Is the clinical cervical extensor endurance test capable of differentiating the local and global muscles?

The findings showed higher levels of global muscle fatigability and smaller size of deep neck extensor muscles in CNP patients. Disability and extensor endurance were found to be associated with extensor muscle size. The results challenge the validity of the clinical extensor muscle endurance test in the differentiation of the deep and superficial extensor muscle endurance and the use of US in the assessment of cervical muscle endurance. Further investigations are needed to judge the superficial and deep muscle endurance in CNP patients.