Application of arbitrary and individualized load quantification strategies over the weekly microcycle in professional soccer players.

The aims of this study were to: (a) determine the differences in external load quantification between arbitrary and individual speed thresholds over the weekly microcycle in professional soccer players, and (b) analyse the association between internal load and different external load quantification strategies (ELQSs). Ten professional outfield players were monitored during training sessions and official matches using 10 Hz GPS devices over a 6-week in-season period. The absolute and relative ("R" before the distance category) distances covered were calculated for the following external load variables: medium-intensity running distance (MIR), high-intensity running (HIR), sprint distance (SD), and very high-intensity running (VHIR). Individualized thresholds were determined based on maximal sprinting speed (MSS) and the last speed achieved during the 30-15 Intermittent Fitness Test (VIFT) of each player. In terms of match-day workload, significant differences (p < 0.05) were observed between arbitrary and individualized strategies (i.e., MSS and VIFT) for the distance covered in MIR, HIR, SD, VHIR, RHIR, RSD, and RVHIR. The MSS strategy compared to arbitrary thresholds revealed significant differences (p < 0.05) for distance covered in HIR, RHIR, and VHIR during all training sessions. The present results showed that arbitrary thresholds lead to underestimation of external load absolute and relative metrics compared to the MSS strategy throughout the microcycle. The VIFT strategy mainly revealed differences in external load quantification regarding MD compared to arbitrary thresholds. Individualized speed threshold strategies did not achieve better associations with internal load measures in comparison with arbitrary thresholds in professional soccer players.

Assessment of over-the-head resuscitation method in an inflatable rescue boat sailing at full speed. A non-inferiority pilot study.

INTRODUCTION: Drowning is a public health problem. Interrupting the drowning process as soon as possible and starting cardiopulmonary resuscitation (CPR) can improve survival rates. Inflatable rescue boats (IRBs) are widely used worldwide to rescue drowning victims. Performing CPR in special circumstances requires adjusting the position based on the environment and space available. The aim of this study was to assess the quality of over-the-head resuscitation performed by rescuers aboard an IRB in comparison to standard CPR. METHODS: A quasi-experimental, quantitative, cross-sectional pilot study was conducted. Ten professional rescuers performed 1 min of simulated CPR on a QCPR Resuscy Anne manikin (Laerdal, Norway) sailing at 20 knots using two different techniques: 1) standard CPR (S-CPR) and 2) over-the-head CPR (OTH-CPR). Data were recorded through the APP QCPR Training (Laerdal, Norway). RESULTS: The quality of CPR was similar between S-CPR (61%) and OTH-CPR (66%), with no statistically significant differences (p = 0.585). Both the percentage of compressions and the percentage of correct ventilations did not show significant differences (p > 0.05) between the techniques. CONCLUSION: The rescuers can perform CPR maneuvers with acceptable quality in the IRB. The OTH-CPR technique did not show inferiority compared to S-CPR, making it a viable alternative when boat space or rescue conditions do not allow the conventional technique to be performed.

Changes of physical match performance after the COVID-19 lockdown in professional soccer players according to their playing position.

The aim of this study was to evaluate the impact of the pandemic lockdown, which included training cessation and home-based training, on physical performance in professional soccer players from the Polish Ekstraklasa according to their playing position. The research was based on 3137 players' individual match performance observations during the 2019/2020 season divided into before (26 matchdays) and after (11 matchdays) lockdown periods. The data were collected using the computerised multiple-camera optical tracking system TRACAB (ChryronHego VID, New York, NY) with a sampling frequency of 25 Hz. Independently of playing position, a significant (p < 0.001) reduction in season resumption metrics of total distance (-0.9%), jogging (-1.6%), running (-3.4%) and high-speed running (-2.5%), with a contemporaneous increase in walking distance (1.4%), was noted in relation to pre-lockdown performance. A reduction in high-speed running was observed in central defenders (p < 0.05), central midfielders (p < 0.01) and forwards (p < 0.05). No significant decrease in sprinting or maximal running velocity was observed. The COVID-19 lockdown negatively influenced the physical performance in professional soccer players.

