Numb Pinkies on Tri Bike

author : AMSSM

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Explanation and tips for dealing with hand numbness

Member Question:

"So I've been riding my new TT bike for going on 2 weeks, I think. I'm feeling more and more confident (first ride was terrifying -- like learning to ride a bike, all over again). Neck and shoulders are less cranky about things. Overall speed is increasing as I become more comfortable with the bike and position. So the issues I am having are really small. My pinkies are going numb. What could I do about the pinched nerves (?) on my arms/hands (I assume it's ulnar nerve and it's getting impinged, perhaps by my elbow pads)? Or is that just something to live with during duathlon season?"

Answer by Jennifer Stromberg, MD, CAQ-SM
Member AMSSM

Congratulations on your new bike! Glad to hear you are starting to feel more comfortable and confident and enjoying your newfound speed. As for your current issue: you are correct that the ulnar nerve provides sensation to the pinky finger. The ulnar nerve is formed when two nerves from your neck (C8 and T1) join together in the brachial plexus near the shoulder and armpit area before passing down into the arm. Once in the arm this nerve not only supplies sensation to your pinky fingers, but also the pinky side of your ring fingers. In addition to sensation the ulnar nerve controls the muscles involved in grip strength and wrist flexion. I agree that it sounds like in your new position on the TT bike your nerves are probably being compressed, so let’s look at where along the line this could be happening and how we may be able to improve your symptoms.

Cyclist’s Palsy

Let’s start at the wrists and work our way up. At the level of the wrists the ulnar nerve enters the hands through a tunnel called Guyon’s canal. This canal is located on the inner aspect of the wrists if you have your hands extended palms-up in front of you. After passing through the canal the nerve splits into superficial and deep branches. The superficial branch provides sensation to the pinky and half of the ring finger on the palm-side only. The deep branch controls some of the muscles involved in grip strength, so depending on where the nerve is being compressed you may note just numbness and tingling, just weakness, or both. Holding the handlebars causes compression in this area so frequently that these symptoms are often referred to as “Cyclist’s Palsy.” Holding the wrists in a hyperextended position or bringing the pinky side of the hand closer to the arm can also make the area more vulnerable to injury. Fortunately, there are a few ways that pressure and tension on the nerve in this area can be alleviated if this is the culprit of your symptoms. One suggestion would be to change hand positions frequently during longer rides, particularly if you are having symptoms. You may also want to look at your normal hand and wrist position and see if you can alter your form to decrease nerve tension and compression- a fit specialist may be useful for guidance on this. Finally, make sure you are using gloves with thin (3mm) foam padding as this has been shown to decrease pressures on the nerve.

Cubital Tunnel Syndrome

The good news about switching from road to aero position is that you have likely taken a lot of pressure off of your wrists. The bad news is that now a lot of that pressure is going through your forearms and elbows and these are also potential sites for nerve compression. The cubital tunnel is a particularly vulnerable area. This is a small space the ulnar nerve must pass through on the inner aspect of the back of the elbow before entering the forearm. If you have ever hit your “funny bone” this is usually the area that is affected. Compression in this area can sometimes also cause numbness to the back of the pinky and ring finger, rather than just the palm side, but not always. In addition to trouble with grip strength wrist flexion may also be affected. Again you need to look at your position on the bike- pressure on the nerve will increase the further you bend your elbows so this should be optimized. Also check to see where your pads are in relationship to your forearms and elbows- it may help to either move the position of the pads to take pressure off the elbows, or to just make sure the area has adequate padding.

The Bottom Line

Switching to an aero position certainly can be beneficial for speed and for the bike to run transition, but proper fit is crucial to optimize performance and avoid risk of injury. When it comes to ulnar nerve compression the aero position can increase stress on the elbows, which is one of the potential sites for compression. If you find you are continuing to have issues despite trying the tips listed above you should consider having a professional bike fit with special attention to these sites and/or seeing your doctor to help determine exactly where the issue is coming from. The nerve can also be compressed between the muscles of the arm, in the neck, or where the nerve passes from the neck into the arm at the brachial plexus. Certain types of injuries or anatomical variants can also make you more susceptible to nerve issues and physical therapy and/or surgery can sometimes be helpful if that’s the case. I would not recommend that you continue to push through these symptoms if they are persistently bothersome for you as over time this can damage the nerve and lead to progressive symptoms which can hinder performance. Best of luck this season and enjoy your new ride!

References

Brubacher, J.W., Leversedge, F.J. Ulnar Neuropathy in Cyclists. Hand Clin 33 (2017) 199-205.

Slane, J., Timmerman, M., Ploeg, H.-L., Thelen, D.G. The Influence of Glove and Hand Position on Pressure Over the Ulnar Nerve During Cycling. Clinical Biomechanics 26 (2011) 642-648.

Jennifer Stromberg, MD, CAQ-SM
Member AMSSM
Carolina Family Practice and Sports Medicine
Cary, North Carolina

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date: March 31, 2017