Erratum. Ingesting a 12% Carbohydrate-Electrolyte Beverage Before Each Half of a Soccer Match Simulation Facilitates Retention of Passing Performance and Improves High-Intensity Running Capacity in Academy Players.

This study investigated the influence of ingesting a 12% carbohydrate plus electrolyte (CHO-E) solution providing 60g of carbohydrate before each half of a 90-min soccer match simulation (SMS) protocol on skill performance, sprint speed, and high-intensity running capacity. Eighteen elite academy (age: 18 ± 2 years) soccer players ingested two 250-ml doses (pre-exercise and at halftime) of a 12% CHO-E solution or electrolyte placebo administered in a double-blind randomized cross-over design. During an indoor (artificial grass pitch) SMS, dribbling, passing, and sprint performance were assessed, and blood was drawn for glucose and lactate analysis. High-intensity running capacity was assessed following the SMS. Dribbling speed/accuracy and sprint speed remained unchanged throughout the SMS. Conversely, passing accuracy for both dominant (mean percentage difference [95% confidence interval, CI]: 9 [3, 15]) and nondominant (mean percentage difference [95% CI]: 13 [6, 20]) feet was better maintained during the SMS on CHO-E (p < .05), with passing speed better maintained in the nondominant foot (mean percentage difference [95% CI]: 5.3 [0.7, 9.9], p = .032). High-intensity running capacity was greater in CHO-E versus placebo (mean percentage difference [95% CI]: 13 [6, 20], p = .010). Capillary blood glucose concentration was higher in CHO-E than placebo at halftime (CHO-E: 5.8 ± 0.5mM vs. placebo: 4.1 ± 0.4mM, p = .001) and following the high-intensity running capacity test (CHO-E: 4.9 ± 0.4mM vs. placebo: 4.3 ± 0.4mM, p = .001). Ingesting a 12% CHO-E solution before each half of a match can aid in the maintenance of soccer-specific skill performance, particularly on the nondominant foot, and improves subsequent high-intensity running capacity.

Influence of coffeeberry extract on soccer specific skill performance during simulated soccer match-play and following fatiguing exercise in academy players.

This study aimed to: i) compare the number of decisions made in official matches between youth academy and professional soccer players and ii) compare the quality and speed of decision-making between youth academy and professional players. In experiment 1 we assessed 12 soccer matches (7 professional and 5 academy matches) through notational analysis. In experiment 2 we assessed 138 soccer players from professional (n = 42) and academy (n = 96) levels. The TacticUP® was used to assess game reading and decision-making skills. Results indicated that professional players make around 56% more decisions than youth academy players in official matches of their respective tournaments. In addition, professional players are quicker in making decisions for all match situations: with the ball (offensive phase), without the ball (offensive and defensive phases), near and distant from the ball. Based on the results, we verified that both in situ (official match) and in vitro (controlled test) situations the speed of decision-making was a distinguishing feature of performance between professional and youth academy players. Keywords: football; game reading; perceptual-cognitive skills; perceptual-motor skills; response time; talent development.

The purpose of this study was to evaluate the anthropometric, sprint, and high-intensity running profiles of English academy rugby union players by playing positions, and to investigate the relationships between anthropometric, sprint, and high-intensity running characteristics. Data were collected from 67 academy players after the off-season period and consisted of anthropometric (height, body mass, sum of 8 skinfolds [∑SF]), 40-m linear sprint (5-, 10-, 20-, and 40-m splits), the Yo-Yo intermittent recovery test level 1 (Yo-Yo IRTL-1), and the 30-15 intermittent fitness test (30-15 IFT). Forwards displayed greater stature, body mass, and ∑SF; sprint times and sprint momentum, with lower high-intensity running ability and sprint velocities than backs. Comparisons between age categories demonstrated body mass and sprint momentum to have the largest differences at consecutive age categories for forwards and backs; whereas 20-40-m sprint velocity was discriminate for forwards between under 16s, 18s, and 21s. Relationships between anthropometric, sprint velocity, momentum, and high-intensity running ability demonstrated body mass to negatively impact on sprint velocity (10 m; r = -0.34 to -0.46) and positively affect sprint momentum (e.g., 5 m; r = 0.85-0.93), with large to very large negative relationships with the Yo-Yo IRTL-1 (r = -0.65 to -0.74) and 30-15 IFT (r = -0.59 to -0.79). These findings suggest that there are distinct anthropometric, sprint, and high-intensity running ability differences between and within positions in junior rugby union players. The development of sprint and high-intensity running ability may be impacted by continued increases in body mass as there seems to be a trade-off between momentum, velocity, and the ability to complete high-intensity running.

