Gut microbiota and physical activity level: characterization from sedentary to soccer players.

Evidence of the relationship between physical activity and gut microbiota composition is steadily increasing. The purpose of the study is to compare the gut microbiota composition of a group of elite male soccer players with a group of subjects with different physical activity levels. Cross-sectional studies were performed on 91 healthy young males, in detail: 17 elite soccer players (23.7 ± 4.2 yrs, BMI 23.2 ± 1.2 kg/m2); 14 with high levels of physical training (24.5 ± 5.6 yrs, BMI 22.7 ± 0.8 kg/m2); 23 with moderate levels of physical training (29.3 ± 3.9 yrs, BMI 22.5 ± 0.8 kg/m2); and 37 healthy men without exercise habits (28.1 ± 5.9 yrs, BMI 22.4 ± 1.0 kg/m2). Relative microbiota composition was determined by analyzing DNA extracted from stool samples. The quality and quantity of extracted DNA were assessed using a Qubit Fluorometer. Differences between subjects' populations were analyzed using a one-way ANOVA, and Bonferroni's post-hoc test was employed to identify localized effects. Elite soccer players and subjects with high physical activity levels showed a significantly higher prevalence of the nine microbiota populations analyzed than subjects with moderate physical training or who were sedentary. No differences were found in the Firmicutes to Bacteroidetes ratio among the different study populations. This study reports the gut microbiota parameters of elite footballers for the first time. In addition, it brings new insights into the effects of different levels of physical activity on the composition of the gut microbiota.

Analysis of Differences in Running Demands between Official Matches and Transition Games of Young Professional Soccer Players according to the Playing Position.

The aim of this study was to compare the running demands of transition games (TGs) and official matches, analysing their requirements according to the performance of each position. An observational design was used to examine the activity of 20 soccer players during official matches and TGs. GPS technology was used to monitor the total distance covered (DC), distance at speeds between 14-17.9 km•h-1, 18-21 km•h-1, and above 21 km•h-1, peak speed, accelerations and decelerations above 2.5 m•s-2, and Player Load for both activities. All players were assigned to groups: centre-backs (CBs), fullbacks (FBs), defensive midfielders (DMFs), offensive midfielders (OMFs), wide midfielders (WMFs) and strikers (Ss). TGs showed greater total DC, DC 14-17.9 km•h-1, DC 18-21 km•h-1, DC >21 km•h-1, accelerations and decelerations >2.5 m•s-2, and Player Load (p < 0.01). CBs, FBs and Ss showed more DC, DC 14-17.9 km•h-1, DC 18-21 km•h-1, DC >21 km•h-1, accelerations and decelerations >2.5 m•s-2 and Player Load in TGs (p < 0.01). In the midfielder positions, transition game players showed greater DC 18-21 km•h-1, DC >21 km•h-1, accelerations and decelerations >2.5 m•s-2 than in matches (p < 0.05). DMFs showed higher total DC (p < 0.05) and WMFs greater DC and DC 14-17.9 km•h-1 (p < 0.01) in these drills. During transition games CBs showed greater DC 14-17.9 km•h-1 than FBs, and greater DC than Ss (p < 0.05). FBs performed more decelerations >2.5 m•s-2 than DMFs and OMFs (p < 0.05). TGs produced a homogenized load in soccer players, independent of their position, which exceeded the external load of official matches.

ISAK-Based Anthropometric Standards for Elite Male and Female Soccer Players.

This study aimed to provide reference values for anthropometric characteristics of elite male and female soccer players, considering a group of individuals from the general population as controls. The anthropometric profiles of 357 elite soccer players [184 males (age 24.3 ± 4.3 y) and 173 females (age 25.2 ± 5.1 y)] participating in the first Italian league (Serie A) and 363 subjects from the general population [188 males (age 24.2 ± 4.8 y) and 175 females (age 25.0 ± 5.1 y)] were measured according to the guidelines of the International Society for the Advancement of Kinanthropometry (ISAK). Reference percentiles for stature, body mass, circumferences, eight skinfolds (biceps, triceps, subscapular, suprailiac, supraspinal, abdominal, front thigh, and calf), breadths, and somatotype were calculated and stratified by player position and sex. No difference (p > 0.05) was found in age between the two groups. Soccer players showed lower values for the sum of the eight ISAK skinfolds than individuals from the general population of the same sex. This suggests lower adipose tissue, as indicated by a lower endomorphic component. The somatotype was endomorphic mesomorph and mesomorphic endomorph for the male and female individuals from the general population, respectively. The male soccer players were ectomorphic mesomorphs, while the females were balanced mesomorphs, defining a sport-specific morphology. This study provides sex- and role-specific anthropometric standards for elite soccer players. Raw anthropometric reference values may be useful for evaluating body composition without using any predictive equations or assumptions.

