Test-Retest Reliability of 3 Specific Strength Tests in Professional Handball Players.

CONTEXT: Current devices to assess strength performance in handball may not be sufficiently sports-specific and reliable methods. Functional electromechanical dynamometry is a new technology that allows the development of accurate strength tests in athletes. PURPOSE: To determine the absolute and relative reliability and to compare the reliability of the right and left side, and mean and peak force of 3 specific strength tests in handball players with a functional electromechanical dynamometer: unilateral pullover, standing lift, and step forward. METHODS: Fourteen male handball players of the first Spanish division (28.79 [4.81] y; 10.38 [4.63] y of professional experience) performed a repeated-measurement design. Three testing sessions were performed (one per week). The first measurement consisted of 4 isometric tests (right and left unilateral pullover, and right and left standing lift) to obtain isometric peak force, and in the second and third sessions, 6 incremental tests until failure (right and left unilateral pullover, and right and left standing lift, right and left step forward) were performed. RESULTS: The tests provided high reliability or acceptable reliability for mean and peak strength of unilateral pullover, standing lift and step forward (intraclass correlation coefficient = .83-.97; coefficient of variation = 3.90-11.57). Effect side was negligible in any of the parameters, except for a small effect side in the left peak force for unilateral pullover and a small effect side on the left side for a step forward. Significant differences in reliability (coefficient of variation ratio > 1.15) were found between the right and left sides and peak and mean force in all exercises except peak force in unilateral pullover and step forward. CONCLUSION: These results confirm that the tests could be applied to assess physical performance in handball at the same time as regular gym training. Moreover, this is an excellent opportunity to individualize the player's weekly load.

The Role of the Specific Strength Test in Handball Performance: Exploring Differences across Competitive Levels and Age Groups.

The aim of this study was to determine if specific physical tests are sufficiently discriminant to differentiate players of similar anthropometric characteristics, but of different playing levels. Physical tests were conducted analyzing specific strength, throwing velocity, and running speed tests. Thirty-six male junior handball players (n = 36; age 19.7 ± 1.8 years; 185.6 ± 6.9 cm; 83.1 ± 10.3 kg; 10.6 ± 3.2 years of experience) from two different levels of competition participated in the study: NT = 18 were world top-level elite players, belonging to the Spanish junior men's national team (National Team = NT) and A = 18 players of the same age and anthropometric conditions, who were selected from Spanish third league men's teams (Amateur = A). The results showed significant differences (p < 0.05) between the two groups in all physical tests, except for two-step-test velocity and shoulder internal rotation. We conclude that a battery combining the Specific Performance Test and the Force Development Standing Test is useful in identifying talent and differentiating between elite and sub-elite players. The current findings suggest that running speed tests and throwing tests are essential in selecting players, regardless of age, sex, or type of competition. The results shed light on the factors that differentiate players of different levels and can help coaches in selecting players.

Distance-based logistic model for cross-classified categorical data.

Logistic regression models are a powerful research tool for the analysis of cross-classified data in which a categorical response variable is involved. In a logistic model, the effect of a covariate refers to odds, and the simple relationship between the coefficients and the odds ratio often makes these the parameters of interest due to their easy interpretation. In this article we present a distance-based logistic model that allows a simple graphical interpretation of the association coefficients using the odds ratio in a contingency table. Two configurations are estimated, one for the rows and one for the columns, as the categories of a polytomous predictor and a nominal response variable respectively, such that the local odds ratio and the distances between the predictor and response categories are inversely related. The associations in terms of the odds ratios, or the ratios of the odds to their geometric means, are interpreted through distances for the most common coding schemes of the predictor variable, and the relationship between the distances related to different codings is investigated in its full dimension. The performance of the estimation procedure is analysed with a Monte Carlo experiment. The interpretation of the model and its performance, as well as its comparison with a two-step procedure involving first a logistic regression and then unfolding, is illustrated using real data sets.

Caracterización clínica e histopatológica de niños con hepatitis autoinmune en un centro de referencia de Bogotá, Colombia / Clinical and histopathological characterization of children with autoimmune hepatitis at a referral center in Bogotá, Colombia

