Does player age influence match physical performance? A longitudinal four-season analysis in Spanish Soccer LaLiga.

This study aims to analyse the evolution of match running performance in relation to the age distribution of professional soccer players using a large-scale analysis. An explorational-longitudinal and retrospective study was designed and a total of 36,883 individual match observations were collected on outfield players competing across four consecutive Spanish LaLiga seasons (from 2015/16 to 2018/19), using an optical tracking system (ChyronHego). Soccer players were divided into 3 age groups: young (18-24 years old), middle-aged (25-30 years old), and seniors (31-41 years old). Relative total distance (TD/min), distance covered at 21-24 km · h-1 (HIRD/min), and > 24 km · h-1 per minute (VHIRD/min) were analysed; also, the number of efforts at 21-24 km · h-1 (Sp21) and > 24 km · h-1 (Sp24) were taken into consideration. Seasons were divided into four phases (P): P1 (matches 1-10), P2 (11-19), P3 (20-29), and P4 (30-38). The results showed that young players covered significantly greater TD, HIRD and VHIRD than the rest of the players (p < .05) in all season phases. In addition, TD significantly decreased along season phases in all player age group (p < .01). Crucially, young players performed significantly greater numbers of Sp21 and Sp24 than the rest of the players (p < .05) in all season phases. In addition, Sp21 and SP24 significantly decreased in middle-aged (p < .01) and senior players (p < .05) across the seasons. This study demonstrated that players' match running performance decreases with increasing years, especially in high-intensity running distances.

Influence of Scoring Systems on Mental Fatigue, Physical Demands, and Tactical Behavior during Soccer Large-Sided Games.

Constraints are common in soccer training to develop physical, technical-tactical, and mental training concurrently. This study examined how different scoring systems influence physical, tactical, and mental demands during large-sided games in soccer. Eighteen youth-elite male (17.39 ± 1.04 y) soccer players completed three 8 vs. 8 large-sided games where the different score systems were i) official score system (OSS; i.e., 1 goal = 1 goal), ii) double the value of the goal-4 min (DVx4; i.e., 1 goal = 1 goal from 0.00 to 7.59 min, and 1 goal = 2 goals from 8.00 to 12.00 min), and iii) double the value of the goal-8 min (DVx8; i.e., 1 goal = 1 goal from 0.00 to 3.59 min, and 1 goal = 2 goals from 4.00 to 12.00 min). Physical demands and tactical behaviors were recorded during tasks using a global positioning system and video camera. Mental fatigue was recorded pre- and post-task using a visual analogue scale. Also, the ratio of perceived exertion and mental load were recorded after tasks were finished. Results reported the highest values of mental and physical demands in DVx4. Mental fatigue increased during all three large-sided games, although this increase was significantly higher in DVx4 compared with OSS (p = 0.006) and DVx8 (p = 0.027). Tactical behavior showed a trend towards more direct play during DVx4, which was less observed during DVx8, and not at all during OSS. In conclusion, changing the scoring system affects physical, tactical, and mental demands.

Age and Maturation Matter in Youth Elite Soccer, but Depending on Competitive Level and Gender.

This study aimed to explore the relevance of the relative age effect (RAE), maturity status and anthropometry, and their influence on coaches' assessment of players' performance, analyzing both genders and different types of academies (elite vs. non-elite). The sample included 603 soccer players (385 male), from the under 12 (U12), under 14 (U14) and under 16 (U16) categories, belonging to elite and nonelite teams. Coaches' assessment of players' performance, chronological age, anthropometric characteristics, maturity offset (MO) and peak height velocity (PHV) were registered. Our results showed that RAE was present in both genders within the elite, but not in the nonelite academies. Early maturity players were overrepresented in the male elite, but not in the female academies. No relationship was found between RAE and anthropometry in male elite academies. Male elite players showed better anthropometric characteristics than nonelite players, while this pattern of results was not found for female players. The coaches' assessment on players' current performance was not influenced by the chronological age nor anthropometry, but it was linked to the PHV. Coaches from nonelite academies rated better in current assessment of performance the taller players. Our findings suggest that maturity status and RAE play an independent and important role in the talent selection process.