Soccer match play and training have been documented to significantly impair players' physical function and affect their perceptual wellness, indicating the necessity of evaluating the response to mixed-content training across a soccer season (Deely et al., 2022, Front Physiol, 13, 911009; Brownstein et al., 2017, Front Physiol, 8, 831; Thomas et al., 2017, Med Sci Sports Exer, 49, 955-964). This study aimed to assess seasonal variation in physical, perceptual, and cognitive functions in response to training among professional academy soccer players, to identify whether players develop increased physical robustness or encounter greater physiological and psychological impairments due to the demanding training and match schedule. Ethical approval was granted for sixteen academy players (age: 18 ± 1 years) to undergo a range of tests at three seasonal points - early, mid, and late - at baseline, immediately post-strenuous training, and at 24, 48, and 72 h. The testing regime encompassed physical performance (countermovement jump [CMJ], ten-to-five repeated jump test [10/5 RJT]), cognitive function (Stroop task, Four-Choice Reaction Time [FCRT] test, Corsi Block Test), and perceptual responses via an adapted Short Questionnaire of Fatigue (SQF). Linear mixed modelling (LMM) was employed to analyse the impact of season phase and testing time-points on training response, incorporating testing measures as dependent variables. Jump performance varied across time-points, with performance maintained immediately post-training, although displaying decrements at 24 h (P &lt; 0.001), 48 h (P &lt; 0.01), and remained unresolved at 72 h (P &lt; 0.05). Season phase exerted a fixed effect on physical function, with vertical jumps decreasing from both early- (P = 0.033, CMJ; P &lt; 0.001, 10/5 RJT) and mid-season (P &lt; 0.001, CMJ; P &lt; 0.001, 10/5 RJT) to late-season. Perceptual measures—soreness, fatigue, and readiness to train—varied across the week, with immediate post-session impairments recovering by 48 and 72 hours. Cognitive function remained relatively stable across the training week, with only a decline in Corsi Block performance noted immediately post-session. An improvement in FCRT from early to mid-season was observed, though accuracy decreased from early to late-season. No interaction between season phase and training week time-points was found across any variable, indicating a consistent training response throughout the season, despite substantial impairments in physical function and declines in perceptual wellness observed post-training. The decrease in physical function during the late-season phase underscores the need for enhanced recovery focus and training load monitoring as the season progresses.

In rugby union, physical characteristics may partially contribute to long-term career progression, especially during adolescence. Therefore, the primary purpose of the study was to evaluate Italian regional rugby union academy players’ (i.e., under-18) anthropometric and physical characteristics during a competitive season. Body mass, height, upper- and lower-body maximal strength, sprint, and high-intensity running ability were assessed in 29 elite players (backs, n = 13, forwards, n = 16). A mixed-design analysis of variance (ANOVA) for repeated measures showed that backs were shorter (ES = 0.59), lighter (ES = 0.94), stronger relative to body mass (bench press; ES = 0.60; deadlift; ES = 0.63; clean ES = 0.63; rowing ES = 0.67), and fitter (shuttle run max; ES = 0.38; shuttle run tot; ES = 0.79) than forwards. However, the forwards achieved greater sprint momentum (initial sprint momentum; ES = 0.97; maximal sprint momentum; ES = 0.98). During the season, players changed in stature, upper-body maximal strength, jumping, and high intensity running (p < 0.05), but not in body weight or lower-body maximal strength (p > 0.05). Maximal strength improved in the first part of the season, whereas jumping and sprinting performances increased in the last part of the season. Therefore, these findings highlight the importance of regularly monitoring the physical development in a long-term perspective, even suggesting that physiological adaptations are heterochronic between positional roles.