Does a short intervention with vibration foam roller recover lifeguards better after a water rescue? A pilot study.

PURPOSE: The aim of this study was to analyze the effects of a recovery program based on foam roller with and without vibration on blood lactate clearance and perceived fatigue after a water rescue. METHODS: A quasi-experimental crossover design was carried out to compare passive (PR) recovery and a short protocol of foam roller (FR) and vibration foam roller (VFR) recovery after a 100 m water rescue in 7 volunteer lifeguards. Blood lactate and perceived exertion were measured before and after the rescue, and also after the 5-min recovery intervention. RESULTS: Blood lactate levels decrease significantly with foam roller (p = 0.013; effect size = 0.97) and vibration foam roller recovery (p < 0.001; effect size = 1.62). Passive recovery did not show significant differences clearing out blood lactate. Fatigue perceived decrease significantly with all the recovery methods, but foam roller has higher effects on the global fatigue and VFR on the legs. CONCLUSION: FR and VFR clear out more blood lactate and decrease fatigue more than PR, with the subsequently increase of the physical conditioning to perform another effort.

Effects of Plyometric Training with Agility Ladder on Physical Fitness in Youth Soccer Players.

The aim of this study was to assess the effects of plyometric training with an agility ladder on components of physical fitness in youth soccer players. A total of twenty male under-13 soccer players were randomly assigned to a plyometric training group with an agility ladder (n=10) or a control group (n=10). Before and after training intervention linear sprint test (5 m, 10 m, 20 m), vertical jump ability (squat jump, countermovement jump and countermovement jump with arms), agility test, and slalom dribble test were assessed. The plyometric training with agility ladder was applied two times per week over six weeks. Data were analyzed using linear mixed model. The plyometric training group showed significant improvements (p<0.001) from pre-test to post-test in countermovement jump, countermovement jump with arms, and slalom dribble test. In the control group, no significant enhancements were obtained in all performance tests (p>0.05). The between-group analysis showed significant differences in countermovement jump with arms (p=0.03), but no significant differences (p>0.05) were found in squat jump, countermovement jump, sprint, agility test, and slalom dribble test. In conclusion, the short-term plyometric training with agility ladder seems to be ineffective and not time-efficient to improve physical fitness in youth soccer players. However, the interpretation of these results must be understood within the sample size limitations.

Effects of Age on Match-related Acceleration and Deceleration Efforts in Elite Soccer Players.

The aim of this study was to examine the effects of chronological age on acceleration and deceleration match performance in professional soccer players. A total of 5317 individual match observations were collected on 420 professional players competing in the Spanish LaLiga during the 2018-2019 season, using a multiple-camera computerised tracking system (TRACAB; ChyronHego, Melville, NY, USA). Players were classified using a k-means cluster analysis into four different age groups: 17-23 years, 24-27 years, 28-30 years, and 31-38 years. Linear mixed models were adjusted to compare the players' match performance according to their age group and playing position (central defenders, external defenders, central midfielders, external midfielders, and forwards). The results showed that players aged between 31-38 years performed a significantly less total number of accelerations (ES=0.30-0.48) and decelerations (ES=0.29-0.49) in comparison with younger players. These age-related physical performance declines were more pronounced among central defenders, central midfielders, and forwards. However, no significant effects were obtained for players' maximum acceleration and deceleration capacities. The current findings provide useful information for coaches and strength and conditioning specialists to better understand the effects of age on players' physical performance and to develop age-tailored training programs.

Acute Effects of Foam Rolling on Blood Flow Measured by Ultrasonography in Soccer Players.