Influence of the Number of Players on the Load of Soccer Players During Transition Games.

The aims of this study were to determine the effect of different compositions in transition games (TGs) on the load of soccer players and to evaluate their performance in physical tests. Using a GPS system, 18 players were monitored during: 3vs2, 2vs1 and 1vs1. Distance covered (DC), DC 18-20.9 km·h-1, 21-23.9 km·h-1,>24 km·h-1, peak speed, accelerations (Acc) and decelerations (Dec)>1.0 m·s-2 and>2.5 m·s-2 and rate of perceived exertion (RPE) were recorded. Before and after each TG, countermovement-jump (CMJ), 15- (S15) and 30 m (S30) speed tests were assessed. TG3vs2 showed greater DC and Dec>1.0 m·s-2 than TG2vs1, and DC, DC 18.0-23.9 km·h-1, Acc>1.0 m·s-2 and Dec>2.5 m·s-2 than TG1vs1 (p<0.01). TG2vs1 achieved higher DC, DC 18.0-23.9 km·h-1, and Acc>2.5 m·s-2 (p<0.01) but lower peak speed (p=0.02) and RPE (p=0.02) than TG1vs1. Post-intervention, TG1vs1 showed lower CMJ and higher S15 (p=0.02), while TG3vs2, showed improvements in CMJ (p<0.01). The three tasks showed large variations for DC>24 km·h-1, Acc>1.0 m·s-2, Dec>1.0 m·s-2 and Dec>2.5 m·s-2. The load of TGs is sensitive to their player composition.

Body Composition Changes in Male and Female Elite Soccer Players: Effects of a Nutritional Program Led by a Sport Nutritionist.

BACKGROUND: Soccer is a game in constant evolution and the intensity of play is increasing. Nutrition can play a role in the physical performance of elite players, maintaining their health and facilitating recovery. It is important to cover players' energy demands, and low energy availability may therefore result in impaired performance. This study aimed to evaluate alterations in body composition to determine the effects of a nutritional program led by a sport nutritionist. METHODS: A group of 88 elite soccer players from a Serie A club in Italy (44 males aged 26.5 ± 3.0 years and 44 females aged 27.1 ± 5.2 years) were enrolled. To evaluate changes in body composition, bioimpedance and anthropometric measurements were obtained following the protocol of the International Society for the Advancement of Kinanthropometry (ISAK). RESULTS: Compared with females, males had more muscle mass and less fat mass in both seasons evaluated. Comparing the first and last seasons, the male soccer players showed increased muscle mass and decreased fat mass while the female soccer players only showed decreased fat mass. CONCLUSIONS: The presence of a specialist sport nutritionist on the staff of professional soccer clubs could be important to ensure energy availability and evaluate body composition during the season.

Current Guidelines for the Implementation of Flywheel Resistance Training Technology in Sports: A Consensus Statement.

