Intermittent claudication: divided into two sub-stages IIa and IIb. Stage IIa: contains patients who walk longer distances before developing claudication symptoms. Stage IIb: consists of patients who walk shorter distances to develop claudication or whose claudication interferes with daily activities.The typical symptom of intermittent claudication in patients with PAD is defined as pain in the muscle tissue caused by walking, which disappears immediately after stopping the movement. Notably, pain always appeared in the same muscle groups after walking a similar distance if the road surface inclination was the same and the same walking speed was maintained. Many patients report lower extremity pain associated with walking rather than with the presence of arterial disease. Many of them suffer from muscle, osteoarthritic or neurological pathologies that can sometimes coexist with occlusive arterial disease. In such cases, it is important to establish a correct set of differential diagnoses, starting with a clinical diagnosis that can be made and subsequently confirmed by noninvasive examination methods. The clinical symptom in these patients is usually arthralgia associated with movement, but pain is also seen during passive movement of the lower extremities. When symptoms of myalgia are present, the painful symptoms do not always appear in the same areas and are not often limited to the muscle groups associated with movement (e.g., gluteus, quadriceps, gastrocnemius). The distance walked in nonvascular claudication is highly variable, and the distance over which it triggers pain varies widely even on the same day. The painful symptoms are not simply discontinued by stopping walking, but the patient has to sit down, lie down, or is forced into a special position, usually after a much longer rest period than in vascular claudication, before the painful symptoms disappear. The muscle groups involved in the claudication gait are very useful for the localization of occlusive lesions. Although the majority of patients describe gastrocnemius claudication, the claudication lesion is actually in the gluteal region, or describe thigh claudication, the lesion is actually in the groin. In claudication due to N-fossa artery disease, the pain is usually located in the gastrocnemius muscle, and claudication due to occlusive lesions of the infrapopliteal artery usually presents as pain in a single toe only.