Cramping when you tense your toes can be due to calcium deficiency, muscular tension fasciitis, nerve damage, and more. The most common cause of cramps when you tense your feet is due to muscular tension fasciitis. 1. Calcium deficiency: Calcium deficiency can cause the symptoms of cramps, because long-term calcium deficiency may lead to a decrease in calcium content in bones and muscles, which can easily induce muscle spasms when tensing the toes, thus causing the symptoms of cramps. 2. Muscular tension fasciitis: muscle tension fasciitis is generally common in exertion, cold and muscle strength is not enough, muscle inflammation exudation is more, muscle fatigue, and then tense feet pulling muscles will cause the muscles can not get a rest, resulting in spasms, cramps. Cramps will aggravate the original damage and inflammation, resulting in persistent pain. 3. Nerve damage: patients with sciatic nerve damage will lead to neurological symptoms, tense toes will lead to nerve stimulation, thus causing cramps. Toe cramps can also be caused by other reasons, common causes include localized nerve compression, insufficient blood supply caused by vascular disease, and other relatively rare herniated discs or spinal stenosis compression of the nerve. For example, due to nerve entrapment or localized muscle injury, you should go to the hospital in time for examination and treatment.