Normative data of Lower-limb muscle flexibility in futsal players

El objetivo de este estudio fue definir cuantitativamente los valores de referencia del perfil de flexibilidad en 20 jugadores profesionales de fútbol sala. Para ello se valoró la flexibilidad de los principales grupos musculares de la extremidad inferior a través de 7 pruebas de rango de movimiento articular pasivo máximo. Los resultados obtenidos demuestran que los jugadores de fútbol sala analizados presentan un perfil de flexibilidad de la extremidad inferior superior a los valores propuestos para población general, a los valores encontrados en sujetos sanos sedentarios, así como en personas físicamente activas. De la misma forma, los valores de flexibilidad de los jugadores de fútbol sala seleccionados son superiores a los observados en otras modalidades deportivas.The purpose of this study was to quantitatively define the normative lower-limb flexibility data in 20 professional futsal players. For it, the flexibility of the major lower-limb muscles was evaluated throughout 7 different peak joint ROM assessment tests. The results of the current study demonstrate that the professional futsal players assessed have higher normative data of lower-limb flexibility than the previously stabilised flexibility normative data for general population, healthy sedentary adults, as well as for recreationally active adults. Likewise, the normative lower-limb flexibility data for the professional futsal players selected are higher than those reported for other sport modalities

Optimal data of lower-limb muscle flexibility in female futsal players

El objetivo fue definir cuantitativamente los valores del perfil óptimo de flexibilidad en 20 jugadoras de fútbol sala. Para ello, se valoró la flexibilidad de los principales grupos musculares del miembro inferior a través de 7 pruebas de rango de movimiento pasivo máximo (ROM). Los resultados del presente estudio definen como ROM óptimo los siguientes rangos para las jugadoras de campo: 43º-52º para gemelo, 48º-54º para sóleo, 148º-154º para glúteo mayor, 99º-118º para musculatura isquiosural, 46º-56º para aductores, 12º-20º para psoas iliaco y 116º-129º para cuádriceps. Para las porteras se han obtenido los siguientes rangos: 40º-46º para gemelo, 40º-47º para sóleo, 150º-155º para el glúteo mayor, 94º-118º para musculatura isquiosural, 45º-54º para aductores, 8º-12º para psoas iliaco y 115º-133º para cuádriceps. Teniendo en cuenta que se ha definido el percentil >80 como el ROM óptimo, sólo 4 jugadoras de campo y 2 porteras presentaban este ROM en cada movimiento evaluadoThe purpose of this study was to define the optimal lower-limb flexibility data for 20 female futsal players. Therefore, the flexibility of the major lower-limb muscles was evaluated throughout 7 different passive range of motion (ROM) assessment tests. The results of this study define the optimal ROM ranges for field players as: 43º-52º for the gastrocnemius, 48º-54º for the soleus, 148º-154º for the gluteus maximus, 99º-118º for the hamstrings, 46º-56º for the adductors, 12º-20º for the iliopsoas, and 116º-129º for the quadriceps. For goalkeepers have obtained the following ranges: 40º-46º for the gastrocnemius, 40º-47º for the soleus, 150º-155º for the gluteus, 94º-118º for the hamstrings, 45º-54º for the adductors, 8º-12º for the iliopsoas, and 115º-133º for the quadriceps. Keeping in mind that optimal ROM values were defined as >80th percentile, only 4 field players and 2 goalkeepers presented this ROM values in each movement assessed

Active stretching and length-tension relationship of the hamstring muscles

El objetivo de este estudio fue investigar el efecto agudo de una rutina de estiramientos estático activos para la extremidad inferior, con parámetros de la carga contextualizados respecto a la realidad físico-deportiva, sobre la relación tensión-longitud excéntrica de la musculatura isquiosural. 49 deportistas recreativos completaron tres sesiones de evaluación, una inicial defamiliarización y dos experimentales (control y estiramientos). Inmediatamente después de ambos tratamientos (control y estiramientos), se valoraron los parámetros isocinéticos pico de fuerza máxima excéntrico, ángulo de fuerza máxima excéntrico y trabajo total excéntrico empleando para ello una posición de tendido prono. Si la modificación de la curva tensión-longitud excéntrica puede ser utilizada como factor de riesgo primario de distensiones de la musculatura isquiosural, los hallazgos de este estudio sugieren que el estiramiento estático activo podría no alterar el riesgo relativo de lesión de la musculatura isquiosural.The purpose of this study was to investigate the acute effect of an active lower limb stretching routine with sports-related training load on the eccentric length-tension relationship of the hamstring. 49 recreational athletes completed three assessment sessions, an initial familiarization session and two experimental sessions (control and stretching in random order). Immediately after both interventions (stretching or control), eccentric isokinetic peak torque, angle of peak torque and total work were measured in prone position. If the modification on the eccentric length-tension relationship can be used as indexes of the risk of hamstring muscle strains, the findings of the present study tentatively suggested that static stretching may not alter the relative risk of hamstring strains

