Background and Study Aim. Body composition plays an important role in determining athletic performance in soccer. Optimal levels of muscle mass and body fat percentage are key factors that influence speed, endurance, strength and overall physical readiness. Understanding and monitoring these parameters is crucial for player development, allowing coaches to design effective training programs tailored to their individual needs.Material and Methods. This study examined the body composition profiles of 66 football players from the academy of PFC Levski Sofia, categorized into four age groups: U15, U16, U17, and second team. Measurements were taken using the InBody 230 bioelectrical impedance analyzer, which assesses key metrics such as skeletal muscle mass, body fat percentage, BMI and fat-free mass. To identify significant age-related trends, advanced statistical methods were used, including descriptive analysis, ANOVA, and regression analysis.Results. The ANOVA results validated these findings, by showing statistically significant differences between age groups (F-statistic = 1199.91, p < 0.05). These results confirmed that anthropometric indices, including weight, height, BMI, and body fat percentage, varied significantly across different age categories, highlighting the importance of customized training and nutrition strategies at each stage of development. The findings revealed a consistent increase in body weight, height and BMI with age, accompanied by a significant decrease in body fat percentage. These trends are in line with existing literature, which reinforces the importance of body composition monitoring as part of player development.Conclusions. This study underscores the importance of body composition monitoring in optimizing performance, preventing injury, and guiding individualized training programs for elite youth soccer players. Customized training and nutrition strategies are essential to ensure optimal physical development and long-term success in competitive soccer.

Aim. This research aims to analyze the success of teams in Europe's strongest club tournaments, the UEFA Champions League and the Europa League, focusing on the role of set-pieces (set plays) in goal scoring. Methods. The study covers the period from September 2022 to June 2023. Modern video processing tools were used for data collection and analysis, including Wyscout for video recording and Hudl Studio for video editing and presentation. Mathematical and statistical methods were used to process the data. A total of 372 goals from 125 Champions League matches and 381 goals from 141 Europa League matches were analyzed. Results. In the Champions League, 59 goals were scored from set-pieces, and 34 penalties were converted. In the Europa League, 67 goals were scored from set-pieces, and 35 penalties were converted. These findings highlight the critical importance of set pieces in generating scoring opportunities and determining match outcomes. Conclusions. The in-depth analysis of UEFA's elite tournaments shows that set pieces play a crucial role in modern football at the highest level. These moments provide significant scoring opportunities and influence the top table positions in European club competitions. Keywords: Soccer; set-pieces; champions league; corner-kicks; soccer goals.

Lower limb strength imbalance and inter-limb asymmetry are relevant neuromuscular screening markers in women’s football, yet data from national-champion squads in Eastern Europe remain limited. The aim of this study was to characterise lower limb isometric knee strength, hamstring-to-quadriceps (H:Q) ratios, and bilateral and unilateral squat jump (SJ) and countermovement jump (CMJ) performance, and to describe their distribution by playing position, in elite Bulgarian female football players. Nineteen players from FC NSA Sofia Women (Bulgarian Women’s Football Champions, 2024/25; age 20.9 ± 4.3 years; height 168.4 ± 4.7 cm; body mass 60.5 ± 8.0 kg; body mass index 21.3 ± 2.7 kg·m ⁻² ) were assessed on a single testing day using a handheld dynamometer (Kineo Intelligent Load) and an optical jump system (Optojump Next). Mean H:Q ratios were 0.58 ± 0.10 (left, 95% CI [0.52, 0.64]) and 0.55 ± 0.07 (right, 95% CI [0.51, 0.60]); the right-limb mean was statistically below the 0.60 reference threshold (t(13) = −2.40, p = 0.032, d = −0.64). Thirteen of fourteen assessed players (92.9%, 95% CI [68.5–98.7%]) presented at least one limb with an H:Q ratio below 0.60. Mean bilateral SJ and CMJ were both 29.2 cm, producing a near-zero elasticity index (0.99 ± 10.6%). Unilateral asymmetry exceeding 10% was observed in 52.9% of players for SJ (95% CI [31.0–73.8%]) and 35.3% for CMJ (95% CI [17.3–58.7%]). Positional profiles are reported descriptively only, given the small subgroup sizes. The findings support routine neuromuscular screening of lower limb strength balance and unilateral jump performance in elite women’s football, and indicate that conditioning programmes should address both hamstring and quadriceps capacity rather than hamstring strength in isolation.

