By Dr. Russell O’Connor FRCPC, Dip Sport Med (CASM) Electromyography, Physiatry and Sports Medicine Phyisician
A common reason for referral to a sports medicine specialist is leg or foot numbness or tingling with exercise. There can be several causes for such symptoms that can arise from muscle, nerve conditions, and medical conditions such as diabetes or even central nervous system problems.
Perhaps the most common condition is “steppers foot” when a persons foot goes numb while using a step masters or elliptical machine. The most common cause for this the constant pressure on the foot. This steady pressure causes the nerves that pass between the toes in the foot to go temporarily numb. Once the person steps off the machine for a few seconds to up to a minute the tingling quickly resolves. This is typically not a serious problem. Solutions include loosening laces, shoes with more forefoot cushion, an orthotic with a metatarsal button, lifting your feet off the pedals like you would when walking normally, cross training with different machines and good calf flexibility.
Occasionally the nerve between the toes (the interdigital nerve) can get impinged and cause pain and electric shocks into the toes and foot. This can develop into a neuronal or thickening of the nerve and be quite painful. Usually this can be detected on history and careful physical examination. This may require adjustment of your activity, modified footwear, and medical treatment with medications or injections.
Muscle and joint fatigue or aches can mimic tingling and numbness in the foot. Occasionally a foot joint or bone problem is causing pain in the foot and the muscles in the leg fatigue much quicker. When this occurs the athlete reports the foot feels weaker and occasionally feels numb or tingly. The clue here is that there is something else one the physical exam of the foot that points the doctor to the fact that the muscles in the foot or leg are the problem.
Another condition that requires a little more investigation is called chronic exertional compartment syndrome. This is an overuse problem and athletes will complain of increasing pain, numbness and weakness of the foot or leg with running typically. The symptoms usually start part way through a run and are not present normally at the start. Often it will make the athlete stop running and take minutes and sometimes hours to fully settle. As this syndrome progresses it can cause pain even at rest and especially the night after the run. Other symptoms can include exercise related numbness into the top or sole of the foot and even a drop foot. This is caused by elevated pressure in one or more of the three muscle compartments in the calf. Strength, and nerve testing at rest is normal. The key here is to test the pressures in the compartments once immediately after exercise and then 1 and 5 minutes. If the pressures in the calf are too high you have your diagnosis. Treatment involves relative rest, determining if orthotics are required, a graduated return to activity, and occasionally surgical release of the high pressure compartment in chronic cases.
Tarsal tunnel syndrome is a relatively rare condition that presents with burning pain and numbness in the soles of the feet. It is often worse at night and the neuropathic burning character or electric shocks is a clue to the diagnosis. It is usually worse with pronation and putting the sciatic nerve on stretch during walking physical exam. Typically this condition starts slowly but increases to the point of not just tingling but also numbness and burning sensations. Before treatment is initiated it is important to make the correct diagnosis. Many time patients are treated for plantar fasciitis, tendinitis, stress fractures and metatarsal before the diagnosis is made. Nerve testing can be done to confirm the diagnosis and imaging is sometimes required. Treatment includes orthotics to decrease stretch across the tarsal tunnel during heel valgus, rest, anti inflammatories, possible steroid injections and even surgical decompression in cases where there is a lesion compressing the nerve.
In older athletes exertional weakness, or numbness in the foot or leg could be the sign of spinal stenosis. Athletes usually, but not always, have a history of low back complaints. The classic pattern is the numbness or weakness is worse with walking or running and better with sitting. Just stopping and standing usually doesn’t help as much as sitting does. Athletes may report they can run up hill easier than down hill. This is due to the fact that you normally lean a little more forward running up hill and lean back running down hill which tends to further narrow the spinal canal. This clue might not be of much help here on Cayman though. A careful history, physical and neurological exam followed by appropriate testing is key to making the diagnosis.
It is important to remember numbness, tingling and weakness can arise from the nerves in the foot, leg, thigh, back or even the spinal cord or brain. Occasionally even non-neurological structures can mimic these symptoms. If these symptoms are persistent and in particular are getting worse seek advice from your doctor, as there is often things that can be done to further investigate and then treat the underlying problem.
Dr. O’Connor is a Physiatrist, Nerve Specialist (EMG), and Sports Medicine Physician. He can be reached at his office in Cayman Physio at 945 – 5747.
