As Seen In The March 2016 issue of The Racing Post.
As part of my pre-fit interview, I ask many questions. Several of my questions are centered on numbness. Do you experience genital numbness while riding or after a ride? Do your hands go numb during a ride or experience limited function of the hands after a ride? Do your feet burn – hot foot – or go numb? The next question that follows a “yes” response would be: How long does it last? How frequent does it occur? Unfortunately, when I ask the question related to genital numbness – especially men – I will frequently get a response of “yes, but that’s normal.” Numbness is a sign of dysfunction and not normal.
Quick note: I am not a doctor or medical professional and your specific case or issue, if not alleviated through changes in your bike fit or fitness, may require consulting a medical professional. While bike fit may and often does help correct the problem, you may have another underlying medical condition.
With that said, acute or short lived numbness tends to be vascular – blood flow – in nature while chronic or long term numbness tends to be neurological – nerves. For instance, if you are experiencing saddle numbness while on the bike and you raise your butt off the saddle and it almost instantly corrects itself, it is typically a vascular restriction. However, you have done a 4 hour ride in the morning and are still numb after the ride has ended tends to be neurological in nature. Vascular issues tend to correct rather quickly once the blood is flowing again. Neurological issues tend to persist for longer periods. Neither should be a part of normal riding.
Within numbness related cycling issues, they tend to relate to 3 primary areas – genitals, feet and hands. I am adding a fourth area to the discussion today – whole leg.
• Genitals – Both men and women can experience genital numbness as a result of cycling. Numbness typically is associated with impingement or pressure on the perineum and more specifically the pudendal artery and pudendal nerve. In my studio, I now leverage saddle pressure mapping. After working with many riders across a vast array of saddles, I have found there no cookie cutter approach here. I wish I could say – as I did in the past – that a cutout alone will correct the pressure related to genital numbness. Review: saddle shape, width, cut out, relief channel, saddle tilt angle, fore/aft and height, cycling shorts.
• Feet – In cycling, it is commonly referred to as “hot foot.” Medically it is called metatarsalagia. This occurs when the bones of the foot through force or structure put pressure on the nerves and vessels in the foot which causes inflammation in the ball of the foot. This results in a burning sensation in the foot. Review: Shoe insoles, shoe fit shape and size, cleat position, pedal system, wedges, met pads, saddle fore/aft and height, tightness of shoe.
• Hands – Whenever your hand is outside of a neutral position, you can invite the impingement of nerves and vessels. I like to see a rider holding the bars with a neutral wrist – like you would find when shaking someone’s hand. The most common issues stem from the median nerve and the ulnar nerve. The median nerve affects more of the hand and the ulnar nerve affects the pinky finger and the outside of the ring finger. Excessive pressure on the hand or the angles in which the hand meet the bar could be the cause. A weak core and/or upper body may also be a factor. Review: hand position on the bars, bar width and shape, saddle angle, saddle fore/aft, upper body and core strength.
• Whole Leg – I have added whole leg numbness to the discussion primarily because it is a lesser known issue with potentially grave results. I became aware of this at the Cycling Specific Injury Management session at Retul in 2014. Whole leg numbness can be the result of kinking the iliac artery. This artery can become kinked thus impeding or completely shutting off the blood flow to the legs. The iliac artery becomes the femoral artery as it passes through the pelvic region – specifically the inguinal ligament. The femoral artery is the primary blood supply to the legs. While it may be related to your position on the bike, this should not be ignored. It should be addressed immediately with a medical professional. I recently worked with a rider that was experiencing this. He was un-aware of exactly what was going on. Under the intense load of training or racing, he would experience significant loss of power, leg pain and leg numbness. He reported that when he stood up, he would feel a cool rush through his legs – the blood flow returning. His previous position resulted in a very low back angle and a closed hip. “Research tends to agree now that an extremely high blood flow, repetitive hip flexion and closed hip angle associated with a more aerodynamic position are the main contributing factors”1 (Burt 104). As much as we love the look of that slammed stem, it may become a problem if it closes the hip to much. Medical Attention and a professional review of your bike fit is required.
1. Burt, Phil. Bike Fit. London: Bloomsbury Publishing Plc, 2014. Print.