Raul Landeo

Determining optimal trial size using sequential analysis

Abstract When characterising typical human movement profiles, the optimal number of trials analysed for each participant should ensure a stable mean. Sequential analysis is one method able to establish the number of trials to stability by assessing a moving point mean against a set bandwidth. As the total trial number determining this bandwidth is selected arbitrarily, the effect of applying different total trial numbers on the results of sequential analysis was investigated. Twenty participants performed 30 trials of overarm throwing, and sequential analyses were applied to three dimensional (3-D) kinematic data over 10, 20 and 30 trial numbers. We found a total of 20 to be the preferred trial number for sequential analyses. Erroneous results were produced consistently by 10 trial number groups, while moving point means were statistically unchanged after the 10th trial. Subsequently, sequential analyses were applied to 20 trials to establish trials to stability in discrete and time series elements of the 3-D kinematic data. The results suggest that a trial size between 13 and 17 provides stable means for overarm throwing kinematics.

Intraindividual Movement Variability Within the 5 m Water Polo Shot

The purpose of this study was to explore movement variability of throwing arm and ball release parameters during the water polo shot and to compare variability between successful (hit) and unsuccessful (miss) outcomes. Seven injury free, subelite, females completed 10 trials of the 5 m water polo penalty shot. Intraindividual coefficient of variation percentage (CV%) values were calculated for elbow and wrist angular displacement, wrist linear velocity and ball release parameters (height, angle and velocity). Coordination variability (elbow/wrist angular displacement) was calculated as the CV% of the mean cross-correlation coefficient. Elbow and wrist displacement variability decreased to 80% of throwing time then increased toward release. Wrist linear velocity variability reduced toward release. Individual CV% values ranged between 1.6% and 23.5% (all trials), 0.4% and 20.6% (hit), and 0.4% and 27.1% (miss). Ball release height and velocity variability were low (< 12%; all trials) whereas release angle variability was high (>27%; all trials). Cross-correlation results were inconclusive. Roles of the elbow and wrist in production of stable ball release height and velocity and control of the highly variable release angle in the water polo shot are discussed and suggested for further study. Optimal levels of variability warrant future investigation.

Technical-tactical differences among university level taekwondo competitors by gender and weight division

espanolObjetivo: El objetivo del presente estudio fue evaluar el comportamiento tecnico-tactico, en funcion del sexo y la categoria de peso, de los competidores del Campeonato de Espana Universitario de Taekwondo de 2011. Metodo: Se analizaron un total de 45 combates de las rondas finales y semifinales del campeonato, con una muestra compuesta por 30 hombres y 31 mujeres. Las variables analizadas fueron: puntuacion obtenida, acciones totales, tipo de accion tactica, zona de golpeo, tipo de tecnica y pierna de golpeo. Resultados/Conclusiones: La prueba U de Mann Whitney mostro diferencias significativas entre hombres y mujeres en el numero total de acciones, tecnicas circulares y penalizaciones. Asimismo, los resultados mostraron diferencias significativas entre sexos en la frecuencia de realizacion acciones circulares en la categoria de peso mosca y pesado, acciones lineales de la categoria gallo y puntuacion total de la categoria de peso ligero. En la categoria de peso medio se hallaron diferencias significativas en las acciones totales, acciones de ataque, acciones al tronco, tecnicas realizadas con la pierna derecha y en tecnicas circulares. El comportamiento tecnico-tactico de los taekwondistas es diferente tanto en funcion del sexo como en funcion del sexo y la categoria de peso, siendo las mujeres las que realizan mas acciones circulares, al tronco, con la pierna derecha y totales que los hombres, mientras que estos reciben mas penalizaciones que las mujeres. EnglishAim: The aim of this study was to evaluate the technical-tactical behavior of the competitors competing in the 2011 University Taekwondo Championship of Spain. Method: The sample consisted of 30 men and 31 women participating in 45 championship finals and semifinals combats. The variables analyzed were: the score, total number of actions, the type of tactical action, the height, the type of technic and kicking leg. Results/Conclusions: The Mann Whitney U test showed significant differences between men and women in total actions, circular techniques and warnings. The results also showed significant gender differences in circular actions in the flyweight and heavyweight categories, in the linear actions in bantamweight and total score in the lightweight category. Significant differences in total actions, attacking actions, actions to the trunk performed techniques with right leg and circular techniques were also found in the middleweight division. The technical-tactical behavior of taekwondo competitors was found to differ between gender or gender and weight divisions. Women were found to perform more circular actions to the trunk with the right leg and total actions than men, who received more warnings than women portuguesObjectivo: O presente estudo teve como objectivo avaliar o comportamento tecnico-tactico dos competidores de taekwondodo Campeonato de Espanha Universitario de 2011, em funcao do genero e da categoria de peso. Metodo: Analisou-se um total de 45 combates nas provas finais e semifinais do campeonato, com uma amostra constituida por 30 homens e 31 mulheres. As variaveis analisadas no estudo foram: pontuacao obtida, accoes totais, tipo de accao tactica, zona de ataque, tipo de tecnica utilizada e perna de ataque. Resultados/Conclusoes:. O teste estatistico U de Mann Whitney revela diferencas significativas entre homens e mulheres no numero total de accoes, tecnicas circulares utilizadas e penalizacoes. Do mesmo modo, os resultados mostraram diferencas significativas entre os sexos na frequencia de realizacoes circulares na categoria de peso ligeiro e pesado, accoes lineares na categoria pesado e pontuacao total na categoria de peso ligeiro. Na categoria de peso medio verificaram-se diferencas significativas nas accoes totais, accoes direita e as tecnicas circulares. O comportamento tecnico-tactico dos praticantes de taekwondo e diferente tanto em funcao do sexo, como em funcao do sexo e categoria de peso, sendo as mulheres as que realizam mais accoes circulares, ao tronco, com a perna directa e totais. Os homens, no entanto, receberam mais penalizacoes do que as mulheres.

A Surrogate Technique for Investigating Deterministic Dynamics in Discrete Human Movement

Entropy is an effective tool for investigation of human movement variability. However, before applying entropy, it can be beneficial to employ analyses to confirm that observed data are not solely the result of stochastic processes. This can be achieved by contrasting observed data with that produced using surrogate methods. Unlike continuous movement, no appropriate method has been applied to discrete human movement. This article proposes a novel surrogate method for discrete movement data, outlining the processes for determining its critical values. The proposed technique reliably generated surrogates for discrete joint angle time series, destroying fine-scale dynamics of the observed signal, while maintaining macro structural characteristics. Comparison of entropy estimates indicated observed signals had greater regularity than surrogates and were not only the result of stochastic but also deterministic processes. The proposed surrogate method is both a valid and reliable technique to investigate determinism in other discrete human movement time series.