¿Influye el liderazgo del entrenador sobre la resiliencia de equipo? Efecto mediador de los conflictos intragrupo y la cohesión grupal / Does coach leadership influence team resilience? Mediating effect of intra-group conflict and group cohesion

Resumen Introducción/objetivo: El presente estudio tiene como objetivo examinar la rela ción entre el liderazgo transformacional del entrenador y las características de resiliencia y la vulnerabilidad bajo presión, así como analizar si los factores del conflicto intragrupo (social y tarea) y de la cohesión grupal (social y tarea), pudieran mediar la relación entre dichas variables. Método: A través de un diseño longitudinal, se incluyó a un total de 301 depor tistas inscritos en los JUDEX, pertenecientes a 34 equipos de fútbol y voleibol, con edades comprendidas entre 13 y 18 años (M = 15.72; DT = 1.33). Resultados: Los resultados mostraron una relación positiva entre el liderazgo transformacional del entrenador y las características de resiliencia, y una asociación negativa respecto a la vulnerabilidad bajo presión. Además, el conflicto intragrupo (social y tarea) actuó como mediador entre la relación del liderazgo trans formacional del entrenador y la resiliencia de equipo. En cuanto al papel mediador de la cohe sión grupal, solo la cohesión tarea actuó como mediadora entre el liderazgo transformacional del entrenador y la resiliencia de equipo. Conclusiones: La presente investigación muestra la importancia del liderazgo del entrenador para mejorar la resiliencia del equipo en categorías de formación, y la influencia positiva que tiene la reducción de los conflictos intragrupo y el aumento de la cohesión tarea durante la temporada.

Abstract Introduction/objective: The present study aimed to examine the relationship be tween transformational coach leadership with the characteristics of resilience and vulnerability under pressure, as well as to analyze whether the factors of intra-group conflict (social and task) and group cohesion (social and task) could mediate the relationship between these variables. Method: Through a longitudinal design, a total of 301 athletes enrolled in the JUDEX, belong ing to 34 soccer and volleyball teams, and aged between 13 and 18 years (M = 15.72; SD = 1.33). Results: The results showed a positive relationship between transformational leadership of the coach and resilience characteristics, and a negative association with respect to vulnerability under pressure. In addition, intra-group conflict (social and task) acted as mediators between the relationship between transformational coach leadership and team resilience. Regarding the mediating role of group cohesion, only task cohesion acted as a mediator between trans formational coach leadership and team resilience. Conclusions: This research draws as main conclusion the importance of the coach's leadership to improve team resilience in youth cate gories, and the positive influence of the reduction of intragroup conflicts and the increase of task cohesion during the season.

Influence of the COVID-19 lockdown on Spanish professional soccer teams' external demands according to their on-field ranking.

The main objective of this study was to analyse the changes in external demand parameters (e.g., total distance, high-speed running distance, accelerations/decelerations) in Spanish professional soccer teams after the COVID-19 lockdown considering their on-field ranking (i.e., teams whose ranking worsened after the COVID-19 lockdown [WRS] vs. teams that improved their ranking after the COVID-19 lockdown [IMP]). A total of 23,527 individual match observations were collected on players competing during the 2019/20 season in the First Spanish Professional soccer League (LaLiga). Goalkeepers and players who participated for less than 10 minutes in each match were excluded. Relative total distance (TD/min), distance covered at 21-24 km · h-1 (HIRD/min) and > 24 km · h-1 per minute (VHIRD/min), high metabolic load distance (HMLD), and the number of accelerations (3 m/s2) and decelerations (< 3 m/s2) performed were analysed by the ChryonHego video-tracking system. These variables were analysed during two differentiated periods, before the COVID-19 lockdown (i.e., 27 matches) and after the COVID-19 lockdown (i.e., 11 matches), and teams were classified into two groups according to their ranking (i.e., WRS vs. IMP). R-Studio was employed for data analysis and a mixed linear model was conducted. A decrease in external demands in all teams after the COVID-19 lockdown was observed, and this decrease was greater in WRS. These results suggest that, after an inactive period (i.e., the COVID-19 lockdown), teams that return with better physical performance, mainly related to high-intensity actions, have more possibilities of improving their final qualifying position.

High metabolic load distance in professional soccer according to competitive level and playing positions.

