Periarthritis of the shoulder (“frozen shoulder”) is a common disease among middle-aged and elderly people, with a high incidence in the age group of 40-60 years. According to statistics, the clinical incidence rate can reach 20.6%. As the name implies, periarthritis is an inflammatory disease that occurs around the shoulder joint and is characterized by “biceps longus tendonitis”, “rostral synostosis”, “subacromial impingement”, and “supraspinatus tendonitis”. It is a collective term for a group of periarthritis diseases such as “supraspinatus tendonitis” and “frozen shoulder”. Although the sites of these diseases vary, they all have a tendency to heal on their own. The natural course of the disease can last from 6 months to 3 years, causing great pain and inconvenience to the patient, who therefore has a very strong desire for treatment. For this type of disease, most doctors tell patients that they should actively perform functional exercises regardless of pain to avoid the loss of shoulder function in the future. However, during the exercise process, some patients may feel a lot of pain and suffering, which brings heavy psychological pressure to the patient. What is the correct way to exercise in the face of this type of disease? As mentioned earlier, frozen shoulder is a generic term for a group of diseases that occur around the shoulder joint. Although they do not all have the same location, they all have a similar pathological basis. To summarize, there are several pathological alterations based on the following factors: inflammatory factors, local microcirculatory factors, mechanical compression factors, nerve injury factors, and fibroproliferative factors. It can also be divided into three main pathological phases according to clinical symptoms: acute phase, adhesive phase, and remission phase. Acute phase: Patients usually present with progressive, diffuse shoulder pain, which may radiate to the upper arm in some patients, and this process may last for 2.5 to 9 months. The pain often worsens at night and is more pronounced when the affected side is lying down and the shoulder joint is under pressure. Treatment during this period may include oral medication or painful spot closure, topical creams to reduce local inflammation and relieve pain as well as physical therapy to improve local blood circulation. At the same time, the affected limb should be appropriately braked and placed in a comfortable position (pain-free position) to avoid excessive activities in order to shorten the duration of the acute phase. Adhesion phase: At this time, the severity of pain is significantly improved compared to the acute phase, mainly due to functional limitations in daily activities (dressing, hair combing, back scratching, etc.), and the dull pain around the shoulder can be induced when performing these movements. In this period, the treatment can be based on external medicine and physiotherapy, aiming at improving local blood circulation and complemented by gentle functional exercises. However, care should be taken not to cause significant pain when performing functional exercises, so as to avoid aggravating the condition due to excessive activities. In remission: At this time, the acute inflammation has subsided through compensatory adjustment, so the pain and muscle strength are nearly normal, but there may be residual symptoms of long-term shoulder joint movement disorders. During this period, we should pay attention to avoid overexertion of the shoulder joint and keep the shoulder joint warm, and appropriately increase the functional exercise of the shoulder joint to restore the motor function of the shoulder joint. Although frozen shoulder has a certain tendency to heal itself, negative treatment may lead to partial loss of shoulder joint function, so functional exercise is considered by most clinicians as an essential tool in the treatment phase. However, blind and incorrect exercise may aggravate the disease, prolong the course of the disease, and not achieve the desired therapeutic effect. In order to obtain better therapeutic results, functional exercises of the shoulder joint should be performed at the right time.