The aims of this study were to investigate gastrocnemius medialis (GM) muscle properties in male academy soccer players (ASP) and age- and sex-matched control participants (CON); and to explore the relationships between GM characteristics and jump performance. Thirty-four participants (ASP, n = 22, age 18.8 ± 1.4 years, height 1.82 ± 0.08 m, mass 75.1 ± 5.9 kg; and CON, n = 12, 22.2 ± 2.9 years, 1.75 ± 0.05 m, 71.6 ± 7.4 kg) completed the following assessments: ultrasound measurements of GM anatomical cross-sectional area (ACSA), volume, muscle thickness (MT), fascicle pennation angle (θp) and fascicle length (Lf); isokinetic dynamometry measurements of isometric plantar flexion and dorsiflexion maximum voluntary torque; and unilateral and bilateral, vertical and horizontal, countermovement jumps (CMJ), and bilateral drop jumps on a force platform. θp (17.4° ± 2.5° vs. 14.3° ± 1.2°, P < 0.001); unilateral horizontal CMJ peak power (30.14 ± 3.53 vs. 23.18 ± 3.72 W kg− 1); and projectile range during unilateral (104 ± 16 vs. 89 ± 12 cm, P = 0.006) and bilateral (140 ± 14 vs. 129 ± 14 cm, P = 0.041) horizontal CMJ were greater in ASP vs. CON. In ASP alone, Lf correlated inversely with vertical CMJ performance but positively with horizontal CMJ performance (R2 ≥ 0.200, P ≤ 0.042). Conversely, θp correlated positively with vertical CMJ performance but inversely with horizontal CMJ performance (R2 ≥ 0.194, P ≤ 0.044). In CON only, ACSA, MT, volume and Lf all correlated inversely with vertical CMJ performance (R2 ≥ 0.366, P ≤ 0.037). The opposing θp and Lf correlations with vertical and horizontal CMJ jump performance in ASP suggest GM architecture influences CMJ performance in a direction-specific manner in this population, while the different correlation patterns between ASP and CON suggest that GM architecture contributes to CMJ performance differently in these two populations.

Player transitions in football are critical for talent development and involve players transitioning to more experienced squads. While transitions provide many positive developmental opportunities for players, the increase in workload, demands, and pressures can potentially cause injury or wellbeing issues. Despite this, they remain an under-investigated area in football and there is limited knowledge on how best the transition process can be managed to prevent adverse outcomes. The aim of this study was to develop a network-based model of player transitions between squads within a professional English football club, through the lens of Distributed Situation Awareness (DSA). The Event Analysis of Systemic Teamwork (EAST) framework was applied to describe and understand the interaction between transition tasks, performance staff, and required information during player transitions. Group model building, and semi-structured interviews with club performance staff were used to develop the EAST analyses. The findings demonstrate the complexity of player transitions, through the interaction of numerous tasks, performance staff, and required information sharing. Negative transition outcomes may result from failures in DSA during fast-paced, reactive situations where information sharing and error recovery are limited. Further, heavy reliance on key individuals, as well as limited involvement of the first team coaches in the transition process may be associated with potentially negative outcomes. The current findings will guide clubs in developing processes to reduce transition-related injuries and wellbeing issues and to increase positive outcomes for players and clubs.

