Contrast Training and Volleyball Players' Jumping Ability

The aim of the study was to compare the effects of three 10-week training interventions on vertical jump performance in volleyball players. Jump performance was assessed using the countermovement jump with arm swing (CMJ+AS) and drop jumps from heights of 20 cm (DJ20) and 60 cm (DJ60). Forty-two male volleyball athletes were recruited, of whom 38 completed the intervention protocol. Participants were assigned to one of three training groups: (i) contrast training with elastic-band assistance (G-CNT), (ii) traditional contrast training (CNT), or (iii) complex training (CTRL). The interventions lasted 10 weeks and included two training sessions per week. Pre- and post-intervention testing was performed using a Kistler 9286BA force platform. During CMJ+AS, jump height (JH), relative peak power (RPP), countermovement time (CMT), and modified reactive strength index (RSImod) were assessed. During DJ20 and DJ60, jump height (JH), relative peak power (RPP), ground contact time (CT), and reactive strength index (RSI) were assessed. Based on the smallest worthwhile change (SWC) in the tested variables, participants were categorized as positive responders, non-responders, or negative responders.

Inclusion Criteria: * Male volleyball players. * Age between 17 and 22 years. * At least 12 months of regular high-intensity resistance training experience. * At least 12 months of technical volleyball training experience. Exclusion Criteria: * Injury sustained within the 3 months preceding enrollment that could affect participation in training or testing. * Training absence exceeding 4 consecutive weeks during the previous 12 months.