 - Walking distance must be limited by IC, which will be confirmed by a 20 decrease in ABI in the worse claudicating limb immediately following the screening treadmill tests. The worse claudicating limb or index leg will be defined either as 1 the most symptomatic leg or 2 the leg with the lowest resting ABI and documented prior to the first pre-screening treadmill test. Post-exercise and resting ABIs will be compared within the same leg at each screening treadmill test. This criterion will not apply to diabetics with non-compressible tibial arteries i.e. only the resting TBI will be measured in these patients. 