Your risk of stroke should be assessed by your doc. If your risk of stroke is "low", aspirin is the treatment of choice. If your risk of stroke is not low, continue taking the warfarin. If your jogging increased clotting time it would already be accounted for in the INR.
Have you had any TIA's? If so, you're at a high stroke risk. The
American Heart Association position is:
"Treating atrial fibrillation is an important way to help prevent stroke. For this reason, the American Heart Association recommends aggressive treatment of this heart arrhythmia.
Drugs are also used to help reduce stroke risk in people with AF.
Long-term use of anticoagulants (drugs that help prevent blood from clotting) in patients with AF and other stroke risk factors can reduce stroke by 68 percent. Aspirin and warfarin are now used for this purpose.
Physicians differ on the choice of drugs to prevent embolic stroke -- stroke caused by a blood clot. It's clear that warfarin is more effective against this type of stroke than aspirin. However, warfarin has more side effects than aspirin.
Patients at high risk for stroke should probably be treated with warfarin rather than aspirin unless there are clear reasons not to do so. Examples include potential bleeding problems or ulcer. Patients over 75 should be monitored especially carefully.
Aspirin is the standard treatment for patients at low risk for stroke"
http://www.americanheart.org/presenter.jhtml?
identifier=4451