The experts from TRIA Orthopaedic Center return today to discuss another common cycling issue–numbness. Marc Swiontkowski, MD discusses the common causes of numbness for cyclists and some easy steps to take to prevent it.
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Prolonged pressure on nerves produces ischemia (loss of small blood vessel blood flow) which in turn produces various symptoms. These are primarily numbness and later tingling and electric shock like symptoms. Rarely in the case of mixed nerves, prolonged pressure can produce weakness and lack of function.
For cyclists the areas of concern are the hands and the crotch. In the hands the median nerve supplies the feeling to the thumb, long, index and half of the ring finger while the ulnar nerve supplies the other half of the ring finger and small (pinky) finger. The ulnar nerve supplies the motor function (power) to a lot of the small muscles in the hand (intrinsic muscles) as well. The pudendal nerve supplies the feeling to the genitalia.
Prevention of the symptoms involved is the best strategy for avoiding these problems. In terms of pressure on the nerves in the hands, changing positions on the handle bars every few minutes is the key.
There are 5 different positions that one can place your hands on standard drop bars- even more postions are provided if you are using an aero bar extension. You should experiment which positions feel the best in terms of control of the steering and generation of power with the pedal stroke. Identify which are your 3-4 favorites and rotate through them every hour during a ride or race.
As far as the crotch goes changing positions is the key there as well. The recommendation is to stand for 100-150 pedal strokes every 5-10 minutes. This will get the pressure off the pudendal nerve and will prevent saddle soreness as well. Standing is particularly valuable when climbing hills and in this situation 50% of time standing as well as 50% sitting are reasonable goals. Standing also provides mandatory changes in hand position which will get the pressure off the median and ulnar nerves.
As with so many potential injury situations in cycling, understanding the principles of prevention is the key to success and comfort while riding for pleasure or competing in this great sport.
