Inclusion Criteria:  Persons who had mild to moderate covid- 19 illness. Asymptomatic period of at least seven days (without chest pain, breathlessness). No musculoskeletal damage. No pregnancy. No visually identified asymmetries in the spinal trunk and lower limbs. None of the subjects has a history of balance training Subjects will not have any diseases of the central nervous system. Subjects with body mass index (BMI)<25 kg/m2.  Exclusion Criteria:  Persons who had more severe covid 19 illnesses and were hospitalized. Persons who had during their illness chest pain breathlessness, palpitation, symptoms, and signs of heart failure.  9. Subjects with cardiopulmonary disorders. 3. A history of previous back or abdominal surgery/injury 4. Evidence of a systemic or musculoskeletal disease within the past six months  -