Cramps when you use your legs may be related to sedentary behavior, electrolyte disorders, and lactic acid buildup. Sedentary will lead to local muscle blood circulation is not good, muscle nutrient supply is not enough, metabolic waste discharge is not good, thus causing muscle contraction dysfunction, cramps. Excessive exercise will lead to a lot of sweating, which will lead to sodium, potassium salt loss of electrolyte disorders, and electrolytes and muscle contraction function related to the maintenance of electrolyte imbalance will lead to muscle contraction dysfunction caused by cramps. Excessive exercise will lead to a large accumulation of lactic acid, excessive lactic acid will stimulate muscle contraction dysfunction, causing cramps. If the symptoms of leg cramps occur when you use your strength, you should go to the regular hospital in time, improve the examination by the doctor according to the specific circumstances of the targeted treatment, so as not to delay the condition.