Thigh weakness may be related to the following reasons: 1. It is due to excessive rest. Many patients are often curled up in bed due to excessive fatigue or because they are lazy. Some patients need to be bedridden for a long time due to the presence of diseases of the lower limbs and trunk. These patients are bedridden for a long time, resulting in disuse atrophy of the lower limb muscles. These patients will feel the symptoms of weakness in their thighs when they go down to the ground for weight-bearing activities; 2, this may be caused by osteoporosis, which is common in the elderly, and once it develops, the initial symptom is weakness in the lower limbs and trunk without any triggering factors; 3, this condition may be caused by peripheral neuropathy, if there is a lumbar disc herniation or the femoral nerve is If there is a herniated lumbar disc or the femoral nerve is under pressure, it will lead to weakness in the muscles of the thighs; 4. This condition may also be caused by excessive fatigue, such as excessive exercise involving the lower extremities or room strain, which will lead to symptoms of weakness in the lower back and knees and weakness in the lower extremities.