If your toes become numb during a run, the cause might be your favorite running companion: your shoes. Tight shoes or shoes with tight laces can constrict your foot and cause numbness. However, that's not the only possible cause. Raynaud's disease, compartment syndrome and neuromas are all possible causes of numb toes. To determine the cause, see your doctor.
Shoes that don't provide enough room for your feet -- particularly in the toe box -- may cause your feet to become numb during exercise. Select shoes that offer ample space in every dimension. If your shoe presses against your foot too tightly, it could pinch a nerve, resulting in numbness. Tight shoes can also cause anterior tarsal tunnel syndrome, according to a 2005 study of foot and ankle injuries in runners conducted by doctors at the University of Washington. This condition causes aching and numbness in the foot, and can be treated by changing your shoes or in more serious cases, corticosteroid injections or surgery.
Raynaud's disease is another possible cause of toe numbness. This rare condition causes your blood vessels to constrict, limiting circulation. More common in women than in men, this disease usually affects your hands in addition to your feet. Cold and stress may worsen the symptoms. See your doctor to determine if this condition is causing your numb toes.
Overexertion at a sport such as running can lead to chronic compartment syndrome which can result in numb toes, reports the American Academy of Orthopaedic Surgeons. Pain and cramping may accompany the numbness during exercise. These symptoms result from a build-up of pressure in the muscles which disrupts the flow of blood and damages nerves and muscles. More common in the calf, it can also affect the feet. A doctor will be able to diagnose this potentially damaging condition.
Interdigital neuromas can also cause numbness or pain in the toes. Neuromas are swollen nerves or areas of scar tissue around the nerves. Running with poor form, such as excessive foot pronation, or rolling of the foot, can cause a neuroma. Tight shoes and repeated weight placed on the forefoot can worsen this condition, which occurs most often in the third and fourth toes. Wider shoes can help relieve this problem, but some cases might require surgery. See a doctor if you suspect you have a neuroma.