Modeling Chickenpox Dynamics with a Discrete Time Bayesian Stochastic Compartmental Model

[EN] We present a Bayesian stochastic susceptible-exposed-infectious-recovered model in discrete time to understand chickenpox transmission in the Valencian Community, Spain. During the last decades, different strategies have been introduced in the routine immunization program in order to reduce the impact of this disease, which remains a public health's great concern. Under this scenario, a model capable of explaining closely the dynamics of chickenpox under the different vaccination strategies is of utter importance to assess their effectiveness. The proposed model takes into account both heterogeneous mixing of individuals in the population and the inherent stochasticity in the transmission of the disease. As shown in a comparative study, these assumptions are fundamental to describe properly the evolution of the disease. The Bayesian analysis of the model allows us to calculate the posterior distribution of the model parameters and the posterior predictive distribution of chickenpox incidence, which facilitates the computation of point forecasts and prediction intervals.This work has been supported by a research grant from the Spanish Ministry of Economy and Competitiveness (MTM2017-83850-P).Corberán-Vallet, A.; Santonja, F.; Jornet-Sanz, M.; Villanueva Micó, RJ. (2018). Modeling Chickenpox Dynamics with a Discrete Time Bayesian Stochastic Compartmental Model. Complexity. 1-9. https://doi.org/10.1155/2018/3060368S19Acedo, L., Moraño, J.-A., Santonja, F.-J., & Villanueva, R.-J. (2016). A deterministic model for highly contagious diseases: The case of varicella. Physica A: Statistical Mechanics and its Applications, 450, 278-286. doi:10.1016/j.physa.2015.12.153Díez-Gandía, A., Villanueva, R.-J., Moraño, J.-A., Acedo, L., Mollar, J., & Díez-Domingo, J. (2016). Studying the Herd Immunity Effect of the Varicella Vaccine in the Community of Valencia, Spain. Lecture Notes in Computer Science, 38-46. doi:10.1007/978-3-319-31744-1_4Stochastic epidemic models with a backward bifurcation. (2006). Mathematical Biosciences and Engineering, 3(3), 445-458. doi:10.3934/mbe.2006.3.445Roberts, M., Andreasen, V., Lloyd, A., & Pellis, L. (2015). Nine challenges for deterministic epidemic models. Epidemics, 10, 49-53. doi:10.1016/j.epidem.2014.09.006Corberán-Vallet, A., & Santonja, F. J. (2014). A Bayesian SIRS model for the analysis of respiratory syncytial virus in the region of Valencia, Spain. Biometrical Journal, 56(5), 808-818. doi:10.1002/bimj.201300194Bjørnstad, O. N., Finkenstädt, B. F., & Grenfell, B. T. (2002). DYNAMICS OF MEASLES EPIDEMICS: ESTIMATING SCALING OF TRANSMISSION RATES USING A TIME SERIES SIR MODEL. Ecological Monographs, 72(2), 169-184. doi:10.1890/0012-9615(2002)072[0169:domees]2.0.co;2Gelman, A. (2006). Prior distributions for variance parameters in hierarchical models (comment on article by Browne and Draper). Bayesian Analysis, 1(3), 515-534. doi:10.1214/06-ba117aLunn, D., Spiegelhalter, D., Thomas, A., & Best, N. (2009). Rejoinder to commentaries on ‘The BUGS project: Evolution, critique and future directions’. Statistics in Medicine, 28(25), 3081-3082. doi:10.1002/sim.369

