Cyclist's Palsy

Chronic ulnar nerve compression is believed to be the primary cause of sensory and motor impairments of the hand in cyclists, a condition termed Cyclist's Palsy, Pic 1. Sensory and motor impairments of the hand are common among both amateur and experienced bicyclists.

                                                          Pic 1 Cyclist's Palsy

This condition, most often presents as numbness and/or paresthesia in the fifth and ulnar aspect of the fourth finger, sometimes accompanied with weakness in the abductors or adductors of these fingers.

For example, Anderson and Bovim (Andersen and Bovim, 1997)  interviewed 169 cyclists after completion of a 540 km  race and found sensory symptoms present in 40% of riders while 19% exhibited motor symptoms.

The duration of Cyclist's Palsy varies widely among riders, persisting anywhere from several days to months (Akuthota et al. 2005).
https://www.ehealthstar.com/conditions/guyons-canal-syndrome 

The ulnar nerve passes into the hand ulnarly to the pisiform, and radially to the hamate, via Guyon's Canal (Akuthota et al.,2005). Upon exiting the canal, the nerve bifurcates into superficial sensory and deep motor branches. The sensory branch provides sensation to the fifth finger and half of the fourth finger while the motor branch innervates the hypothenar muscles as well as several other small muscles groups in the hand (Kennedy  2008), Pic 2.

 

                                     Pic 2.  Ulnar nerve and its branches in the hand.

Josh Slane  and  his colleagues   in 2011, published a study  in  Clinical Biomechanics.  The purpose of this study was to quantitatively evaluate the effects that hand position and glove type can have on pressure over the ulnar nerve, specifically in the hypothenar region of the hand.

Thirty-six experienced cyclists participated. Subjects rode at a constant cadence and power output on a stationary bicycle with their hands in the tops, drops and hoods of a standard drop handlebar, Pic 3.  A high resolution pressure mat was used to record hand pressure with no gloves, unpadded gloves, foam-padded gloves and gel-padded gloves. Wrist posture was simultaneously monitored with a motion capture system.

Laser scans of the subject's hand were separately acquired to register pressure maps onto the hand anatomy.

                               Pic 3.  Three hand positions on a standard handle bar.

Average peak hypothenar pressures of 134–165 kPa were recorded when cyclists did not wear gloves. A drops hand position induced the greatest hypothenar pressure and most extended wrist posture.

Padded gloves were able to reduce hypothenar pressure magnitudes by 10 to 28%, with slightly better pressure reduction achieved using thin foam padding.

Conclusion of this study was that  the hand pressure magnitudes and loading patterns seen in steady-state cycling are of sufficient magnitude to induce ulnar nerve damage if maintained for long periods. Wearing padded gloves and changing hand position can reduce the magnitude and duration of loading patterns, which are both important to mitigate risk for Cyclist's Palsy during extended rides.

                                                                      Haralampos Haralampakis

                                                                               Physiotherapist

Sources:

Akuthota, V., Plastaras, C., Lindberg, K., Tobey, J., Press, J., Garvan, C., 2005. The effect of long-distance bicycling on ulnar and median nerves: an electrophysiologic evaluation of cyclist palsy. Am. J. Sports Med. 33, 1224–1230.

Andersen, K.V., Bovim, G., 1997. Impotence and nerve entrapment in long distance

amateur cyclists. Acta Neurol. Scand. 95, 233–240.

Kennedy, J., 2008. Neurologic injuries in cycling and bike riding. Neurol. Clin. 26, 271–279.

Slane,  J.,  Timmerman,Μ.,  Ploeg,Η-L.   Thelen, D,. 2011.  The influence of glove and hand position on pressure over the ulnar nerve during cycling, Clinical Biomechanics 26 (2011) 642–648