ABSTRACT: Alonso-Calvete, A, Padrón-Cabo, A, Lorenzo-Martínez, M, and Rey, E. Acute Effects of Foam Rolling on Blood Flow Measured by Ultrasonography in Soccer Players. J Strength Cond Res 35(11): 3256-3259, 2021-In recent years, foam rolling (FR) has become a popular device for recovery to increase range of motion and decrease pain after sport practice and competition. However, there is little evidence about the underlying physiological effects of FR, specifically in blood flow parameters. Thus, the aim of this study was to analyze acute effects of FR on blood flow parameters (maximal velocity and maximal volume) measured by Doppler ultrasonography in soccer players. Twelve soccer players were assessed in 3 different situations: pre-FR intervention, immediately after FR intervention, and 30 minutes after FR intervention. The femoral artery was measured in the dominant leg with subjects in horizontal lying position. Before the intervention, subjects completed one familiarization session with FR. The FR intervention consisted of 2 sets, each with 45 seconds of FR and 15 seconds of rest between sets with a high-density foam roller in quadriceps, hamstrings, and iliotibial band. Results showed a significant increase in both maximal velocity (p < 0.001; effect size [ES] = 0.81) and maximal volume (p = 0.001; ES = 1.73) after intervention in comparison with pretest, but after 30 minutes, there were no significant differences. Therefore, this increase of the blood flow could promote important advantages for postexercise recovery, suggesting an acute effect that may contribute to the understanding of local physiological mechanism of FR.

Is it feasible "scoop and run while playing" resuscitation on a rescue water craft? A randomized simulation study with lifeguards.

OBJECTIVE: Response time is a predictive factor for survival of drowning victims and lifesaving. Rescue Water Craft (RWC) are lifeboats very common in lifeguards operations. The aim of this study was to analyze the feasibility of providing effective mouth-to-mouth ventilations and/or cardiopulmonary resuscitation (CPR) on the RWC while sailing at different speeds. METHOD: A quasi-experimental cross-over block design was used to test during one minute efforts the effectiveness of Mouth to Mouth ventilation (MM-only) and CRP, at the beach and sailing at two diferents speeds 5 knots(kn) and 10 kn with calm sea. Quality CPR reference were 2015 ERC guidelines. RESULTS: The data obtained from 13 lifeguards were included, that means that 78 resuscitation test were completed. The MM-only performance skills reached 69.7% ± 40.4 for 5 kn and 60.0% ± 41.8 for 10 kn (p = .59). For full CPR, performance was 74.4% ± 24.2 and 68.5% ± 23.9 respectively. Quality of MM and CPR decreased, not significantly, while sailing at 5 kn and 10 kn [(Q-MM; 5 kn: 59.9% ± 37.8 vs. 10 kn: 43.2% ± 41.4, p = .42)(Q-CPR; 5 kn: 64.8% ± 21.2 and 10 kn: 60.6% ± 21.0, p = .44)]. MM-only and CC variables were significantly worse on RJS when compared with resuscitation at the beach (p < .05). A trend for better results by lifeguards previously training on RJS was observed. CONCLUSIONS: Resuscitation techniques on board of a RWC are feasible and therefore they could be an option for lifeguards when their training, sea conditions, distance and the victim's characteristics allow it. CPR maneuvers may be highly effective at 10 kn, both for MM-only and CPR, however, the quality of the ventilations dramatically worsen with increasing speed.

Elite Soccer Players do Not Cover Less Distance in the Second Half of the Matches When Game Interruptions Are Considered.

ABSTRACT: Rey, E, Kalén, A, Lorenzo-Martínez, M, López-Del Campo, R, Nevado-Garrosa, F, and Lago-Peñas, C. Elite soccer players do not cover less distance in the second half of the matches when game interruptions are considered. J Strength Cond Res XX(X): 000-000, 2020-This study aimed to analyze quantitative differences in the physical demands of male elite soccer players between the first and second halves during official matches, accounting for effective playing time (the duration of play after subtracting the game interruptions) and playing positions. A total of 4,249 individual match observations of 412 outfield players competing in the Spanish first division league (LaLiga) were undertaken during the 2018-2019 season, using a computerized tracking system (TRACAB, Chyronhego, New York, NY). The players were classified into 5 positional roles: central defenders (CD), external defenders (ED), central midfielders (CM), external midfielders (EM), and forwards (F). The main results showed that in contrast to those observed when total playing time was considered, independent of playing position, there were no significant differences on high-speed running (HSR) (5.5 ± 2.4 vs. 5.5 ± 2.4 m·min-1) and sprint (5.3 ± 3.3 vs. 5.4 ± 3.3 m·min-1) distances between the first and second halves in professional soccer players when the effective playing time was considered. However, differences in match running performance at HSR and sprint distances between the first and second halves were dependent on players' playing position. Whereas ED and EM maintained HSR and sprint efforts during the second half, CD and CM significantly increased (p < 0.001) the distance covered at sprint during the second period of the match. Contrarily, F were unable to maintain their HSR (6.2 ± 2.3 vs. 5.9 ± 3.3 m·min-1) and sprint (7.0 ± 3.5 vs. 6.5 ± 3.4 m·min-1) match running performances during the second half. Such findings demonstrate that total playing time could overestimate fatigue-induced performance declines. Thus, effective playing time and playing position should be taken into account when interpreting the match running performance of professional soccer players.

