Perfil de actividad durante el juego en futbolistas infantiles

En fútbol, el patrón de actividad de jugadores adultos, tanto masculinos como femeninos, ha sido ampliamente estudiado, pero son escasos los estudios que han centrado su atención en el análisis de los desplazamientos de los jugadores de categorías infantiles. Un mayor conocimiento de las demandas de este deporte en las etapas iniciales permitiría la confección de programas de entrenamiento más acordes con las características de los chicos de estas edades. El objetivo del presente estudio fue cuantificar de los desplazamientos en jugadores de fútbol de categoría infantil (12,2 ± 0,6 años; 156 ± 0,8 cm y 51 ± 5,2 kg) que pertenecían a la selección de la ciudad autónoma de Melilla, mediante la aplicación de dispositivos basados en tecnología GPS. Los resultados obtenidos certifican que el fútbol infantil es una especialidad deportiva intermitente en la que se intercalan actividades de alta intensidad con situaciones del juego que permiten que el jugador recupere estando parado, andando o con una velocidad de carrera muy baja. La tasa trabajo-descanso fue de 1:3,5 y la distancia media recorrida por minuto fue aproximadamente de 100 m. Esta distancia varía disminuyendo de forma lineal conforme transcurre el partido, existiendo diferencias significativas entre el inicio y el final del juego, lo que indicaría la aparición de la fatiga. Los esfuerzos de alta intensidad que se realizan implican el 6,1% del tiempo de juego y el 16,3 % de la distancia recorrida, efectuando un sprint máximo de entre 10 y 15 m de media, cada 141 segundos. La aplicación de tareas que reproduzcan la intensidad del juego durante cortos periodos de tiempo (no superiores a 10 minutos) aseguraría una elevada intensidad de trabajo durante los entrenamientos

Perfil d’activitat durant el joc en futbolistes infantils

Al futbol, el patró d’activitat dels jugadors adults, tant masculins com femenins, ha estat estudiat àmpliament, però són escassos els estudis que han centrat l’atenció en l’anàlisi dels desplaçaments dels jugadors de categories infantils. Un coneixement més gran de les demandes d’aquest esport en les etapes inicials permetria la confecció de programes d’entrenament més concordes amb les característiques dels nois d’aquestes edats. L’objectiu del nostre estudi va ser quantificar dels desplaçaments en jugadors de futbol de categoria infantil (12,2 ± 0,6 anys; 156 ± 0,8 cm i 51 ± 5,2 kg) que pertanyien a la selecció de la ciutat autònoma de Melilla, mitjançant l’aplicació de dispositius basats en tecnologia GPS. Els resultats obtinguts certifiquen que el futbol infantil és una especialitat esportiva intermitent en la qual s’intercalen activitats d’alta intensitat amb situacions del joc que permeten que el jugador recuperi estant aturat, caminant o amb una velocitat de carrera molt baixa. La taxa treball-descans va ser d’1:3,5 i la distància mitjana recorreguda per minut va ser aproximadament de 100 m. Aquesta distància varia i disminueix de forma lineal en el transcurs del partit: hi ha diferències significatives entre l’inici i el final del joc, la qual cosa indicaria l’aparició de la fatiga. Els esforços d’alta intensitat que es realitzen impliquen el 6,1 % del temps de joc i el 16,3 % de la distància recorreguda; efectuen un esprint màxim d’entre 10 i 15 m de mitjana, cada 141 segons. L’aplicació de tasques que reprodueixin la intensitat del joc durant curts períodes de temps (no superiors a 10 minuts) asseguraria una elevada intensitat de treball durant els entrenaments

A Panel Data Toolbox for MATLAB

Panel Data Toolbox is a new package for MATLAB that includes functions to estimate the main econometric methods of balanced and unbalanced panel data analysis. The package includes code for the standard fixed, between and random effects estimation methods, as well as for the existing instrumental panels and a wide array of spatial panels. A full set of relevant tests is also included. This paper describes the methodology and implementation of the functions and illustrates their use with well-known examples. We perform numerical checks against other popular commercial and free software to show the validity of the results

A Data Envelopment Analysis Toolbox for MATLAB

The Data Envelopment Analysis Toolbox is a new package for MATLAB that includes functions to calculate the main data envelopment analysis models. The package includes code for the standard radial input, output and additive measures, allowing for constant and variable returns to scale, as well as recent developments related to the directional distance function, and including both desirable and undesirable outputs when measuring efficiency and productivity; i.e., Malmquist and Malmquist-Luenberger indices. Bootstrapping to perform statistical analysis is also included. This paper describes the methodology and implementation of the functions, and reports numerical results using a reliable productivity database on US agriculture to illustrate their use

A panel data toolbox for MATLAB

Panel Data Toolbox is a new package for MATLAB that includes functions to estimate the main econometric methods of balanced and unbalanced panel data analysis. The package includes code for the standard fixed, between and random effects estimation methods, as well as for the existing instrumental panels and a wide array of spatial panels. A full set of relevant tests is also included. This paper describes the methodology and implementation of the functions and illustrates their use with well-known examples. We perform numerical checks against other popular commercial and free software to show the validity of the result

OTP-PRL: an app for occupational risk prevention in policing activities

Background: The rapid progress in information and communication technologies has promoted the development of smartphone applications (apps) for a wide variety of purposes including workplace safety. However, no specific apps for occupational risk prevention in the police domain seemingly exist as yet. In this work, an app running under the iOS and Android operating systems was developed to help police officers become acquainted with policing-related occupational risks and to prevent their damaging consequences. Results: The proposed app, which uses an iterative user-centered design to avoid occupational risks in policing activities, was assessed for performance by a group of users and experts through a System Usability Scale (SUS) questionnaire. The mean overall score for the questionnaire was 82.3. The app has backend support to facilitate continual improvement through contributions from users and administrators. A field test revealed increased awareness of policing occupational risks after using the app in many users. Conclusions: A novel product that covers the needs of ORP requirements of police officers has been developed

