“Pedal pushers palsy” and “unicyclists sciatica” might not mean much to you, but when you can’t wee without pain and you can’t get an erection its time to get concerned. Instances of neural damage caused by normal cycling activity have come to light over the last 20 years. This article seeks to explore the causes, effects and solutions to two of the most common nerve-compression problems associated with cycling.

Picture this: A fairly inexperienced cyclist decides to take part in a two day 209 km race. After about 30 km things start to go wrong. He begins to experience severe pain in his backside and a pressing need to urinate. Whilst urinating he notices that his penis is shriveled and numb. The pain passes after a few minutes so he chooses to continue and finishes the race, although further pain forces more brief stops. He subsequently experiences a complete loss of erections lasting some three weeks, and even 5 months later they lack full rigidity and are short lived.

Or this: A student in the throws of revising for his finals wanders down to the local bike shop for a diversion. He ends up coming out with a new Mountain Bike, and spends the remainder of the day charging around, over and up anything he can find. By evening he notices a “strange” feeling in his palms, and by the following morning has lost the vast majority of grip strength in both hands. So much so that he can just hold a pen but writing is extremely difficult. Recovery is frighteningly slow exam-proximity wise, but grip-strength returns to acceptable levels within two weeks.

Control Circuit
The nervous system is the body’s electrical circuitry which co-ordinates and controls almost everything it does; from the more obvious roles in voluntary movements and sense of touch, to subconscious changes in blood vessel diameter which underlie emotional and sexual responses.
Although nerve cells are situated within or immediately adjacent to the brain or spinal cord, cell processes or “axons” emanate out to make contact with every part of the body in unbroken connections. Within the body tissues axons form bundles containing hundreds or thousands of fibres. These nerves branch and subdivide until every target is reached by the appropriate axon. To minimise the risk of accidental damage, nerves are often deep-set within the tissue but are forced to the surface at joints or bony tissues such as the hand; in such instances the nerves run along the most protected side e.g. armpit, palm of hand. The human body developed its protection strategy over millions of years whilst operating as a free-standing unit. The use of optional extras, such as bicycles, can leave normally well protected areas vulnerable to activity related injury.
Light compression of a nerve can produce unusual sensations, such as tingling or numbness, but normal function is restored almost immediately after the removal of pressure. Swelling and bruising of the nerve, or the surrounding non-neural tissue can lead to a more prolonged disruption of function, which lasts until the swelling subsides. Trauma to the nerve itself can damage the insulating layer present around many axons and lead to poor transmission of nerve impulses. Recovery is fairly slow but should be complete. If the axons themselves become damaged the flow of essential requirements from the nerve cell-body is disrupted, and the portion of the axon downstream of the injury site may die. Given time, axons can sprout from the site of lesion and re-establish contact with their target. In such cases recovery may be very slow and often incomplete. Nerves can also be indirectly damaged by pressure on associated blood vessels. This disturbance interrupts or reduces the flow of blood to the nerve depriving the tissues of oxygen and nutrients, resulting in so-called ischaemic neuropathy. Again, recovery is slow and sometimes incomplete.