BACKGROUND:Elite adolescent footballers experience periods of rapid growth and maturation alongside their intense training programs. Therefore, their nutritional habits should reflect this and be tailored to support healthy growth and recovery [1]. Research has shown that U12/13 and U15 footballers within Category One Academy require approximately 2859 ± 265 kcal.d (range 2275-3903 kcal.d) and 3029 ± 262 kcal.d (range 2738-3726 kcal.d), respectively, to fuel their training programs [2]. Food choices can be influenced by a range of physiological, psychological, and social factors, with nutrition knowledge being recognized as an important determinant of nutritional adherence among elite adolescent footballers. However, an ongoing limitation regarding assessing nutrition knowledge is the availability of high-quality, valid procedures, as well as a lack of specificity for certain sports and cohorts. Therefore, the aim of this study was to develop and validate a nutrition knowledge tool, which is based on the most recent football/youth nutrition guidelines, for use with English football academies. METHODS:Recruitment of participants involved three different cohorts: (1) an expert panel for the initial item development of the questionnaire via modifying a previously validated tool, the A-NSKQ, (2) an adolescent football player cohort in which much of the analysis would be conducted, and (3) a university student cohort to provide a construct validity comparison. A robust methodology was followed, incorporating content and face validity and item analysis with techniques from classical test theory (CTT). Content validity involved recruiting experts from the industry (nutrition/sport science/academia) to review the initial items and provide objective feedback via a content validity index (CVI) score. Once this was complete, a sample of the adolescent cohort the tool was intended for was recruited to complete the questionnaire and provide live feedback on readability (face validity). Finally, both the full adolescent cohorts completed the questionnaire (n = 66), alongside a cohort of university-educated students (n = 109), to prove the construct validity of the tool. RESULTS:The resulting tool has 32 items, split across two subsections: general nutrition knowledge (GNK) and sport nutrition knowledge (SNK), and takes around eight minutes to complete. Content and face validity were confirmed by field experts and a sample of participants from whom the tool was intended, respectively. Modifications to the items were made due to the findings of the difficulty index, distractor utility and discrimination index. Evidence of construct validity was examined for the tool by comparing the results from nutrition-educated participants (63 ± 10%) vs non-nutrition-educated participants (52 ± 11%) (p = < 0.001). The test-retest reliability of the tool was confirmed, with a strong correlation (r = 0.77, p = < 0.001) between the individual scores of the adolescent footballers on the two attempts of the test, approximately three weeks apart. CONCLUSION:The final version of the tool presents a valid and reliable tool, specific to the sport of football, that practitioners can use to measure the effectiveness of nutrition curriculums within English football academies.

Mechanical properties of the deep muscle fascia are important in myofascial force transmission and injury; however, its investigation by shear wave elastography (SWE) in the literature is minimal. Regional differences in biarticular muscle stiffness have implications in mechanism of injury. To determine region-specific differences in rectus femoris (RF) fascia and muscle stiffness, 20 healthy participants completed two visits in which RF fascia (FAS) and superficial (SUP) and deep (DEEP) muscle regions were assessed by SWE in three muscle regions (proximal - PROX, medial - MED and distal - DIST) and at three muscle lengths (relaxed - REL, neutral - NEU and passively stretched - PAST). DEEP was consistently stiffer than SUP muscle tissue (all p < 0.01) in all conditions and regions, except for REL PROX. Regional differences in SWV in all of FAS, SUP and DEEP were dependent upon local strain. Hip extension increased proximal tissue stiffness above medial and distal regions (all p < 0.001) and conditions of hip flexion (p < 0.001, p = 0.004 and p = 0.002, respectively). Similarly, knee flexion increased distal tissue stiffness above conditions of knee extension (all p < 0.001). Stretching the muscle by hip extension and knee flexion (PAST) removed differences between the regions in FAS, SUP and DEEP and increased medial SWV above REL and NEU (all p < 0.001). These results provide novel insight into regional differences in biarticular muscle and fascial tissue stiffness, implying that local strain increases stiffness in the adjacent region. These findings may have implications in force generation and region-specific mechanisms of injury.

The adaptive response to football is a complex physiological process that occurs across various levels of biological of organisation as a system attempts to adapt to training and match stimuli both acutely and chronically. Despite extensive research on football training adaptations, no systematic mapping exists of the measurement approaches used across different biological levels, creating gaps in our understanding of how researchers operationalise and study adaptive processes in this complex sport. A scoping review per PRISMA-ScR was conducted. Eligible studies included peer-reviewed articles assessing acute and chronic physiological, neuromuscular, biomechanical, or physical performance responses to training interventions and match play in healthy, uninjured male football players (professional, semi-professional, youth, university levels) using pre-post measurements. SportDiscus, PubMed, Web of Science Core Collection, and Scopus were searched to June 19, 2025. Three reviewers independently screened titles, abstracts, and full texts against eligibility criteria. 472 studies met inclusion criteria. Study outcome measures were extracted and categorised by biological level. Of 472 studies, 217 (46%) measured at a single level, 146 (31%) at two levels, 84 (18%) at three levels, and 25 (5%) at four levels. Organism-level measurement was most common, appearing in 336 studies (71%). The most frequently used outcome measures at each level were countermovement jump (organism level, n = 148), lactate (cellular level, n = 75), maximal heart rate (tissue/organ level, n = 65), and VO2max (organ system level, n = 42). This review represents the first attempt to systematically map measurement approaches across cellular through organism biological levels in football adaptation research, revealing concentrated effort towards organism-level assessments with limited multi-level integration. The findings reveal where football adaptation research has focused but not yet how well those approaches capture adaptive mechanisms.