BACKGROUND: Flywheel resistance training has become more integrated within resistance training programs in a variety of sports due to the neuromuscular, strength, and task-specific enhancements reported with this training. OBJECTIVE: This paper aimed to present the consensus reached by internationally recognized experts during a meeting on current definitions and guidelines for the implementation of flywheel resistance training technology in sports. METHODS: Nineteen experts from different countries took part in the consensus process; 16 of them were present at the consensus meeting (18 May 2023) while three submitted their recommendations by e-mail. Prior to the meeting, evidence summaries were developed relating to areas of priority. This paper discusses the available evidence and consensus process from which recommendations were made regarding the appropriate use of flywheel resistance training technology in sports. The process to gain consensus had five steps: (1) performing a systematic review of systematic reviews, (2) updating the most recent umbrella review published on this topic, (3) first round discussion among a sample of the research group included in this consensus statement, (4) selection of research group members-process of the consensus meeting and formulation of the recommendations, and (5) the consensus process. The systematic analysis of the literature was performed to select the most up-to-date review papers available on the topic, which resulted in nine articles; their methodological quality was assessed according to AMSTAR 2 (Assessing the Methodological Quality of Systematic Review 2) and GRADE (Grading Recommendations Assessment Development and Evaluation). Statements and recommendations scoring 7-9 were considered appropriate. RESULTS: The recommendations were based on the evidence summary and researchers' expertise; the consensus statement included three statements and seven recommendations for the use of flywheel resistance training technology. These statements and recommendations were anonymously voted on and qualitatively analyzed. The three statements reported a score ranging from 8.1 to 8.8, and therefore, all statements included in this consensus were considered appropriate. The recommendations (1-7) had a score ranging from 7.7 to 8.6, and therefore, all recommendations were considered appropriate. CONCLUSIONS: Because of the consensus achieved among the experts in this project, it is suggested that practitioners and researchers should adopt the guidelines reported in this consensus statement regarding the use of flywheel resistance technology in sports.

Heart rate variability, recovery and stress analysis of an elite rally driver and co-driver during a competition period.

To ensure both optimal health and performances, monitoring physiological and psychological states is of main importance for athletes. It is well known that monitoring heart rate variability and using validated questionnaires is useful for monitoring both the health and training status of athletes of different sports. Motorsports such as rally require high levels of physical and mental preparation thus information about psychophysiological status of rally athletes is fundamental. The aim of this study was to assess the autonomic regulation, stress, recovery conditions of one driver and one co-driver competing at the Italian National Rally Championship during their competition period. Heart rate variability parameters, acute recovery and stress states were assessed the day before, during the two days of race and the day following the races. Results showed that driver and co-driver had a sharp decrease of mean RR intervals, root mean square of successive differences between normal heartbeats, and standard deviation of the N-N interval during race days, while the stress index showed the inverse trend, and this behaviour was clearly visible in the Poincaré plots and power spectrum density graphs. The acute recovery and stress states questionnaire showed significant differences in recovery and stress scoring for the driver but not for the co-driver, although the trends were similar. This study describes the psychophysiological demands of a rally competition period suggesting that a daily evaluation of heart rate variability, recovery, stress states is useful for monitoring health status in rally athletes and could be implemented to make decision about training and recovery strategies.

Relative Match Load in Young Professional Soccer Players during Soccer-7 and Soccer-11.

The aim of this study was to analyze the differences in internal and external load during Soccer-7 and Soccer-11, comparing positional requirements and neuromuscular fatigue in both modalities. Twenty-four young soccer players were monitored in Soccer-7 and Soccer-11 matches using global positioning systems. Total distance covered (TD), distance covered at high speed (HSR), distance covered at very high speed (VHSR), peak speed, accelerations (Acc) and decelerations (Dec) and rate of perceived exertion (RPE) were recorded differentiating between central backs (CB), midfielders (MF), external players (EX) and forwards (FW). Neuromuscular fatigue were assessed using a jump test. During Soccer-11, players showed significantly higher TD, HSR and VHSR, with low Acc and greater RPE compared with Soccer-7. During Soccer-11, all positions recorded significantly greater TD, distance at HSR and at VHSR than Soccer-7. In terms of playing position, CB, MF and FW achieved significantly higher Peak Speed during Soccer-1, but there was no difference for EX. During Soccer-7 all positions performed significantly higher numbers of Acc. Although the Soccer-7 modality is considered an optimal format for the development of young soccer players, there is a significant difference in match running activity for all playing positions with respect to the Soccer-11 format.

Different pitch configurations constrain the external and internal loads of young professional soccer players during transition games.

