Running is not far away from the leg is not strong may be because of the previous excessive fatigue, calcium metabolism abnormalities and lumbar spine lesions and other reasons. 1. Excessive exertion before: If you have carried out heavy physical labor or strenuous exercise before running, the lactic acid accumulates in the lower limbs, and even the blood vessels spasm, the blood supply to the lower limbs is insufficient, and the lower limbs will have the feeling of acidity and weakness after a little bit of activity, which is even more obvious when you are running. 2. Abnormal calcium ion metabolism: Because calcium ions play an important role in the process of neurotransmitter release and nerve impulse conduction, when calcium ion metabolism is abnormal in the body, such as high blood calcium content, it can affect the contraction of the muscles, which can cause the phenomenon of running not far away from the legs to run out of energy. 3. Lumbar spine lesions: including lumbar intervertebral disc herniation, lumbar intervertebral stenosis, lumbar spine tuberculosis and other lumbar spine lesions, can be due to the compression of the lower limb nerves, and make the patient run not far leg is not strong. If running is not far away from the legs, at the same time, combined with other discomforts, you need to consult a doctor in a timely manner, by a professional doctor to clarify the cause of the disease, to formulate an individualized diagnosis and treatment plan.