Efectos del COVID-19 en la carga externa en el fútbol de alto nivel / COVID-19 Effects in External Load in High Level Football

Analizamos el efecto del cese de la competición por COVID-19 en el rendimiento físico de jugadores de fútbol de la 1ª división española). La muestra se estratificó en tres grupos: rondas 1ª-3ª; 25ª-27ª y 28ª-30ª. Las comparaciones por pares fueron Student-t y Mann-Whitney U. Usamos un valor p de ≤0.05 como criterio para la significación estadística. Los valores de umbral para evaluar las magnitudes del tamaño del efecto se realizaron a través (d de Cohen). Tras el parón, las distancias recorridas aumentaron en los equipos locales y visitantes. Hubo un ligero descenso de los esfuerzos de alta intensidad entre el post-confinamiento y las jornadas (25ª-27ª). Comparados el 1er y 3er periodo, los valores fueron ligeramente superiores (rondas 28ª-30ª). Eso mismo se observó en las de aceleraciones y desaceleraciones, con mayores diferencias entre los periodos (1º y 3º). Hubo diferencias, cuando se comparó la reanudación con las jornadas previas al parón. (AU)

We analyzed the effect of the cessation of competition for COVID-19 on the physical performance of soccer players in the 1st Spanish division). The sample was stratified into three groups: 1st-3rd rounds; 25th-27th and 28th-30th. Pairwise comparisons were Student-t and Mann-Whitney U. We used a p-value of ≤0.05 as the criterion for statistical significance. Threshold values​​for evaluating effect size magnitudes were made using (Cohen's d). After the break, the distances traveled increased for the local and visiting teams. There was a slight decrease in high intensity efforts between post-confinement and the days (25th-27th). Comparing the 1st and 3rd period, values ​​were slightly higher (rounds 28-30). The same was observed in those of accelerations and decelerations, with greater differences between the periods (1st and 3rd). There were differences when the resumption was compared with the days before the break. (AU)

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.

Sperm DNA fragmentation as a result of ultra-endurance exercise training in male athletes.

Intensive sports practice seems to exert negative effects on semen parameters; in order to assess these effects, the objective of this study was to assess semen, including DNA fragmentation, and hormone parameters in elite triathletes. Twelve high-level triathletes preparing for a National Triathlon Championship participated in the study. The qualitative sperm parameters analysed were volume, sperm count, motility, morphology and DNA fragmentation; when needed, additional testing was performed. Assessed hormones were testosterone (T), cortisol (C) and testosterone-cortisol ratio (T/C). Maximum oxygen consumption and training characteristics were also assessed. Hormonal values and physical semen parameters were within normal ranges. DNA fragmentation showed high values (20.4 ± 6.1%). Round cells in semen were higher than normal (2.8 ± 1.5 million/ml), with the presence of macrophages. Correlations were found for several parameters: concentration of round cells positively correlated with progressive sperm motility (p = .01) and sperm morphology (p = .02); contrarily, the correlation found with DNA fragmentation was negative (p = .04). Sperm DNA fragmentation and the T/C ratio, however, were correlated in a positive manner (p = .03). As evidenced by the observed results, sperm DNA fragmentation is affected by high-level sports practice; therefore, high loads of endurance training could potentially interfere with the athlete's fertility potential.

Impact of physical activity and exercise on male reproductive potential: a new assessment questionnaire.

Male athletes in general are subjected to the same causes of infertility as the general population, but sports practice itself may be possibly an additional infertility factor or, at least an aggravating factor for a previously existing fertility condition; on the contrary, being physically active has been hypothesized to favor hormonal and seminological processes and could be beneficial for fertility. In this relationship, the different inherent parameters of physical activity-exercise (training volume, intensity, objective, organization and frequency) are of paramount importance. Therefore, this review discusses both the negative and positive impact of physical exercise on the male reproductive potential. Clear knowledge is lacking on this topic as incongruences exist due to the fact that studies lack standardization in assessment tools or research protocols. So that future studies can reveal more information regarding exercising male fertility, we introduce a unique questionnaire developed with the intent to help standardize future studies on male fertility and exercise.

