Children with Down syndrome often exhibit diminished physical fitness levels and lower bone mass. Numerous factors contribute to this decrease in bone mass density, including decreased levels of leptin, reduced muscle mass and strength, impaired balance, and skeletal abnormalities. These factors further exacerbate the risk of developing osteoporosis in this population. Therefore, it is crucial to prioritize interventions that focus on maximizing peak bone mass during childhood in order to enhance the quality of life for adults with Down syndrome. The study aims to compare the impact of core stability exercises and respiratory muscle strengthening exercises on bone mineral density in children with Down syndrome. Sixty Children with Down syndrome will be assessed and included in this study. The age of children will range from 10 to 13 years. Children will be allocated randomly into three groups (control and two study group A & B). The control group receives a physical therapy program, study group A receives traditional physical therapy program with core stability exercises, and study group B receives traditional physical therapy program with respiratory muscle strengthening exercises. Groups will be evaluated using dual energy X-ray absorptiometry DXA (DPX-IQ, version 4.6A). Bone mineral density (BMD) of femoral neck and lumbar spine will be determined and the mean density will be expressed as g/cm2.

Inclusion Criteria:

• Age will range from 10-13 years
• Diagnosed with Down syndrome.
• Children with the ability to understand and follow verbal commands and instructions used during training and tests
• Able to stand and walk independently

Exclusion Criteria:

• Any neurological, mobility disorders, vision or hearing loss, cardiac anomalies or musculoskeletal disorder
• With asthma or any chronic chest diseases
• With significant tightness or deformities in the lower limbs and limber spine