Background: High metabolic load distance provides global information about the soccer players' total high-intensity activities. Thus, this study aimed to examine the Spanish professional soccer players' high metabolic load distance profile, comparing competitive level and playing positions. Methods: A total of 18,131 individual match observations were collected from outfield players competing during the 2018/2019 and 2019/20 seasons in the First and Second Spanish Professional Soccer Leagues (LaLiga™). High Metabolic Load Distance (HMLD; distance covered with a power consumption above 25.5 W·kg-1 and accelerations or decelerations (e.g., accelerating from 2 to 4 m·s-2 for 1 s) were included), and HMLD per minute (HMLDmin) were analyzed by the ChryonHego® video-tracking system. Players were classified according to their playing position as follows: Central Backs (CB), Full Backs (FB), Center Midfields (CM), Wide Midfields (WM), and Forwards (FW). Results: No differences between competitive levels were found in any variable when all players were analyzed conjointly except for HMLDmin overall and during the second half. However, when playing positions were considered, differences between competitive levels were observed in all positions, mainly in HMLD and HMLD during the first-half variables. In addition, several differences between playing positions were observed, with CB presenting the lowest values in all variables compared to their counterparts in both competitive levels, whereas CM in First Division and WM in Second Division showed the highest values in the HMLD variables. Discussion: The findings are of interest to analyze the HMLD in professional soccer players, enabling the adaptation and individualization of training in this population according to the competitive level and specific playing position of each player.

Analysis of the Effect of Injuries on Match Performance Variables in Professional Soccer Players: A Retrospective, Experimental Longitudinal Design.

BACKGROUND: Knowing the impact of injuries is essential for their adequate management during reconditioning programs. OBJECTIVE: This study aimed to analyze the changes in match performance parameters in professional soccer players after sustaining an injury, which was defined according to injury severity. METHODS: Two-hundred and seven injuries related to one hundred and sixty-one professional soccer players from the Spanish LaLiga™ were considered for this study. All the injuries were classified according to their severity as minor (from 4 to 7 missed days), moderate (from 8 to 28 missed days), and major (more than 28 missed days). Through Mediacoach® videotracking system, time and external demand variables were collected and subsequently compared between pre-injury and return to play periods. The analyzed variables were (in m min-1): relative distance covered (RD; total distance covered·min-1), distance covered walking (0-6 km h-1), distance covered jogging (6-12 km h-1), distance covered running (12-18 km h-1), distance covered at intense running (18-21 km h-1), distance covered at high-speed running (21-24 km h-1), and sprinting (> 24 km h-1) distance covered. RESULTS: Significant reductions in playing time after suffering moderate and major injuries were observed. Significant reductions after minor injuries were observed in jogging (> 6 km h-1) and running (6-12 km h-1), while significantly greater distances at intense running (18-21 km h-1) and high-speed running (21-24 km h-1) were covered by players who suffer major injuries. Finally, relevant decreases in the maximum speed achieved after moderate and major injuries were found. CONCLUSIONS: In conclusion, this study shows the importance of high loads during reconditioning programs, as well as implementing strategies that allow reaching levels of maximum speed values after the return to play.

Relación entre los conflictos intra-grupo y el rendimiento en deportes colectivos: efecto mediador de la eficacia colectiva / Relação entre conflitos intra-grupo e desempenho em esportes coletivos: efeito mediador da eficácia coletiva / Relationship between intra-group conflicts and performance in collective sports: mediator effect of collective efficacy

El presente estudio tuvo como objetivo analizar la relación entre el conflicto intra-grupo y el rendimiento percibido a final de temporada, y examinar como actúa la eficacia colectiva como variable mediadora en esta asociación. Participaron 420 jugadores semi-profesionales y amateurs (M = 22,40; DT = 4,71) de baloncesto, balonmano, fútbol y voleibol. Los resultados mostraron que el conflicto intra-grupo (tarea y social) se relacionó negativamente con el rendimiento percibido del equipo, y que la eficacia colectiva mostró resultados significativos actuando como mediadora entre la relación de el conflicto intra-grupo (tarea y social) y el rendimiento percibido del equipo. Por lo tanto, es importante destacar que los conflictos intra-grupo parecen empeorar las percepciones sobre el rendimiento grupal y que la eficacia colectiva puede suavizar esta relación negativa, consiguiendo un aumento en el la percepción de los jugadores sobre el rendimiento del equipo a final de temporada. (AU)