Findings on sperm alterations and DNA fragmentation, nutritional, hormonal and antioxidant status in an elite triathlete. Case report / Hallazgo de alteraciones en semen, nutricionales, hormonales, del estado antioxidante y fragmentación de ADN en un triatleta de élite. Caso clínico / Descoberta das alterações no sêmen, nutricionais, hormonais, o antioxidante status e fragmentação de DNA em triatleta de elite. Relato do caso

Objective. The present case study analyzes semen quality, nutritional patterns, and hormonal and oxidative status of an international high-level triathlete with a low-volume, high-intensity training load. Method. The athlete was 26 years old, having participated in competitions since he was 13 years old, and practiced professional triathlon for the last five years. The qualitative sperm parameters analyzed were volume, sperm count, motility, morphology, and DNA fragmentation (additional testing performed as needed). Salivary hormones measured were T, C, and T/C. Seminal plasma total antioxidant capacity was measured. Maximum oxygen consumption and training characteristics were assessed. To determine habitual food intake and its possible repercussion on oxidative status, a quali-quantitative frequency questionnaire of 136 different foods was used and subsequently analyzed using specific software. Results. Hormonal and physical semen parameters were within normal ranges. Sperm morphology and DNA fragmentation showed abnormal values (3.9% and 38.33%). Round cells in semen were higher than normal (2.3 million/ml), with presence of macrophages. Apoptotic and necrotic events were observed. Total antioxidant capacity, although not compromised, was low. Dietetic intake was characterized by excess protein and appropriate overall antioxidant intake (with slight deficit and excess of some specific nutrients) according to recommended values. Conclusions. In this high-intensity endurance athlete, sperm parameters, mainly sperm morphology and DNA fragmentation, are altered. Further knowledge is needed with regards nutritional antioxidant intake and other dietetic strategies oriented toward avoiding oxidative damage in semen of high-performance triathletes. Moreover, adequate nutritional strategies must be found and nutritional advice given to athletes so as to palliate or dampen the effects of exercise on semen quality (AU)

Objetivo. El presente estudio de caso analiza la calidad de semen, patrones nutricionales y status hormonal y oxidativo de un triatleta internacional de alto nivel con carga de entrenamiento de bajo volumen y alta intensidad. Método. Atleta de 26 años de edad, con una práctica deportiva competitiva desde los 13 años, y cinco años de triatlón profesional. Los parámetros cualitativos analizados en semen fueron: volumen, contaje espermático, motilidad, morfología, y fragmentación de ADN, con pruebas adicionales según necesidad. Las hormonas salivares cuantificadas fueron: T, C, y T/C. La capacidad antioxidante total fue medida en plasma seminal. También se analizó el consumo máximo de oxígeno y características de entrenamiento. Para determinar la ingesta alimentaria habitual y su posible repercusión sobre el estado oxidativo, se utilizó un cuestionario de frecuencia de consumo cuali-cuantitativa, de 136 alimentos, analizado mediante software informático. Resultados. Los valores hormonales y parámetros físicos seminales estaban dentro de la normalidad. La morfología y fragmentación de ADN espermático mostraron valores anormales (3.9% y 38.33%). Aparecía un elevado número de células redondas (2.3 millones/mL), con presencia de macrófagos. Se observaron eventos apoptóticos y necróticos. La capacidad antioxidante total, aunque no alterada, estaba baja. La ingesta dietética se caracterizó por un exceso proteico y consumo adecuado de antioxidantes (con ligero déficit y exceso de algunos nutrientes específicos), según valores recomendados. Conclusiones. El ejercicio de resistencia de alta intensidad altera los parámetros espermáticos, principalmente morfología y fragmentación de ADN. Es necesario obtener mayor información sobre el efecto de antioxidantes y otras estrategias dietéticas con relación al daño oxidativo en el semen de triatletas de alto rendimiento, al igual que hallar estrategias nutricionales adecuadas para paliar o amortiguar los efectos del ejercicio sobre la calidad del semen (AU)