PurposeTo understand key stakeholder's perceptions of effective performance support in professional football.Methodological approachThis research utilised qualitative data captured from in-depth semi-structured interviews with senior leaders in professional football (N = 13). To help achieve the aim of the study, sporting directors (SD), head coaches, and heads of performances from England and Scotland were purposively invited to take part in the study. All interviews were reviewed and retroductive analysis was conducted to generate themes and sub-themes that helped explain the structures and mechanisms that shape the reality of the performance support environment.FindingsEffective performance support in professional football is aligned to simultaneously supporting the club's vision and head coach's approach. Additionally, it has clearly defined Key Performance Indicators (KPIs) which contribute to the delivery of the football strategy. Finally, it is delivered by practitioners with effective professional, interpersonal, and intrapersonal knowledge, and is regularly reviewed.Practical implicationsThis paper provides clarity on the requirements for effective performance support. This research provides key considerations and strategic recommendations for football leaders seeking to enhance performance departments.

Purpose: Feedback is information that is provided to aid reflection and learning and enhance future performances. Due to the increased demands of professional soccer and governance around staffing structures, the number of stakeholders delivering and receiving feedback has grown over the past 2 decades. The aim of the present study was to explore the feedback strategies used in professional men's soccer in England. Methods: One hundred thirty-nine respondents comprising coaches (n = 34), players (n = 39), and performance staff (n = 66) from the English Premier League and football leagues completed an online survey. The survey included 19 questions on giving and receiving feedback. Results: Daily verbal interactions such as conversations and informal chats were the primary source of feedback and were highly prevalent between the 3 groups (59%-80%). Feedback was delivered frequently (daily/weekly) by all stakeholders at regular time points (before, during, and after training and matches), with >75% of coaches reporting giving feedback at all time points. Two-way feedback was also prevalent, with >76% of participants delivering or receiving feedback 2 ways. Conclusions: The data highlighted the importance of verbal communication within the process of optimizing professional soccer players' development and performance. Professional soccer clubs should focus on interpersonal and intrapersonal skill development and an approach that facilitates positive interactions between staff and players within the optimal environment (ie, time and space). We recommend further exploration of stakeholders' perceptions and effectiveness of feedback in influencing decision making and informing behavior change.

Tissue biomechanical properties are important for optimizing musculoskeletal performance and reducing injury risk. The MyotonPRO was developed as a simple, portable, noninvasive, and highly reliable method for the estimation of muscle stiffness. It has not, however, been comprehensively validated against shear wave elastography (SWE), a validated ultrasound-based method for assessing tissue stiffness. To assess this, 20 participants completed two visits in which rectus femoris (RF) stiffness was measured twice with the MyotonPRO device and SWE at three distinct muscle regions (proximal, medial, and distal), three muscle lengths (relaxed-REL, neutral-NEU, and passively stretched-PAST), and four depths (skin-SKIN, fascia-FAS, superficial muscle-SUP, and deep muscle-DEEP). Additionally, subcutaneous adipose tissue thickness (SAT) was recorded at each location under every condition using B-mode ultrasound imaging. When pooling the regions in REL, the MyotonPRO exhibited a weak significant negative correlation with SWE in DEEP (r = -0.27, p = 0.020), but not at SKIN, FAS, or SUP. In NEU and PAST, stiffness estimated by the MyotonPRO had a moderate positive relationship with SWE in the SKIN (r = 0.66, p < 0.001; r = 0.60, p < 0.001), but weaker relationships with deeper tissue (FAS, r = 0.26, p = 0.023; r = 0.20, p = 0.069; SUP, r = 0.24, p = 0.036; r = 0.26, p = 0.023; DEEP, r = 0.315, p = 0.008; r = 0.454, p < 0.001, respectively). Stiffness measured by the MyotonPRO exhibited significant moderate-to-strong negative correlations with SAT in every region under every condition, except for medially in REL. These results suggest that the two methods cannot be used interchangeably to estimate the stiffness of the RF muscle.

