ECSS Paris 2023: OP-AP15
INTRODUCTION: Force-velocity profile (FVP) measures an athletes ability to generate force and speed during movements like sprints. In soccer, sprinting and change of direction (COD) are crucial for both attacking and defensive actions. These performance may vary based on player’s position (e.g., forwards, defenders and midfielders). This study examines the differences in FVP and COD parameters across different positions in a U-21 soccer players. METHODS: Fifteen professional male U21 Czech National team soccer players participated, categorized by positions: forwards (n = 5), defenders (n = 5) and midfielders (n = 5). Player performed a 40-meter linear sprint and the COD test using the 1080 Sprint system (1080 Motion AB, Sweden). FVP parameters were assessed using the linear sprint with a 3 kg isotonic resistance, analyzing theoretical maximum force (F0), theoretical maximum velocity (V0), and maximal power output (Pmax). Each player completed three trials, with best attempt used for analysis. COD performance was measured using a modified 15-0-5 protocol, assessing maximal acceleration (MaxAcc) and maximal deceleration (MaxDec). Players performed two trials for each turning direction (right and left leg), with the best attempt analyzed. Position differences were evaluated using the delta percentage (Δ%) and Cohens d effect. RESULTS: Midfielders had highest F0 (8.04 ± 0.41 N/kg), which was 5.27% greater than defenders (7.62 ± 0.34 N/kg) with a large effect (Cohen d = 1.13). Forwards presented greatest V0 (9.65 ± 0.40 m⋅s-1), 3.94% higher than defenders (9.27 ± 0.47 m⋅s-1) and 4.04% greater than midfielders (9.26 ± 0.27 m⋅s-1), with a larger effect (Cohen d = 0.86 – 1.15). In the COD test, midfielders exhibited better performance, achieving 8.10% higher MaxAcc (7.63 ± 0.74 m⋅s-2) and 7.39% higher MaxDec (9.42 ± 0.76 m⋅s-2) compared to forwards (MaxAcc = 7.06 ± 0.85 m⋅s-2, MaxDec = 8.77 ± 0.60 m⋅s-2, respectively), with moderate to large effects (Cohen d = 0.72 - 0.94). CONCLUSION: This study that U21 Czech soccer players demonstrated position-specific differences in FVP and COD performance. Midfielders demonstrated higher F0, MaxAcc and MaxDec, reflecting the importance of agility and change direction actions for it position. Forwards excelled on V0 supporting their role in making faster dashes behind the defense and exploiting spaces in the offensive phase. These findings may be valuable for developing specific training programs that focus on enhancing the parameters most relevant to each position.
Read CV Adam LipčákECSS Paris 2023: OP-AP15
INTRODUCTION: Curvilinear sprint (CS) performance is crucial in football, as a significant portion of sprints during match play occur along curved paths. Weighted sprints are commonly used to enhance performance in linear sprinting, but their application to CS remains underexplored. The addition of extra weight influences the centripetal force needed to maintain a curved trajectory, potentially affecting performance. This study aimed to assess whether additional weight during curvilinear sprints influences linear and CS performance, as well as jump performance, compared to unweighted CS training. METHODS: Eighteen female football players (age: 16.3 ± 1.2 years; body mass: 58.1 ± 7.2 kg; height: 167.1 ± 4.6 cm) participated in the study. Over two consecutive days, they performed 30-m LS, left and right unloaded CS (CSL, CSR) and loaded CS (9.15-m radius, 2 maximal repetitions, additional load: 10% of body mass), and jump tests, including squat jumps (SJ), countermovement jumps (CMJ), and drop jumps (DJ). The players were divided into two groups: one group performed CS with additional weight equivalent to 10% of their body mass, while the other group performed CS without additional weight (control group). The 6-week intervention included one session per week, with the control group sprinting 80-160 meters weekly (720 m total) and the weighted group sprinting 72-144 meters weekly (612 m total). Distance, speed, and acceleration were monitored using the GPEXE lt system (Exelio SRL, Udine, Italy). Peak speed (Speak), peak acceleration (Apeak), and acceleration-speed (AS) profiles (A0, S0, ASslope) were calculated. Additionally, jump height was calculated for SJ, CMJ, and DJ. A two-way repeated-measures ANOVA was conducted to assess the effects