Objetivo: O presente estudo de caso analisa a qualidade de sêmen, padrões nutricionais, estado hormonal e oxidativo de um triatleta internacional de alto nível com carga de treinamento de baixo volume e alta intensidade. Método: Atleta de 26 anos de idade, com uma pratica esportiva desde os 13 anos e cinco anos de triátlon profissional. Os parâmetros qualitativos analisados no sêmen foram: volume, contagem espermática, motilidade, morfologia, e fragmentação de DNA com testes adicionais dada necessidade. Os testes hormonais salivares foram: Testosterona, Cortisol e a razão testosterona/cortisol. A capacidade antioxidante total foi medida no plasma seminal. Também foi analisado o consumo máximo de oxigênio e características do treinamento. Para determinar a ingesta alimentar habitual e sua possível repercussão sobre o estado oxidativo, foi utilizado um questionário de frequência de consumo quali-quantitativo de 136 alimentos, a partir do uso de um software especifico. Resultados: os valores e parâmetros hormonais e físicos seminais estavam dentro da normalidade. A morfologia e fragmentação do DNA espermático mostraram valores anormais (3,9% e 38,33%). Apresentando um elevado número de células redondas (2,3 milhoes/mL), com presença de macrófagos. Se observaram eventos apoptóticos e necróticos. A capacidade antioxidante total, ainda que não alterada, estava baixa. A ingesta dietética foi caracterizada por um excesso proteico e consumo adequado de antioxidantes (com ligeiro déficit excesso de alguns nutrientes específicos) segundo valores recomendados. Conclusões: o exercício de resistência de alta intensidade altera os parâmetros espermáticos, principalmente morfologia e fragmentação do DNA. Faz-se necessário obter maiores informações sobre o efeito de antioxidantes e outras estratégias dietéticas com relação ao dano oxidativo no sêmen de triatletas de alto rendimento, e traçar estratégias nutricionais adequadas para atenuar os efeitos do exercício sobre a qualidade do sêmen

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)

Potencia máxima, potencia óptima y espectro óptimo en el entrenamiento de la potencia del miembro superior ( bench press): una revisión / Maximum power, optimal load and optimal power spectrum for power training in upper-body (bench press): a review

Es un hecho que el deporte de alto rendimiento se ha caracterizado durante los últimos años por un entrenamiento cada vez más específico en el que técnicos y deportistas tienden a utilizar ejercicios y cargas de entrenamiento que se asemejan significativamente a las acciones que debe realizar el deportista durante la competición. Los principios de individualidad y especificidad son dos de los aspectos que mejor explican esta tendencia. En esa línea, esta revisión trata de analizar y entender lo que la bibliografía especializada señala con la realización de uno de los ejercicios más populares que se emplean en el desarrollo de la potencia del upper-body: bench press en sus diferentes variantes(AU)

It is a fact that high performance sport has been characterized in recent years as a more specific training and in which coaches and athletes tend to use exercise and training loads which significantly resemble athletes' real actions during competition. Principles of individuality and specifity are two aspects which best explain this trend. In that vein, this review analyzes and understands what specialized literature says to reach one of the most popular exercises used in upper-body power development: bench press in its different variants(AU)

The limitations of scaling laws in the prediction of performance in endurance events.

In the twentieth century, scientists have examined running speed over various distances, analyzing world records and studying the ability of an athlete to sustain a given speed. Assuming that running speed expresses the response of a non-linear multisystemic behavior, the relationship between these two variables (distance vs. velocity) can therefore be evaluated by applying scaling laws that fulfill the key principles of specificity and individuality of each athlete, yet responding to bioenergetic and functional patterns that are well-known to sports physiology. Since speed loss as distance increases exhibits fractal behavior, with small changes in the speed-reduction curve due to the effect of fatigue, it must be recognized that no universal scaling law can account, with acceptable precision, for the effect exerted by fatigue on potential speed at any given moment in a race. Power laws using a range of scaling exponents provide technical staff and athletes with a reliable, non-invasive tool for planning of training schedules, predicting athletes' performances over various distances and comparing the performance of specialists in different track events. The equations for the scaling laws for the distances investigated here were: V1500=15.00 × D⁻°·¹° (R²=0.99); V3000=12.76 × D⁻°·°8 (R²=0.99); V5000=11.55 × D⁻°·°7 (R²=0.99); V10,000=11.59 × D⁻°·°7 (R²=0.99); V21,095=10.78 × D⁻°·°6 (R²=0.97); V42,175=10.27 × D⁻°·°57 (R²=0.99).

