Patients receiving anticoagulation treatment are allowed to participate with international normalized ratio (INR) established within the therapeutic range Patients receiving anticoagulation treatment are allowed to participate with international normalized ratio (INR) established within the therapeutic range Patients must not be on any anticoagulation Patients who have had a deep vein thrombosis or pulmonary embolus within the past 6 months are eligible if they are on stable therapeutic anticoagulation International normalized ratio (INR) and activated partial thromboplastin time (aPTT) =< 1.5 x ULN (or on stable dose of therapeutic anticoagulation, such as low-molecular-weight heparin, warfarin or rivaroxaban) International normalized ratio (INR) and activated partial thromboplastin time (aPTT) =< 1.5 x ULN (this applies only to patients who do not receive therapeutic anticoagulation; patients receiving therapeutic anticoagulation, such as low-molecular-weight heparin or warfarin, should be on a stable dose) International normalized ratio (INR) and activated partial thromboplastin time (aPTT) =< 1.5 x ULN (this applies only to patients who do not receive therapeutic anticoagulation; patients receiving therapeutic anticoagulation, such as low-molecular-weight heparin or warfarin, should be on a stable dose) International normalized ratio (INR) =< 1.5 x ULN (this applies only to patients who do not receive therapeutic anticoagulation; patients receiving therapeutic anticoagulation, such as low-molecular-weight heparin or warfarin, should be on a stable dose) Activated partial thromboplastin time (aPPT) =< 1.5 x ULN (this applies only to patients who do not receive therapeutic anticoagulation; patients receiving therapeutic anticoagulation, such as low-molecular-weight heparin or warfarin, should be on a stable dose) International normalized ratio (INR) and activated partial thromboplastin time aPTT =< 1.5 x ULN (This applies only to patients who do not receive therapeutic anticoagulation; patients receiving therapeutic anticoagulation, such as low-molecular-weight heparin or warfarin, should be on a stable dose) Patients requiring therapeutic anticoagulation