1. Investigación

Isokinetics is a tool commonly used in professional soccer. There is ongoing debate among researchers as to the isokinetic reference values a player should have. Objectives: To determine the absolute peak torque (PT) and average work of professional soccer players in relation to their positions on the field, and to establish the reference values for these variables. Methods: Purposeful sampling was used to select 289 professional soccer players. The sample included 32 goalkeepers, 100 defenders, 98 midfielders, and 59 strikers. The participants were measured preseason. The players were asked to perform a 10-minute warm-up on an exercise bike, and then to perform 5 repetitions at low speed, 10 at medium speed, and 25 at high speed, with 30 to 40-s of rest between each set of repetitions. The contraction method was concentric-concentric in a dynamometer Isomed 2000. Results: The average age, weight, and height of the players was 21.9 years, 74.3 kilograms, and 1.8 meters, respectively. The goalkeepers presented higher PT at the 3 measured speeds, and the higher average work at 180°/s and 240°/s in relation to defenders and midfielders. The strikers presented higher average work at 240°/s in relation to midfielders, and higher PT in relation to the defenders and midfielders. Absolute values. were shown and reference values were established. Conclusions: The goalkeepers and strikers were the players that showed the greatest differences in their favor in relation to the other positions. The peak torque values and average work were described in relation to the player’s position on the field. This study resulted in the creation of a tool for health professionals working with professional soccer players, providing reference values for these players in relation to their position on the field that can be used as benchmarks, by health professionals, to optimize soccer players’ performance

Few studies have previously evaluated isokinetic parameters in female soccer players in comparison to those in males. The aim of this study was to describe normative quadriceps (Q) and hamstring (H) muscle strength values in professional female soccer players and to examine differences between dominant leg (DL) and nondominant leg (NDL). A standardized test protocol of concentric knee extension and flexion test protocol was conducted using the dynamometer isokinetic system (IsoMEd 2000). All the participants were healthy female professional soccer players from Spanish first and second division teams. Players were assessed for peak torque (PT) and maximum work (MW) values at 60º/s, 180º/s, and 240º/s. The mean difference was 7.17 (p-value = 0.0036), 4.4 (p-value = 0.0386), and 4.25 Nm (p-value = 0.0241) at speed 60º, 180º, and 240º/s, respectively. No statistically significant differences were detected for H–Q values between DL and NDL. This difference was 6.44 (p-value = 0.0449), and 5.87 J (p-value = 0.0266) at speed 60º, and 180º/s. The present study can be a tool that health professionals working with female professional soccer players in their care can use to assess and monitor a particular player.

El isocinético es una herramienta de uso común en el fútbol profesional. Sigue habiendo debates en curso entre los investigadores sobre los valores que debe desarrollar un jugador. OBJETIVOS: establecer los valores de referencia en dinamometría isocinética en futbolistas profesionales. MÉTODOS: se utilizó un muestreo intencionado para seleccionar a los futbolistas profesionales. Los participantes fueron medidos en pretemporada. Calentaron durante 10 minutos en una bicicleta estática antes de realizar 5 repeticiones a baja velocidad, 10 a velocidad media y 25 a alta velocidad con 30-40 s de descanso entre ellas. Se usó el dinamómetro Isomed 2000. RESULTADOS: la edad, el peso y la altura media de los jugadores fue de 21,9 años,74,3 kilogramos y 1,8 metros. Los valores de referencia para los parámetros isocinéticos medidos han quedado establecidos en función de la demarcación al ejercer ésta un efecto directo. CONCLUSIONES: Las demarcaciones de portero y de delantero fueron las que mostraron mayores diferencias a su favor en relación al resto de demarcaciones. Los resultados del presente estudio son una herramienta para los profesionales de la salud que trabajan con futbolistas profesionales.