Effects of Eight Weeks of Unilateral Complex Training on Musculoskeletal Function, Inter-Limb Strength Asymmetry, and Athletic Performance in Competitive Basketball Players

Background: Unilateral complex training has been proposed as an effective strategy to improve lower-limb neuromuscular function; however, its effects on isokinetic strength, inter-limb strength asymmetry, and athletic performance in competitive basketball players remain insufficiently investigated. This study examined the effects of an eight-week unilateral complex training program on lower-limb isokinetic strength, strength asymmetry, hamstring-to-quadriceps (H/Q) ratio, and athletic performance in young male basketball players. Methods: Twenty-nine competitive male basketball players (age: 19.14 ± 0.99 years) competing in the Turkish Basketball Youth League and U18 League were randomly assigned to an experimental group (n = 15) or a control group (n = 14). The experimental group performed unilateral complex training twice weekly for eight weeks in addition to regular basketball practice, whereas the control group continued routine basketball training only. Before and after the intervention, lower-limb isokinetic strength (60°·s−1), bilateral strength asymmetry, H/Q ratio, countermovement jump (CMJ), Abalakov jump, 20-m sprint performance, and force-platform-derived jump variables were assessed. Data were analyzed using two-way mixed-design analysis of variance. Results: Significant Group × Time interactions were observed for right and left knee flexor strength and left knee extensor strength (all p < 0.05). Bilateral quadriceps and hamstring strength asymmetries were significantly reduced by approximately 47% and 63%, respectively, accompanied by an improvement in the left H/Q ratio (p < 0.05). The intervention also produced significant improvements in CMJ height, Abalakov jump performance, flight time, time to takeoff, and 20-m sprint performance (all p < 0.05), whereas no significant interaction was found for peak force (p > 0.05). Conclusions: Adding an eight-week unilateral complex training program to regular basketball training was associated with improvements in selected lower-limb isokinetic strength and athletic performance outcomes, reductions in measured inter-limb strength asymmetry indices, and a side-specific improvement in the left H/Q ratio in competitive young male basketball players. However, because the control group did not receive an additional time- and volume-matched training stimulus, these findings should be interpreted as the effects of adding the overall training program rather than as evidence of the specific effects of its unilateral or complex components.