Riding bicycles is undoubtedly good for us: great for fitness, cardiovascular health, and burning off those delicious high-energy foods when we over-indulge. But a range of insidious chronic ailments can affect cyclists who spend extended periods on their bikes.
Research published recently in the Journal of Sexual Medicine suggests that regular cycling can potentially affect the sexual health of women. While not a new idea, the latest work finds that what matters most is the configuration of the bicycle and its consequences for riding position.
Reports dating back many years indicate that excessive cycling may lead to infertility in males. This is probably due to impaired thermoregulation of the testes, which must be kept cooler than internal body temperature to maximise healthy sperm production. But another family of genital complaints has a different cause. Most common is genital numbness, or loss of feeling, potentially leading to erectile dysfunction.
To understand how these conditions arise from cycling, let’s look more closely at the anatomy of the pelvis and genitalia, together with the nerves and blood vessels supplying the area.
Under pressure
Biomechanically, the pelvis is a series of boney arches connecting between the lower vertebral column and the legs which can absorb very large loading forces. When we sit upright, with our legs flexed forwards at the hips (as when sitting at a desk, for example), our weight is supported by an expanded part of the pelvis deep in each buttock (the “ischial tuberosities”).
Our external genitalia (male or female) sit below the front arch of the pelvis (the “pubis”) and are mostly out of the way in a normal sitting position.
But things change if we assume the extreme forward-leaning position that cyclists employ to reduce wind resistance. The weight of the body onto the bicycle saddle is still taken mostly by the ischial tuberosities, but the hips are flexed and the pelvis is now tilted forward. This orientation can create undue pressure between the genital region and the bicycle saddle.
Excessive pressure on the genitalia can cause local inflammation and swelling. A less obvious problem, however, is pressure on the nerves and blood vessels that supply the genitalia.
The external genital tract has a rich blood supply necessary for erection and glandular secretions during sexual activity. Changes in blood flow are regulated by a complex system of nerves that mostly operate without our conscious control.
Losing your nerve
Another set of highly sensitive nerves respond to mechanical stimulation of the genital tract. The endings of all these nerves communicate with the spinal cord via a major neural pathway, the “pudendal nerve.” The trouble for cyclists is that this nerve, and its associated blood vessels, pass very close to the pubic region of the pelvis on their way to the genitalia.
When in their characteristic streamlined, forward-leaning position, cyclists can put excessive pressure on the pudendal nerve, as the front of the saddle pushes up against the pubis. Nerves don’t cope well with constant physical pressure. At first, the pressure produces abnormal firing patterns, which are interpreted by our brains as the feeling of “pins and needles”. This strange feeling should be read as a warning sign: your nerves are potentially in trouble!
If pressure on the nerve is not released, the nerve fibres may no longer transmit their messages. Should the damaged nerves be sensors, we experience numbness in the area they usually monitor; should they regulate blood flow, functions dependent on blood flow, such as erection, will fail.
The situation is compounded if the blood vessels themselves are also compressed. Maintained blockage of blood flow to any part of the body will lead to oxygen deprivation and potentially death of the tissue.
Not the end
So what can cyclists do about this? Options include changing saddle design to reduce pubic pressure, and making sure you rise up off you saddle when going over rougher terrain. And the research in the Journal of Sexual Medicine finds that simply raising the handlebars a little compared with the height of the saddle, thereby slightly reducing the pressure on the pudendal nerve, can significantly reduce genital numbing in female cyclists. Although they didn’t examine longer-term effects, the implication is that this will reduce the risk of impaired genital function.
As valuable as these new observations are, it is important not to devalue the nett health benefits of cycling for most people. Nevertheless, perhaps we should heed the advice of the Irish novelist, Flann O’Brien (Brian O’Nolan) in The Third Policeman and his theory of “atomics”, later upgraded to the theory of “mollycules” in The Dalkey Archive: “The gross and net result of [excessive cycling] is that people who spend most of their natural lives riding iron cycles over the rocky roadsteads of this parish get their personalities mixed up with the personalities of their bicycle as a result of interchanging of the atoms (mollycules) of each of them and you would be surprised at the number of people in these parts who are half people and half bicycles.”
Murray Webster
Forestry-Ecology Consultant/Contractor
So, ... my upright riding position on my mountain bike with relatively broad seat is probably OK then. This is really a problem for road-cyclists on racing bikes?
Lorna Jarrett
PhD candidate, science education; Physics teacher
Important point!
Ian, can you please clarify whether this applies to all cyclists or only people on road bikes with handlebars down at saddle-height?
Seems to me that unnecessary scare-mongering is going to drive people away from cycling even more, including people who'd never consider getting on a road bike.
Ian Gibbins
logged in via Facebook
Yes - the original research article was referring only to riders with the handlebars down low already. I hoped I made this point clear (in the bit just under the micrograph). I was really surprised at the statistics that have been published showing the prevalence of these conditions.
Lorna Jarrett
PhD candidate, science education; Physics teacher
Thanks Ian,
I'd suggest then, changing the title from "Cyclists..." to "Road-bikers..." and putting in illustrations of the different types of bikes, to make the point clear.
I feel sure this research is going to be misconstrued by people who're thinking of, or recently have taken up cycling as a form of exercise or for commuting. In Australia, cycling is already seen as a deviant form of behaviour - we don't need anymore myths going around!
I propose we call for the Amsterdam bike as the new standard. With pink leopardskin decal and flowers on the handlebars. And right of way over everyone.
