The most common causes of soreness and pain on the outer side of the calf are over-exercise, soft tissue injury, lumbar disc herniation, peripheral neuropathy, varicose veins of the lower extremities, tumors, etc. If the symptoms persist, it is recommended to seek medical treatment in time. 1. Excessive exercise: If the patient has performed strenuous physical activities, such as kicking a soccer ball and other sports, this may cause the accumulation of lactic acid on the outer side of the calf, and the metabolism of lactic acid may cause soreness and pain on the outer side of the calf. 2. Soft tissue injury: history of trauma to the lateral calf or muscle sprains can cause soreness and pain in the lateral calf, and severe pain should be excluded from fractures. 3. Herniated lumbar intervertebral discs: when lumbar intervertebral discs undergo degenerative changes with age, they may compress the surrounding soft tissues, causing pain and numbness in the lower limbs, which may also cause soreness and swelling in the outer calf. 4. Peripheral neuropathy: If the patient has peripheral neuropathy, it can also produce calf pain, such as diabetes, nutritional deficiencies, alcoholism, can cause peripheral nerve damage. 5. Varicose veins of the lower limbs: patients with varicose veins of the lower limbs may have no obvious symptoms at the initial stage, but with the passage of time, they may have soreness and pain on the outer side of the calf. 6. Tumor: Soreness on the outer side of the calf may be caused by primary bone tumor or metastatic tumor from other parts of the body, which will cause pain when the tumor presses on the nerves or blood vessels. Causes of lateral calf pain are more reasons, may also be associated with lower limb thrombosis, osteoarthritis, fasciitis and other diseases, it is recommended to go to the hospital in time to find out the cause of the disease, by the doctor targeted treatment.