This study aimed to describe the acceleration–speed (AS) profile of soccer players during competition and to analyse their seasonal changes and inter-player differences. The AS profile values (theoretical maximum acceleration (A₀) and speed (S₀)) of 14 elite soccer players were studied in 18 matches, which were divided into five season periods. The main findings showed the A₀ (6.20 ± 0.51 m/s²) and S₀ (9.18 ± 0.58 m/s) average team season values. Significant individual changes (p < 0.05 and effect size (Eta-squared, η²) > 0.5) were confirmed for A₀ (Players 4 and 8) and S₀ (Players 6, 8 and 11). Additionally, standard deviations (SD±) confirmed small (±0.20–0.60) to moderate (±0.60–1.20) seasonal variations for most players in A₀ (SD range: ±0.22 to ±0.69 m/s²) and S₀ (SD range: ±0.27 to ±0.90 m/s). SD showed small to moderate inter-player differences for each period for A₀ (SD range: ±0.39 to ±0.61 m/s²) and S₀ (SD range: ±0.53 to ±0.61 m/s). In summary, coaches are recommended to assess the AS profile to diagnose potential player seasonal changes in sprinting performance, especially for A₀, which seems to be more sensitive to variations than S₀.

Background: The study aimed to analyze the relationship between the mechanical parameters of the horizontal force–velocity profile (Hzt FV profile) and performance over two different change of direction (COD) protocols (505test and modified 505test [M505test]) to assess the influence of mechanical parameters of Hzt FV profile on COD deficit (CODD) in soccer players among different categories. Methods: Seventy-seven soccer players, divided into playing levels, participated in the following assessments: Hzt FV profile, 505test and M505test. Spearman correlation coefficient (r_s [p < 0.05]) and a linear regression model were used to determine the relationship between COD performance and mechanical parameters of sprint (maximum power output [P_max], maximum horizontal force production [F₀] and maximum velocity application [V₀]). Results: Results suggest that: (1) V0 is highly correlated with 505test [Professional (r_s = −0.682, p < 0.01); Amateurs (r_s = −0.721, p < 0.01); U18DH (r_s = −0.736, p < 0.01); U18LN (r_s = −0.569, p < 0.01)]; (2) F₀ is strongly correlated to M505test F₀—M505test [Professional (r_s = −0.468, p < 0.05); Amateurs (r_s = −0.690, p < 0.01); U18DH (r_s = −0.642, p < 0.01); U18LN (r_s = −0.658, p < 0.01)]; and (3) significant differences were observed in Professionals vs. U18LN comparison [505test (U = −37.7, p = 0.000); M505test (U = −26.9, p = 0.000)]. Conclusions: A significant relationship exists between strength levels and COD performance depending on task demands. Horizontal force (F₀) is crucial in statics COD, while high-speed force production (V₀) is decisive in dynamics COD. Finally, higher-level players demonstrate greater efficiency in COD.

This study aimed to compare maximum acceleration and speed capabilities in professional soccer players, both derived from the acceleration-speed (AS) profile (theoretical maximum acceleration [A0] and speed [S0]) and direct assessment (maximum acceleration [MaxAcc] and speed [MaxSpeed]), according to both (i) sex and the sports level, and (ii) the playing position. A total of 737 professional women and men soccer players were monitored during 5–10 official matches. Data were collected using 18-Hz GPS devices to derive AS profiles and directly measure acceleration and speed output. Across all playing levels, professional men soccer players demonstrated significantly (p < 0.01) higher values than female players for A0 (d = 1.14–1.87), S0 (d = 3.88–4.82), MaxAcc (d = 0.57–1.22), and MaxSpeed (d = 2.46–2.81). Likewise, players of higher sports levels showed superior output than their lower counterparts (First Men’s Division > Second Men’s Division > Under 20 Men’s Division; p < 0.05). Position-specific analysis revealed that midfielders had significantly (p < 0.05) lower MaxSpeed values than other positions such as full-backs (d = 0.63–1.17), wide midfielders (d = 0.82), and forwards (d = 0.67–1.06) in both the First and Second Divisions. Conversely, wide midfielders in the Under 20 Men’s Division exhibited significantly (p < 0.05) higher A0 values than central defenders (d = 0.78). These findings highlight the importance of conducting sex- and position-specific analyses of the AS profile to effectively monitor acceleration and speed capacities across different sports levels in professional soccer.