Inter-limb asymmetry is recognized as a key factor influencing performance and injury risk in elite youth football. This study aimed to assess lower limb asymmetry in U16 players using vertical jump tests—Squat Jump (SJ) and Countermovement Jump (CMJ)—and isokinetic assessments via the Kineo Intelligent Load system. Eighteen elite U16 male players (age 15.9±0.3 years) performed SJ and CMJ tests on a contact platform, with the Elasticity Index (EI) calculated. Isokinetic tests (leg extension and curl) at 60°/s and 300°/s were conducted using Kineo. Asymmetry was determined for each variable using standard formulas, with >10% considered clinically significant. Paired t-tests and correlation analyses compared limbs and explored links between strength and jump performance. No significant group-level differences between limbs were found (p>0.05), but several players exceeded the clinical threshold, especially in hamstring strength. EI values fell within normal reference ranges (≈15–25%) and correlated moderately with isokinetic strength at certain velocities (e.g., r=0.51 for leg extension at 60°/s). Correlations between jump height and absolute strength were weak (r=-0.15 to 0.13), indicating the multifactorial nature of jump performance. Combining jump and isokinetic testing provides valuable insights into asymmetry and neuromuscular function. While no significant group-level asymmetries were observed, several players exceeded the clinical threshold, particularly in hamstring strength, highlighting the need for individualized monitoring to prevent injuries and guide performance training.

Background: The lower-limb neuromuscular profile of football match officials remains poorly characterised, and inter-limb asymmetry and the eccentric utilisation ratio (EUR) have not been examined in this population. The objective was to characterise jump-derived neuromuscular performance in male professional referees and to test the hypotheses that referees outperform assistant referees and that asymmetry prevalence is independent of competitive level. Methods: In this retrospective cross-sectional study, 125 male Bulgarian First and Second League officials (33.4 ± 6.1 years) completed squat jump (SJ), countermovement jump (CMJ), and unilateral CMJ testing with an optical system. Two-way analyses of covariance (Type III) were adjusted for age and body mass, with Hedges’ g effect sizes. Results: Trial-to-trial reliability was excellent after exclusion of five technically failed trials (ICC = 0.92–0.95). Referees outperformed assistant referees in SJ (g = 0.68), CMJ (g = 0.70), and estimated relative peak power (g = 0.70; all Holm-adjusted p = 0.001). First League officials were older (36.5 vs. 30.5 years), and no league effect remained after adjustment (p ≥ 0.50). Median asymmetry was 8.5%; 46.8% of officials exceeded 10%, independent of league and role. Mean EUR was 1.01 ± 0.06. Conclusions: Officiating role, rather than competitive level, was associated with lower-limb explosive performance. Asymmetry and EUR values warrant longitudinal investigation.

Muscle strength and bilateral asymmetry of the lower limbs are relevant to injury risk and performance in football, yet their age-related development in adolescent players outside elite Western European cohorts is insufficiently described. This study determined age-related differences in lower-limb strength and muscular balance in Bulgarian male football players. A total of 122 players aged 13 to over 19 years from three clubs were assessed at the end of the competitive season. Maximal concentric knee extension and flexion peak force of both legs was measured at 60°/s using a system with electronically controlled resistance (Kineo); relative strength (force per body mass) was used for the main between-age comparisons to control for growth. Age differences were analysed with ANOVA and Tukey tests (extension) and Kruskal–Wallis with DSCF comparisons (flexion) across seven age groups. Relative strength differed significantly with age (extension η²_p = 0.28–0.36; flexion ε² = 0.43–0.49), rising most up to 16 years and then plateauing. The concentric H/Q balance index ranged from 0.48 to 0.62. The findings provide a descriptive developmental profile relevant to individualised strength programming in youth football.