If you are a regular runner, you have probably experienced your share of leg aches and pains, and have possibly had some foot discomfort. While in most cases pain is the primary symptom and a stress fracture or plantar fasciitis the most common causes of this pain, foot numbness also is a frequent occurrence and often localizes to bottom of one or both feet.
A neuroma is a thickening of the tissue surrounding a nerve. A Morton's neuroma involves the nerve that runs between the third and fourth metatarsal bones of the foot. According to Dr. Mark Steckel, this nerve can become chronically irritated in runners who overpronate or have anatomical peculiarities such as claw or hammer toes. Runners feel pain and numbness in the ball of the foot. Running on hard surfaces and wearing overly tight shoes can exacerbate the problem, which is treated using ultrasound, metatarsal pads, orthotics or surgery.
Tarsal Tunnel Syndrome
The lower body counterpart to the better-known carpal tunnel syndrome, tarsal tunnel syndrome results in numbness in the bottom of the heel as a result of compression of the posterior tibial nerve supplying this region. According to Dr. Cathy Fieseler, the most common causes are abnormal growths such as bone spurs or cysts, too-tight shoes and biomechanical problems such as overpronation. Treatments include orthotics, rest, a steroid injection and, in some cases, surgery.
A variety of footwear issues can lead to numbness throughout the feet. Tying your shoelaces too tightly is perhaps the most frequent cause of foot numbness, although this normally affects the top of the foot. Shoes that are too tight in the heel area compress the nerve supplying the sole of the foot, resulting in less of sensation ranging from tingling to numbness. Experiment with different lacing techniques or change your shoes to alleviate this problem.
While most instances of foot numbness in runners are attributable to a problem with the nerve supply to the area, an interruption in blood supply -- either in the foot itself or at a location higher up in the body -- can lead to similar symptoms in the bottom of the foot. The most common culprits are hardening of the arteries, high blood pressure, smoking, poor diet, cold weather and diabetes. Treatment involves addressing the underlying medical problem with lifestyle modification, medications or both.