Table 4. Changes in neuromuscular performance for pre- and post-PHV boys after the 8-week jump training intervention (mean ± SD). Maturity group Treatment group Condition 20-m sprint (s) CMJ (cm) SJ (cm) RSI (mm/ms) Isokinetic strength (Nm) Pre-PHV EXP Pre 3.24 ± 0.32 21.4 ± 5.2 20.0 ± 5.3 0.53 ± 0.14 101.4 ± 21.4 Post 3.03 ± 0.32 23.7 ± 5.7 24.0 ± 6.6 0.74 ± 0.22 114.5 ± 21.7 p-value p < 0.001 p = 0.001 p < 0.001 p < 0.001 p < 0.001 Effect size 0.62 (moderate) 0.41 (small) 0.65 (moderate) 1.00 (large) 0.58 (moderate) CON Pre 3.29 ± 0.46 22.7 ± 6.3 21.5 ± 6.0 0.68 ± 0.31 106.6 ± 23.8 Post 3.24 ± 0.46 22.4 ± 6.6 21.8 ± 6.9 0.64 ± 0.25 110.5 ± 27.2 p-value p = 0.156 p = 0.491 p = 0.729 p = 0.353 p = 0.050 Effect size 0.11 (trivial) -0.05 (trivial) 0.05 (trivial) -0.14 (trivial) 0.15 (trivial) Post-PHV EXP Pre 2.99 ± 0.29 25.8 ± 5.7 25.0 ± 6.4 0.71 ± 0.25 145.7 ± 28.3 Post 2.89 ± 0.32 27.6 ± 7.0 26,4 ± 8.0 0.79 ± 0.28 159.0 ± 28.9 p-value p = 0.003 p = 0.045 p = 0.226 p = 0.059 p = 0.001 Effect size 0.32 (small) 0.28 (small) 0.20 (small) 0.30 (small) 0.46 (small) CON Pre 2.94 ± 0.46 25.7 ± 5.1 24.1 ± 6.4 0.70 ± 0.19 150.1 ± 33.4 Post 2.95 ± 0.49 25.3 ± 5.4 24.5 ± 5.1 0.71 ± 0.21 148.8 ± 33.4 P - value p = 0.843 p = 0.597 p = 0.731 p = 0.794 p = 0.812 Effect size -0.02 (trivial) -0.08 (trivial) 0.07 (trivial) 0.05 (trivial) -0.04 (trivial) PHV = peak height velocity; CMJ = countermovement jump; SJ = squat jump; RSI = reactive strength index; effects sizes are presented as Cohen’s d.