3D ground reaction force synergy patterns in Wushu Changbing PiJi characterized by multivariate functional principal component analysis

We employ multivariate functional principal component analysis to elucidate the kinetic synergy mechanisms of Wushu Changbing PiJi, a high-lethality offensive technique characterized by a maximal-effort strike using a long staff. Altogether, 50 elite athletes performed 14 maximal-effort PiJi trials. The 3D ground reaction forces were modeled as continuous vector functions to extract synergy modes. As our main

Findings: , the analysis identified that PiJi is governed by five primary kinetic patterns, represented by the first five principal components (PCs) (cumulative explained variance: 71.2%), which reveal a hierarchical control of the movement. Specifically, the foundational level (PC1 and PC2) quantified vertical-support-dominant explosive force modulation and sequential temporal coupling, while the regulatory level (PC3, PC4, and PC5) characterized micro-strategies, including ML-dominant terminal stabilization with secondary AP braking, the lateral stability-propulsion trade-off, and vertical-AP force vector regulation with terminal ML stabilization, respectively. These

findings indicate that PiJi is governed by specific low-dimensional synergy modes. By quantifying these continuous waveform features, we successfully identified the force generation mechanisms of long weapons embedded within traditional Wushu philosophy, providing a scientific basis for establishing a modern scientific training framework, and offering a broadly applicable framework for research on complex weapon-based movements.