Ratio de sexo en la descendencia de futbolistas profesionales: estudio preliminar / Sex ratio in the offspring of professional soccer players: preliminary study / Proporção sexual em filhos de jogadores profissionais de futebol: estudo preliminar

OBJETIVO: Analizar si el entrenamiento de alta carga de los deportistas masculinos de élite puede influir en la proporción de sexo de sus descendientes. MÉTODO: Diseño observacional, descriptivo y transversal. Participaron 15 futbolistas, siendo condición necesaria que en el momento del estudio se encontrasen deportivamente activos, sin problemas de fertilidad y con descendencia. Las variables de estudio fueron el sexo de la descendencia, el número de hijos y el orden de nacimiento, y cargas de volumen e intensidad. El análisis estadístico consistió en relacionar las variables de carga, volumen e intensidad de ejercicio físico, con el sexo de los hijos, a través de la prueba de Ji cuadrado, teniendo en cuenta un nivel de significación p < 0.05. RESULTADOS: La descendencia fue de 28 hijos (13 niños, 15 niñas). El análisis de volumen e intensidad no reflejó diferencias significativas en la proporción niño/niña (p = 0.935; p = 0.296 respectivamente). En cambio, dentro de la población de niñas nacidas se observaron más nacimientos como consecuencia del entrenamiento de alta intensidad (p = 0.037). CONCLUSIONES: Este es el primer artículo hasta la fecha que evalúa la influencia del ejercicio físico de alta carga sobre el sexo de la descendencia de varones deportistas. Pese a que el número de niñas no ha sido significativamente mayor al de niños, se observa mayor número de niñas nacidas cuando el entrenamiento es de alta intensidad

OBJECTIVE: To analyze whether the high load training of elite male athletes can influence the sex ratio of their offspring. METHOD: Observational, descriptive cross-sectional study. Fifteen male soccer players participated from the study according to the following criteria at the time of the study: being engaged in sports practice and competition, no fertility issues and live offspring. The study variables were the sex of the offspring, the number of children and the order of birth, and volume and intensity loads. The statistical analysis consisted in relating the variables of volume and intensity load with frequency tables by means of the Chi square test, with margin of error p <0.05. RESULTS: The offspring was 28 children (13 boys, 15 girls). Volume and intensity analysis did not show significant differences in the boy/girl ratio (p = 0.935, p = 0.296 respectively). In contrast, within the population of girls, more births were observed as a consequence of high intensity training (p = 0.037). CONCLUSIONS: This is the first article to date that assesses the influence of high-load physical exercise on the sex of the offspring of male athletes. Although the number of girls has not been significantly greater than that of boys, there is a greater number of girls born when the training is of high intensity

OBJETIVO: Analisar se o treinamento de alta carga de atletas de elite do sexo masculino pode influenciar na proporção sexual de seus descendentes. MÉTODO: Estudo observacional, transversal e descritivo. Quinze jogadores de futebol do sexo masculino participaram do estudo de acordo com os seguintes critérios na época do estudo: estar envolvido na prática de esportes e competição, sem problemas de fertilidade e prole viva. As variáveis de estudo foram o sexo da prole, o número de filhos e a ordem de nascimento e as cargas de volume e intensidade. A análise estatística consistiu em relacionar as variáveis de volume e intensidade da carga com tabelas de frequência por meio do teste Qui-quadrado, com margem de erro p <0,05. RESULTADOS: A prole foi de 28 crianças (13 meninos e 15 meninas). A análise de volume e intensidade não mostrou diferenças significativas na relação menino / menina (p = 0,935, p = 0,296 respectivamente). Por outro lado, na população de meninas, mais nascimentos foram observados como consequência do treinamento de alta intensidade (p = 0,037). CONCLUSÕES: Este é o primeiro artigo até o momento que avalia a influência do exercício físico de alta carga sobre o sexo de filhos de atletas do sexo masculino. Embora o número de meninas não tenha sido significativamente maior que o de meninos, há um maior número de meninas nascidas quando o treinamento é de alta intensidade

Birth sex ratio in the offspring of professional male soccer players: influence of exercise training load.