The effect of age on between-match physical performance variability in professional soccer players.

This study aimed to analyse the effect of age on between-match variability of physical performance in professional soccer players. For this purpose, observations on entire match performance were collected on 787 professional soccer players competing in the first or second division of Spanish league during the 2017-2018 season. Players were classified into six groups according to their age: G1 (≤22.5 years), G2 (22.6-25.1 years), G3 (25.2-27.5 years), G4 (27.6-30.1 years), G5 (30.2-33.1 years) and G6 (≥33.2 years). Coefficients of variation (CVs) were calculated individually for each player and performance variable: total distance, low- intensity, medium-intensity, high-intensity running (HIR), sprinting, number of HIR, number of sprints, average speed and maximal speed. The main finding of this study was that players under 25.2 years (G1 and G2) showed lower CVs for high-intensity activities (HIR and sprinting) in comparison with players over 33.1 years (G6). These findings provide useful information for soccer coaches, who could put extra attention on physical performance of the oldest players when they have to play an entire match, because their performance is more variable and uncertain in comparison with the youngest.

Effects of Different Recovery Duration on External and Internal Load Measures during Bouts of Small-Sided Games.

The aim of this study was to analyse the effects of different recovery times between bouts of small-sided games (SSG) on external and internal load variables in semi-professional soccer players. Sixteen male semi-professional soccer players performed three 4 vs. 4 + goalkeeper SSG training sessions, each with different recovery bout duration: short (1 min) (SSG1), medium (2 min) (SSG2), and long (4 min) (SSG4). Time motion and neuromuscular measures were collected during all SSGs, in addition, the rating of perceived exertion (RPE) was determined at the end of the last bout of each SSG. Results showed a significant increase in the total number of accelerations (p = 0.016, ES = 0.97, large) and decelerations (p = 0.022, ES = 0.81, large) in SSG4 compared to SSG1. In terms of the internal load, SSG2 showed significantly higher RPE values (p = 0.011, ES = 1.00, large) in comparison with SSG1. If the sessions' focus is on neuromuscular training, longer recovery times between SSG bouts should be used. Conversely, if the aim is to reach a higher total and running distance at different intensities, a 2-min recovery period between bouts may be more appropriate.

Examining Variations Between Everyday Life Handedness and Lateral Preferences for Sport-Specific Skills in Children.

Purpose: This study aimed to analyze both sport-specific lateral preferences and handedness for everyday life tasks among school-aged children. Method: A total of 533 children (254 males and 279 females) aged 6 to 15 years old were assessed. Children's handedness was determined according to the laterality score from Edinburgh Handedness Inventory (EHI), while lateral preferences were assessed for 16 different sport-specific tasks. Results: The percentage of children with a left hand preference was lower for unilateral (10.5-14.3%) than for bilateral (19.5-31.7%) tasks. An increased prevalence of left-sided preference was also obtained for foot tasks (13.3-26.8%) and rotation along the vertical axis (28.5%). Similarly, hand preference for unilateral sport-specific tasks and EHI scores were largely correlated (r = 0.551-0.630), while these correlations were lower for bilateral hand tasks (r = 0.148-0.418), foot tasks (r = 0.201-0.386) and rotation preference (r = 0.129). Moreover, left-handed children evidenced less lateralized behavior for sport-specific tasks than right-handed children. Conclusions: The current study has shown that sport-specific lateral preferences and their correlations with handedness vary considerably depending on the task and individual characteristics in developmental ages. These findings emphasize the relevance of task-specific assessments of lateral preferences when looking at sports skills during childhood.

