The main reasons for the thickening and hardening of the trapezius muscle are: bad habits, lifting heavy objects and fitness factors. 1. Bad habits: obliques become thick and hard, mostly due to the usual bad habits and posture caused by chest, hunchback, neck forward, usually often shrug the shoulders, etc., will lead to the upper trapezius muscle is overly tense, so that the obliques become thick. 2. Lifting heavy objects: engaged in heavy physical work or upper limb strength is relatively poor people, in lifting heavy objects often borrow the power of the shoulders, resulting in developed shoulder and back muscle groups, the situation is that the trapezius muscle becomes thick and hard. 3. fitness factors: like to engage in fitness exercise crowd, fitness of certain equipment and action will be targeted exercise trapezius muscle, or some action involved in the shoulder and back muscle groups, such as pull-ups to form a strong back, resulting in the trapezius muscle thickening and hardening. For muscle thickening and hardening caused by trapezius strain, you can take the method of hot compresses and physical therapy to gradually loosen the muscles.