DDAVP vs. Exercise in Patients With Mild Hemophilia A

Inclusion Criteria: * Patients ≥13 years of age and ≤21 years of age with Mild Hemophilia A (MHA), with a historical baseline FVIII:C level of ≥5% to ≤40% followed at either the Hospital for Sick Children or St. Michael's Hospital (Toronto). * Patients ≥13 years of age and ≤21 years of age with genetically confirmed Mild Hemophilia A (MHA), with FVIII:C level of ≥5% to ≤50% followed at either the Hospital for Sick Children or St. Michael's Hospital (Toronto). Exclusion Criteria: * A currently circulating or history of a previous inhibitor ( ≥0.5 BU) within the past 5 years. As inhibitor development in MHA is rare, it is not expected that any patient will be excluded for this reason. * Any FVIII infusion or DDAVP use in the preceding week. This is to avoid an residual FVIII still being present in a patient who has taken an extended half-life FVIII. * Co-existence of a congenital bleeding disorder other than MHA (e.g. VWD). * Prior history of coronary artery disease or pulmonary disease, severe arthropathy interfering with ability to exercise. * Patients on beta-blockers, anti-platelet agents or regular non-steroidal anti-inflammatory medications (e.g. Celebrex). * Patients with an active infectious or inflammatory condition. This includes HIV, active hepatitis B or C as reflected in elevated AST, ALT, RNA positivity for hepatitis B or C. * Patients who are active (defined as smoking daily) smokers (cigarettes, marijuana). This exclusion is put into place as we do not know i…