Morgan, OJ, Drust, B, Ade, JD, and Robinson, MA. Change of direction density: A novel consideration of consecutive changes of direction in elite youth soccer. J Strength Cond Res 39(8): e1010-e1016, 2025-This study aimed to characterize change of directions (CODs) based on density (number of CODs within 10 seconds), locomotor activity (walk, jog, stride, and sprint), and movement direction pre- and post-COD (forwards, sideways, and backwards), relative to playing position. In total, 24 elite male English Premier League academy soccer players (mean +/- SD; age: 19.0 +/- 1.9 years, height: 179.9 +/- 7.0 cm and body mass: 71.9 +/- 6.4 kg) were individually filmed during 10 competitive matches. In total, 7,399 CODs were observed. Level of significance was p <= 0.05. An average of 84 +/- 23 multiple COD events per player, per game occurred with no significant difference between position. Six CODs within 10 seconds were the average maximum density across positions (1.4 +/- 1.2), with 9 CODs within 10 seconds being the maximum observed. Overall, 94% of multiple COD events were 2, 3, and 4 CODs within 10 seconds collectively, and were each performed significantly more than all other density categories (5-9 CODs in 10 seconds) (p < 0.001). Jogging and striding pre- and post-COD were the most common locomotor activities (p < 0.05). Change of directions were rarely surrounded by sprinting (1.4 +/- 1.4) with <1% of total CODs with a sprint (pre and post) with approximately half of CODs (53%) occurring in a forward movement pre- and post-COD. Change of directions seem to be performed as multiple events, in multiple directions, at mostly submaximal locomotor activities, with some positional differences for movement direction and locomotor activity pre- and post-COD. These data provide valuable guidance for practitioners for testing, conditioning, and rehabilitating soccer players.

Shear wave elastography (SWE) is a reliable method of estimating stiffness of superficial rectus femoris (RF) muscle at various muscle lengths. Its reliability has not been assessed in deeper muscle regions or its overlying fascia and skin tissue. 20 healthy participants completed two visits in which RF shear wave velocity (SWV) was measured twice, separated by 30mins, at four depths (skin-SKIN, fascia-FAS, superficial muscle-SUP, and deep muscle-DEEP) in three positions (relaxed-REL, neutral-NEU, and stretched-STR). Relative reliability was determined by intraclass correlation coefficients and absolute reliability was assessed by standard error and bias of measurements. SWE reported poor to good relative intra-day reliability (ICC, 0.33-0.82) but good to excellent absolute intra-day reliability (SEM, 0.14-0.25 m/s; bias, -0.12-0.07). Relative SWE inter-day reliability was moderate to excellent (ICC, 0.54-0.91) and absolute reliability was good to excellent (SEM, 0.12-0.21 m/s; bias, -0.05-0.06). Reliability was highest in the order of STR, NEU, REL with regards to position, with SKIN and FAS reliability greater than in muscle. SUP measurements reported greater reliability than DEEP. Therefore, SWE is a reliable method of estimating SKIN, FAS, SUP and DEEP RF tissue stiffness. To optimise repeatability, measurements should be taken from stretched superficial tissue.

The aims of this study were to investigate (i) differences in gastrocnemius medialis (GM) tendon properties between adult male soccer players from an English category one academy (ASP) and male control participants (CON); and (ii) the relationships between GM tendon properties and jump performance. The GM tendon force–elongation relationship was measured in 13 ASP (mean ± SD height 1.81 ± 0.07 m; mass 73.6 ± 5.4 kg; age 18.8 ± 1.2 years) and 11 CON (1.74 ± 0.05 m; 71.2 ± 7.6 kg; 22.3 ± 3.0 years) using a combination of dynamometry, ultrasonography and electromyography. Participants also performed a series of unilateral and bilateral countermovement jumps (CMJ) and bilateral drop jumps on a force platform. GM tendon properties did not differ between groups but maximal tendon elongation correlated inversely with unilateral vertical CMJ peak power ( r = −0.427, P = 0.037). Furthermore, leg stiffness and peak force during a drop jump correlated with GM tendon stiffness ( r = 0.431–0.462, P = 0.035–0.023), maximal tendon force and Achilles tendon CSA ( r = 0.409–0.737, P ≤ 0.047). These results suggest that GM tendon properties do not differ between ASP and CON but a stiffer GM tendon may facilitate the production of larger forces to increase power output during a unilateral vertical CMJ. Furthermore, higher force and stiffness outputs are achieved during a drop jump by stronger individuals with larger and stiffer GM tendons, which could lead to greater pitch-based performance and may represent a protective mechanism to shield the tendon against injury.

