Current research has shown that approximately 30% of patients improve with exercise, while 30% continue to deteriorate and the rest show no change. The changes produced at a biochemical and cellular level due to exercise are unknown. To help better understand this, our study will assess the entire range of proteins expressed before and after exercise in the skeletal muscle tissue of patients with intermittent claudication. This will help to identifying key proteins that have a role in improving patient symptoms and outcome.