TY  -  JOUR
AU  -  Shen, Boyu
AU  -  Kim, Youngsuk
AU  -  Meng, Xiangwei
AU  -  Kim, Sukwon
AU  -  Zhu, Bin
T1  -  Distance scaling in volleyball overhead passing: evidence of motor-module reweighting and motor-primitive gain modulation
PY  -  2026
Y1  -  2026-01-01
DO  -  10.1728/4733.47494
JO  -  Medicina dello Sport
JA  -  Med Sport
VL  -  79
IS  -  1
SP  -  31
EP  -  49
PB  -  Il Pensiero Scientifico Editore
SN  -  1827-1863
Y2  -  2026/06/30
UR  -  http://dx.doi.org/10.1728/4733.47494
N2  -  Summary. Aim. This study examined how volleyball players scale overhead passing distance by modulating muscle synergy structure. Methods. Twenty-four experienced, right-hand–dominant male volleyball players performed overhead passes to targets at 2.5, 5.0, and 7.5 m. Surface electromyography was recorded from 11 upper-limb, trunk, and lower-limb muscles. Muscle synergies were extracted using non-negative matrix factorization. Motor modules were defined as muscle-weighting patterns, whereas motor primitives were defined as the corresponding time-varying activation profiles. Module similarity was assessed using cosine similarity, and distance-dependent changes in motor primitives were evaluated using one-dimensional statistical parametric mapping. Results. Three synergies were consistently identified across all passing distances with high reconstruction quality. Increasing passing distance did not require additional synergies. Instead, longer passes were characterized by reweighting of M1–M2 toward greater lower-limb contribution, while M3 remained highly stable. Motor-primitive peak timing was largely preserved across distances, whereas activation amplitudes increased within specific time windows. Conclusion. Distance scaling in volleyball overhead passing appears to be achieved primarily through reweighting of existing motor modules and gain modulation of motor primitives rather than through recruitment of additional synergies or temporal reorganization. These findings provide a synergy-based explanation of how players increase passing distance while maintaining temporal coordination and may help coaches design distance-progressive passing drills that preserve technical consistency.
ER  -