Impotence: the hard facts
The perineum, lying between the anus and genitals is a prime example of a site that under normal circumstances occupies a protected position. However, add a wedge of metal and leather in the shape of a bicycle saddle and the situation changes dramatically. Impotence, anal, scrotal and penile numbness, altered ejaculatory sensation, disturbed urination, decreased awareness of defecation and, occasionally, incontinence, are all symptoms reported by cyclists with no other predisposition to such symptoms (e.g. bladder infection, diabetes). The problem has been named, somewhat appropriately, “Alcock syndrome”, after the canal which conducts the pudendal nerve across the perineum to innervate the anus and genitals. Pressure on the perineum caused by a hard saddle may result in indirect compression of the pudendal nerve within this canal which in turn can result in genital insensitivity. The extreme physical stress to which the perineum is subjected during cycling may also cause friction within the canal causing direct and longer lasting damage to the axons themselves. The pudendal blood vessels also pass through the canal, so compression has the potential to obstruct blood flow and cause ischaemic neuropathy. However, Alcock syndrome may only be part of the picture; compression of the pudendal nerve or associated blood vessels against the bones at the front of the pelvis may also be an important cause of nerve injury.
Cycling over rough terrain is likely to increase the risk of trauma to the pudendal nerve, and the choice of a good saddle was cited as a high priority at an international urology conference late last year. However, this elevated risk to the MTB rider may be balanced to some extent by the increased time spent riding out of the saddle, by more frequent dismounts (voluntary or accidental) and by the use of full suspension bikes.
It is reassuring that in the majority of cases of pudendal nerve injury a full recovery was made. Once other causes for the neuropathy were eliminated, little intervention was made by the physicians and recovery was recorded after typically 1-2 months of forced abstinence from cycling. The case cited at the start of this article seems exceptional in the duration of symptoms, and may reflect the great extent of the damage incurred.
So how can the risk of pudendal nerve damage be minimised? Most reports cited bicycle set-up and, to a lesser extent, riding technique as being central to the issue; a member of the Association of British Cycling Doctors stated that no damage should result from rides of less than 4000 km provided these two criteria are correctly addressed.

Bicycle setup
Achieving the correct saddle height is important, not only to maximise transmission of the riders power, but also to avoid nerve injury; saddles set too high or too low have been cited as causes of neuropathy. The saddle should be set such that the knees are slightly bent and foot slightly extended when the ball of the foot is on the pedal at its lowest point. The saddle itself should be horizontal or slightly nose down; nose up is bad! Bars should be a little lower than the saddle. Traditional metal frame and leather saddles, or the modern padded versions with which most MTBs are equipped, seem equally acceptable if of good quality and correctly set up. If nerve compressions recur in the face of correct set-up, then the modern saddles, particularly those aimed specifically at this problem and possessing a soft gel nose may help. (See our MTB Setup guide)

Riding Technique
Rising out of the saddle occasionally, especially if numbness is setting in, removes the source of pressure and is normally sufficient to ease the problem at this stage. On rough terrain, especially when combined with a fast descent, it is important to minimise the time spent in the saddle as the vibrational energy is transmitted directly into the body. Standing with the pedals horizontal and knees slightly bent enables much of the jarring to be absorbed by the legs. Riders who drop their saddle whilst riding over the rough should return it once better terrain is reached. Height markers scratched onto the seat-post and a quick release bolt are useful in these instances.
If you experience pain or numbness which isn’t resolved by a short period out of the saddle, it’s time to stop and check your bike set-up. If you experience symptoms which persist long after riding has ceased, take yourself (and perhaps this article) along to your GP.

It's different for girls
Curiously, women seem to be absent from reports of cycling-related pudendal neuropathy although they feature in reports of another marker of perineal stress, “cyclists’ accessory testicles”. Women obviously possess different genitals, but the pattern of nerves innervating them is akin to the male and so it would be reasonable to expect similar neurological disorders. There are several possible reasons why this does not appear to be the case:

Numb Digits
Nerve compressions in the hand are also a common cycling associated problem. These can occur after a single heavy impact, or as a result of repeated blows to the base of the palm. In cyclists the symptoms often occur after prolonged riding, particularly over rough terrain. Riding with poorly padded gloves or no gloves at all, or with unpadded bars permits riding vibrations to be transmitted directly to the palms and nerves. Most commonly reported are compressions of the ulnar nerve which runs down the little finger side of the wrist and palm. Equipment that concentrates handlebar pressure on this region, such as 2 finger brake levers and thumb shifters may exacerbate the problem. Symptoms include clawing of the little finger, and tingling and muscle weakness concentrated in the two fingers furthest from the thumb. The median nerve is more deeply set as it passes the wrist and perhaps as a result of this is less frequently seriously damaged. However, in a study of Taiwanese national squad cyclists more than a quarter showed mild damage to this nerve. Recovery from palm nerve compressions may be rapid if spotted early or incomplete if there is extensive damage. Abstinence from cycling effects a cure in most cases. The best and simplest way to avoid such nerve compressions is to wear gloves with a well-padded palm. Regular changes in grip position also help as do bar ends and suspension forks.