Member Case Study: Numb Toes on the Bike

author : AMSSM

comments : 0

After I have been cycling for about an hour the three middle toes on my left foot go tingly and then hurt like the blazes. Any clue as to what may be going on?

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Member Question from kns57

"After I have been cycling for about an hour the three middle toes on my left foot go tingly and then hurt like the blazes. If I get off and massage them for about five minutes I can then get in another 30 minutes of cycling and then it starts  all over. After about 2 hours my right foot will also start up. This will also happen on the run but they will eventually get numb and I can work through it. On the bike I can't seem to work through it.

I've working on building up the potassium levels - no change.
I'm well hydrated.
I stretch before starting out.

Any clue as to what may be going on?"

Answer from Arnold Ramirez MD

Member AMSSM

It appears that your symptoms are the result of a compressive neuropathy, in other words, a “pinched nerve”. The key is to determine which nerve is involved and where it is being “pinched”. From your description of the distribution of your numbness it seems that the L5 nerve root is involved which originates in the spine from the 5th lumbar vertebrae and travels down to the toes. This nerve can be compressed anywhere from the buttocks, as part of the sciatic nerve (by sitting in the saddle too long), to the foot, as part of the medial plantar nerve (which can occur with excessive foot pronation). Given that your symptoms occur on the run as well as the bike it is more likely that nerve compression is happening at the foot/ankle level.

It would be helpful to know if your symptoms affect more of the top or the bottom of the toes. Symptoms just on the top of the foot suggest the origin is from the superficial peroneal nerve which can be compressed at the knee or lateral lower leg. Finally, toe pain in cyclists can be caused an even more local phenomenon where the irritation results from the shoe/pedal interface.

My suggestions to you would be to first check if your shoes support excessive pronation even on the bike. Second, make sure that your seat height is not too high to prevent excessive downward toe-pointing during the down-stroke. Another tip is to make sure the laces and straps on your shoes are not too tight. Trying different cleat positions or biking shoes can possible solve the problem. Finally, backing down biking mileage by 25% -50% and then gradually building back up can also potentially help.

Good Luck!
Arnold Ramirez MD

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date: September 25, 2009