The present study aimed to analyze the relationship between intra-group conflict and team perceived performance at the end of the season, and to examine the mediating effect of collective efficacy on this relationship. 420 semi-professional and amateur players (M = 22,40; SD = 4,71) of basketball, handball, soccer and volleyball participated. The results showed that intra-group conflict (task and social) was negatively related to team performance and collective efficacy showed significant results acting as a mediator between the relationship of intra-group conflict (task and social) and team perceived performance. Therefore, it is important to highlight that intra-group conflict seems to worsen the collective functioning and that collective efficacy can soften this negative relationship, achieving an increase in team performance at the end of the season. (AU)

O presente estudo teve como objetivo analisar a relação entre conflito intra-grupo e desempenho percebido no final da temporada, e examinar como a eficácia coletiva atua como uma variável mediadora nesta associação. Participaram 420 jogadores semiprofissionais e amadores (M = 22,40; DT = 4,71) de basquete, handebol, futebol e voleibol. Os resultados mostraram que o conflito intra-grupo (trabalho de casa e social) estava negativamente relacionado ao desempenho percebido da equipe e que a eficácia coletiva apresentou resultados significativos atuando como mediador entre a relação do conflito intra-grupo (trabalho de casa e social) e o desempenho percebido da equipe. Portanto, é importante destacar que o conflito intra-grupo parece agravar o funcionamento coletivo da equipe e que a eficácia coletiva pode amenizar essa relação negativa, conseguindo um aumento na percepção do desempenho da equipe no final da temporada. (AU)

Coach Encouragement During Soccer Practices Can Influence Players' Mental and Physical Loads.

This study analyzed the influence of the coaches' encouragement on the mental and physical load in soccer practices. The participants were 36 semiprofessional Spanish soccer players (Mage = 22.40; SD = 2.25) belonging to two male teams and one female team. Following the same practices' design and order, two training sessions of each team were completed. In one session, coaches maintained a passive verbal attitude, whereas in the other session, coaches intervened with an active attitude through continuous general encouragement. The mental load and fatigue were measured using self-reported questionnaires (Likert scales), and internal and external physical loads were quantified using the rating of perceived exertion and the Global Position System. A t-test for related samples and magnitude based on an inference spreadsheet was performed. The results demonstrated that mental and internal physical loads increased when coaches participated with active verbal encouragement. Especially, increases in performance satisfaction, mental effort, and RPE values, and decreases in unsafety values were detected due to encouragement interventions. Nevertheless, the external physical load did not show a clear trend. Based on these findings, coaches can use this information to manipulate their verbal encouragement during practices according to their physical and mental objectives with specific soccer strategies.

Can Rules in Technical-Tactical Decisions Influence on Physical and Mental Load during Soccer Training? A Pilot Study.

This study aimed to analyze the effects of rules limitations in pass decisions during soccer tasks on physical and mental load reported by players. Participants were 40 semiprofessional Spanish soccer players (Mage = 22.40, SD = 2.25) from two male teams. Two training sessions with four tasks (same tasks with different score system: two maintaining ball possession games with goalkeepers, and two maintaining ball possession games) in counterbalanced order between teams were completed. To achieve a goal during limitation tasks, a minimum number of players had to participate in the passes before the goal. Internal (perceived effort and heart rate) and external physical load (distances), mental load (validated adaptation of the NASA-TXL) and fatigue (VASfatigue) were quantified. Paired t-test and magnitude-based inference were conducted. The results showed significantly higher mean speeds (p < 0.01), effort perception (p < 0.001), and mental fatigue (very likely positive) during possession games with restrictions. Additionally, performance satisfaction obtained significantly higher values with goalkeepers and pass restrictions (very likely positive). External physical load showed no significant differences between situations. The influence of mental fatigue on internal load and the complexity of the tasks could explain these results. Coaches can use this information to manipulate the training load in ecological conditions.

