 Peripheral arterial disease is a common condition affecting approximately 64 of 56-77 year olds. This condition restricts bloody supply to calf muscles. Pain occurs after walking a short distance and increases in intensity until the person stops, where the pain then gradually subsides. It can be limiting or occasionally debilitating and has been shown to have considerable deleterious effects of patients quality of life. Shock wave therapy has been shown to promote new blood vessel formation and improved healing amongst other findings. This study aims to identify whether shock wave therapy that is applied to the calf muscles causes such an effect to improve the blood supply to the calf muscles, reduce pain, improve walking ability and quality of life. 