[Prevención del ahogamiento desde la educación para la salud escolar. Evaluación del proyecto piloto SOS 112.] / Drowning prevention through school health education. Evaluation of the SOS 112 pilot project.

OBJECTIVE: Drowning represents one of the main causes of child mortality. Water-related incidents are preventable and should be addressed through health education. The aim of this study was to evaluate an educational program for eight-year-old students based on a song with content on drowning prevention. METHODS: A feasibility pilot study was conducted, including forty-six children enrolled in a public school in Santiago de Compostela (A Coruña, Spain). The study was developed in three phases. In the first step, a group of experts and musicians created the educational content and the song. Secondly, the evaluation tool was developed, and finally, the program was implemented based on flag recognition, how to help in a drowning situation, safe swimming attitudes, and information about the emergency phone number 112. The percentage of correct responses by children before and after the educational intervention were compared using the McNemar test. RESULTS: Approximately half of the children were unaware of the meaning of the flags. After listening to the song, all students identified the meaning of the red flag, and over 90% recognized the green and yellow flags (p<0.001). Before the intervention, children correctly identified, on average, 75.3% of the safe water attitude pictograms. This perception of safe attitudes significantly increased post-intervention (p<0.001), with recognition of 86.4% of the correct behaviours. The overall water safety score also significantly improved by 22.7% after the intervention (p<0.001). CONCLUSIONS: The educational song is a resource to promote the learning of signals and concepts related to child drowning prevention.

OBJETIVO: El ahogamiento representa una de las principales causas de mortalidad infantil. Los incidentes acuáticos son prevenibles y deben ser abordados desde la educación para la salud. El objetivo de este estudio fue evaluar un programa educativo en alumnado de ocho años basado en una canción con contenido para la prevención del ahogamiento. METODOS: Se realizó un estudio piloto de viabilidad que incluyó a cuarenta y seis niños/as escolarizados en un centro público de Santiago de Compostela (A Coruña, España), siendo desarrollado en tres fases. En el primer paso, un grupo de expertos y músicos crearon el contenido educativo y la canción. En segundo lugar, se elaboró la herramienta de evaluación y, finalmente, se implementó el programa basado en el reconocimiento de las banderas, en cómo ayudar en un ahogamiento, en las actitudes seguras para el baño y en información sobre el teléfono de emergencias 112. El porcentaje de respuestas correctas antes y después de la intervención educativa se compararon utilizando la prueba de McNemar. RESULTADOS: Aproximadamente la mitad de los niños/as desconocía el significado de las banderas. Después de la audición de la canción, todos los escolares identificaron el significado de la bandera roja y más del 90% reconoció la bandera verde y amarilla (p<0,001). Antes de la intervención, los niños identificaron correctamente, en promedio, el 75,3% de los pictogramas de actitudes acuáticas seguras. Esta percepción de actitudes seguras aumentó significativamente postintervención (p<0,001), reconociendo el 86,4% de las conductas correctas. La puntuación general de seguridad del agua también mejoró significativamente después de la intervención un 22,7% (p<0,001). CONCLUSIONES: La canción educativa es un medio para favorecer el aprendizaje de las señales y conceptos sobre la prevención del ahogamiento infantil.

Evolution of physical and technical parameters in the Spanish LaLiga 2012-2019.

This study aimed to examine the position-specific evolution of technical and physical parameters in the Spanish LaLiga over an eight-season period. Match performance data of players were analysed for eight consecutive seasons from 2012/2013 to 2019/2020. A total of 32,775 individual match observations were analysed using a computerised tracking system (TRACAB, Chyronhego, New York, USA). The players were classified into five positional roles: central defenders (CD; match observations = 9,089), external defenders (ED; match observations = 7,876), central midfielders (CM; match observations = 8,276), external midfielders (EM; match observations = 3,949), and forwards (F; match observations = 3,585). Generalised linear models were used to analyse the differences in players' match performance according to the season and playing position. Total distance decreased by 3.2% in the final season versus the first season (p < 0.01, effect size = 0.37) in all playing positions. The number of efforts made at high-intensity running (HIR) increased across the eight seasons (ranging from 14.6% in ED to 9.2% in EM). However, whereas CD (+8.2%), ED (+9.5%), CM (+9.3%), and F (+8.0%) increased HIR distance from 2012 to 2020, no significant differences were found for EM (+1.7%). Overall, no differences were found in the number of total passes, short passes, long passes, and pass accuracy. Interestingly, CD increased the number of total passes (30.60%), short passes (31.5%), and long passes (26.5%). Finally, players performed 46.0% less tackles, 40.8% less clearances, and 10.0% more interceptions over the eight-season period. These findings may be useful for position-specific technical and physical training and talent identification.

