Question: I have a pinched nerve that has led to a numb foot bottom on my left side. This injury came on suddenly after a hard 12 miler last Sunday. I know the pinch originates on the lower back. I have rested and been taking Advil but no change. Even sitting, walking, standing i am feeling the numbness. Any suggestions? I am supposed to run a half in two weeks and getting nervous it may not happen.Response from Running Times medical expert, Cathy Fieseler:Foot numbness may be due to a number of different problems. A ruptured disc in the lumbar spine may compress one of the nerves that affects the foot. A nerve may be compressed in the foot, ankle or lower leg causing areas of numbness in the foot. Peripheral neuropathy is another possible cause of foot numbness; this disorder has numerous causes, including metabolic diseases such as diabetes. Neuromuscular disorders can also cause numbness in the foot.The first step is to determine the source of the numbness. You sound confident that the disorder originates in your back, but I will review other possible causes too.If there is a ruptured disc, muscle weakness will also be present. This will affect your gait, possibly causing an injury. Additionally, the impact forces while running may further damage an already injured disc. Treatment may include rehabilitation exercises, medications and possible injections for management of pain, and on occasion, surgery may be warranted.If a nerve is compressed in the leg or foot, this might or might not impact the strength of some muscles. Compression of a nerve may be due to tight shoes or clothing, entrapment by a muscle or other soft tissue or scarring of the nerve. Alleviating the compression may be as simple as better fitting gear or may involve manipulation of the tissues manually, with injections, or surgically.Peripheral neuropathies and neuromuscular disorders require treatments that are dependent on the specific cause of the disorder. These can be progressive disorders that have a better prognosis when treatment is initiated early.The bottom line - seek medical evaluation to determine the source of your foot numbness so that the appropriate treatment may be initiated, even if this means missing the half marathon, with the goal of ultimately prolonging your running career.Good luck.