The aims of this study were to compare the influence of transition game (TG) size on the external and internal loads of young professional soccer players and to describe the high-speed profile of these drills in response to pitch dimensions. Eighteen young professional soccer players (age: 16.1 ± 0.3 years; height: 178.3 ± 5.4 cm; weight: 70.1 ± 6.2 kg) performed a 3vs2 TG on pitches measuring 40 × 30 m (TG30), 40 × 50 m (TG50) and 40 × 70 m (TG70) m. Distance covered (DC); accelerations-decelerations above 1.0 m · s-2 and 2.5 m · s-2; rate of perceived exertion (RPE); maximal heart rate and time above 90%; DC at 18.0 to 21.0 km · h-1 (DC 18-20.9 km · h-1); DC at 21.0 to 23.9 km · h-1 (DC 21-23.9 km · h-1); DC above 24.0 km · h-1 (DC > 24 km · h-1); and peak speed and sprint profile (duration, distance and maximal speed) were measured. TG30 achieved lower DC, DC above 18 km · h-1, peak speed, sprint distance and RPE than TG50 and TG70 (p < 0.01 and p < 0.05) and lower sprint duration and maximal speed sprint than TG70 (p < 0.01). TG30 and TG50 achieved higher Acc > 1.0 and > 2.5 m · s-2 respectively than TG70 (p < 0.05). TG70 showed greater DC above 21 km · h-1, peak speed, sprint distance and maximal speed sprint than TG50 (p < 0.01). Soccer coaches should use larger TGs to overload variables related to high speed and sprint demands during training and smaller TG formats to stimulate the accelerations of the soccer players.

Internal and External Loads of Young Elite Soccer Players during Defensive Small-Sided Games.

The aim of this study was to evaluate the effects of different time periods on the internal and external loads of soccer players during small-sided games (SSGs). Seventeen young soccer players performed a SSG of 5 vs. 5 + 5 with 2 floaters, where two teams had possession of the ball, and one had to recover it. With established periods of 30 s (SSG30), 1 min (SSG1) or 2 min (SSG2), teams participated in a defensive role for these periods of time. Total distance covered, moderate speed running distance, high speed running distance, sprint running distance, accelerations, decelerations and Player Load were monitored using global positioning systems devices. The maximal heart rate and modified training impulse were monitored using heart rate monitors. The rating of perceived exertion (RPE) was also measured. Data showed a small increase between SSG30 and SSG1 in Player Load (ES = -0.35; p < 0.01), and a small increase in high speed running (ES = -0.41; p < 0.05) and sprinting (ES = -0.47; p < 0.01) between SSG30 and SSG2. Also, SSG1 showed a small increase in sprinting (ES = -0.57; p < 0.01) and accelerations (ES = -0.37; p < 0.05) with respect to SSG2. In addition, SSG2 showed a small increase in the RPE with respect to SSG30 (ES = 0.46; p < 0.05). The results indicate that shorter defensive periods in SSGs increased high speed running, while longer defensive periods promoted greater perceived exertion. Manipulation of the duration of defensive periods in SSGs is a variable that should be considered in soccer training.

The Influence of Pitch Dimensions during Small-Sided Games to Reach Match Physical and Physiological Demands on the Youth Soccer Players.

The aims of this study were to (i) analyze the physical and physiological responses of four matches competition and (ii) to investigate the relationships among three different pitch dimensions of small-sided game (SSG) on the youth soccer players. Fifteen male U19 soccer players (age 17.3 ± 0.5 years, height 175.7 ± 5.6 cm, weight 68.5 ± 8.6 kg, playing experience 7.8 ± 1.4 years) were randomly assigned to three play areas: small (50 m2), medium (SSG-m, 150 m2) and large (SSG-l, 250 m2) area per player including goalkeeper. During the 4-week intervention, both groups performed three sets of 8 min with a passive rest period of 5 min between games. Differences in time-motion characteristics of players were measured with the Global Positioning System and assessed using a repeated measures ANOVA to compare the three game conditions and the magnitude-based inference to evaluate the pairwise comparison effects. The results showed that only the variables distance covered between 7.0-12.9 km·h-1 was not statistically significantly different among game conditions (p < 0.05; η = 0.21; small) and physiological response (i.e., hear rate of playing time spent 85-89% HRmax) also showed differences (p < 0.05; η = 0.25; small). The responses in SSG-m and SSG-l established them ass the format sizes ideal for replicating the physical responses during match competition. These findings could provide relevant information for coaches for use adequate pitch size (areas of 150 m2 and 250 m2) to reach the match-play scenarios found in match competition.

Effects of Bout Duration on Load, Sprint, and Jump Ability During a One-on-one Transition Task.

