After a period of sports injury, after a period of treatment and rest, the swelling and pain symptoms gradually disappear, and many people think that they have fully recovered, but it is not true. In the later stage of injury recovery, the function of the injured site must be strengthened without increasing pain Sexual exercise, to prevent tissue deformation or functional changes caused by long-term metabolic disorders in the injured area, only in this way can you fully recover. According to this passage, what is the correct understanding? ['After a long period of sports injury and treatment.', 'Functional exercise is an adjuvant treatment for sports injuries.', 'Late injury recovery is the best stage for functional exercise.', 'Whether the pain symptoms are sufficient to determine whether the patient is recovering.']