Surfers as aquatics rescuers in Portugal and Spain: Characteristics of rescues and resuscitation knowledge.

The aim of this study was to analyze the rescues carried out by surfers from Portugal and Spain, their knowledge of rescue and resuscitation and their perception and risk behavior while surfing. An online survey was conducted in 2048 surfers from Portugal and Spain, with questions regarding the demographic characteristics, experience, perception and risk behavior of the surfers; rescues attended by the surfers and surfer's knowledge and experience in rescue and resuscitation. Concerning the number of rescues carried out by surfers, 78.5% of the participants had to carry out at least one rescue in their lifetime. A significant association was found between the years of surfing experience, the surfing level and the number of rescues carried out (p < 0.05). Thirty-five-point eight percent of the surfers never attended a cardiopulmonary resuscitation (CPR) course and 76.2% had no work experience as a lifeguard. Correspondingly, the vast majority of the surfers analyzed did not have the essential knowledge about rescue and resuscitation. This study provides evidence of the important role that surfers play in saving lives on Portuguese and Spanish beaches. The results suggest that the number of rescues conducted by surfers each year in Portugal and Spain is relevant to reducing the number of fatalities that occur along coasts.

Tensiomyographic Assessment of Contractile Properties in Elite Youth Soccer Players According to Maturity Status.

Little is known about how muscle contractile properties are affected by biological maturation in elite youth soccer players. This study aimed to determine the effects of maturation on contractile properties of rectus femoris (RF) and biceps femoris (BF) muscles assessed by tensiomyography (TMG) and provide reference values for elite youth soccer players. One hundred twenty-one elite youth soccer players (14.98 ± 1.83 years; 167.38 ± 10.37 cm; 60.65 ± 11.69 kg) took part in the study. The predicted peak height velocity (PHV) was used in order to establish players' maturity status (Pre-PHV, n = 18; Mid-PHV, n = 37; Post-PHV = 66). Maximal radial displacement of the muscle belly, contraction time, delay time, and contraction velocity for RF and BF muscles were recorded. One-way ANOVA showed no significant differences between PHV groups for any tensiomyography variables in RF and BF muscles (p > 0.05). Our results established that maturity status did not show a significant effect in mechanical and contractile properties on RF and BF muscles evaluated by TMG in elite youth soccer players. These findings and reference values can be useful for strength and conditioning coaches of elite soccer academies in order to optimize the evaluation of neuromuscular profiles.

The "DrownSafe" Project: Assessing the Feasibility of a Puppet Show in Teaching Drowning Prevention to Children and Parents.

Drowning remains a prominent global pediatric health concern, necessitating preventive measures such as educational initiatives for children and caregivers. In this study, we aimed to assess the feasibility and educational effectiveness of an interactive puppet show centered on teaching water safety to children and parents. A 30 min original theater performance, featuring two actors and three puppets (a girl, a crab, and a lifeguard), was conducted. Subsequently, 185 children (aged 4 to 8) and their 160 parents (134 mothers and 26 fathers) participated in this quasi-experimental study. Pre- and post-show tests were administered to evaluate knowledge and behaviors regarding aquatic environments. Prior to the puppet show, 78% of the children exhibited basic aquatic competency. Only 33% considered swimming alone risky. Following the intervention, 81.6% of the children changed their perception of the risks of solo beach activities, showing improved knowledge regarding contacting an emergency number (from 63.2% to 98.9%, p < 0.001). The intervention increased parents' intention to visit lifeguard-patrolled beaches and improved their CPR knowledge with regard to drowning victims by 58.8%. In conclusion, a drowning prevention puppet show positively impacted children and parents, potentially enhancing safety behaviors during water-related leisure activities, warranting its consideration part of comprehensive drowning prevention strategies.

