Running calf lateral pain is considered to be caused by muscle strain, thromboembolic vasculitis, lumbar disc herniation and other reasons. 1. Muscle strain: long-term or high-intensity use of the calf, when more than the maximum length of muscle deformation, can cause partial or total rupture of muscle fibers, muscle swelling, congestion and other phenomena, thus causing running calf pain and swelling on the outside. 2. Thromboembolic vasculitis: Smoking, advanced age and other factors can cause thrombosis in the blood vessels of the limbs, stimulate the local blood vessels and block the lumen, causing inflammatory manifestations such as vascular edema and other inflammatory manifestations, which will result in abnormal sensations of heaviness, weakness, numbness and pins and needles in the lower limbs, and in severe cases, symptoms such as cold feet and intermittent claudication can occur. 3. Lumbar disc herniation: when the nucleus pulposus of the lumbar intervertebral disc presses or stimulates the lumbar nerve root, it can cause pain in the lumbar back and radiate to the lower limbs, resulting in lower limb pain, soreness, heaviness, weakness, pins and needles, numbness, and other abnormal sensations and motor performance. Running calf lateral pain and many other reasons, it is recommended to consult a doctor in a timely manner to clarify the diagnosis, under the guidance of the doctor for targeted treatment.