Ultrasonographic measurement of neck muscle recruitment: a preliminary investigation.

Chronic cervical pain is a common source of disability in society, and evidence suggests that individuals with neck pain have impairment of the deep cervical flexor (DCF) muscles. This study investigated the recruitment pattern of the neck muscles, particularly the DCF, during the Craniocervical Flexion Test (CCFT), using ultrasound measurement of muscle activity in asymptomatic subjects. In a cross-sectional design, 10 subjects, of both sexes, with no history of neck pain participated in the study. Participants were instructed to perform the CCFT, and changes in thickness from resting baseline values during the five incremental stages of the test were obtained for DCF and sternocleidomastoid (SCM) muscles using ultrasonography. The most significant changes found in DCF thickness were between phase 1 and phases 4 (p<0.001) and 5 (p= <0.001). For SCM, differences were most significant between phases 1 and 3 (p<0.001), 4 (p<0.001), and 5 (p<0.001); and between phases 3 and 5 (p<0.003). No differences were found between DCF and SCM muscles. The present study confirms the evidence that CCFT increases DCF recruitment. However, the ultrasonography test protocol did not identify differences in recruitment between deep and superficial neck muscles. The present study confirms the evidence that the CCFT challenges the cervical spine and that DCF activity is increased during this maneuver.