Isokinetic evaluation of knee muscles in soccer players: discriminant analysis [Avaliação isocinética dos músculos do joelho em jogadores de futebol: análise discriminante]; [Evaluación isocinética de los músculos de la rodilla en jugadores de fútbol: análisis discriminante]

Introduction: Muscle activity in soccer players can be measured by isokinetic dynamometer, which is a reliable tool for assessing human performance. Objectives: To perform isokinetic analyses and to determine which variables differentiate the under-17 (U17) soccer category from the professional (PRO). Methods: Thirty four players were assessed (n=17 for each category). The isokinetic variables used for the knee extension-flexion analysis were: peak torque (Nm), total work (J), average power (W), angle of peak torque (deg.), agonist/ antagonist ratio (%), measured for three velocities (60°/s, 120°/s and 300°/s), with each series containing five repetitions. Three Wilks' Lambda discriminant analyses were performed, to identify which variables were more significant for the definition of each of the categories. Results: The discriminative variables at 60°/s in the PRO category were: extension peak torque, flexion total work, extension average power and agonist/antagonist ratio; and for the U17s were: extension total work, flexion peak torque and flexion average power. At 120°/s for the PRO category the discriminant variables were: flexion peak torque and extension average power; for the U17s they were: extension total work and flexion average power. Finally at 300°/s, the variables found in the PRO and U17 categories respectively were: extension average power and extension total work. Conclusion: Isokinetic variables for flexion and extension knee muscles were able to significantly discriminate between PRO and U17 soccer players. RESUMO Introdução: A atividade muscular em jogadores de futebol pode ser medida por meio do dinamômetro isocinético, que é um instrumento confiável para avaliação do desempenho humano. Objetivos: Conduzir análises isocinéticas e discriminar quais variáveis diferenciam a categoria sub-17 (S17) da profissional (PRO). Métodos: Trinta e quatro jogadores de futebol (n=17 para cada categoria) foram avaliados. As variáveis isocinéticas utilizadas para a análise de extensão-flexão do joelho foram: pico de torque (Nm), trabalho total (J), potência média (W), ângulo de pico de torque (graus), razão agonista/antagonista (%), testadas em três velocidades (60°/s, 120°/s e 300°/s), com cada série contendo cinco repetições. Três análises discriminantes foram feitas usando o método Wilk's Lambda para identificar quais variáveis fariam uma discriminação significativa entre as duas categorias. Resultados: As variáveis discriminantes a 60°/s na categoria PRO foram: pico de torque extensores, trabalho total flexores, potência média de extensores e razão agonista/antagonista; e para os S17 foram: trabalho total de extensores, pico de torque de flexores e potência média de flexores. A 120°/s para a categoria PRO as variáveis discriminantes foram: pico de torque de flexores e potência média de extensores; para os S17 foram: trabalho total de extensores e potência média de flexores. A 300°/s, as variáveis encontradas para as categorias PRO e S17 foram, respectivamente: potência média de extensores e trabalho total de extensores. Conclusão: As variáveis isocinéticas para os músculos do joelho flexores e extensores foram capazes de fazer uma discriminação significativa entre jogadores de futebol PRO e S17. RESUMEN Introducción: La actividad muscular en jugadores de fútbol puede ser medida por medio del dinamómetro isocinético, que es un instrumento confiable para evaluación del desempeño humano. Objetivos: Conducir análisis isocinéticos y discriminar qué variables diferencian la categoría sub-17 (S17) de la profesional (PRO). Métodos: Fueron evaluados treinta y cuatro jugadores de fútbol (n=17 para cada categoría). Las variables isocinéticas utilizadas para el análisis de extensión-flexión de la rodilla fueron: pico de torque (Nm), trabajo total (J), potencia media (W), ángulo de pico de torque (grados), razón agonista/antagonista (%), probadas en tres velocidades (60°/s, 120°/s y 300°/s), con cada serie conteniendo cinco repeticiones. Fueron realizados tres análisis discriminantes usando el método Wilk's Lambda para identificar qué variables harían una discriminación significativa entre las dos categorías. Resultados: Las variables discriminantes a 60°/s en la categoría PRO fueron: pico de torque extensores, trabajo total flexores, potencia media de extensores y razón agonista/antagonista; y para los S17 fueron: trabajo total de extensores, pico de torque de flexores y potencia media de flexores. A 120°/s para la categoría PRO las variables discriminantes fueron: pico de torque de flexores y potencia media de extensores; para los S17 fueron: trabajo total de extensores y potencia media de flexores. A 300°/s, las variables encontradas para las categorías PRO y S17 fueron, respectivamente: potencia media de extensores y trabajo total de extensores. Conclusión: Las variables isocinéticas para los músculos de la rodilla flexores y extensores fueron capaces de hacer una discriminación significativa entre jugadores de fútbol PRO y S17

