycle parking spaces. This study used a GIS-based location-allocation method to optimally locate the bicycle parking facility in car parking spaces. Through a case study in the city centre of Leiden, the results show with the small amount of car parking spaces, bicycle parking shortage can be largely relieved.Civil Engineering | Construction Management and Engineerin
Night train services: A stated choice experiment: exploring preferences for night trains
No full textTransport, Infrastructure and Logistic
Soccer-specific accuracy and validity of the local position measurement (LPM) system
No full textLimited data is available on accuracy and validity of video-based GPS and electronic tracking systems particularly with reference to curved courses and short high intensity running activities The main goal of this study was to assess soccer specific accuracy and validity of the radio-frequency based local position measurement (LPM) system (1000 Hz) for measuring distance and speed during walking and sprinting Three males walked and sprinted 4 soccer-specific courses 10 times each Distance and speed recorded by LPM were compared to actual distance and speed measured by measuring tape and timing gates In addition, accuracy was assessed The static accuracy (SD of the mean) is 1 cm for devices put on the pitch and 2-3 cm when worn by participants LPM underestimates actual distance (mean difference at most -1 6%) Coefficient of variation becomes larger at higher speed and Increased turning angle With regard to speed validity correlations are high (range 0 71-0 97) The LPM speed is significantly and systematically lower, although absolute and relative differences are small, between -0 1 km h(-1) (-1 3%) and -0 6 km h(-1) (-3 9%) The typical error of the estimate increases with increased speed but does not increase with increased turning angle Because the reported differences are small we conclude that the LPM system produces highly accurate position and speed data in static and dynamic conditions and is a valid tool for player tracking in soccer and ball team sports in general (C) 2010 Sports Medicine Australia Published by Elsevier Ltd All rights reserve
What do Football Coaches want from Sport Science?
No full textSport science can contribute to the body of knowledge that influences practice and performance. Despite this, knowledge transfer from sport science to football coaches needs further improvement. The present study's purpose is to gain insight in current sport science needs and perceived barriers among professional football coaches. A 29-question digital survey was sent to a database of professional football coaches. Answering options were: check boxes, open fields, and 5-point Likert scales. 75 football coaches (mean +/- SD age: 50.0 +/- 10.1 years) completed the survey. Coaches had 24.3 +/- 7.0 years of experience as a player and 25.5 +/- 13.7 years as a coach, and five had a university degree. The coaches evaluated their technical and tactical knowledge as good. Knowledge on physical skills was rated slightly lower and knowledge on mental skills lowest, but still fair. Top five of domains that the coaches wanted to know more about were Mental skills, Physical skills, Group dynamics, Monitoring load and capacity, and Talent development. The top five perceived barriers for using sport science in daily football practice was Conservatism in clubs, Lack of money, Lack of specific football knowledge of scientists, Poor applicability of sports science in practice, and Lack of time. Personal contact with sport scientists was most preferred to gain knowledge in sport science. Results suggest that there is an interest in applying sport scientific knowledge into football practice. An overview of coaches' sport science knowledge gaps and perceived implementation barriers could improve the integration of sport science and practical knowledge in work environments
A match-derived relative pitch area facilitates the tactical representativeness of small-sided games for the official soccer match
No full textSmall-sided games (SSGs) are a promising training format in soccer to replicate (situations of) the official match across all age groups. Typically, SSGs are played on a smaller relative pitch area (RPA; i.e., <150 m2) than the match (320 m2 RPA), which results in different tactical demands. To create a more precise replication of tactical match demands in SSGs with less than 11 players per team, a match-derived RPA (320 m2) may be considered because this affords a similar playing area per player. In addition, subgroup analysis is necessary to deal with the different number of players in match and SSGs. Therefore, this study aims to investigate tactical demands of matches and various SSGs-with a different number of players and played on 320 m2 RPA-in talented youth soccer players. Twelve elite soccer teams in 4 age categories (under-13, under-15, under-17, and under-19) played official matches and 4 vs. 4 + goalkeepers (GKs), 6 vs. 6 + GKs, and 8 vs. 8 + GKs. Positional data were collected to calculate tactical variables (interpersonal distances, length, width, and surface areas) for all players and for 2- and 4-player subgroups. Corresponding tactical variability (coefficients of variation expressed as percentages) was determined for all players. Results demonstrated that in each age category, with an increase in number of players, team distances increased and tactical variability decreased. Subgroup analyses revealed similar team distances in matches and SSGs with the exception of larger interpersonal distances in 4 vs. 4 + GKs than the match in under-13, under-15, and under-17. Match-derived RPA in SSGs facilitates the tactical representativeness for the match. Soccer coaches can use such SSGs for an optimal tactical match preparation
