LAUSR

Abstract Dello Iacono, A, Martone, D, Milic, M, and Padulo, J. Vertical- vs. horizontal-oriented drop jump training: chronic effects on explosive performances of elite handball players. J Strength Cond Res 31(4): 921–931, 2017—This study aimed to assess the chronic effects of vertical drop jump (VDJ)– and horizontal drop jump (HDJ)–based protocols on neuromuscular explosive abilities, such as jumping, sprinting, and changes of direction (COD). Eighteen elite male handball players (age 23.4 ± 4.6 years, height 192.5 ± 3.7 cm, weight 87.8 ± 7.4 kg) were assigned to either VDJ or HDJ group training twice a week for 10 weeks. Participants performed 5–8 sets × 6–10 repetitions of vertical alternate (VDJ) or horizontal alternate (HDJ) 1-leg drop jumps, landing from the top of a platform 25 cm in height. Before and after training, several performance, kinetic, and kinematic variables were assessed. The HDJ led to greater improvement of the sprint time (−8.5% vs. −4%, p ⩽ 0.05) and COD performance in comparison with the VDJ (−7.9% vs. −1.1%, p ⩽ 0.05), whereas the VDJ caused greater improvement in the vertical jump compared with the HDJ (+8.6% vs. +4.1%, p ⩽ 0.05). Moreover, the VDJ regimen compared with the HDJ induced greater changes in the kinetic variables associated with vertical jumping performance, such as peak ground reaction forces (+10.3% vs. +4.3%), relative impulse (+12.4% vs. +5.7%), leg spring stiffness (+17.6% vs. +4.6%), contact time (CT) (−10.1% vs. −1.5%), and reactive strength index (+7.2% vs. +2.1%); all comparisons with p ⩽ 0.05. Conversely, the HDJ regimen was able to improve the short-distance and COD performances by increasing the step length (+3.5% vs. +1.5% with p ⩽ 0.05) and reducing the CT on COD (−12.1% vs. −2.1% with p ⩽ 0.05) more than the VDJ. This investigation showed the crucial role that specific plyometric regimens play in optimizing similar biomechanical featured functional performances, such as jumping, sprinting, and COD.