Abstract
BACKGROUND: Forward head posture (FHP) is a common postural deviation in the sagittal plane. Despite the growing interest in FHP, research on gait biomechanics in individuals with FHP remains scarce. This study aimed to investigate gait biomechanics in FHP, with a gait performance-based craniovertebral angle (CVA) cut-off. METHODS: Forty-eight participants were included in the study, with CVA measurements used to assess head-and-neck posture. Three-dimensional kinematic and kinetic data were collected using a motion capture system during three walking trials at preferred speeds. Spatiotemporal gait parameters, joint angles, joint moments, joint powers, joint forces, center of mass (COM) trajectories, and COM-to-joint (knee and ankle) angles were analyzed. Time-series data were compared between the two groups using statistical parametric mapping to identify potential changes during the gait cycle. RESULTS: Forty-eight participants were divided into control (n = 26) and FHP (n = 22) groups based on a CVA cut-off of 44 degrees determined by K-means clustering. There were no significant differences in spatiotemporal gait parameters between the control and FHP groups. However, the FHP group exhibited significantly increased trunk flexion during the loading response and initial midstance (2.21–14.50%, p = 0.047), as well as pre-swing and initial swing phases of the gait cycle (46.45–68.86%, p = 0.039). The COM-to-knee angle was significantly reduced during mid-swing in the FHP group (71.26–87.92%, p = 0.007). Additionally, significant differences in sagittal knee joint power and longitudinal joint forces at the knee and ankle were observed in the final stages of the gait cycle (p < 0.05). No significant differences were found in COM trajectories or other gait parameters. CONCLUSION: This study identified phase-specific compensatory trunk flexion in individuals with FHP, despite preserved overall gait characteristics. A CVA cut-off of 44 degrees was proposed as a criterion for diagnosing FHP based on walking performance. These findings suggest that individuals with FHP employ specific biomechanical adaptations to maintain gait stability and underscore the importance of considering biomechanical adaptations in FHP diagnosis. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12891-025-08882-8.