The Health Assessment Questionnaire evaluates the functionality of the individual using eight parameters and 20 items. The parameters are classified as dressing, standing, eating, walking, hygiene, reaching, grasping, and other activities. Each item is scored as 0 (without any difficulty), 1 (with some difficulty), 2 (with a lot of difficulty), and 3 (unable to do at all). The total score is between 0-3, with a high score indicating low functionality.

Ten questions assess the quality of life-related to dermatological findings. The first and second questions are about symptoms and feelings, the third and fourth questions are about daily activities, the fifth and sixth questions are about leisure time activities, the seventh question is about work and school, the eighth and ninth questions are about interpersonal relationships and the tenth question is about treatment. The items are scored as 3 (quite a lot), 2 (very much), 1 (slightly), 0 (not at all), 0 (not relevant) between 0-30. A high score indicates a decrease in quality of life.

Muscle strength will be measured with a hand dynamometer (Lafayette Instrument®, Lafayette, IN) routinely used in the rheumatological rehabilitation unit. The dynamometer allows maximal isometric strength to be measured objectively and reliably using a standardized protocol. High values indicate a high strength value. In our study, deltoid, biceps, wrist extensors, quadriceps, gluteus maximus, gluteus medius, ankle dorsiflexion, and neck flexors isometric muscle strength values will be measured with a hand dynamometer in the appropriate evaluation position for each muscle. For each position, three measurements (3 seconds of contraction, 30 seconds of rest) will be made, and mean values will be calculated.

The balance status of the individual is evaluated by getting up from a back-supported chair and walking 3 meters at a normal walking speed and returning to the chair and the time of sitting on the chair is measured and recorded in seconds.

To evaluate lower extremity strength, the individual stands upright on a chair with his/her arms crossed on his/her chest and then sits down again. The individual is asked to repeat at his/her own pace for 30 seconds. The score of this assessment test is the number of times the individual stands up fully from a sitting position with arms crossed within 30 seconds.

The individual is asked to walk quickly without running on a 10-metre path. It is recorded in seconds in the evaluation made with three repetitions.

Quality of life is a 36-item generic scale that assesses the quality of life with eight parameters (physical functioning, social functioning, role limitations due to physical complaints, role limitations due to emotional problems, mental health, energy-vitality, bodily pain (BP), general health perception), each parameter is scored between 0-100. A high score indicates a good quality of life.

The individual diagnosed with myositis will asked to show the pain, fatigue, and disease activity status in the last week on a 10 cm long Visual Analogue Scale (VAS). A high score shows worse pain, fatigue, and disease activity status.

The Manual Muscle Test-8 (MMT-8) is one of the most popular instruments for measuring muscle strength. It is a shorter version of the original instrument in which the individual^s eight dominant proximal, distal, and axial muscle groups are tested unilaterally. Each muscle group examined is scored from 0-10 (0 = extreme weakness and 10 = normal strength) depending on how much it can move against gravity or pressure applied by the examiner.

To measure the individual^s lower extremity strength and dynamic balance, the time to ascend and descend a 10-step staircase with a handrail in the range of 16-20 cm as fast as possible is recorded in seconds.