Do you have tingling, burning, numbness or the feeling of having a sock bunched under your foot?
When we experience sensations in our feet that are unusual or bothersome, it's our foot's way of trying to let us know that something different is happening. Notice, it's not necessarily trying to tell us there is something wrong, just something different. If the sensation is something known to us, such as tingling, then you can rest assured that there is pressure on a nerve somewhere. Tingling is a sensation well known to our conscious brain that is associated with a nerve that has "fallen asleep" or has been compressed for a period of time. Burning pain is also well known to us and is a strong indicator of something that the foot is unhappy about. When body parts or skin burn, they are hardly ever associated with anything good. Therefore, when we sense a burning, it's our brain's way of saying that something isn't right. The bunched sock sensation may sound unusual, but it's actually quite common. I have a lot of patients that would swear their sock is bunched under their foot, or there is a pebble in their shoe or they've been walking on a pad, yet none of that is happening. This is the the brain's attempt to understand a sensation that is foreign to it, something it can't explain. As adults, we can rationalize the world around us, make sense of what we feel and do on a daily basis. We've learned to do this through repetition and understanding. Imagine yourself as an infant who experiences touch, taste, sound, and sight for the first time, without being able to put anything into any context. In time we learn to associate what we sense with given situations. The aforementioned sensations unfortunately (or fortunately) come to us later in life, after we've formed opinions about most everything we could possibly imagine. The brain is given the task of trying to understand a new sensation it is experiencing, all while having those very sensations blunted through shoes! So before you think you are going crazy, just realize, it's your conscious mind's attempt at trying to come up with something it "thinks" might be happening. It tries to match the sensation with a known experience.
So what does all this mean? Clearly, without examining an individual with these specific complaints, it would be impossible to be sure that the diagnosis matches the symptoms. Think of these as typical, rather than the gospel. Also, understand that things do happen for a reason. When one thing in the body is off, and you didn't hurt yourself or fall off your bike, there are likely MANY things that are off and just waiting to be known!
Tight shoes would be the most common. Bike shoes are often too narrow, and if not too narrow, they are often strapped too tight. If not strapped too tight, when on rides longer than an hour OR pushing a big gear/low cadence OR cranks that are too long/poor bike fit, then your feet can swell into the shoes making them functionally tight. I wrote a blog about the perception of shoe fit that you can read here.
This often occurs as a progression of tingling. If the foot is compressed, or more specifically, if a nerve is compressed, then numbness will result. There are many nerves in the foot. They enter the foot behind the inside ankle bone and into the arch, dividing into smaller nerves that ultimately reach the toes. If your entire foot is going numb, the tibial nerve is likely being compressed. Most people have heard of Carpal tunnel syndrome within the hand: however, the foot has Tarsal tunnel syndrome. If it is specific to the entire ball of the foot and toes, that's usually a mechanical cause, especially if only one foot, but could be the start of a systemic condition (we must rule out Diabetes which is a major cause of numbness/neuropathy). Lower cadence, poor bike fit, big ring riding, poor shoe fit, poor cleat position or choice could all lead to this as well.
Morton's neuroma is probably the best known of all nerve-related foot issues. Simply, it's when the metatarsals behind the 3rd and 4th toes (piggy that had roast beef and piggy that had none) compress the nerves that feed the brain information about those two toes. The nerve often becomes inflamed and causes the burning sensation. Without inflammation, the sensation would just be numbness. Bottom line here is that the front of the foot just needs more room to spread. When that becomes impossible, we sometimes have to take the nerve out. Permanent numbness is often better than burning that interferes with your athletic desires.
This could be a nerve or it could be a joint. Usually nerve pain (actual pain, not just a sensation of something) has a burning quality to it. The smaller joints of the foot however often elude our learned experience. To our brains, they are just there and they do their job and like to be left alone. The normal state of being for the small joints in the ball of the foot are for the toes to be stabilized against the ground when we load our foot with weight or pressure. As our bodies move over our feet, those toes need to remain stable so that the joints bend properly. IF, one of those joints start to lose stability (and it is almost always the 2nd toe - next to big toe), then as our bodies move over our foot, the joint moves in a way the brain isn't used to. The toe shifts a little on the metatarsal and that little bit of play in the joint is enough for a fluid shift to occur. This fluid shift is sensed by the brain and feels as though something is under the foot or in the foot. When these problems become progressive, hammertoes, stress fractures, dislocated toes, or other deformities may develop. These should definitely be looked at sooner rather than later, so that necessary steps can be taken to avoid progression into deformities that are more difficult to treat.
Hope that helps and stay healthy!