of time (pre- vs. post-intervention) and group (weighted vs. control), as well as the time × group interaction. Bonferroni post-hoc tests were conducted to identify specific pairwise differences. Partial eta squared (η²) was calculated to report effect sizes. The significance level was set at p<0.05. RESULTS: There were significant main effects of time for CSR Speak (F = 26.8, p = 0.0013, η² = 0.42) and CSR S0 (F = 10.2, p = 0.0152, η² = 0.22), while no significant results were observed for any other variables (all F < 5,2, all p > 0.057). Bonferroni post-hoc tests revealed significant improvements in CSR Speak for both groups, while no significant differences within groups were observed for CSR S0. However, the weighted group demonstrated a trend toward better intervention effects for CSR S0. CONCLUSION: Our results suggest that the 6-week intervention with limited training volume primarily improved CSR, the players weaker side in curvilinear sprinting, regardless of the group. Improvements observed in both groups indicate that a 10% body mass load may not provide sufficient stimulus to significantly enhance centripetal force during curvilinear sprints. A greater training volume or higher load might be required to elicit more substantial adaptations.
Read CV Darjan SmajlaECSS Paris 2023: OP-AP15
INTRODUCTION: In top-class football, lower-limb power, along with the ability to effectively utilize the stretch-shortening cycle, plays a fundamental role in profiling physical performance among both adult and young players (1). The Countermovement Jump test (CMJ) have been widely used to assess lower-limb power, with relative take-off power (Wtake-off) being a critical variable (2). Despite CMJ is globally used as a gold-standard assessment across various levels of competition and age-categories, a clear understanding of the neuromuscular capacities of high-level adult and young football players remains limited. Therefore, the current study aims to evaluate the differences in the relative Wtake-off during CMJ across different age-categories and during pre-season vs in-season periods in each category. METHODS: One hundred and thirty-one elite football players across different age categories of an Italian Serie A club were divided into the following categories: U14 (n=27), U15 (n=22), U16 (n=24), U17 (n=24), U18 (n=13) and PRO (n=21). Data were collected during pre-season (July/August 2023) and in-season period (October to March 2024). Each participant performed three maximal CMJ on force plates (ForceDecks, VALD, Brisbane, Australia) with a complete recovery between each repetition. For each participant, the CMJ with the higher relative Wtake-off (W∑kg-1) was considered for the analysis. A paired t test was used for the pre-season vs in-season comparison and a one-way ANOVA for repeated measures was utilised to determine the between age-categories difference. The magnitude of the differences was assessed using Cohenís d (d) effect size with 95% confidence intervals [95% CI]. RESULTS: The Figure 1 shows the relative Wtake-off in the CMJ during the in-season period for each age-category. For between-age comparisons the Wtake-off were higher in PRO (d = 0.79 to 1.98) compared to U14 (P < 0.001), U15 (P < 0.001), U16 (P < 0.001), U17 (P = 0.031), U18 (P = 0.017). Additionally, U14 and U15 showed lower (P < 0.05; d = -0.86 to -1.31) Wtake-off than other age-categories. As shown in Figure 2, Wtake-off during the in-season period was higher (P = 0.015) compared to the pre-season, but only for PRO (d = -0.58 [-1.03 to -0.11]). No differences were found in pre-season vs in-season for other age-categories. CONCLUSION: The Wtake-off during CMJ was higher in PRO compared to younger players (U14 to U18). As expected, U14 and U15 showed lower Wtake-off compared to older age-categories, highlighting reduced neuromuscular capacities in younger players. Coaches and football scientists may use these findings to guide neuromuscular performance development in youth elite football. PRO values could serve as benchmarks for power capacity in top-class football. Additionally, tracking the changes in Wtake-off over the season may help to optimize strength and power training, potentially accelerating individual development and facilitating the transition between youth to PRO football.
Read CV Andrea RiboliECSS Paris 2023: OP-AP15