This study examined the training load on professional soccer players during transition games performed with different bout durations and their effects on speed and jump tests. Fourteen young soccer players played a transition game of different bout durations: 15 (TG15), 30 (TG30), and 60 (TG60) seconds. Total distance covered (DC), accelerations and decelerations above 1.0 and 2.5 m·s-2, rate of perceived exertion (RPE), maximal heart rate (HRmax) and above 90% (HR>90), distance covered between 18.0-20.9 km·h-1 (DC 18.0-20.9 km·h-1), 21.0-23.9 km·h-1 (DC 21.0-23.9 km·h-1), above 24.0 km·h-1 (DC>24.0 km·h-1), peak speed, sprint profile, sprint, and countermovement jump tests were recorded. TG15 obtained greater DC, DC>21.0 km·h-1, Player load, Acc>2.5 m·s-2 than TG30 and TG60 (p<0.01) and Acc<2.5 m·s-2, Dec>2.5 m·s-2 than TG60 (p<0.01). TG30 showed more HR>90 and RPE (p<0.01) than TG15, and DC, DC>18.0 km·h-1, Player load, Acc>2.5 m·s-2, Dec>2.5 m·s-2, HR>90 and RPE than TG60 (p<0.01 and<0.05). Transition games showed lower sprint and jump results after the intervention (p<0.01). Bout duration has been configured as an important constraint that influences the transition games and the performance of soccer players.

Hamstring muscle architecture and myotonometer measurements in elite professional football players with a prior strained hamstring.

The purpose of this study was to compare the fascicle length, angle pennation and mechanical properties of the biceps femoris long head (BFlh) in dominant and non-dominant limbs in previously injured and uninjured professional football players. Fifteen professional football players were recruited to participate in this study. Seven players had suffered a BFlh injury during the previous season. Myotonometry mechanical properties were measured in the proximal, common tendon and distal BFlh using MyotonPRO, and angle pennation and fascicle length were also measured. We observed significantly higher distal BFlh frequency, stiffness, decrement, relaxation and creep than in the common tendon and proximal BFlh. The previously injured players showed significantly higher frequency and stiffness, and lower relaxation and creep in the dominant BFlh than did uninjured players. There were no significant differences between the fascicle length and angle pennation in previously injured and uninjured BFlh. Myotonometric measurement provides a quick and inexpensive way to check the properties of the BFlh in professional football players. Professional football players with previous BFlh injury showed higher intrinsic tension and a poorer capacity to deform than did players with no injury to the BFlh.

Muscle Architecture, Morphology, and Mechanical and Functional Properties of Biceps Femoris Long Head in Professional Soccer Players with a Prior Healed Injured Hamstring.

OBJECTIVE: The aim of the present study was to compare the fascicle length, pennation angle, muscle thickness and stiffness of the biceps femoris long head, and eccentric hamstring strength between injured dominant limbs, injured non-dominant limbs, uninjured dominant limbs and uninjured non-dominant legs in previously injured players, and between dominant and non-dominant legs in uninjured elite soccer players. MATERIALS AND METHODS: Twenty elite soccer players participated in this study. Ultrasound imaging and MyotonPRO were used to determine the morphological and mechanical properties of the biceps femoris long head. Isokinetic and Nordic hamstring exercises were used to assess eccentric hamstring strength. RESULTS: Previously injured players showed substantially lower fascicle length and muscle thickness, and significantly higher biceps femoris long head stiffness than uninjured players, without differences between limbs. CONCLUSION: The morphological and mechanical properties of elite soccer players with hamstring injury history were different from those in uninjured players. The lack of differences between limbs showed that these values are characteristics of individual players that must be considered in the design of programs to prevent BFlh injury.

Neuromuscular characteristics of agonists and antagonists during maximal eccentric knee flexion in soccer players with a history of hamstring muscle injuries.

