One of my clients, a hard training triathlete, recently asked me for my thoughts on using Advil before strength and cardio training. Advil, or ibuprofen, is part of a class of medicines call NSAIDS (Non-Steroidal Anti-Inflammatories). They act on the pain center of the brain and also act to reduce inflammation in the muscle tissue.
To begin answering this question, one has to understand what inflammation actually is: a protective response by the body. Swelling occurs as your body's own way of immobilized damaged areas. NSAIDS can help reduce the pain and swelling but as they do this, they are also reducing the body's natural ability to protect and heal itself. Repeatedly dosing on pain relievers and anti-inflammatories before training can casue stomach upset, interfere with the healing process, and make you susceptible to further injuries.
Be very careful. Listen to your body. If you have a constant nagging injury, see an orthopedist or physical therapist and learn how you can address the underlying causes rather than mask the problem with medication. In the extreme, there are some studies that suggest that use of ibuprofen during prolonged endurance exercises such as an Ironman can lead to dehydration, hyponatremia and kidney failure, because it alters kidney function (however, I haven't found any documented cases of this happening).
Bottom line: Advil is medicine. Avoid prolonged and chronic use of any medicine that your doctor has not approved, before OR after exercise.