Chronic Neck Pain Affects Shoulder Muscle Activity and Postural Control During Functional Reach

Chronic neck pain may affect sensorimotor integration, which is critical for postural control. Accordingly, this study investigated whether individuals with chronic neck pain display altered muscle activation and postural control compared with those of healthy adults while performing functional reach tasks. Three-dimensional kinematic analyses and electromyographic analyses were performed. 20 individuals with chronic neck pain and twenty healthy adults were recruited. The reach distance, anterior displacements of the centers of mass and pressure, and activity of the cervical muscles were recorded during functional reach tasks. Compared with the healthy adults, the individuals with chronic neck pain showed significantly smaller anterior displacements of the centers of mass and pressure and reduced muscle activity of the upper trapezius muscle. However, no difference in the reach distance was observed between the two groups. It is speculated that a functional reach task may not be sensitive enough to detect changes in the postural control of individuals with chronic neck pain. For individuals with chronic neck pain, a combination of clinical measures and quantitative assessments of the centers of mass and pressure is suggested to facilitate the early detection of changes in postural control.