The sensation of a hot flow in the leg may be a sudden increase in the amount of blood circulation, or a sudden release of nerve compression. There are two possible reasons for this sensation: First, a bulging lumbar disc. The lumbar intervertebral discs may compress the lumbar spinal nerves due to the effect of excessive pressure, or regular and repeated pressure stimulation, which causes the discs to swell. Since the fibrocartilage on the outer side of the lumbar disc, which has not ruptured, will make this state of bulging, it may be lifted at any time, and the state of compression of the lumbar nerve, will be lifted at any time. When the state is lifted, the compression is also lifted, and an abnormal sensation will appear in the leg, similar to the feeling of a hot current in the leg. Secondly, the blood circulation in the legs becomes impaired. This sensation occurs when the posture of the leg is changed, or when the obstruction of blood circulation disappears.