Conducting Resisted Sled Sprint Load–Velocity Profiling in Female Rugby League Athletes—Reliability and Sled Load Using Velocity Decrement

Martin, A, Duhig, S, Bourne, M, Minahan, C, and Bellinger, P. Conducting resisted sled sprint load-velocity profiling in female rugby league athletes-Reliability and sled load using velocity decrement. J Strength Cond Res XX(X): 000-000, 2025-Resisted sled sprinting (RSS) is a training method used to improve short distance sprinting performance. Previous research has individualized sled loads using a 50% velocity decrement (VDEC) to achieve an optimum load (LOPT percentage of body mass [%BM]) targeting maximum power output (Pmax [W·kg-1]). However, RSS load-velocity (L-v) profiling to determine a 50% VDEC has predominantly been conducted in male cohorts. Sampling exclusively female athletes, the aims of this study are to (a) determine the interday reliability of the L-v slope and LOPT at 50% VDEC and (b) provide L-v profiling protocol recommendations for sled loading and relative trial distances. Sixteen female rugby league athletes (age: 21.29 ± 7.09 years; BM: 74.94 ± 11.42 kg; height: 1.71 ± 0.05 m) completed a minimum of 2 familiarization sessions followed by L-v testing on 2 days 7 days apart. Using the coefficient of variance (CV), an acceptable absolute interday reliability of LOPT (%BM) was found when derived from trial peak velocity (Vpeak) and trial average velocity of the maximum velocity plateau (VAVGMVP) (CV = 1.82-4.39%, CV = 1.33-5.09%). Poor to excellent or good relative reliability was determined for Vpeak (intraclass correlation coefficient [ICC3,1] = 0.73 [0.26 to 0.90]) and VAVGMVP (ICC3,1 = 0.62 [-0.12 to 0.87]). Using Vpeak (m·s-1) and VAVGMVP (m·s-1) methods, the %BM required to induce a 50% VDEC ranged from ≈59 to 72% BM and from ≈58 to 71% BM, respectively. Resisted sled sprinting L-v profiling load protocols are recommended to range between 25 and 100% BM to achieve a reliable L-v slope, while relative trial distances should range between 10 and 30 m in female field sport athletes.