Effects of cervicothoracic postures on the stiffness of trapezius muscles.

The purposes of this study were to (1) examine the effects of different cervicothoracic postures on the stiffness of trapezius muscles and (2) compare the stiffness of the dominant and non-dominant trapezius muscles. Twenty-one healthy participants joined in this project. After maintaining different cervicothoracic postures for 2 min, MyotonPRO was used to measure the stiffness of the trapezius. The results showed that (1) the stiffness of trapezius muscles was significantly affected by different cervicothoracic postures. With the increase of neck flexion angle, the stiffness of the trapezius muscles increased (p < 0.05). The muscle stiffness of upper back relaxed was higher than that of upper back upright (p < 0.05). (2) The trapezius muscles on the non-dominant side were stiffer than that on the dominant side (p < 0.05). Poor cervicothoracic postures will increase the stiffness of upper, middle and lower trapezius muscles. Keeping the neck and upper back upright will keep the muscle stiffness at a low level, so as to reduce the occurrence of neck and shoulder fatigue and pain.