If your toe goes numb during a run, take a look at your shoes before you jump to any conclusions. Tight shoes and tight lacings can compress your nerves and cause you to lose sensation in your toes, including your big toe. If picking up a more comfortable pair of shoes doesn't help, consult a doctor to see if an underlying medical condition is causing your numb toe.
Tight or ill-fitting shoes could compress the nerves of your foot, causing numbness. Your shoes should fit comfortably in all dimensions, including height, width and length, says Paraic McGlynn, director of applied cycling science at the Serotta International Cycling Institute, in "Bicycling" magazine. Ensure that your big toe is not touching the end of your shoe. When lacing your shoes, don't lace them too tightly, which could also compress the nerves and cause numbness.
During a run, the nerves on the bottom of your feet endure a lot of pressure. The nerves underneath the balls of your feet are particularly affected. This pressure could cause tingling or numbness in your big toe or other toes. According to the Foot and Ankle Center of Washington, a swollen nerve, or neuroma, could also cause your toe to turn numb. Ultrasonic imaging is one method used to determine the presence of a neuroma.
Orthotic devices such as insoles may provide relief from toe numbness. Supports placed underneath the toes may increase pressure on the toes and worsen numbness. An orthotic device for runners should leave ample room for the toes, be somewhat rigid and conform closely to the arch of your foot. Choose a total contact orthotic, which conforms to your arch and removes pressure from the ball of your foot.
Numbness in your lower body could indicate a potential problem in the lower spine, such as a herniated disc. Disc degeneration and spine misalignment can also cause your toe to feel numb. Nerve-root syndromes in the lower back can also cause low back pain and leg pain accompanied by toe numbness.
Overexertion during running can lead to compartment syndrome, a serious condition that requires immediate medical intervention. According to the American Academy of Orthopaedic Surgeons, symptoms include leg pain, toe numbness and cramping caused by pressure in the muscles that cuts off circulation and damages muscles and nerves. This condition is more common in the calf, but can also occur in your feet. The rare condition Raynaud's disease can also cause your big toe to turn numb. This disease occurs more often in women than in men, and limits circulation by constricting your blood vessels. Usually the hands are affected as well as the feet. Cold and stress can aggravate the symptoms, according to Cedars-Sinai Medical Center.