scholarly journals A new approach to quantify angles and time of changes-of-direction during soccer matches

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251292
Author(s):  
Tomohiro Kai ◽  
Shin Hirai ◽  
Yuhei Anbe ◽  
Yohei Takai
Keyword(s):  
Relative Frequency ◽  
Soccer Player ◽  
Soccer Players ◽  
Positioning System ◽  
New Approach ◽  
Frequency Distributions ◽  
Local Positioning System ◽  
Relative Frequency Distribution ◽  
The Difference ◽  
Coordinate Data

Background and aims Soccer players frequently perform change-of-directions (CODs) at various speeds during matches. However, tracking systems have shown limitations to measure these efforts. Therefore, the aim of the present study was to propose a new approach to measure CODs using a local positioning system (LPS), and clarify position-related difference in profile of CODs by using the approach. Methods The x- and y-coordinate data for each soccer player were measured with a local positioning system. Speed, acceleration, jerk, and direction of speed were derived from the coordinate data. Based on accelerations of above 2 m/s2, the onsets and ends of CODs derived from jerk were identified (COD duration). Changes of direction of speed (θCOD) were determined for the corresponding period. Six collegiate male soccer players performed CODs according to 13 set angles (0–180°; every 15°) so that differences between θCOD and set angle could be determined (Exp. 1). Relative frequency distributions of θCOD and number of CODs were determined in 79 collegiate and amateur male soccer players during 9 soccer matches (Exp. 2). Results In Exp. 1, θCOD was positively related to set angle (r = 0.99). Each θCOD was smaller than the corresponding set angle, and the difference became greater with increasing COD angle. In Exp. 2, The number of CODs in a match was 183 ± 39 across all positions. There were no significant position-related differences in the number of CODs. The duration of a COD was 0.89 ± 0.49 s across all positions. The relative frequency distribution of θCOD revealed that the number of CODs at 0–15° and 105–135° tended to be higher than those at other angles during soccer matches. Further, θCOD was affected by the speed at the onset of COD during soccer matches (Exp. 2). Conclusions The current findings demonstrate that θCOD derived from direction of speed and jerk may be a new indicator for evaluating COD during soccer matches.

Association between running quality and loads seen with accelerometry data obtained from female soccer players

2020 ◽  
pp. 1-7
Author(s):  
Paul Jones ◽  
Patrick Ivey ◽  
Ben Skutnick ◽  
Adam R. Cocco ◽  
Chris E. Colborn ◽  
...  
Keyword(s):  
Correlation Analysis ◽  
Global Positioning System ◽  
Soccer Player ◽  
Soccer Players ◽  
Gps Data ◽  
Positioning System ◽  
Velocity Change ◽  
Pearson Product Moment Correlation ◽  
Global Positioning ◽  
Female Soccer Player

BACKGROUND: Global positioning system (GPS) data, when obtained from athletes offers unique information on their performance. Given the information GPS data provides, it is important to identify data most pertinent to an athlete’s performance. OBJECTIVE: We evaluated a GPS-based running quality variable to predict the variance in total player load (TPL) and player load per minute (PLPM) from female soccer player (n= 26) data. METHODS: Running quality was the ratio of the displacement per minute to total distance covered. TPL was quantified as the sum of velocity change rates in all three planes of motion, while PLPM was a ratio of load generated per minute of activity. RESULTS: With a logarithmic transformation of TPL data, a Pearson Product Moment Correlation analysis revealed running quality accounted for significant (r=-0.65) amounts of our criterion’s variance, which implied higher running quality led to lower log (TPL) values. With PLPM as our dependent variable, running quality correlated with significant (r= 0.63) amounts of our criterion’s variance. CONCLUSIONS: Movement efficiency appears to be an important contributor to our correlations. We suggest running quality be examined as a correlate to performance in other sports in which running is crucial to success.

Inter-country inequality as a dynamic process and the problem of post-industrial development

2018 ◽  
pp. 5-29 ◽  
Author(s):  
L. M. Grigoryev ◽  
V. A. Pavlyushina
Keyword(s):  
Economic Growth ◽  
Political Institutions ◽  
Industrial Development ◽  
Modern World ◽  
New Approach ◽  
Development Level ◽  
The World ◽  
Long Time ◽  
The Difference ◽  
Post Industrial

