Effects of complex training on jump performance and neuromuscular activation in volleyball athletes: A controlled...

This study examined the integrated effects of complex training combining barbell back squats (BBS) and drop jumps (DJ) on jump performance and concentric-phase neuromuscular activation in volleyball athletes. In a randomized controlled design, twenty male volleyball athletes were allocated to an intervention group (IG, n = 10) or a control group (CG, n = 10). The IG completed an 8-week, twice-weekly complex training protocol (BBS followed by DJ), with loads progressively adjusted according to individual 1RM values, whereas the CG performed an intensity-matched BBS protocol. Primary outcomes were countermovement jump (CMJ) and approach jump (AJ) height and propulsion impulse (expressed in BW·s), while concentric-phase integrated electromyography (iEMG) and root mean square (RMS) amplitude were secondary outcomes. The results showed that, compared with the CG, the IG exhibited greater improvements in both CMJ and AJ height (CMJ: Δ = 6.13 vs 2.65 cm; AJ: Δ = 7.28 vs 2.78 cm; both p < 0.05). In addition, gains in propulsion impulse were larger in the IG (CMJ: Δ = 0.06 vs 0.02 BW·s; AJ: Δ = 0.08 vs 0.03 BW·s; both p < 0.05). Furthermore, electromyography revealed task-specific recruitment patterns: under BBS, the quadriceps and tibialis anterior showed higher iEMG and RMS values, whereas under DJ the lateral and medial heads of the gastrocnemius were more strongly activated, indicating complementary effects across key lower-limb muscle groups. Taken together, these findings indicate that an 8-week BBS-DJ complex program, compared with resistance training alone, is more effective in improving jump performance and propulsion impulse and in optimizing task-specific concentric activation patterns of the lower-limb musculature in volleyball athletes, and may serve as a feasible and evidence-based prescription for volleyball-specific conditioning.