Does institutional quality matter for trade? Institutional conditions in a sectoral trade framework

This article examines the extent to which national institutional quality affects bilateral sectoral trade flows, as well as whether the conditioning role of institutions for trade has been waxing or waning with time. Based on a new trade theory framework, we derive a sectoral gravity equation, including novel variables corresponding to the exporter’s labour competitiveness levels, along with importer’s price indices and sectoral incomes, and analyse industry specific bilateral trade flows of 186 countries for the period 1996-2012. We address potential endogeneity and econometric drawbacks by means of Poisson Pseudo-Maximum Likelihood estimation methods. The results indicate that both the institutional conditions at destination and the institutional distance between exporting and importing countries are relevant factors for bilateral trade. Moreover, the effect associated to institutional conditions at destination moderately increases over time. This is a robust outcome across economic sectors, with higher values for agriculture and raw materials than for manufacturing and services

Un análisis de las patologías musculoesqueléticas en clarinetistas

There are few studies about pathologies suffered by musical instrumentalists, and less dedicated to clarinet players. This article reports a study with a total of 38 clarinet players, who answered a questionnaire designed by the authors based on questionnaires used in previous studies. The data show that the most important pathologies were backache (26,3%) and tendinitis in right hand (21,1%), detecting as possible causes a bad posture when playing (34%) and an increase in the practising time (26,4%).Existen pocos estudios sobre las patologías que padecen instrumentistas musicales, y aún son más escasos aquellos que se dedican plenamente al estudio de clarinetistas. En el presente estudio han participado un total de 38 clarinetistas, utilizándose un cuestionario diseñado por los autores de este trabajo a partir de los utilizados en estudios previos. Los datos encontrados revelan como patologías más relevantes el dolor de espalda (26,3%) y la tendinitis en la mano derecha (21,1%), detectándose como posibles causas una mala postura corporal en el momento de tocar (34%) y un aumento en el tiempo de estudio (26,4%)

Effects of a Caffeine-Containing Energy Drink on Simulated Soccer Performance

[Background] To investigate the effects of a caffeine-containing energy drink on soccer performance during a simulated game. A second purpose was to assess the post-exercise urine caffeine concentration derived from the energy drink intake. [Methodology/Principal Findings] Nineteen semiprofessional soccer players ingested 630±52 mL of a commercially available energy drink (sugar-free Red Bull®) to provide 3 mg of caffeine per kg of body mass, or a decaffeinated control drink (0 mg/kg). After sixty minutes they performed a 15-s maximal jump test, a repeated sprint test (7×30 m; 30 s of active recovery) and played a simulated soccer game. Individual running distance and speed during the game were measured using global positioning satellite (GPS) devices. In comparison to the control drink, the ingestion of the energy drink increased mean jump height in the jump test (34.7±4.7 v 35.8±5.5 cm; P<0.05), mean running speed during the sprint test (25.6±2.1 v 26.3±1.8 km · h−1; P<0.05) and total distance covered at a speed higher than 13 km · h−1 during the game (1205±289 v 1436±326 m; P<0.05). In addition, the energy drink increased the number of sprints during the whole game (30±10 v 24±8; P<0.05). Post-exercise urine caffeine concentration was higher after the energy drink than after the control drink (4.1±1.0 v 0.1±0.1 µg · mL−1; P<0.05). [Conclusions/significance] A caffeine-containing energy drink in a dose equivalent to 3 mg/kg increased the ability to repeatedly sprint and the distance covered at high intensity during a simulated soccer game. In addition, the caffeinated energy drink increased jump height which may represent a meaningful improvement for headers or when players are competing for a ball

Recovery kinetics of knee flexor and extensor strength after a football match

© 2015 The Authors. Published by PLOS. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0128072We examined the temporal changes of isokinetic strength performance of knee flexor (KF) and extensor (KE) strength after a football match. Players were randomly assigned to a control (N = 14, participated only in measurements and practices) or an experimental group (N = 20, participated also in a football match). Participants trained daily during the two days after the match. Match and training overload was monitored with GPS devices. Venous blood was sampled and muscle damage was assessed pre-match, post-match and at 12h, 36h and 60h post-match. Isometric strength as well as eccentric and concentric peak torque of knee flexors and extensors in both limbs (dominant and non-dominant) were measured on an isokinetic dynamometer at baseline and at 12h, 36h and 60h after the match. Functional (KFecc/KEcon) and conventional (KFcon/KEcon) ratios were then calculated. Only eccentric peak torque of knee flexors declined at 60h after the match in the control group. In the experimental group: a) isometric strength of knee extensors and knee flexors declined (P<0.05) at 12h (both limbs) and 36h (dominant limb only), b) eccentric and concentric peak torque of knee extensors and flexors declined (P<0.05) in both limbs for 36h at 60°/s and for 60h at 180°/s with eccentric peak torque of knee flexors demonstrating a greater (P<0.05) reduction than concentric peak torque, c) strength deterioration was greater (P<0.05) at 180°/s and in dominant limb, d) the functional ratio was more sensitive to match-induced fatigue demonstrating a more prolonged decline. Discriminant and regression analysis revealed that strength deterioration and recovery may be related to the amount of eccentric actions performed during the match and athletes' football-specific conditioning. Our data suggest that recovery kinetics of knee flexor and extensor strength after a football match demonstrate strength, limb and velocity specificity and may depend on match physical overload and players' physical conditioning level.Published versio