Biomechanical Analysis of Chin Tuck Exercise with a Subject-Specific Neck Model for the Forward Headed

There are various correctional exercise methods for forward head posture (FHP) with insufficient scientific criteria for the best choices. The purpose of this research was to understand the biomechanical effect of the chin tuck exercise on FHP, focusing on the major neck extensor muscles splenii and the major flexor muscle with musculoskeletal dynamics analysis software SIMM. Subjects are divided into two groups: normal head posture (NHP) and FHP. Kinematic alignment of the cervical spine model of each subject in the FHP group was modified according to the medical images of each subject. A motion analysis system was used to obtain the trajectories of the cervical spine during the chin tuck exercise. Inverse dynamics analysis was performed for the chin tuck exercise to compare muscle forces, intervertebral joint forces, and torques between the two groups. For the FHP group, average muscle forces were approximately 33% of those of the NHP group. Average joint forces and torques of the FHP group were approximately 38.0% and 20.2% higher during protraction and 36.1% and 25.3% lower during retraction, respectively, than the NHP group. From the present analysis, the therapeutic effects of the chin tuck exercise on FHP might be inferred. This study suggests that inverse dynamics analysis with a subject-specific musculoskeletal model might be useful to estimate the correctional effects of various exercises.