Seasonal training load and wellness monitoring in a professional soccer goalkeeper
No full textThe purpose of this investigation was to: (a) quantify the training load practices of a professional soccer GK, and (b) investigate the relationship between the training load observed and the subsequent self-reported wellness response. One male goalkeeper playing for a team in the top league of the Netherlands participated in this case study. Training load data were collected across a full season using a global positioning system (GPS) device and session rating of perceived exertion (session-RPE). Data was assessed in relation to the number of days to a match (MD- and MD+). In addition, self-reported wellness was assessed using a questionnaire. Duration, total distance, average speed, PlayerLoadTM and load (derived from session-RPE) were highest on MD. The lowest values for duration, total distance and PlayerLoadTM were observed on MD-1 and MD+1. Total wellness scores were highest on MD and MD-3 and were lowest on MD+1 and MD-4. Small to moderate correlations between training load measures (duration, total distance covered, high deceleration efforts and load) and the self-reported wellness scores were found. This exploratory case-study provides novel data about the physical load undertaken by a goalkeeper during one competitive season. The data suggest there are small to moderate relationships between training load indicators and self-reported wellness. This weak relation indicates that the association is not meaningful. This may be due to the lack of position-specific training load parameters we can currently measure in the applied context
Examination of the external and internal load indicators' association with overuse injuries in professional soccer players
No full textOBJECTIVES: Research in professional soccer focusing on the relevance of external and internal load indicators for injury prevention is scarce. This study examined the relationship between load indicators and overuse injuries. DESIGN: Prospective cohort study. METHODS: Data were collected from 35 professional male soccer players over two seasons. Following load indicators were examined: total distance covered (TD), distance covered at high speed (THSR; >20kmh(-1)), number of accelerations (ACCeff; >1ms(-2)), number of decelerations (DECeff; 1.18) resulted in a higher injury risk. In contrast, a lower injury risk was found when comparing medium ratios for ACCeff (0.87-1.12), DECeff (0.86-1.12), and RPE x duration (0.85-1.12) to low ratios. CONCLUSIONS: Findings demonstrate that mainly external load indicators are associated with increased or decreased injury risk. The monitoring of various load indicators is recommended for injury prevention in professional soccer
Relationships Between the External and Internal Training Load in Professional Soccer: What Can We Learn From Machine Learning?
No full textPURPOSE: Machine learning may contribute to understanding the relationship between the external load and internal load in professional soccer. Therefore, the relationship between external load indicators and the rating of perceived exertion (RPE) was examined using machine learning techniques on a group and individual level. METHODS: Training data were collected from 38 professional soccer players over two seasons. The external load was measured using global positioning system technology and accelerometry. The internal load was obtained using the RPE. Predictive models were constructed using two machine learning techniques, artificial neural networks (ANNs) and least absolute shrinkage and selection operator (LASSO), and one naive baseline method. The predictions were based on a large set of external load indicators. Using each technique, one group model involving all players and one individual model for each player was constructed. These models' performance on predicting the reported RPE values for future training sessions was compared to the naive baseline's performance. RESULTS: Both the ANN and LASSO models outperformed the baseline. Additionally, the LASSO model made more accurate predictions for the RPE than the ANN model. Furthermore, decelerations were identified as important external load indicators. Regardless of the applied machine learning technique, the group models resulted in equivalent or better predictions for the reported RPE values than the individual models. CONCLUSIONS: Machine learning techniques may have added value in predicting the RPE for future sessions to optimize training design and evaluation. Additionally, these techniques may be used in conjunction with expert knowledge to select key external load indicators for load monitoring
