Neck Angle in the Handstand Changes the Pattern of Multi-Joint Variability

This study investigated the effects of neck angle on center of mass (CM) stability and joint angle variability in the handstand. Seven experienced female gymnasts performed handstands in extended, neutral, and flexed neck angles. Kinematic data were collected using a 3D motion capture system, and variability was assessed for wrist, elbow, shoulder, hip, and neck angles and, CM position. The findings showed that the extended neck angle posture exhibited the lowest CM variability, aligning with its prevalent use in practice and competition. Regression analyses revealed that joint angle variability was significantly corelated to CM motion, with the typical extended neck angle related to shoulder, wrist, and neck angle variability contributions (33%, 23%, and 21%, respectively). In contrast, the neutral neck angle was moderately corelated to hip variability (32%), while the flexed neck angle showed a dominant reliance on neck angle variability (63%). The results show the strong role of neck angle in the postural variability of the handstand that is mediated by joint angle variability, visual information and tonic reflex support.