We analyze the correlation between the change in activity counts from baseline to 48-week and the change in Brooke scale score from baseline to 48-week. The grades on the Brooke scale range from 1 to 6; 1 means that the patient is able to start with arms at the sides and can abduct the arms in a full circle until they touch above the head, while 6 means that they are unable to raise their hands to their mouth and have no useful function of the hands.

We analyze the correlation between the change in activity counts from baseline to 48-week and the change in 6MWT results from baseline to 48-week. The 6MWT assesses distance walked over 6 minutes.

We analyze the correlation between the change in activity counts from baseline to 48-week and the change in NSAA scores from baseline to 48-week. The NSAA is a 17-item rating scale that is used to measure functional motor abilities in ambulant children with Duchenne Muscular Dystrophy (DMD). It includes several items assessing abilities that are necessary to remain functionally ambulant, items assessing abilities, such as head raise and standing on heels that can be partly present in the early stages of the disease and a number of activities such as hopping.

Each item can be scored on a 3 point scale using simple criteria: 2 -Normal achieves goal without any assistance; 1 -Modified method but achieves goal independent of physical assistance from another person; 0 -Unable to achieve independently.

A total score can be achieved by summing the scores for all the individual items. The score can range from 0, if all the activities are failed, to 34, if all the activities are achieved.

We analyze the correlation between the change in activity counts from baseline to 48-week and the change in PUL scores from baseline to 48-week.

The PUL includes 22 items with an entry item to define the starting functional level (which corresponds to the Brooke scale) and 21 items subdivided into shoulder level (4 items), elbow level (9 items), and distal (i.e., wrist and fingers) level (8 items). For weaker patients, a low score on the entry item (i.e., less than 4 point of Item A) means that shoulder-level items do not need to be performed. Each dimension can be scored separately with a maximum score of 16 for the shoulder level, 34 for the elbow level, and 24 for the distal level. A total score can be achieved by adding the three-level scores, with a maximum global score of 74 points.

We analyze the correlation between the change in activity counts from baseline to 48-week and the change in mobility and self-care domain scores of PEDI-CAT from baseline to 48-week.

Te PEDI-CAT incorporates a computer-adaptive platform with 276 items based on parental or caregiver reporting, and has four domains that cover daily activities, mobility, social/cognitive function, and responsibility. The PEDI-CAT yields a single score scaled from 0 to 100 for both Mobility and Self-care, with higher scores indicating greater function.

We analyze the correlation between the change in activity counts from baseline to 48-week and the change in EQ-5D from baseline to 48-week.

EuroQol EQ-5D is a preference-based HRQOL measurement tool for the five dimensions of 'exercise ability', 'self-management', 'daily activity', 'pain/discomfort', and 'anxiety/depression' in terms of 'no problem', 'somewhat Evaluated on three levels of 'having a problem' and 'having a serious problem', and the overall level was evaluated on a thermometer-shaped 20 cm vertical visual analogue scale with 0 points for the lowest health and 100 points for the highest health status.

We analyze the correlation between the change in activity counts from baseline to 48-week and the change in EQ-5D from baseline to 48-week.

The Child Health Questionnaire - Parent form 50 (CHQ-PF50) consists of 50 questions and 12 scales (Physical function, Role/social limitations-physical, Role/social limitations-emotional/ behavioral, Mental health, Self-esteem, Behavior, Bodily pain/discomfort, General health perceptions, Family activities, Parent impact on time, Parent emotional impact) and 2 global items (Global behavior and global general health), 2 summary scores (Physical and a psychosocial summary scores) is a tool to evaluate the quality of life of children. The raw score is converted into a converted score between 0-100, and the higher the score, the better the quality of life.

We analyze the correlation between change in activity from baseline to 48-week and the change in quantitative muscle ultrasonography from baseline to 48-week. We will measure the echogenicity of the muscles at 12 sites including deltoid, biceps brachii, wrist/finger flexors, rectus femoris, tibialis anterior, medial gastrocnemius, masseter, sternocleidomastoid, geniohyoid and diaphragm. The average gray scale of above muscles will be analyzed with ImageJ software (https://imagej.nih.gov).

We analyze the correlation between change in activity from baseline to 48-week and the change in DMD upper limb PROM from baseline to 48-week. DMD upper limb PROM is a patient reported outcome measure designed to assess upper extremity performance in daily life. It includes 32 items and each item will be scored on a 3 point scale: 2-can do task easily; 1-can do tast with difficulty; 0-impossible without help. A total score is the summation of the scores for all individual items. The score can range from 0 to 64.

We analyze the correlation between change in activity from baseline to 48-week and the change in pulmonary function test from baseline to 48-week. Maximal inspiratory pressure and maximal expiratory pressure will be measured with spirometry (Spirovis, Cosmed Srl, Rome, Italy).