Ruptures of the anterior cruciate ligament in soccer

Ruptures of the anterior cruciate ligament (ACL) are serious, common and costly injuries. The present 12-year investigation was undertaken to examine the frequency of ACL ruptures and identify the game events that may have contributed to the cause of these injuries in male soccer players across a French district. A retrospective questionnaire was used to record the players’ age at the time of injury, laterality, standard of play, playing position and injured side. The characteristics of the injury situations were described in detail to investigate the game events involved in each case. A total of 934 ruptures was reported. Significantly more ruptures were sustained in a non-contact versus a contact situation (p<0.01). Of the total number of lesions, 34.5% occurred during a pivot action. The right knee was affected more than the left knee (p<0.001), irrespective of the dominant side of the player. Certain game events reported in the injury situations were shown to be related to player's age, standard and position. While these results have confirmed observations from previous investigations on ACL ruptures in soccer, the analysis of a considerably larger number of injury cases has brought new findings to the literature as well as recommendations for future research

Retour au sport après plastie du ligament croisé antérieur : critères utilisés dans les cubs professionnels de football

Résumé Objectifs Analyser la démarche suivie par les médecins de clubs professionnels de football lorsqu’ils décident, en pratique quotidienne, d’autoriser le retour compétitif après plastie du ligament croisé antérieur chez un footballeur. Matériels et méthodes Trente-sept médecins responsables de clubs professionnels de football français et belges (Ligue 1, n = 15 ; Ligue 2, n = 14 ; Division 1 belge, n = 8) ont rempli un questionnaire à choix multiple concernant : (1) les critères utilisés afin de déterminer si un joueur est apte à reprendre la compétition après plastie du ligament croisé antérieur ; (2) l’importance relative de chacun de ces critères ; (3) le rôle éventuel d’intervenants spécifiques (kinésithérapeute…) dans cette décision. Résultats Plus de 80 % des médecins interrogés ont déclaré utiliser au moins huit critères (sur 17 proposés) afin d’évaluer la capacité d’un footballeur à reprendre la compétition après plastie du ligament croisé antérieur. Les trois critères considérés comme les plus déterminants étaient, par ordre d’importance : la stabilité dynamique du genou lors d’un exercice spécifique au football, la force musculaire et la récupération complète ou quasi complète d’amplitudes articulaires de flexion et d’extension de genou. Pour certains de ces critères (notamment la force musculaire), nous constatons cependant un manque de consensus sur les modalités pratiques d’évaluation, sur les paramètres ainsi que sur les valeurs-limites tolérées afin de garantir un retour sur terrain sécurisé. La prise en compte de l’avis du kinésithérapeute et du préparateur physique par une très nette majorité de médecins souligne l’importance d’un travail pluridisciplinaire. Conclusion L’utilisation de différents critères objectifs afin d’autoriser le retour compétitif après plastie du ligament croisé antérieur semble être une réalité dans le football professionnel. Des études supplémentaires devraient cependant contribuer à préciser les modalités des épreuves ainsi que des valeurs-seuils. ________________________________________ Summary Purpose To analyze how sport physicians decide, in their daily practice, when a professional soccer player with a reconstructed anterior cruciate ligament is able to get back to competitive activities. Materials and methods Thirty-seven physicians for professional French and Belgian soccer teams filled in a specific questionnaire dedicated to: (1) return-to-play criteria after anterior cruciate reconstruction; (2) the importance they assigned to each of these criteria in the return-to-play decision; (3) the potential role of professionals, such as physiotherapists or physical coaches in this decision. Results More than 80% of the respondents declared to use at least eight criteria in order to assess the player's ability to return to competitive soccer after anterior cruciate ligament reconstruction. The most important ones were (in order of importance): dynamic knee stability during a specific soccer exercise, muscle strength performance and normalization of knee flexion and extension ranges of motion. For most of these criteria (notably muscle strength), there was a lack of consensus about the choice of assessment parameters and the limit values allowing physicians to authorize or forbid the return-to-competition. A large majority of participants stated to take into consideration advices from physiotherapists or physical coaches for the return-to-play decision. Conclusion Sport physicians of professional soccer teams use relevant criteria to assess players’ ability to return to full sport after anterior cruciate ligament reconstruction. Further studies are required to determine the choice of assessment parameters and the limit values to assist physicians in return-to-play decisions

Critères de retour sur le terrain

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