Absolute and Relative Sprint Acceleration in Female Rugby Union Players Across Age Categories and Playing Positions

ABSTRACT: Fink, B, Ordóñez-Vega, J, Uthoff, A, Floría, P, Jiménez-Lozano, M, Rodriguez-Rosell, D, and Gálvez-González, J. Absolute and relative sprint acceleration in female rugby union players across age categories and playing positions. J Strength Cond Res XX(X): 000-000, 2026-This study aimed to (a) describe the absolute and relative acceleration capacity of female rugby union players by analyzing differences across age categories (i.e., under-14 [U14], under-16 [U16], under-18 [U18], and Senior) and playing positions (i.e., backs and forwards) and (b) examine the partial relationships between sprint acceleration variables and maximum velocity (Vmax), using age as a covariate. One hundred fifty-one female rugby union players (U14: n = 35; 13 ± 0.89 years, U16: n = 33; 16 ± 0.50 years, U18: n = 33; 17 ± 0.73 years, and Seniors: n = 50; 25.36 ± 3.51 years) performed two 50-m linear sprints on a single day. Radar-derived velocity-time data were fitted to a mono-exponential model to derive Vmax and τ. The results showed that U14 backs and U14-U16 forwards displayed lower τ and higher percentage of maximum velocity at 5 m (%Vmax 5-m), 10 m (%Vmax 10-m), and 15 m (%Vmax 15-m) compared with their U18 and Senior counterparts. However, no significant differences in τ were found between playing positions in any of the age categories. Younger forwards (i.e., U14 and U16) showed higher %Vmax 5-m and 10-m, whereas backs excelled in velocity at 5 m (V5), 10 m (V10), and 15 m (V15) across all age categories (p < 0.050). Moreover, after adjusting for age, first-order partial correlations (rp) showed that τ was significantly associated with %Vmax 5-m, 10-m, and 15-m (rp = -0.61 to -0.62) and with V5, V10, and V15 (rp = 0.49 to 0.55). In conclusion, relative acceleration-related variables (i.e., τ and %Vmax 5-m, 10-m, and 15-m) provide specific and complementary information on acceleration capacity, supporting their application for performance monitoring and programming in female rugby union players.