RecruitingDiagnostic testImaging Skeletal Muscle Mitochondrial OXPHOS Activity In Acute Lymphoblastic Leukemia SurvivorsThe participants are being asked to take part in this trial, because the participant is a survivor of childhood cancer or agreed to be part of a volunteer group to understand the relation between cancer and cancer treatment and muscle weakness in survivors of Acute Lymphoblastic Leukemia (ALL). ALL is cancer of the blood and bone marrow. Primary Objective • To compare muscle mtOXPHOS activity and satellite cell content among ALL survivors and controls. Secondary Objective * To evaluate the association between muscle mtOXPHOS, muscle satellite cell content and physical performance in ALL survivors. * To evaluate the association of muscle morphology and epigenetics with muscle mtOXPHOS in ALL survivors.