Diseño y validación del Cuestionario para valorar la Carga Mental en los Deportes de Equipo (CCMDE) / Desenho e validaçao de um Questionário para quantificar a Carga Mental em Equipes Esportivas (QCMEE) / Design and validation of a Questionnaire to quantify the Mental Load in Team Sports (QMLST)

El objetivo del presente estudio fue diseñar y validar un cuestionario para valorar la carga mental en los deportes de equipo. Este cuestionario está formado por cuatro ítems en formato Likert (0-10): exigencia física, cognitiva, emocional y afectiva, y fue diseñado mediante acuerdo entre expertos (n = 10). Un total de 218 jugadores semiprofesionales de fútbol (M= 22.40; DT= 2.25) completaron el cuestionario tras finalizar un entrenamiento. Se analizó la fiabilidad mediante Alfa de Cronbach y coeficiente de Omega. Además, para la validez concurrente se realizó un análisis de correlaciones bivariadas, utilizando la Escala Visual Analógica y laEscala de Percepción del Esfuerzo. Los resultados muestran que este cuestionario presenta una adecuada consistencia interna (α= .73; ω = .75) y validez concurrente (p< .05). Por tanto, es una herramienta válida y fiable que permitirá a los entrenadores y preparadores físicos valorar la carga mental específica en los deportes de equipo. (AU)

The aim of the present study was to design and validate a questionnaire to quantify the mental load in team sports. Four items with Likert scale format (1-10) composed the instrument: physical, cognitive, emotional and affective exigence. A group of expert judges (n = 10) participated in the design. Later, a total of 218 semi-professionals soccer players (M= 22.40; SD= 2.25) answered the questionnaire after a training session. The internal consistency was evaluated with Cronbach ́s α(.73) and ω(.75). The concurrent validity was evaluated with Visual Analogue Scale ́s and Ratio Perceived Exertion ́s bivariate correlations (p< .05). Thus, the present questionnaire is a reliability and adequate instrument for asses the specific mental load in team sports. (AU)

O objetivo do presente estudo foi elaborar e validar um questionário para quantificar a carga mental em esportes coletivos. Quatro itens com formato de escala Likert (1-10) compuseram o instrumento: exigência física, cognitiva, emocional e afetiva. Um grupo de juízes especialistas (n = 10) participou do projeto. Um total de 218 jogadores semiprofissionais de futebol (M = 22,40; DP = 2,25) responderam ao questionário após um treino. A consistência interna foi avaliada com α de Cronbach (0,73) e ω (0,75). A validade concorrente foi avaliada com as correlações bivariadas da Escala Visual Analógica e Razão Percebida do Esforço (p <0,05). Assim, o presente questionário é um instrumento confiável e adequado para avaliar a carga mental específica em esportes coletivos. (AU)

A Longitudinal Exploration of Match Running Performance during a Football Match in the Spanish La Liga: A Four-Season Study.

This study aimed to analyze and compare the match running performance during official matches across four seasons (2015/2016-2018/2019) in the top two professional leagues of Spanish football. Match running performance data were collected from all matches in the First Spanish Division (Santander; n = 1520) and Second Spanish Division (Smartbank; n = 1848), using the Mediacoach® System. Total distance and distances of 14-21 km·h-1, 21-24 km·h-1, and more than 24 km·h-1, and the number of sprints between 21 and 24 km·h-1 and more than 24 km·h-1 were analyzed. The results showed higher total distances in the First Spanish Division than in the Second Spanish Division (p < 0.001) in all the variables analyzed. Regarding the evolution of both leagues, physical demands decreased more in the First Spanish Division than in the Second Spanish Division. The results showed a decrease in total distance and an increase in the high-intensity distances and number of sprints performed, although a clearer trend is perceived in the First Spanish Division (p < 0.001; p < 0.01, respectively). Knowledge about the evolution of match running performance allows practitioners to manage the training load according to the competition demands to improve players' performances and reduce the injury rate.

Mental Load and Fatigue Assessment Instruments: A Systematic Review.

Mental load and fatigue are important causes of performance decreases and accidents in different activities. However, a robust systematic review, detailing the instruments used to quantify them, is currently lacking. The purpose of this study was to summarize and classify by derivations the validated instruments used to quantify mental load and fatigue. The most representative electronic databases in the scope of this review, PubMed, WOS, Scopus, SPORTDiscus, and PsycINFO (until September 2020) were searched for studies that included instruments to analyze mental load and fatigue. The quality of the selected studies was scored using a quality assessment checklist. A total of 40 papers were included. Most of the papers used subjective scales (75%) to quantify mental load and fatigue, with a small presence of behavioral (n = 5) and objective techniques (n = 5). Less is known about the analysis of mental load and fatigue using a combination of derivations. Despite the high cost and complexity of objective techniques, research that applies these measures is important for further analysis of brain processes in mental load and fatigue. The design of a battery of tests that include the three types of derivations also seems necessary.