No sport for old players. A longitudinal study of aging effects on match performance in elite soccer.

OBJECTIVES: This study aimed to examine the effects of age on match-related physical and technical-tactical performance in elite soccer players using a longitudinal design. METHODS: Data were collected from 154 players who competed in the Spanish first division (LaLiga) between the 2012-13 and 2019-20 seasons. A total of 14,092 individual match observations were analyzed using a computerized tracking system (TRACAB, Chyronhego, New York, NY). The players were classified into five positional roles: central defenders (n = 37); external defenders (n = 44); central midfielders (n = 34); external midfielders (n = 22); and forwards (n = 17). RESULTS: The main results showed that (a) soccer players decreased by an average of 0.56% their total distance covered for each year that they got older. Similarly, the number of high-intensity efforts and distance covered at high-intensity running decreased by 1.80% and 1.42% per year, respectively; (b) players significantly increased their pass accuracy by an average of 0.25% each year that they got older; (c) the detrimental effect of age on total distance and high-intensity running was greater for external defenders, external midfielders, and forwards; and (d) the positive effect of age on pass accuracy was greater for central defenders and central midfielders. CONCLUSIONS: Elite soccer players with long-term careers were unable to maintain their match-related physical performance as they got older. However, players can annually improve their technical-tactical skills with increasing age as a possible compensation mechanism against physical performance declines related to aging.

The Effect of Substitutions on Team Tactical Behavior in Professional Soccer.

Player substitutions are one of the main options for the coach to change tactical behavior of his team. Purpose: The present study therefore investigates the effect of player substitutions on tactical behavior in high-performance soccer using positional data. Method: The sample consisted of 659 substitutions from 234 matches played in the German Bundesliga during the season 2016-2017. Substitutions were classified either as neutral (n = 485), defensive (n = 45), or offensive (n = 129) according to the player's roles. The teams' tactical behavior before and after each substitution was analyzed using team centroid, inter-team centroid distance, team length and width, length per width (LpW) ratio, stretch index, and space control for the whole pitch and for each third as the dependent variables. Results: The linear mixed model analysis showed different effects for neutral, defensive, and offensive substitutions. Teams displayed significantly lower stretch index after defensive substitutions. LpW ratio increased with neutral and offensive substitutions, while inter-team distance decreased. The position of the team centroid, space control in the middle third and in the attacking third were also greater following an offensive substitution. Conclusions: These findings demonstrate that player substitutions effectively change tactical behavior of teams. Soccer coaches should perform more offensive substitutions to elicit a higher defensive pressure and improve goal-scoring opportunities, especially due to greater space control in the attacking third. In contrast, defensive substitutions can be used to increase defensive effectiveness through increases in team compactness.

Small-sided games in female soccer players: a systematic review.

INTRODUCTION: This systematic review aimed to analyze the literature on small-sided games (SSGs) from a physiological and physical perspective in female soccer players. EVIDENCE ACQUISITION: A systematic review of Web of Science, PubMed, Scopus and SPORTDiscus was performed according to PRISMA (Preferred, Reporting Items for Systematic reviews and Meta-Analysis) Guidelines. Studies informed about physical and/or, physiological-responses during SSGs played by young and/or adult amateur and/or professional female soccer players were included. Information regarding study information, population, intervention data, instruments, variables analyzed, and outcomes were elucidated. EVIDENCE SYNTHESIS: The search returned 2944 records. After screening against set criteria, a total of 13 manuscripts were fully reviewed. The present review grouped studies according to the three following age categories taking sample's mean age into account: Under-19 as young players and senior female players (>19 years old). The most common topics of analysis were: 1) player number; 2) pitch area and game surface; 3) sex differences; and 4) training regimens. CONCLUSIONS: This review provides useful information on the complex relationship between technical, physical and physiological interactions in SSGs and how manipulating these types of variables can improve the soccer training process.