Ultrasound Investigation of Dorsal Neck Muscle Deformation During a Neck Rotation Exercise.

OBJECTIVES: Neck-specific exercise can reduce neck pain and increase function, but information on how different neck muscle layers are activated during neck exercises is scarce. The aim of this study was to investigate deformation and deformation rate in 5 dorsal neck muscles and the correlation among these muscles during a loaded dynamic exercise used in clinical practice. METHODS: Deformation and deformation rate were investigated in 5 dorsal right-sided neck muscles in 20 individuals without neck pain using ultrasonography and speckle-tracking analyses. Repeated-measures analysis of variance was used to measure differences between the muscles, and correlations between neck muscles were analyzed with Kendall's tau. RESULTS: Deformation in left (contralateral) rotation showed significant differences among the muscles (P = .01), with higher deformation of the semispinalis capitis muscle compared with the trapezius muscle (P = .02). There were no significant differences among the 5 neck muscles in right (unilateral) rotation (P = .46). There were significant differences in deformation rate among muscles in both right and left rotation (P < .01). The trapezius muscles have the lowest deformation rate in right rotation (P < .01). In left rotation, the trapezius and multifidus muscles showed lower deformation rates compared with most of the other muscles (P < .03). Almost all muscles were correlated in both deformation and deformation rate. CONCLUSION: The quadruped standing loaded dynamic neck exercise seemed to activate all the investigated neck muscles, with a tendency for more activation of the semispinalis capitis.