BACKGROUND: Muscle strain injuries (MSIs) in the hamstrings are among the most prevalent injuries in elite soccer. We aimed to examine the relation between biomechanical maladaptation in eccentric strength and neuromuscular factors separated by their time and frequency domains. METHODS: 20 elite soccer players with a previous history of unilateral MSI in the M. biceps femoris (BF) long head and 20 without MSI participated. Knee flexion torques, rate of torque development (RTD) and electromyographic signals (EMG) of the BF, the M. semitendinosus (SMT) and knee extensors were obtained during unilateral maximal eccentric knee flexions performed at slow (30°/s) and fast (120°/s) angular speeds. Root mean squares and mean power frequency (MF) was calculated. RESULTS: In the group with a history of MSI, reduced maximal eccentric flexion torque (slow eccentrics -8±11, p<0.05; fast eccentrics -18±13 N*m, p<0.05) and RTD (-33±28 N*m/s, p<0.05; -95±47 N*m/s, p<0.05) concomitantly occurred with diminished agonistic myoelectrical activities (-4±5% of MVC, p<0.05; -10±7% of MVC, p<0.05) and MFs (-24±13 Hz, p<0.05; -24±18 Hz, p<0.05) in the BF. Simultaneously, antagonistic myoelectric activity was elevated (+4±3% of MVC, p<0.05; +3±3% of MVC, p<0.05) in MSI affected legs as compared to unaffected legs for both eccentric contractions. Deficits in myoelectrical activity (r2 = 0.715, p<0.05; r2 = 0.601, p<0.05) and MF (r2 = 0.484, p<0.05; r2 = 0.622, p<0.05) correlated with deficits in maximal torque in the affected leg in the MSI group. Analysis of SMT demonstrated no significant differences. CONCLUSION: Positive relationships between neuromuscular deficits and the reduced eccentric strength profile underpin neuronal inhibition after MSI. This persistent involvement of dysfunctional synergist and antagonist neural hamstring function in strength weakness is of clinical relevance in sports medicine for prevention and rehabilitation.

Congested Period in Professional Youth Soccer Players Showed a Different High Decelerations Profile in the Group Performance and a Specific Positional Behaviour.

Present soccer demands are increasing in terms of running requirements and the number of matches until youth soccer players experience several periods of fixture congestion during the season. Currently, congested periods have not been extensively studied in this population. For this reason, this study aimed to compare the running demands of professional youth soccer players in congested periods according to their specific playing positions. Twenty youth players were grouped according to their position: Central Defenders (CD), Fullbacks (FB), Midfielders (MF), Wide Midfielders (WM) and Strikers (ST). A GPS system was used to monitor the players during the first (M1), second (M2) and third (M3) matches played during a congested period, measuring their total distance covered (TDC), DC 18.0−20.9 km·h−1, DC 21.0−23.9 km·h−1, DC > 24.0 km·h−1, number of high accelerations (>2.5 m·s−2), number of high decelerations (<2.5 m·s−2) and peak speed (km·h−1). M1, M2 and M3 showed the same TDC, DC 18.0−20.9 km·h−1, DC 21.0−23.9 km·h−1, DC > 24.0 km·h−1, number of high accelerations, and peak speed (p > 0.05). The statistical analysis showed significant differences between M1, M2 and M3 in the decelerations recorded between M1 and M3 (p < 0.05). Likewise, each position showed specific behaviours during the congested period, with all showing at least one difference in DC 18.0−20.9 km·h−1, 21.0−23.9 km·h−1 or >24.0 km·h−1 between M1, M2 and M3 (p < 0.05). In conclusion, coaches should pay attention to the fatigue produced by the number of high decelerations. Secondly, an individualized training protocol should be considered according to the running requirements of each position when youth professional soccer players are involved in a congested period.

Influence of Tactical Behaviour on Running Performance in The Three Most Successful Soccer Teams During the Competitive Season of The Spanish First Division.

The purpose of this study was to analyze the influence of tactical behavior on physical performance of the three best Spanish soccer teams. Team 1 employed a 1-4-4-2 formation with compact defence and direct attacks, Team 2 employed an indirect style of play with a 1-4-3-3 formation and Team 3 used a 1-4-3-3 formation with elaborate attacks and strong counter-attacks. 816 individual situations of 54 professional soccer players categorized as fullbacks (FB), central defenders (CD), central midfielders (MF), wide midfielders (WM), and strikers (S) were included in the analysis. Their performance was examined with a player-tracking system. The analyzed variables included total distance covered, distance covered above 14, 21 and 24 km·h-1, as well as distance covered in possession of the ball and without possession of the ball. Team 2 covered a substantially lower distance >14 km·h-1 than Team 1 and substantially lower distances >14, >21, and >25km·h-1 than Team 3. No differences in running activity were found between Teams 1 and 3. However, there were substantial differences between the specific positions of the three teams. CD in Team 1 covered the lowest distance by a substantial margin in almost all variables analysed, whereas MF travelled substantially greater distances than did other positions. WM in Team 1 covered the greatest distance >18 and >21km·h- 1, while S in Team 2 had the lowest distance covered in almost all the variables, and FB in Team 3 showed the lowest total distance covered and distance covered >14km·h-1. WM in Team 2 had the greatest distance covered in possession, while S in Team 3 had the greatest distance covered out of possession. The results indicate that different team formations and associated tactical demands have a significant influence on running performance.