The present study seeks to identify neural correlates of high performance in ecological valid, sporting tasks and quantify the differences between high skilled and low skilled players. To do this, Esports is chosen to be the sporting model to facilitate clean brain activity recordings whilst playing sport, something that is considerably more challenging with traditional sports. Participants are first separated into a skilled or unskilled group based on their Esports performance using objective classification measures to identify the presence of a higher and lower performing groups. Their brain activity is then recorded as they complete a visuomotor psychophysics task and Esports aim-training tasks. The first task requires discrete movements, the second sequential movements. Results indicate that there are several key differences in the brain activity of skilled players that facilitate a higher level of performance. Firstly, skilled players display enhanced response in time-domain activity of occipital parietal electrodes, displaying significantly higher p100 amplitude (sensor-space) and higher p300 amplitude (source-space). Peak decoding using MVPA, classifying brain activity between skilled or unskilled players, is achieved during the first 300ms of the response. Furthermore, skilled players modulate visual attention, gated by alpha oscillations, to release the visual system before target onset. As a result, visual information is consciously accessed more readily to be utilized for a motor response. Skilled players show an increase in frontal-midline theta during Esports performance facilitating management of cognitive load and repeated execution of precise movements. Due to the nature of the model, applied implications are suggested for both coaches and athletes of all sports to utilize this research. Specifically, performance improvement of players could be facilitated by identifying deficits in their brain activity and talent identification, by observing the neural correlates reported in developing players. Future research should focus on adapting evoked, rather than induced brain activity recording during Esports competition. ### Competing Interest Statement The authors have declared no competing interest.

Purpose: Global navigation satellite system device-derived metrics are commonly represented by discrete zones with intensity often measured by standardizing volume to per-minute of activity duration. This approach is sensitive to imprecision in duration measurement and can lead to highly variable outcomes-transforming data from zones to a gradient may overcome this problem. The purpose of this study was to critically evaluate this approach for measuring team-sport activity demands. Methods: Data were collected from 129 first-team and 73 academy matches from a Scottish Premiership football club. Gradients were calculated for velocity, acceleration, and deceleration zones, along with per-minute values for several commonly used metrics. Means and 95% CIs were calculated for playing level, as well as first-team positional groups. Within-subject coefficients of variation were also calculated for match level, position, and individual groups. Results: The gradient approach showed consistency with per-minute metrics when measuring playing level and position groups. With coefficients of variation of 10.8% to 26.9%, the gradients demonstrated lower variability than most per-minute variables, which ranged from 10.7% to 84.5%. Conclusions: Gradients are a potentially useful way of describing intensity in team sports and compare favorably to existing intensity variables in their ability to distinguish between match types and position groups, providing evidence that gradient variables can be used to monitor match and training intensity in team sports.

This study investigated the extent of injury incidence and burden in a professional women football team of the Scottish Women's Premier League during two seasons. All injuries causing time-loss or required medical attention were recorded prospectively. A total of 671 injuries, 570 requiring medical attention and 101 causing time-loss were recorded in 41 players. Injuries occurring with National Team resulted in 12% of the club's international players' lay-off. Overall injury incidence was 11.1/1000-hours and burden was 368.9 days/1000-hours. Injury incidence (23.9/1000-hours vs 8.2/1000-hours) and burden (1049.8 days/1000-hours vs 215.1 days/1000-hours) were higher for match compared to training. Foremost mechanism of match injury burden was indirect-contact, which was different than the non-contact predominantly observed for training injury burden. Injury incidence, burden and patterns differed between training, match and playing positions. Tailoring injury-risk reduction strategies considering context, circumstances and playing position deserve consideration to enhance player's injury resilience in professional women footballers.

Professional soccer players typically perform regular training sessions and match play for most of the yearly macrocycle with limited time focused on solely developing physical development. The COVID-19 outbreak in 2020 caused mass disruption to professional soccer but provided an opportunity for an alternative approach to training in attempt to develop professional soccer players physical fitness levels. In a non-randomised and non-controlled study, we aimed to assess the effectiveness of a 13-week remote based physical training programme on physical fitness levels in elite professional soccer players. Twenty professional soccer players undertook body composition assessments, a countermovement jump (CMJ) test, eccentric hamstring strength test and a submaximal 30–15 intermittent fitness test (IFT) pre- and post-remote based training programme. Body mass (79.3 ± 6.7 vs. 80.0 ± 7.3 kg), skinfold thickness (54.1 ± 14.8 vs. 56.7 ± 15.2 mm), maximum CMJ height (38.4 ± 3.4 vs. 40.9 ± 4.1 cm), eccentric hamstring strength (1035 ± 158 vs. 1009 ± 140 n) and percentage max heart rate reached in submaximal 30–15 IFT (81.3 ± 5.2 vs. 82.3 ± 7.3%) were maintained (all P > 0.05) from pre- to post training programme, respectively. Although team-based soccer specific training load was removed, and the training programmes prescribed had an increased physical focus, fitness levels were maintained. This suggests that alternative modes of training can potentially be used in instances where team-based soccer specific training load isn’t required or is unavailable, without negatively impacting physical development.