The possible causes of jerky leg shaking when getting up and stretching include poor sleeping posture, calcium deficiency, overwork, and fasciitis. 1. Poor sleeping posture: During sleep, the activity of the human body is generally reduced, and if you lie on your back for a long time, or lie prone, or the calf muscle tissues are compressed by objects for a long time, and other poor sleeping posture, it may lead to the phenomenon of passive spasm, and there is a twitching and shaking of the legs when you get up and stretch your legs. 2. Calcium deficiency: If the usual intake of calcium-containing food is too little, or malnutrition, it will lead to calcium deficiency, and a prolonged lack of calcium will easily lead to osteoporosis or muscle malnutrition, which will lead to the phenomenon. 3. Excessive fatigue: it may be due to insufficient sleep or rest, walking too long, etc., resulting in too much fatigue, a large accumulation of lactic acid metabolic waste products in the legs, resulting in muscle spasms, the phenomenon. 4. Fasciitis: Fasciitis is a kind of non-specific inflammation that occurs in the myofascia, and pain, muscle stiffness, and a feeling of heavy pressure will occur under the stimulation of inflammation, and the phenomenon may also occur. Getting up and stretching jerky shaking legs may also have other reasons, it is recommended to go to the regular hospital in time, improve the relevant examination, clear cause, under the guidance of the doctor to give targeted treatment or treatment.