Background: Isometric cervical flexor system exercise (ICF) and isometric cervical extensor system exercise (ICE) are cervical stabilization techniques that have been used to restore cervical crossed syndrome (CCS)-associated forward head posture. However, the therapeutic effects and underlying motor control mechanisms remain elusive.
Purpose: The purpose of present study was investigating the concurrent therapeutic effects of ICF and ICE on muscle size, muscle imbalance ratio, and muscle recruitment sequence using ultrasound imaging and electromyography.
Methods: A total of 18 participants (7 females; age=24±4.0 years) with CCS associated with forward head posture underwent ICF and ICE. Paired t-test analysis was used for statistical analysis.
Results: Paired t-test analysis showed that sternocleidomastoid thickness was greater during ICF than ICE. Similarly, cross-sectional area and horizontal thickness of the longus colli were greater during ICE than ICF. The upper trapezius/lower trapezius muscle imbalance ratio and the pectoralis major/lower trapezius muscle imbalance ratio were significantly decreased during the application of ICE compared to ICF.
Conclusions: These results provide compelling, mechanistic evidence as to how ICE is more beneficial for the restoration of neuromuscular imbalance than ICF in individuals with CCS.
Keywords: Forward head posture; motor control; muscle imbalance; rehabilitation.