50-year-old legs have no power for more reasons, may be related to excessive exercise, lumbar disc herniation, osteoporosis and so on. 1. Excessive exercise: overwork or acute and chronic injuries caused by soreness, usually due to the muscles produce a large amount of lactic acid is not metabolized, or not discharged from the body to form a feeling of soreness and weakness. 2. Lumbar disc herniation: the patient’s nucleus pulposus compresses the nerve root for a long time, and insufficient blood supply to the nerve root can occur. Nerve root ischemia and lack of oxygen, resulting in nerve paralysis, unable to transmit motor signals to the leg muscles, leg muscles lose innervation manifested in leg weakness. 3. Osteoporosis: mostly seen in postmenopausal women, due to the decrease of estrogen level, can not effectively inhibit osteoclasts, resulting in active osteoclasts, osteoporosis, leg weakness and other symptoms. At the age of 50, leg weakness can also be seen in electrolyte disorders and other causes, it is recommended to consult a doctor in a timely manner, follow the doctor’s instructions for further examination, with the help of the doctor to clarify the causes, and targeted treatment or therapy.