STUDY QUESTION: Can the exercise training load of elite male athletes influence the sex ratio of their offspring? SUMMARY ANSWER: This is the first study assessing the influence of exercise training load on the offspring sex ratio of children from male professional athletes, observing a bias toward more females being born as a result of both high-intensity and high-volume loads, with intensity having the greatest effect. WHAT IS KNOWN ALREADY: There is a relatively constant population sex ratio of males to females among various species; however, certain events and circumstances may alter this population sex ratio favoring one sex over the other. STUDY DESIGN, SIZE, DURATION: Observational, descriptive cross-sectional study with a duration of 3 months. PARTICIPANTS/MATERIALS, SETTING, METHODS: Seventy-five male professional soccer players from First Division soccer teams. Offspring variables were sex of the offspring, number of children and order of birth. Exercise training variables were volume and intensity. MAIN RESULTS AND THE ROLE OF CHANCE: Total offspring was 122 children (52 males (42.6%), 70 females (57.4%)). Analysis revealed that increase in either the volume (P < 0.001) or intensity (P < 0.001) of training by the players shifted the birth offspring ratio more toward females. Within the sample of females born, more births (i.e. number) were observed as a consequence of training at the highest intensity (45 out of 70; P < 0.001), no such pattern occurred within males (P > 0.05). When female versus male births were compared within each intensity, only the high-intensity comparison was significant (45 (75%) females vs 15 (25%) males, P < 0.001). LIMITATIONS, REASONS FOR CAUTION: While this is the first study assessing differences in the sex ratio of the offspring of male athletes (i.e. soccer players), we acknowledge there are limitations and confounders within our approach; e.g. small sample size, ethnic background and variations in the timing of intercourse relative to ovulation as well as in sex hormone levels. As such, we propose that future research is needed to confirm or refute our findings. It is recommended that such work expand on the measurements obtained and conduct direct assessment of sperm characteristics. WIDER IMPLICATIONS OF THE FINDINGS: The findings of the study support the fact that different stressors on the body may alter the sex of the offspring. While in the present study the stressor is the excessive training load of soccer players, other events may lead to similar results. The bias in offspring sex ratio may have important implications for demography and population dynamics, as well as genetic trait inheritance. STUDY FUNDING/COMPETING INTEREST(S): There is no funding nor competing interests. TRIAL REGISTRATION NUMBER: N/A.

Applying graphs and complex networks to football metric interpretation.

This work presents a methodology for analysing the interactions between players in a football team, from the point of view of graph theory and complex networks. We model the complex network of passing interactions between players of a same team in 32 official matches of the Liga de Fútbol Profesional (Spain), using a passing/reception graph. This methodology allows us to understand the play structure of the team, by analysing the offensive phases of game-play. We utilise two different strategies for characterising the contribution of the players to the team: the clustering coefficient, and centrality metrics (closeness and betweenness). We show the application of this methodology by analyzing the performance of a professional Spanish team according to these metrics and the distribution of passing/reception in the field. Keeping in mind the dynamic nature of collective sports, in the future we will incorporate metrics which allows us to analyse the performance of the team also according to the circumstances of game-play and to different contextual variables such as, the utilisation of the field space, the time, and the ball, according to specific tactical situations.

Análisis y evaluación del lanzamiento de esquina (córner) en el fútbol de alto nivel / Analysis and evaluation of the corner kick in soccer at the highest level

Objetivo. Analizar cuál es la trascendencia del córner durante un partido de fútbol y conocer cuáles son las acciones principales que tienen lugar durante un saque de esquina en el fútbol profesional masculino de alto nivel. Métodos. Se analizaron 333 lanzamientos de esquina ejecutados en 35 partidos correspondientes a cinco competiciones internacionales de selecciones nacionales. Para su análisis se establecieron 370 posibles soluciones potenciales que fueron categorizadas a partir de cuatro niveles: lado de lanzamiento; profundidad del saque de esquina; posición del campo a la que se lanza el balón y acciones de segunda jugada. Resultados. El número de córneres por partido fue de 9,54 ± 1,02 (varianza: 11,79; rango: 5 - 18). Su número se comporta como una distribución de Poisson. Las características dominantes son los lanzamientos del lado derecho (52,4%) frente al izquierdo (47,6%); los saques largos (82,8%) sobre los cortos (17,2%); los lanzamientos al centro (53,7%) sobre los que se envían al primer poste (28,2%) o el segundo poste (28,2%). En la finalización de la jugada, los despejes (182 - 58,9%) y los contraataques (31 - 10,0%) superaron a los saques de esquina que terminan en remates a portería (53 - 17,2%) o se convierten en goles (5 - 1,6%). Conclusiones. El córner es una acción frecuentemente utilizada en un partido de fútbol, pero con un bajo nivel de efectividad (1,6/partido). Entendemos que, dado el bajo número de goles que suelen marcarse en un partido, la máxima optimización de estas acciones tácticas alcanza un valor relevante en el fútbol moderno(AU)

Objective. To analyze the corner significance during a soccer game and to know which are the main actions that occur during a corner kick in senior male professional soccer. Methods. We analyzed 333 corner kicks executed in 35 games, corresponding to five national team international competitions. For its analysis, 370 possible solutions were categorized based on four levels: Kick side, corner kick deepness; field position at which the ball is thrown and second play actions. Results. The number of corners per game was 9.54 ± 1.02 (variance: 11.79; range: 5 - 18). Its behavior follows the Poisson distribution. The key features are the right side kicks (52.4%) vs. left side (47.6%); the long kicks (82.8%) over the short ones (17.2%); the center kicks (53.7%) over the ones sent to the first post (28.2%) or the second post (28.2%). At the end of the play, the number of clearances (182 - 58.9%) and counterattacks (31 - 10.0%) outperformed the number of corner kicks ending in shots on goals (53 - 17.2%) or becoming in goals (5 - 1.6%). Conclusion. The corner is a common action used during a soccer match but with a low effectiveness level (1.6/match). We understand that, given the low number of goals scored during a game, the maximum optimization of these tactical actions reaches a relevant value in modern soccer(AU)