Increases in physical (e.g., high-intensity running and sprinting), technical (e.g., passing rate), and tactical (e.g., player density) aspects made elite level soccer more challenging within the past years. The aim of the study was to evaluate whether these evolutions are also been reflected in changes in anthropometric and fitness characteristics between former (2002 to 2005) and current (2012 to 2015) elite Austrian youth development center (U13 to U14) and soccer academy (U15 to U18) players. A battery of anthropometric, general and soccer-specific fitness tests was conducted annually at the end of each year. Independent t-test and Cohen’s d (ES) were calculated to compare the two four-year periods (2530 vs. 2611 players) at each age group separately. Current players were significantly faster in 20 m sprint (ES = 0.26–0.50) and reaction test (ES = 0.15–0.39, except for U18), but less flexible at sit-and-reach (ES = –0.19 to –0.55), in all age categories. Whereas height (ES = 0.26–0.32), body mass (ES = 0.11–0.18) and countermovement jump (ES = 0.24–0.26) increased significantly at youth development center level, current academy players performed superior at shuttle sprint (ES = 0.21–0.59), hurdles agility run (ES = 0.24–0.49), and endurance run (ES = 0.11–0.20). These changes over time in speed, change-of-direction ability, lower-body power, coordination, and endurance were attributed to modern training approaches (e.g., modified games and change-of-direction drills) and modifications in selection politics (e.g., coaches favor speed and decision-making skills).

This study examined (1) the distances and speeds covered during match play for U11 to U16 English Premier League Academy players, (2) the differences in match performance between retained and released players and (3) the effect of calculating speed zones in different ways when analysing match performance. Eighty-one academy outfield players (10–16 years old), competing in 11-a-side matches, were analysed using a 1-Hz global positioning system with three speed zones (absolute, squad and individual). Pitch dimensions were 78.7 × 54.1 m (U11 and U12), 88.0 × 64.2 m (U13) and 100.8 × 68.2 m (U14–U16). Match durations were 20 min × 2 + 15 min × 2 or 25 min × 3 (U11), 25 min × 3 (U12 and U13) and 40 min × 2 (U14–U16). The matches were part of the regular series of inter-academy matches between Premier League Academies during a season. Completion of at least a half of the duration of a match in two separate matches (mean ± s = 3.1 ± 0.8 matches; range: 2–4 matches) was the criterion for inclusion in the study. Total match running distance increased with age from ~5700 (U11) to ~6700 m · h−1 (U15) (P < 0.01). Using the absolute speed zones, it was possible to discern differences in high-intensity (>6.0 m · s−1) distance covered with age (U11: 29 m · h−1, U16: 164 m · h−1, P < 0.01). Using the squad speed zones, it was possible to discern differences between retained and released players in the U11/U12s (moderate-speed running) and in the U15/U16s (walking, jogging and low-speed running) (P < 0.01). Thus, total and high-intensity running distances increase with age, and walking, jogging, low-speed running and moderate-speed running distances are greater in retained than in released players and these differences are best identified through the use of absolute and squad speed zones, respectively.

ABSTRACTPurpose: The powerful activity profile of elite soccer match play has not been documented appropriately to inform specific maximal power assessment and development criteria. The aims of the current study were to develop a reliable soccer-specific powerful action (SSPA) notational analysis coding system that could be used to compare frequency and durations of powerful actions during elite youth soccer match play. Methods: Sixteen elite male English Premier League (EPL) Academy players (19 ± 1 yrs) were recorded by an individual camera during 16 competitive EPL U18 and U21 games. Video footage was analyzed using performance analysis software and SSPAs were coded according to the following categories: initial acceleration, leading acceleration, sprint, unilateral jump and bilateral jump. Results: The SSPA coding system demonstrated very good inter- and intra-rater reliability (kappa coefficients ≥ 0.827). Elite youth EPL soccer players undertook significantly more initial (31 ± 9) and leading (37 ± 12) accelerations than sprints (8 ± 3; p = .014, d = 1.7, and p < .001, d = 1.7, respectively) and jumps (6 ± 5; p = .002, d = 1.7 and p < .001, d = 1.7, respectively). Players performed a significantly greater number of initial and leading accelerations with action durations below 1.5 s compared to above 1.5 s (p = .001, d = 1.6, and p = .002, d = 1.4), respectively. Conclusions: Our SSPA coding system provides a reliable observational instrument for quantifying the frequency and duration of powerful actions performed during elite soccer match play. In our sample of elite youth soccer players, horizontal accelerations of short duration (< 1.5 s) from different starting speeds appear the most dominant powerful action in elite youth soccer match play.