Inter-limb asymmetry in youth elite soccer players: Effect of loading conditions.

The presence of inter-limb asymmetries can influence strength performance and represent an injury risk factor for team sport athletes. The present study aimed to investigate the effects of changes in resistance loads using different assessment modalities on the magnitude and the direction of inter-limb asymmetry within the same leg. Fifteen young elite soccer players from the same professional academy performed rear-foot-elevated-split-squat-test at different loading conditions (body mass with no overload, 25% of body mass, 50% of body mass 50%), isokinetic knee flexor (concentric 30°·s-1, concentric 60°·s-1, eccentric 90°·s-1) and extensor (concentric 60°·s-1, eccentric 60°·s-1). The outcomes from the agreement analyses suggested moderate level agreement between body mass vs body mass 25% (Kappa = 0.46), with no agreement or fair agreement for the other between-assessment comparison. Our results demonstrated that the magnitude and direction of within-limb strength imbalances were inconsistent when compared within the same assessment under different resistance load conditions.

Effect of ball inclusion on jump performance in soccer players: a biomechanical approach.

OBJECTIVE: In soccer, vertical jump means jumping toward a ball. Since no vertical jump test includes the ball as a reference element, the effect that the ball would have in a vertical jump test is unknown. The aim of this study was to examine the biomechanical differences between run-up vertical jump measurements without (Run-up Vertical Jump) and with ball inclusion (Heading Test). METHODS: Twelve semi- and professional soccer players were recruited. Athletes performed both jump tests in a biomechanical laboratory, where kinetic and spatiotemporal variables were collected and compared using a Student's dependent t-test for paired samples. RESULTS: Overall, players performed a different jumping strategy during the heading test compared to the run-up vertical jump, exhibiting: 1) higher horizontal velocity during initial contact (+45.3%, P ≤ .001), 2) shorter contact time, greater rate of force development, and total impulse during push-off (+27.5%, +53%, and +10.6%, respectively, P ≤ .008), 3) higher CoM horizontal and resultant velocity during take-off (+76.1% and 20.5%, respectively, P ≤ .001), 4) better vertical jump performance (+4.3%, P ≤ .0001), and 5) larger body angle rotation during landing (+63.3%, P = .006), compared to run-up vertical jump (effect size: 0.78 to 3.7). CONCLUSION: In general, soccer players display greater vertical jump heights in heading test, which highlights the importance of including an overhead ball during soccer-specific jump tests. Coaches and practitioners are encouraged to assess, and perhaps develop, the jumping ability of soccer players using a suspended ball as a specific target.

High-speed Training in a Specific Context in Soccer: Transition Games.

The aims of this study were to compare the load of three tasks designed to train features of soccer: a transition game, a small-sided game with a change of playing area, and a large-sided game. Twenty young elite players performed these tasks. Variables measured were total distance covered (DC), distance covered at 14.0-17.9 km·h-1 (DC 14.0-17.9 km·h-1), distance covered at 18.0-21 km·h-1 (DC 18-21 km·h-1), distance covered > 21 km·h-1 (DC>21 km·h-1), peak speed, accelerations and decelerations > 1.0 and > 2.5 m·s-2, player load, and rate of perceived exertion. Transition games produced greater DC 18-21 km·h-1, DC>21 km·h-1, peak speed and Acc>2.5 m·s-2 than the other drills (p<0.01) and higher DC 14-17.9 km·h-1 (p<0.01), Dec>1 m·s-2 (p<0.05) and Dec>2.5 m·s-2 (p<0.01) than the large-sided game. Both sided games produced more DC (p<0.01), Acc>1 m·s-2 (p<0.01) and player load (p<0.01 and p<0.05, respectively) than the transition game. During the small-sided game, significantly higher DC 14-17.9 km·h-1, DC 18-21 km·h-1 and DC>21 km·h-1 were recorded in comparison with the large-sided game (p<0.01). The studied parameters showed lower variation in the transition game. Coaches could use transition games to train high speed running in counter-attack contexts.