The phenomenon of economic growth is studied by economists and statisticians in various aspects for a long time. Economic theory is devoted to assessing factors of growth in the tradition of R. Solow, R. Barrow, W. Easterly and others. During the last quarter of the century, however, the institutionalists, namely D. North, D. Wallis, B. Weingast as well as D. Acemoglu and J. Robinson, have shown the complexity of the problem of development on the part of socioeconomic and political institutions. As a result, solving the problem of how economic growth affects inequality between countries has proved extremely difficult. The modern world is very diverse in terms of development level, and the article offers a new approach to the formation of the idea of stylized facts using cluster analysis. The existing statistics allows to estimate on a unified basis the level of GDP production by 174 countries of the world for 1992—2016. The article presents a structured picture of the world: the distribution of countries in seven clusters, different in levels of development. During the period under review, there was a strong per capita GDP growth in PPP in the middle of the distribution, poverty in various countries declined markedly. At the same time, in 1992—2016, the difference increased not only between rich and poor groups of countries, but also between clusters.

Words are constructions, too: A construction-based approach to English ablaut reduplication

Linguistics ◽  
2020 ◽  
Vol 58 (6) ◽  
pp. 1701-1735
Author(s):  
Jeroen van de Weijer ◽  
Weiyun Wei ◽  
Yumeng Wang ◽  
Guangyuan Ren ◽  
Yunyun Ran
Keyword(s):  
New Approach ◽  
The Difference

AbstractIn this article we present a new approach to words of the type zigzag, chitchat, etc. in English. Such words form a formal (phonological) and functional (semantic) pattern in English. We argue that this pattern should be analysed in a construction-based approach, which has clear advantages over other approaches, e.g. analyses involving extragrammaticality or a synchronically productive reduplication process. We propose to extend the construction-based approach beyond its original scope (syntactic constructions) to words that may even no longer be morphologically complex. Finally, we make a tentative suggestion about how the difference between productive and unproductive patterns could be captured in the construction-based approach.

scholarly journals Variations of Accelerometer and Metabolic Power Global Positioning System Variables across a Soccer Season: A Within-Group Study for Starters and Non-Starters

2021 ◽  
Vol 11 (15) ◽  
pp. 6747
Author(s):  
Hadi Nobari ◽  
Rafael Oliveira ◽  
Marefat Siahkouhian ◽  
Jorge Pérez-Gómez ◽  
Florin Cazan ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Soccer Players ◽  
Positioning System ◽  
Metabolic Power ◽  
Early Season ◽  
Professional Soccer ◽  
Global Positioning ◽  
Lower Load ◽  
System Variables ◽  
In The Beginning

The aims of this study were to analyze the within-group weekly metabolic power average (wMPA), weekly acceleration zones (wAcZ), and weekly deceleration zones (wDcZ), in starter and non-starter professional soccer players, based on different periods of the full season (pre-, early-, mid-, and end-season). Twenty-one professional soccer players (age, 28.3 ± 3.8 years; height, 181.2 ± 7.1 cm; body mass, 74.5 ± 7.7 kg; BMI, 22.6 ± 1.0 kg·m2) were monitored during the full season in the highest level of the Iranian Premier League. WMPA, wAcZ, and wDcZ at three different zones (wAcZ1, wAcZ2, wAcZ3, wDcZ1, wDcZ2, wDcZ3) were collected using Global Positioning System. ANOVA was applied to analyze within-group changes across the different periods of the full season. In general, starters presented higher values in the beginning of the season (pre- and early-season) and lower values at mid- and end-season. Specifically, starters showed significant differences in early- vs. mid-season for wMPA, wAcZ1, and wDcZ1 (p < 0.05), plus early- vs. end-season for wMPA and wAcZ1 (p < 0.01). In addition, non-starters showed higher values in the pre-season that decreased until the end-season for wMPA, wAcZ1, and wDcZ1. Regarding wAcZ2, wDcZ2, wAcZ3, and wDcZ3, non-starters presented higher values in early-season that decreased until the end-season. Specifically, non-starters showed significant differences in pre- vs. mid-season for wMPA, wAcZ1, and wDcZ1; pre- vs. end-season for wMPA, wDcZ1, wDccZ2, and wDcZ3; early- vs. mid-season for wMPA, wAcZ1, wDcZ1, wAcZ2, and wDccZ2; early- vs. end-season for wMPA, wAcZ1, wDcZ1, wAcZ2 wDccZ2, wAcZ3, and wDcZ3; and mid- vs. end-season for wMPA, wAcZ1, and wAcZ3 (p < 0.05). In conclusion, starters were revealed to have higher values in pre- and early-season, and lower values in mid- to end-season, while non-starters were revealed to have lower load values in pre- and end-season and higher load values in early- and mid-season. This study provides extra insights over the season for starters and non-starters, respectively. Data can be used by coaches to better training periodization across soccer season.

