25 boys, ages ranging from 6 to 16 years, diagnosed with Duchene's muscular Dystrophy (DMD) will participated in the study. They will be selected from the Pediatric Rehabilitation Center of Deraya University's outpatient clinic in El-Minia district, Minia-Egypt. The outcome will be assessed motor performance will be assed by Bruininks-Oseretsky Test of Motor Proficiency Second Edition (BOT™-2) : balance, running speed and agility, bilateral coordination and strength and by Blue Cherry; Geratherm Respiratory. It is used to measure vital capacity (VC), forced expired volume in one second (FEV1), FEV1/FVC, FEV1/VC, and peak expiratory flow (PEF) to provide objective information for monitoring lung health.

Inclusion Criteria:

• the diagnosis is Duchene's muscular Dystrophy only not other types,
• ambulated with or without assistance,
• oriented and endurance enough to understand orders to perform ventilation on the Blue Cherry; Geratherm Respiratory device.

Exclusion Criteria:

• any cognitive or neurological condition (other than Duchene's muscular Dystrophy),
• history of previous surgical operations that can affect pulmonary functions, and structural scoliosis

25 ages ranging from 6 to 16 years, diagnosed with Duchene's muscular Dystrophy will participate in this study. They were selected from Pediatric rehabilitation center of Deraya university out-patient clinic in El-Minia district, Minia,