Relationship Between Vertical Force-Velocity Metrics and Sprinting Performance in Female Rugby Union Athletes.

Agar-Newman, DJ, Tsai, M-C, Phillips, K, Patterson, R, and Klimstra, M. Relationship between vertical force-velocity metrics and sprinting performance in female rugby union athletes. J Strength Cond Res 40(7): 769-775, 2026-Sprinting is important across field sports and research in women is deficient; therefore, the aim of this study was to investigate the relationship between gym-based vertical force-velocity profile (v-FVP) metrics and 40 m time in female rugby athletes. Data from 50 athletes, mean (± SD) age 20.30 ± 2.02 years, mass 74.86 ± 12.10 kg, height 1.69 ± 0.05, and 40 m time 6.15 ± 0.36 seconds were sampled. First, Pearson correlation coefficients were examined between 40 m time and v-FVP metrics, and second, v-FVP variables were input into a linear mixed model to examine their effect on 40 m time, accounting for individual differences (random effects). There were significant correlations (p < 0.01) between 40 m time and several v-FVP metrics, leading to the inclusion of Maximal Mechanical Power (pMax, W·kg-1) and the Slope of the Force-Velocity Relationship (SFV, N·s·m-1·kg-1) in the linear mixed model. The linear mixed model showed pMax (β = -0.09) and SFV (β = 0.02) as significant predictors (p < 0.01) of 40 m time. The model explained a substantial proportion of the variance (conditional R2 = 0.93), with fixed effects accounting for 46.79% of the variance. Correlations of the fixed effects indicated a strong negative relationship between pMax and baseline 40 m times, while SFV showed a low positive correlation with baseline 40 m times. These results suggest that practitioners using a v-FVP in their test battery should seek to improve and monitor changes in pmax and SFV for the purposes of improving sprint performance over 40 m.