The aim of this study was to investigate the frequency of change of directions (COD) and examine the influences of position, leg dominance and anthropometrics on COD in elite youth soccer match play. Twenty-four elite male English Premier League (EPL) academy players (19.0 ± 1.9 years) were individually recorded during ten competitive U18s and U23s matches. Video footage of individual players was analysed using a manual notation system to record COD frequency, direction, estimated angle and recovery time. The influences of position, anthropometrics and leg dominance were accounted for. Elite youth soccer players performed on average 305 ± 50 CODs with on average 19.2 ± 3.9 seconds of recovery. Frequency of CODs were independent of position, leg dominance, anthropometry and occurred equally between left and right direction and forwards and backwards direction. CODs were mostly ≤90° (77%) and there were significantly less CODs in the 2nd half (-29, ES = 1.23, P<0.001). The average and peak within match demands within 15 and five-minute periods were 49 and 62 CODs, and 16 and 25 CODs respectively. This study is the first to illustrate COD frequencies of elite youth soccer match play, providing practitioners guidance to prepare soccer players for competitive match demands.

Pickering, C, Suraci, B, Semenova, EA, Boulygina, EA, Kostryukova, ES, Kulemin, NA, Borisov, OV, Khabibova, SA, Larin, AK, Pavlenko, AV, Lyubaeva, EV, Popov, DV, Lysenko, EA, Vepkhvadze, TF, Lednev, EM, Leońska-Duniec, A, Pająk, B, Chycki, J, Moska, W, Lulińska-Kuklik, E, Dornowski, M, Maszczyk, A, Bradley, B, Kana-ah, A, Cięszczyk, P, Generozov, EV, and Ahmetov, II. A genome-wide association study of sprint performance in elite youth football players. J Strength Cond Res 33(9): 2344-2351, 2019-Sprint speed is an important component of football performance, with teams often placing a high value on sprint and acceleration ability. The aim of this study was to undertake the first genome-wide association study to identify genetic variants associated with sprint test performance in elite youth football players and to further validate the obtained results in additional studies. Using micro-array data (600 K-1.14 M single nucleotide polymorphisms [SNPs]) of 1,206 subjects, we identified 12 SNPs with suggestive significance after passing replication criteria. The polymorphism rs55743914 located in the PTPRK gene was found as the most significant for 5-m sprint test (p = 7.7 × 10). Seven of the discovered SNPs were also associated with sprint test performance in a cohort of 126 Polish women, and 4 were associated with power athlete status in a cohort of 399 elite Russian athletes. Six SNPs were associated with muscle fiber type in a cohort of 96 Russian subjects. We also examined genotype distributions and possible associations for 16 SNPs previously linked with sprint performance. Four SNPs (AGT rs699, HSD17B14 rs7247312, IGF2 rs680, and IL6 rs1800795) were associated with sprint test performance in this cohort. In addition, the G alleles of 2 SNPs in ADRB2 (rs1042713 & rs1042714) were significantly over-represented in these players compared with British and European controls. These results suggest that there is a genetic influence on sprint test performance in footballers, and identifies some of the genetic variants that help explain this influence.

This study examined whether deep ocean mineral (DOM) supplementation improved high-intensity intermittent running capacity after short-term recovery from an initial bout of prolonged high-intensity running in thermoneutral environmental conditions. Nine healthy recreational male soccer players (age: 22 ± 1 y; stature: 181 ± 5 cm; and body mass 80 ± 11 kg) completed a graded incremental test to ascertain peak oxygen uptake (V·O2PEAK), two familiarisation trials, and two experimental trials following a double-blind, repeated measures, crossover and counterbalanced design. All trials were separated by seven days and at ambient room temperature (i.e., 20 °C). During the 2 h recovery period after the initial ~60 min running at 75% V·O2PEAK, participants were provided with 1.38 ± 0.51 L of either deep ocean mineral water (DOM) or a taste-matched placebo (PLA), both mixed with 6% sucrose. DOM increased high-intensity running capacity by ~25% compared to PLA. There were no differences between DOM and PLA for blood lactate concentration, blood glucose concentration, or urine osmolality. The minerals and trace elements within DOM, either individually or synergistically, appear to have augmented high-intensity running capacity in healthy, recreationally active male soccer players after short-term recovery from an initial bout of prolonged, high-intensity running in thermoneutral environmental conditions.

