20. Patients receiving anti-coagulation treatment with an agent such as warfarin or low molecular weight heparin may be allowed to participate with the following criteria: For patients on prophylactic anticoagulation therapy (low-dose warfarin): INR level < 1.5; Patients on prophylactic dose or full dose low molecular weight heparins are eligible provided that the patient has no active bleeding or pathological condition that carries a high risk of bleeding;