A hard tendon felt in the left lower groin may be caused by physiological factors, constipation, and colon tumors. 1. Physiological factors: it may be touching the iliotibial fascia in the left lower groin. The iliotibial fascia is the thickest fascia in the human body, it is the tendon that combines the gluteus maximus muscle and the broad fascia tensor muscle, and it can be touched in the left lower abdomen near the hip bone, which belongs to the normal tissues of the human body, so there is no need to worry about it. 2. Constipation: If the patient is constipated, when the fecal matter left in the intestinal tube, mainly located in the descending colon and sigmoid colon, may also be in the position of the left lower groin to feel the strip hard like a hard tendon of things. 3. Colon tumor: when the patient’s colon area occurs tumor lesions, the patient may be in the left lower groin of the abdominal wall feel a strip of hard like a sinew-like phenomenon. Therefore, if the patient feels a hard muscle in the left lower groin, and accompanied by other uncomfortable symptoms, it is recommended to go to the hospital in time, to clarify the cause of the disease, and timely treatment.