Experience

2021 ◽  
Vol 13 (1) ◽  
pp. 1-16
Author(s):  
Michela Fazzolari ◽  
Francesco Buccafurri ◽  
Gianluca Lax ◽  
Marinella Petrocchi
Keyword(s):  
Relative Frequency ◽  
Service Providers ◽  
Real Data ◽  
Online Reviews ◽  
Purchase Decision ◽  
The Past ◽  
Supervised Classifiers ◽  
Relative Frequency Distribution ◽  
Opinion Spam ◽  
Fake Reviews

Over the past few years, online reviews have become very important, since they can influence the purchase decision of consumers and the reputation of businesses. Therefore, the practice of writing fake reviews can have severe consequences on customers and service providers. Various approaches have been proposed for detecting opinion spam in online reviews, especially based on supervised classifiers. In this contribution, we start from a set of effective features used for classifying opinion spam and we re-engineered them by considering the Cumulative Relative Frequency Distribution of each feature. By an experimental evaluation carried out on real data from Yelp.com, we show that the use of the distributional features is able to improve the performances of classifiers.

scholarly journals Measuring Gait Velocity and Stride Length with an Ultrawide Bandwidth Local Positioning System and an Inertial Measurement Unit

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 2896
Author(s):  
Pratham Singh ◽  
Michael Esposito ◽  
Zach Barrons ◽  
Christian A. Clermont ◽  
John Wannop ◽  
...  
Keyword(s):  
Gold Standard ◽  
Gait Speed ◽  
Inertial Measurement Unit ◽  
Stride Length ◽  
Measurement Unit ◽  
Gait Velocity ◽  
Positioning System ◽  
Inertial Measurement ◽  
Measurement Systems ◽  
Local Positioning System

One possible modality to profile gait speed and stride length includes using wearable technologies. Wearable technology using global positioning system (GPS) receivers may not be a feasible means to measure gait speed. An alternative may include a local positioning system (LPS). Considering that LPS wearables are not good at determining gait events such as heel strikes, applying sensor fusion with an inertial measurement unit (IMU) may be beneficial. Speed and stride length determined from an ultrawide bandwidth LPS equipped with an IMU were compared to video motion capture (i.e., the “gold standard”) as the criterion standard. Ninety participants performed trials at three self-selected walk, run and sprint speeds. After processing location, speed and acceleration data from the measurement systems, speed between the last five meters and stride length in the last stride of the trial were analyzed. Small biases and strong positive intraclass correlations (0.9–1.0) between the LPS and “the gold standard” were found. The significance of the study is that the LPS can be a valid method to determine speed and stride length. Variability of speed and stride length can be reduced when exploring data processing methods that can better extract speed and stride length measurements.

scholarly journals Characteristics of anteroposterior curvatures of the spine in soccer and futsal players

2017 ◽  
Vol 18 (4) ◽  
Author(s):  
Krystyna Chromik ◽  
Anna Burdukiewicz ◽  
Jadwiga Pietraszewska ◽  
Aleksandra Stachoń ◽  
Paweł Wolański ◽  
...  
Keyword(s):  
College Students ◽  
Statistical Analysis ◽  
Injury Prevention ◽  
Analysis Of Variance ◽  
Statistical Significance ◽  
Body Posture ◽  
Soccer Players ◽  
Prevention Training ◽  
The Difference ◽  
Post Hoc

AbstractPurpose. The aim of the study was to determine differences in anteroposterior spine curvatures between futsal players, soccer players, and non-training students. The results may contribute to the development of present-day knowledge of posturometry, and its implementation in training can help reduce the risk of body posture disorders in athletes. Methods. The examined group consisted of 48 athletes and 38 non-training college students. Body posture parameters were measured with the use of Posturometr-S. The normality of distribution was checked with the Shapiro-Wilk test, and the differences between the groups were measured with ANOVA and the Bonferroni post-hoc test. The level of statistical significance was set at p < 0.05. Results. The analysis of angle values revealed the widest and most similar measurements in the group of futsal players and soccer players. The analysis of variance proved statistically significant differences between the soccer players and futsal players (p = 0.003). The difference between the soccer players and non-training students was statistically significant. The highest γ angular value was measured in non-training students, followed by futsal players and soccer players. The statistical analysis revealed significant differences between the non-training students and futsal players, as well as non-training students and soccer players (p < 0.001). Conclusions. A complex assessment of athletes’ body posture is crucial in injury prevention. Training overloads may often lead to disorders of the organ of locomotion and affect the correct body posture in athletes. This, in turn, may result in pains and injuries.

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