Abstract
Backward running is common in handball defense and relies heavily on proprioceptive control when visual information is limited. Twenty-eight male handball players were allocated to three groups: experimental novice group with blindfold training (n = 7), control novice group with the same training without blindfold (n = 7), and target professional group (n = 14). Both novice groups completed a 6-week balance program (3 × 20 min/week). Lower-limb kinematics during backward running were captured with a 6-camera motion analysis system, and inter-joint coordination was quantified by Mean Absolute Relative Phase (MARP) and Deviation Phase (DP) for ankle-knee and knee-pelvic couplings. At baseline, professionals showed greater ankle-knee MARP than novices (ANOVA F(2,25) = 9.42, p < 0.001). Representative means (mean ± SD): ankle-knee MARP novices 1.62-1.79 vs. professionals 3.83. After training, ankle-knee MARP increased in both novice groups (experimental: t(6) = 4.72, p < 0.001; control: t(6) = 5.02, p < 0.001), approaching professional values (post-training novices ≈ 3.22-3.26). Post-training between-group differences were non-significant for ankle-knee MARP (ANOVA F(2,25) = 1.24, p = 0.30), while ankle-knee DP showed a group effect (F(2,25) = 5.12, p = 0.01; experimental vs. professional t(19) = 3.12, p = 0.01). A short-term balance program improved ankle-knee coordination during backward running in novice male players; additional blindfolding did not yield extra benefit over 6 weeks. These findings can inform short-term training and rehabilitation planning for handball, while long-term effects require future study.