Member Case Study: Toe Pain and Numbness on Over 80 Mile Rides.

author : AMSSM

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On the long bike rides of 80+ miles I get very strong pain in my toes. I slow down my pace and I might recover, but when I hit the next hill it is back. Could this be some kind of circulation issue?

Member Question from G. Parris

I just finished my first IM in Louisville. Here is my issue. On the long bike rides of 80+ miles I get very strong pain in my toes. I slow down my pace and I might recover, but when I hit the next hill it is back. Once I get this far I have to get off the bike and rest the dogs three to five minutes before I go again at 18 to 20 pace. I have tried to hold down to 16 mph to stay away from the issue, but during IM Louisville it happened three times. My average pace was 15.5mph. It also happened at every long ride during training.

I thought that because I am 50 and I came from sprints last year that it was a training issue. However, after looking at all the IM bike times (I lost 300 places) and knowing I had no issues on the run (I gained 300 places), I am wondering, could there be more to this? In fact the last 13 miles were enjoyable.

Could this be some kind of circulation issue? The type of pain is almost like a numbness, similar to when I was a kid and my hands got really cold in the snow then tried to thaw-out inside.

This is so painful that I will not do IM any more, and just stick with HIM and Marys.

Answer from Quynh Bao Hoang, MD (Pediatric Resident, Children’s Hospital of Orange County, CA) and Chris Koutures, MD, FAAP (Pediatrics and Sports Medicine, Anaheim Hills, CA)

Members AMSSM

The toe pain in both feet during long bike rides, particularly going uphill, appears to be positional in nature, namely when your knees are bent and your feet are in dorsiflexion (foot positioned closer to your shin). This suggests either mechanical or neurovascular issues. Pain and numbness in your feet and toes when biking is often caused by pressure around the foot usually due to improper shoe fit or cleat position. Bringing in your bike to have the fit and setup evaluated, along with an evaluation of your pedaling technique, is highly recommended. Tight-fitting shoes or cleats contribute to pressure around the foot, leading to irritation of tendons across the top of the foot and compression of the nerves. This can be corrected by loosening the shoe straps. Also, wearing wider shoes reduces compressive forces and choosing longer cleats helps maintain proper cleat position.

Entrapment Syndrome

A second underlying cause of toe pain could be an entrapment syndrome, either of nerve branches in the lower leg or foot, or an entrapment of an artery that supplies blood to the foot. During activity, there is increased blood flow to the exercising muscles of the foot. This leads to swelling of the muscles that then compress nerves or blood vessels.

Depending on the exact location of the toe pain, your symptoms may be due to nerve entrapment at the knees or increased pressure of a nerve in the lower leg and foot from repetitive muscle contraction. If your symptoms are mainly on the plantar aspect (soles of your feet), then the pain is likely due to irritation of the plantar nerves, which are the smaller nerves that branch off the tibial nerve. The tibial nerve runs behind the knee, goes down the calf, wraps around below the inner ankle, and ends on the inside of the arch. Prolonged knee bending (flexion) can lead to impingement of this nerve as it exits behind the knee, causing some of the toe pain. Raising the seat to decrease the extent of knee flexion can relieve some of the symptoms. Also, if you are flat-footed, having arch supports in your shoes may help decrease the tension on the nerves in the arch.

If the pain is more on the top of your foot/toes, then superficial peroneal nerve entrapment is a possibility. This nerve branches off the common peroneal nerve that exits behind the knee as well. Thus, you can see why when the knees are flexed during biking, the nerve can be impinged. Here again, raising the height of the seat position could alleviate some of the pain.

Nerve compression in the back and arterial entrapment

The fact that you are symptomatic in both feet also raises concern for nerve compression in the back, since both the tibial nerve and the common peroneal nerve branch off the sciatic nerve.

As mentioned, another cause of toe pain is entrapment of an artery that supplies blood to the feet. Although rare, popliteal artery entrapment syndrome occurs when there is intermittent compression of the popliteal artery causing pain and cramping. The cause of this is usually a variation in the anatomy where the popliteal artery is in relation to the gastrocnemius (one of the calf muscles) and typically both legs are involved. As a consequence, positions requiring constant flexion, like during prolonged biking, can compress this artery behind the knees. Furthermore, when the foot is in dorsiflexion, there is tension in the gastrocenemius, which places additional compression on the artery. Again, raising the height of the seat and ensuring proper cleat position can reduce symptoms. With aging, obstructive peripheral artery disease becomes more prevalent, and would be a reasonable concern to consider as well.

Conclusion

Professionals that could assist you include a cycling coach or mechanic trained in proper bike fitting, your primary care physician to evaluate your general cardiovascular status, and a sports medicine physician to further study the biomechanical issues. Don’t be surprised if the sports medicine physician asks you to ride 80+ miles before the visit because determining the cause of exercise-related pain often requires evaluating the patient after exercise.

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date: November 12, 2008