The effect of a 40-min nap opportunity was investigated during the day following a late evening simulated soccer match. Twelve male amateur soccer players (23 ± 3 years; 77.3 ± 5.3 kg; 1.76 ± 0.04 m) performed the Loughborough-intermittent-shuttle test at 21h00 and the following day they completed the sleepiness scale after either a nonap (N0) or 40-min nap (N40) opportunity that began at 14h00. At 17h00, participants performed the 5-m shuttle run test (5mSRT) (6 × 30-s with 35-s in-between; best distance (BD) and total distance (TD) were calculated). After performing the 5mSRT, they provided their rating of the perceived exertion (RPE) and rated their muscle soreness. Sleepiness scores were significantly lower in N40 in comparison with N0 (P < 0.05). A significant increase of TD (+64.5 m) and BD (+9.6 m) after N40 compared to N0 was observed (P < 0.05). The improved performance was associated with reduced levels of muscle soreness and lower RPE. In conclusion, a daytime 40-min nap opportunity after a late evening simulated soccer match improves short-term repetitive maximal performance in soccer players, and has positive effects on perception of sleepiness, muscle soreness, and RPE.

An observed relationship between soccer match duration and injury has led to research examining the changes in lower extremity mechanics and performance with fatiguing exercise. Because many fatigue protocols are designed to result in substantial muscular deficits, they may not reflect the fatigue associated with sport-specific demands that have been associated with the increasing incidence of injury as the match progresses. Thus, the aim of this study was to systematically analyze the progressive changes in lower extremity mechanics and performance during an individualized exercise protocol designed to simulate a 90-minute soccer match. Previous match analysis data were used to systematically develop a simulated soccer match exercise protocol that was individualized to the participant's fitness level. Twenty-four National Collegiate Athletic Association Division I soccer players (12 men, 12 women) participated in 2 testing sessions. In the first session, the participants completed the Yo-Yo Intermittent Recovery Test Level 1 to assess their fitness level and determine the 5 submaximal running intensities for their soccer match simulation. In the second test session, progressive changes in the rating of perceived exertion (RPE), lower extremity performance (vertical jump height, sprint speed, and cutting speed), and movement mechanics (jumping vertical stiffness and terminal landing impedance) were measured during the soccer match simulation. The average match simulation running distance was 10,165 ± 1,001 m, consistent with soccer match analysis research. Time-related increases in RPE, and decrements in sprinting, and cutting speed were observed, suggesting that fatigue increased as the simulation progressed. However, there were no time-related decreases in vertical jump height, changes in lower extremity vertical stiffness in jumping, or vertical impedance during landing. Secondary analyses indicated that the coordinative changes responsible for the maintenance of stiffness and impedance differed between the dominant and nondominant limbs. Despite an increase in RPE to near exhaustive levels, and decrements in sprint and cutting performance, the participants were able to maintain jump performance and movement mechanics. Interestingly, the coordinative changes that allowed for the maintenance of vertical stiffness and impedance varied between limbs. Thus, suggesting that unilateral training for performance and injury prevention in soccer-specific populations should be considered.

Hamstring strain injuries are a prevalent burden in soccer. Low strength, muscle fatigue, and inter-limb differences in hamstring strength are associated with hamstring injury risk. Previous research shows increased hamstring injury incidence in soccer at the end of each half or the end of the match, respectively. This study aims at evaluating the aforementioned risk factors of hamstring injury over the course of a simulated soccer match. Ten active soccer players carried out the Loughborough Intermittent Shuttle Test, during which hamstring strength of both legs was assessed on seven occasions via the optimized 90:20 Isometric Posterior Chain Test. Hamstring strength of each limb and inter-limb differences in hamstring strength over the course of the Loughborough Intermittent Shuttle Test were parameters of interest. Repeated measures ANOVA were used to analyze the development of hamstring strength and limb-asymmetries in hamstring strength during the simulated soccer match. Compared to pre-match values, hamstring strength was significantly decreased after 15 and 30 minutes of simulated soccer match for the non-dominant and dominant leg, respectively. There were no further variations in hamstring strength within the simulated soccer match for either leg. We did neither measure significant recovery of hamstring strength to pre-match values at the beginning of the second half, as suspected by previous research, nor inter-limb differences, or a deterioration of limb asymmetries in hamstring strength during the simulated soccer match. Players who only participate for a short period in a soccer match may be exposed to the same risk of suffering hamstring injury like players who compete for a longer duration. Decreasing hamstring strength partly depicts the pattern of hamstring injury incidences during soccer matches. Additional factors may influence the increasing hamstring injury rate at the end of each half or the later stages of a match, respectively.