Aleš Filipčič

Split-Step Timing of Professional and Junior Tennis Players

Abstract The purpose of the study was to determine the timing of a split-step in three categories of tennis players in four groups of strokes. Subjects were divided into three groups: male and female junior, and male professional tennis players. During two tournaments, all matches were recorded with two fixed video cameras. For every stroke, the timing of the split-step between the opponent’s impact point when hitting the ball and the player’s split-step was measured. A two-way analysis of variance (ANOVA) was used to determine the differences between groups of strokes, players and the interaction Player x Stroke Group. A Tukey post-hoc test was employed to determine specific differences. The results revealed differences between players in detecting the opponent’s movement, stroke and ball flight, which were reflected in different split-step timings. Each tennis player has his/her own timing mechanism which they adapt to various game situations. Response times differ significantly depending on the game situation. On average, they are the lowest in the serve, and then gradually rise from the return of the serve to baseline game, reaching the highest values in specific game situations. Players react faster in the first serve than in the second one and in the return of the serve, the response times are lower after the return of the second serve

Lateral Asymmetry in Upper and Lower Limb Bioelectrical Impedance Analysis in Youth Tennis Players

El tenis es un deporte que requiere movimientos asimetricos de los miembros dominantes y puede conducir a una distribucion asimetrica de la masa muscular. El objetivo fue determinar el volumen y grado de asimetria lateral de los miembros superiores e inferiores en tenistas juveniles utilizando un analisis de impedancia bioelectrica. Se aplico la prueba T para encontrar diferencias entre el brazo dominante y no dominante y las piernas y muslos derecho e izquierdo en cuatro categorias de edad. No hubo diferencias significativas en la masa magra de las piernas derecha e izquierda en los grupos de edad: 12 y menor, 14 y menor, y 16 y menor. Sin embargo, hubo diferencias significativas en la masa magra de las circunferencias de los brazos dominante y no dominante en los cuatro grupos de edad. Todos los jugadores jovenes de tenis tenian mayor masa magra en las circunferencias de los brazos del miembro dominante. Los jugadores de tenis en el grupo de 18 anos y menor, tenian valores medios mas altos de masa magra de la pierna derecha, con diferencias estadisticamente significativas. No hubo diferencias significativas entre las circunferencias de los muslos derecho e izquierdo en todos los grupos de edad. Los resultados muestran que es posible determinar con un procedimiento simple no invasivo y rapido, como la impedancia bioelectrica, la asimetria en jugadores de tenis.

Differences in Movement Speed Before and After a Split-Step Between Professional and Junior Tennis Players

Abstract This study investigated tennis players’ speed before, during and after the split-step, deceleration before and acceleration after the split-step in four different stroke groups in three age categories. Seven male professional, eleven male and ten female junior tennis players were recorded with video cameras at official tournaments. Using the SAGIT system, we gathered data on 8,545 split-steps. Tennis players performed a split-step in 82.9% of cases. A tennis player’s speed, deceleration and acceleration were measured 0.2 s before and after the split-step. Differences between categories and stroke groups for each of the five variables were analyzed with a two-way ANOVA. The differences between the groups of players were generally much higher in the speed before, during and after the split-step than in the deceleration before and acceleration after the split-step. Most of these differences were observed between the various stroke groups. These results suggest that players use three types of movement while performing a split-step. In the first type, which is typical of serving and returning, the speed before, during and after the split-step is lower (0.55 to 1.2 m/s). The second type of movement is characteristic of baseline strokes where tennis players achieve higher speed than in the first type (0.7 to 1.66 m/s). The third type occurs in strokes where a tennis player is moving or already at the net (0.78 to 1.9 m/s). Movement in tennis is an area that requires constant development in terms of designing and upgrading movement patterns, increasing speed and practice in specific game situations.

Secular Trends in Body Dimensions among Young Tennis Players from 1992 to 2008

Diversos estudios han examinado las caracteristicas y estado fisico de ninos y jovenes. El objetivo de este estudio fue encontrar la tendencia de los cambios para determinadas caracteristicas morfologicas de jovenes tenistas (hombres y mujeres) de distintas edades, en los periodos 1992-2000-2008. Ademas, encontrar cambios en las variables seleccionadas de jugadores de tenis jovenes y compararlos con los resultados de ninos y ninas de la misma edad en la poblacion escolar normal. Las variables de la muestra incluyeron altura y peso corporal e indice de masa corporal (IMC). El analisis multivariado de varianza revelo diferencias estadisticamente significativas en todos los factores principales (grupo, edad, sexo y periodo) y, ademas, en las interacciones de grupo-periodo, grupo-edad y grupo-sexo. El analisis univariado de varianza revelo diferencias estadisticamente significativas en la altura corporal e IMC entre los grupos de jugadores de tenis y la misma poblacion en edad escolar para ambos sexos y entre los tres grupos de edad (12-13 anos, 14-15 anos, 16-17 anos) para altura y peso corporal e IMC. Las comparacion entre sexos indican diferencias estadisticamente significativas solo en las variables altura y peso corporal. Los cambios en las caracteristicas morfologicas observadas senalan un aumento de la altura y peso corporal e IMC tanto en la poblacion escolar como en los jovenes jugadores de tenis.