Pain when hooking the toes upward may be caused by lactic acid buildup, muscle strain, fasciitis, Achilles tendon injury and other factors. 1. Lactic acid buildup: When the patient exercises too much, resulting in a large amount of lactic acid buildup in the muscles and other soft tissues due to anaerobic respiration, it can lead to pain in the calf muscles when the toes are hooked upwards. 2. Muscle strain: If the warm-up before exercise is not sufficient or strenuous exercise, it can lead to strain of calf and ankle muscles, tendons and other soft tissues due to excessive traction, which will cause pain when the toe is hooked upwards. 3. Fasciitis: when there is aseptic inflammation of calf or plantar fascia due to various reasons, it will cause a series of clinical symptoms such as muscle spasms, and there will be pain when the toes are hooked upwards. 4. Achilles tendon injury: when the exercise is strenuous or improperly exerted, it can lead to Achilles tendon tear or rupture, and the symptoms of pain when hooking the toes upward will appear. There may be other reasons for the pain when hooking the toes upward, it is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.