A deterministic model for highly contagious diseases: The case of varicella

[EN] The classic nonlinear Kermack-McKendrick model based upon a system of differential equations has been widely applied to model the rise and fall of global pandemic and also seasonal epidemic by introducing a forced harmonic infectivity which would change throughout the year. These methods work well in their respective domains of applicability, and for certain diseases, but they fail when both seasonality and high infectivity are combined. In this paper we consider a Susceptible-Infected-Recovered, or SIR, model with two latent states to model the propagation and evolutionary history of varicella in humans. We show that infectivity can be calculated from real data and we find a nonstandard seasonal variation that cannot be fitted with a single harmonic. Moreover, we show that infectivity for the present strains of the virus has raised following a sigmoid function in a period of several centuries. This could allow the design of vaccination strategies and the study of the epidemiology of varicella and herpes zoster. (C) 2016 Elsevier B.V. All rights reserved.Acedo Rodríguez, L.; Moraño Fernández, JA.; Santonja, F.; Villanueva Micó, RJ. (2016). A deterministic model for highly contagious diseases: The case of varicella. Physica A: Statistical Mechanics and its Applications. 450:278-286. doi:10.1016/j.physa.2015.12.153S27828645

A Bayesian stochastic SIRS model with a vaccination strategy for the analysis of respiratory syncytial virus

[EN] Our objective in this paper is to model the dynamics of respiratory syncytial virus in the region of Valencia (Spain) and analyse the effect of vaccination strategies from a health-economic point of view. Compartmental mathematical models based on differential equations are commonly used in epidemiology to both understand the underlying mechanisms that influence disease transmission and analyse the impact of vaccination programs. However, a recently proposed Bayesian stochastic susceptible-infected-recovered-susceptible model in discrete-time provided an improved and more natural description of disease dynamics. In this work, we propose an extension of that stochastic model that allows us to simulate and assess the effect of a vaccination strategy that consists on vaccinating a proportion of newborns.This work has been supported by Grant Number MTM2014-56233-P from the Spanish Ministry of Economy and Competitiveness.Jornet-Sanz, M.; Corberán-Vallet, A.; Santonja, F.; Villanueva Micó, RJ. (2017). A Bayesian stochastic SIRS model with a vaccination strategy for the analysis of respiratory syncytial virus. SORT. Statistics and Operations Research Transactions. 41(1):159-175. https://doi.org/10.2436/20.8080.02.56S15917541

Non-parametric probabilistic forecasting of academic performance in Spanish high school using an epidemiological modelling approach

Academic underachievement is a concern of paramount importance in Europe, and particularly in Spain, where around of 30% of the students in the last two courses in high school do not achieve the minimum knowledge academic requirement. In order to analyze this problem, we propose a mathematical model via a system of ordinary differential equations to study the dynamics of the academic performance in Spain. Our approach is based on the idea that both, good and bad study habits, are a mixture of personal decisions and influence of classmates. Moreover, in order to consider the uncertainty in the estimation of model parameters, a bootstrapping approach is employed. This technique permits to forecast model trends in the next few years using confidence intervals. Unfortunately, the obtained results do not suggest improvement in academic performance for the coming years.Cortés López, JC.; Sánchez Sánchez, A.; Santonja, FJ.; Villanueva Micó, RJ. (2013). Non-parametric probabilistic forecasting of academic performance in Spanish high school using an epidemiological modelling approach. Applied Mathematics and Computation. 221(15):648-661. doi:10.1016/j.amc.2013.06.070S6486612211

Asymptotic rejection of sinusoidal disturbances based voltage balance control in back-to-back power converters

This paper addresses the imbalance problem of the dc-link capacitor voltages in the three-level diode-clamped back-to-back power converter. In order to cope with it, a mathematical analysis of the capacitor voltage difference dynamics, based on a continuous model of the converter, is first carried out. It leads to an approximated model which contains explicitly several sinusoidal functions of time. In view of this result, the voltage imbalance phenomenon can be addressed as an output regulation problem, considering the sinusoidal functions as exogenous disturbances. Thus, a novel approach to deal with the mentioned problem in the back- to-back converter is presented. Then, the particular features of the disturbances are used to design several controllers. They all follow an asymptotic disturbance rejection approach. In this way, the estimations of the disturbances are used to apply a control law that cancels them while regulating the capacitor voltage balance as well. Finally, the performance of the proposed control laws is evaluated, presenting the simulation results obtained when the different controllers are implemented.MICINN-FEDER DPI2009-0966