Resumen La hepatitis autoinmune (HAI) es una enfermedad hepática inflamatoria progresiva poco frecuente en niños y adolescentes, la cual es un reto diagnóstico para clínicos y patólogos. Describimos las características clínicas, bioquímicas e histopatológicas de 21 pacientes pediátricos con HAI diagnosticados en los últimos 14 años. Las biopsias hepáticas se reevaluaron para analizar detalladamente los hallazgos histopatológicos. De los 21 casos evaluados, 12 (57,1%) fueron mujeres, la mediana de edad fue 14 años, y 17 (80,9%) tenían HAI tipo 1. Los signos clínicos más frecuentes fueron ictericia (66,7%) y coluria (44,4%); también hubo evidencia de hipertensión portal con várices esofágicas (47,1%) y esplenomegalia (41,2%). El 11,8% de los pacientes tenía antecedentes de otras enfermedades autoinmunes. El 89,5%, 88,9% y 60,0% de los casos tenía elevación de aminotransferasas, hiperbilirrubinemia y bajos niveles de albúmina sérica, respectivamente. Las biopsias reevaluadas mostraron infiltrado linfoplasmocitario portal (94,4%), hepatitis de interfase (77,8%) y formación de rosetas (50,0%). En el 42,9% de las biopsias se hallaron inclusiones hialinas en las células de Kupffer. Cerca del 33,5% de los casos mostró cirrosis en la biopsia inicial. A pesar del tratamiento inmunosupresor, 4 pacientes requirieron trasplante hepático y 2 están en lista de espera. La HAI en niños puede manifestarse con ictericia y coluria, signos de hipertensión portal, aminotransferasas elevadas, hiperbilirrubinemia y anticuerpos circulantes. Las inclusiones hialinas en las células de Kupffer pueden ser un hallazgo útil en el diagnóstico histopatológico de la HAI en niños.

Abstract Autoimmune hepatitis (AIH) is a progressive inflammatory liver disease. It is uncommon in children and adolescents, and is a diagnostic challenge for clinicians and pathologists. We describe the clinical, biochemical and histopathological characteristics of 21 pediatric patients with AIH diagnosed in the last 14 years. Liver biopsies were reassessed to analyze histopathological findings in detail. Of the 21 cases evaluated, 12 (57.1%) were girls and young women, the median age was 14 years old, and 17 (80.9%) had type 1 AIH. The most frequent clinical signs were jaundice (66.7%), choluria (44.4%), evidence of portal hypertension with esophageal varices (47.1%), and splenomegaly (41.2%). Histories of other autoimmune diseases were found in 11.8% of these patients. Elevated levels of aminotransferases were found in 89.5% of the patients, hyperbilirubinemia was found in 88.9%, and 60.0% of the cases had low levels of serum albumin. Reassessed biopsies showed portal lymphoplasmocytic infiltrate (94.4%), interface hepatitis (77.8%) and rosette formation (50.0%). Hyaline inclusions were found in Kupffer cells in 42.9% of the biopsies. About 33.5% of the cases showed cirrhosis at the initial biopsy. Despite immunosuppressive treatment, four patients required liver transplantation and two are on the waiting list. AIH in children can manifest with jaundice, choluria, signs of portal hypertension, elevated aminotransferases, hyperbilirubinemia and circulating antibodies. Hyaline inclusions in Kupffer cells may be a useful finding in the histopathological diagnosis of AIH in children.

Distance stability analysis in multidimensional scaling using the jackknife method.

Stability or sensitivity analysis is an important topic in data analysis that has received little attention in the application of multidimensional scaling (MDS), for which the only available approaches are given in terms of a coordinate-based analytical jackknife methodology. Although in MDS the prime interest is in assessing the stability of the points in the configuration, this methodology may be influenced by imprecisions resulting from the inherently necessary Procrustes method. This paper proposes an analytical distance-based jackknife procedure to study stability and cross-validation in MDS in terms of the jackknife distances, which is not influenced by the Procrustes method. For each object, the corresponding jackknife estimated points are considered as naturally clustered points, and stability and cross-validation are analysed in terms of the MDS distances arising from the jackknife procedure, on the basis of a weighted cluster-MDS algorithm. A jackknife-relevant configuration is also proposed for cross-validation in terms of coordinates, in a cluster-MDS framework.

A latent class distance association model for cross-classified data with a categorical response variable.

In this paper we propose a latent class distance association model for clustering in the predictor space of large contingency tables with a categorical response variable. The rows of such a table are characterized as profiles of a set of explanatory variables, while the columns represent a single outcome variable. In many cases such tables are sparse, with many zero entries, which makes traditional models problematic. By clustering the row profiles into a few specific classes and representing these together with the categories of the response variable in a low-dimensional Euclidean space using a distance association model, a parsimonious prediction model can be obtained. A generalized EM algorithm is proposed to estimate the model parameters and the adjusted Bayesian information criterion statistic is employed to test the number of mixture components and the dimensionality of the representation. An empirical example highlighting the advantages of the new approach and comparing it with traditional approaches is presented.

Concordancia entre observadores en la determinación de la edad gestacional por medio de la prueba de Ballard

Entre el 1 de diciembre de 1989 y el 28 de febrero de 1990 se estudiaron 50 recién nacidos. El peso promedio al nacimientofue de 2814 gr, SD 653 g y la edad gestacional varió entre 30 y 47 semanas, con un promedio de 38.3 semanas y SD de 3.0 semanas. Dos pediatras y dos residentes de primer año evaluaron cada recien nacido con respecto a la edad gestacional por el método descrito por Ballard en 1979. La variable principal fue la edad gestacional y la correlación entre las variables se calculó por el método Kappa. El estudio mostró una gran variabilidad entre los observadores haciendo clínicamente inútil la prueba. Estos resultados merecen una posterior evaluación en nuevos estudios