The numbness and weakness of the legs and feet when going up the stairs may be related to pathological factors such as lumbar intervertebral disc herniation or Guillain-Barre syndrome, or physiological factors such as poor physical fitness. 1. Pathological factors: peripheral nerve compression, such as lumbar disc herniation, the protruding disc on the nerve root caused by compression, the stairs will lead to numbness and weakness of the legs and feet. Nerve infection inflammation, such as Guillain-Barre syndrome, the peripheral nerves are attacked by the autoimmune system, nerve conduction is damaged, so the activity will appear numbness and weakness of the legs and feet and other symptoms, followed by numbness and weakness of the feet on the stairs. 2. Physiological factors: if their physical condition is poor, long-term exercise is relatively small, cardiopulmonary function is not enough, oxygen demand can not be met, so that the stairs will have numbness and weakness of the feet, and even appeared to have no strength to climb up the legs, this is a normal fatigue reaction, with personal physical condition, muscle endurance differences, usually whether to adhere to the body of the training and so on have a relationship. Stairway foot numbness and weakness may also be caused by other reasons, timely consultation to avoid delay.