Sickle cell disease (SCD) is the most frequent life-threatening genetic hemoglobinopathy in the world and occurs due to the synthesis of abnormal hemoglobin S (HbS).Cells with sickle cell hemoglobin are stiff and sticky. When they lose their oxygen, they form into the shape of a sickle or crescent. This can cause pain and tissue damage. Significant decrease in exercise capacity was seen in sickle cell anemic children. In the absence of a guidelines that can guide the prescription of exercise in SCD children. This study is a step for determine the forms of prescription of pain on the balance and muscle strength to build up in future studies a safety of physical exercises for children with sickle cell anemia and improve their functional abilities.

Sickle cell anemia is a serious life-limiting and potentially life-threatening condition that causes disruption in the lifestyle of the affected child. Pain is a common and severe symptom of sickle cell disease (SCD) and is the major reason that patients seek health care services. Some researchers supported the fact that an important impairment in balance control and muscle strength in children with sickle cell disease due to pressure pain tolerance problems and other factors. Significant decrease in exercise capacity was seen in sickle cell anemic children. The altered muscle function and balance observed in SCD children may collectively be the result of pressure pain tolerance impairment. As your physical fitness improves, your body becomes more efficient at getting oxygen into the bloodstream and transporting it to the working muscles. Along this observational correlational study design; Eighty children from both sexes will be participated in this study. Forty normal healthy children will be selected from primary governmental schools at Alexandria governorate and forty children with sickle cell anemia will be selected from Alexandria University Students Hospitals For evaluation of muscle strength hand held dynamometer (Lafayette) is one of the best methods to detect the muscle strength. It is an ergonomic hand-held device for objectively quantifying muscle strength

Inclusion Criteria:

• Age range range was 9-14 years old.
• Could follow given instructions.
• Children with Sickle cell anemia were medically stable, and take their medications regularly.
• Children with Sickle cell anemia had experience of chronic pain that lasts more than 6 months.
• All children with Sickle cell anemia have average weight, height, and body mass index based on their age percentiles.
• All normal healthy children did not participating in regular sport activities, particularly including lower limb strengthening.

Exclusion Criteria:

• Defined cardiovascular or respiratory disorders.
• Renal failure.
• Myocardial infarction, mainly within last month.
• Unstable angina.
• Recent thoracoabdominal surgery.
• Thoracic or abdominal aneurysm or current pneumothorax.
• Painful vaso-occlusive crises.
• Muscular contractures, Joints' stiffness, or deformities.
• Neuromuscular problems i.e., myositis or peripheral neuropathy.

Forty normal healthy children from primary governmental schools at Alexandria governate, and Forty children with sickle cell anemia from Alexandria University Students Hospitals.