A speckle tracking application of ultrasound to evaluate activity of multilayered cervical muscles.

OBJECTIVE To evaluate the capacity of the ultrasound-based method of speckle tracking analysis to detect changes in multilayered dorsal neck muscle activity induced by performing a lifting task. SUBJECTS Twenty-one healthy individuals. DESIGN Participants performed a loaded lifting task in 3 different postural orientations of the neck (neutral, flexed and forward head posture). Ultrasound images were recorded and speckle tracking analysis was used to quantify muscle deformation and deformation rate over 3 equal time-periods during the lifting sequence (rest, mid-lift and end-lift). RESULTS Significant main effects of postural orientation for the deformation measure (p < 0.05) and time for the deformation rate measure (p < 0.05) were observed in all dorsal muscles examined. Significant time by postural interactions for the deformation measure were observed in the trapezius, semispinalis cervicis and multifidus (p < 0.05) and in the semispinalis cervicis (p < 0.05) for the deformation rate measure. CONCLUSION Speckle tracking analysis ultrasound measurements can detect differences in multilayered muscle activity of the dorsal neck induced by postural variations during a lifting task. Findings for the deformation and the deformation rate measures suggest that they quantify a different, albeit related, mechanical event during muscle contraction in a functional task such as lifting.