The causes of leg extension cramps include cold lower limbs, hypocalcemia, and gastrocnemius muscle spasm. 1. Cold lower limbs: due to inadequate warming measures, the patient’s lower limbs are cooled, resulting in the leg muscles being in a state of stress, and when the patient stretches his legs, cramps will occur. 2. Hypocalcemia: If the electrolyte imbalance in the patient’s body occurs, hypocalcemia occurs, resulting in inhibition of neuromuscular conduction, which leads to an increase in neuromuscular excitability, triggering the symptoms of cramps when the patient stretches his legs. 3. Gastrocnemius muscle spasm: If the patient suddenly straightens the leg, it may pull on the gastrocnemius muscle, thus stimulating the gastrocnemius muscle, causing spasm of the gastrocnemius muscle and cramps. There are many reasons for leg cramps, it is recommended that patients go to the hospital in time to improve the relevant examination, to clarify the cause of the disease, and comply with the doctor’s instructions for treatment.