Many therapeutic trials in DMD exclude non-ambulatory boys and men. Rate of progression in these non-ambulatory patients has been studied but consensus has not been reached for what measures are most reliable and reproducible. Furthermore, any treatment trial would be expected to demonstrate improved function and improvement in quality of life. Therefore, function, strength, and quality of life must be understood and standardized. While the goal of this proposal is to standardize clinical outcomes for therapeutic trials, careful understanding of the progression of DMD in non ambulatory boys may also lead to better medical treatment.