Echocardiographic study of structure and functional cardiac profile of football referees.

AIM: The aim of this study was to analyze, through echocardiography, the structure and functional cardiac profile of national category Spanish soccer referees. METHODS: The sample consisted of 54 licensed referees, who belonged to the Football Inter-Insular Federation of Las Palmas. The sample presented a mean age of 28.52 ± 6.39 years, a height of 1.76 ± 0.07 m, a body mass of 77.26 ± 10.74 kg and a Body Mass Index of 24.90 ± 2-73 kg/m2. The diastolic and systolic dimensions of the left ventricle were 50.03 ± 4.79 mm and 33.74 ± 5.23 mm, respectively. The thicknesses of the interventricular septum and the posterior wall of the left ventricle were 9.77 ± 1.53 mm and 9.47 ± 1.54 mm, respectively. The left ventricular mass was 112.80 ± 26.53 g/m2, the diastolic volume of the left ventricle 135.09 ± 39.63 mL and the ejected volume 47.34 ± 12.44 mL/m2. RESULTS: This study shows that the echocardiographic profile of football referees is characterized by presenting an increase in the left ventricular mass caused by an increase of the cardiac chambers and a normal systolic and diastolic function. The values obtained by football referees were higher than those found in sedentary people and lower than in professional football players. CONCLUSION: These differences may be due to the different physical training workloads employed by football players and referees.

Male powerlifting performance described from the viewpoint of complex systems.

This paper reflects on the factors that condition performance in powerlifting and proposes that the result-generating process is inadequately described by the allometric equations commonly used. We analysed the scores of 1812 lifters belonging to all body mass categories, and analysed the changes in the results achieved in each weight category and by each competitor. Current performance-predicting methods take into account biological variables, paying no heed to other competition features. Performance in male powerlifting (as in other strength sports) behaves as a self-organised system with non-linear interactions between its components. Thus, multiple internal and external elements must condition changes in a competitor's score, the most important being body mass, body size, the number of practitioners, and the concurrency of favourable factors in one individual. It was observed that each behaved in a specific form in the high level, according to the individuals' circumstances, which make up the main elements of the competitive system in every category. In powerlifting, official weight categories are generally organised in three different groups: light (<52.0 to <60 kg), medium (<67.5 to <90.0 kg) and heavy (<100 to >125 kg) lifter categories, each one of them with specific allometric exponents. The exponent should be revised periodically, especially with regard to the internal dynamics of the category, and adjusted according to possible changes affecting competition.

Cinética hormonal (GH, IGF-I) en entrenamiento extensivo de fuerza / Growth hormone and insulin-like growth factor-1 kinetics in extensive strength training

Este trabajo estudia la respuesta de dos hormonas anabólicas: hormona de crecimiento (GH) y factor de crecimiento tipo insulina (IGF-I), en ocho varones, estudiantes de Educación Física, sometidos a un entrenamiento de fuerza con cuatro ejercicios de cargas submáximas con un movimiento de piernas (1/2-squat) y otro de brazos (bench press o bench press inclinado). Cada sujeto hace 70 repeticiones de piernas con un peso medio de 125.63ñ6.65 Kg. y 70 repeticiones de brazos con un peso medio de 56.56ñ7.90 Kg. (1RMBench Press: 79.43ñ11.00 Kg.; 1RM-Bench Press inclinado: 75.12ñ8.78 Kg.; 1RM-1/2Squat: 156.36 ñ8.18 Kg.Se demuestra que aunque el entrenamiento de fuerza de carácter extensivo provoca aumentos significativos de GH e IGF-I inmediatamente después de finalizar el ejercicio, en la fase de recuperación, la GH regresa rápidamente a los niveles iniciales, mientras que la IGF-I no lo hace (AU)