Lorna Jarrett
PhD candidate, science education; Physics teacher
I saw some very flash sprung leather saddles in Amsterdam.
Paul Richards
strategic foresight
Lorna - You will love this then, if it is good enough for a Crown Princess ........... http://www.copenhagenize.com/2012/07/crown-princess-cargo.html
Ryan Farquharson
Research Officer
The title should really read "Road cyclists with poor bicycle geometry, inflexible pelvises and weak core muscle strength beware..."
Lorna Jarrett
PhD candidate, science education; Physics teacher
Thanks Paul.
More amazing yet are the bikes with front seating for up to 4 small kids. Couples cycling hand-in-hand are also a common sight in Amsterdam - often with children standing on the parcel-carrier (looks like the upright design is working fine for Dutch fertility).
I have some wonderful photos of Amsterdam bikes, but thesis-writing has to take priority over creating online albums...
Russell Hamilton
Librarian
Lorna, I have a Dutch bike, which I hate for many reasons, but not for its seat, because I only got 20 yards from the shop before I turned around and went back and asked for a different saddle - it came with one of those rock hard leather ones.
So, we're looking at the saddles in the shop and I find one that seems nice and springy, but the guy says "That's a woman's saddle". Why? "Because it's broad, see". But it seemed the most comfortable (note: with my svelte figure, I don't particularly need a broad saddle) so now I have a transexual Dutch bike, but no problems with comfort.
Lorna Jarrett
PhD candidate, science education; Physics teacher
"a transexual Dutch bike"
After a weekend in Amsterdam, nothing would surprise me.
BTW I understand those leather saddles require some breaking in. Where (and why) did you buy your Dutch bike?
Russell Hamilton
Librarian
Hi Lorna,
I think I would have broken before the saddle did. I stupidly decided to buy my Gazelle (there's a distributor in Sydney) from a picture in a magazine. Because it had fenders, a carrier, but most especially, a light that was powered by a generator inside the hub. And I liked the idea of 'European quality'.
Well, it turned out to made of heavy, heavy steel, the light stopped working after a few months and my local bike shop can't fix it, it's hub gears are a constant problem ..... so, disappointing.
Lorna Jarrett
PhD candidate, science education; Physics teacher
Hi Russell,
I wasn't game to get on a bike in Amsterdam, but they did look huge and heavy. I suppose the closest thing they have to hills are the bridges over the canals - ans they don't half come whizzing down them.
However I did enjoy the relaxed and casual attitude that seems to permeate cycling in Amsterdam - no helmets, no lycra, couples and families cycling together, insane paint-jobs and plastic flower decorations. And all this despite the climate! Couldn't have anything to do with all those coffee shops could it?
Russell Hamilton
Librarian
Lorna - you might enjoy the segment of this program:
http://www.rnw.nl/english/radioshow/whats-mine-mine
called "The bakfiets sting" (A bakfiets is a kind of Dutch bicycle that looks more like a wheelbarrow on wheels). I would have thought Holland was a safe place for bikes ... apparently not!
Seamus Gardiner
Citizen
Not nice to read before my morning ride...
Read moreThis is a complex probelem out in the real world.
The relative risk of ED in cycling is comparable to running. The aetiology (in cycling) is chronic compression of the perineal artey or sudden/repeated trauma (ie from mountain bike riding/ rough roads){sorry murray mountain bikers are probably more at risk}.
Studies in the matter have demonstrated that wider saddles mitigate the problem as does a gel interface (over foam). Having a saddle with no…
Riddley Walker
.
Choice of saddle must be personal, but my Brooks B12 is way more comfortable than any gel saddle I have used. It has quite a lot of "give and flex", whereas the gels are on a hard plastic base.
Seamus Gardiner
Citizen
Hi Ridley,
yeah I'm not a big fan of gel either, I was just pointing out that what research has been done in this field has come up with some conclusions about reducing perineal pressure (wide saddles, gel etc).
The studies have not been very comprehensive, however, and my opinion is that more needs to be done looking at fitting shape to rider rather than make sweeping statements based upon a few studies.
A lot of new racing saddles use flexible hulls to deliver comfort, support and to reduce perineal pressure... I have never used a brooks saddle but i know people swear by them.
Geoff Russell
Computer Programmer, Author
Male racing cyclists use seats that are extremely narrow for most of their width. The idea being that (almost) the only thing that touches the seat are those ischial tuberosities ... bum bones. The only reason for the front part of the seat is that you can use it to steer with your thighs while your hands are off the bars (typically while feeding on a long ride). There are subtle differences in the seats used by female racing cyclists which I don't understand. But they too are quite narrow.
Paul Richards
strategic foresight
Width, shape, type, aside simply ensuring the saddle is at least tilted forward and not horizontally aligned, and never slightly nose up.Saddle tilted forward force the rider to rest on the rear portion of the seat and widest part of any saddle.
Read moreLook at bicycles and you will often see saddles tilted up at the front, particularly BMX riders bikes. Habits develop and are hard to break.
The rider feels no pubis pressure sitting on the rear potion of any saddle, a lesson from Lance Armstrong's…
Seamus Gardiner
Citizen
Paul,
At the risk of getting into another flame war with you, the UCI rule dictates that the saddle angle shall be no more than 3 degrees from horizontal, it doeasn't dictate that saddles should not be horizontal (horizontal being defined as a level placed upon rear and nose of saddle).
http://www.uci.ch/Modules/BUILTIN/getObject.asp?MenuId=&ObjTypeCode=FILE&type=FILE&id=NTI0MDY&LangId=1
http://www.bicycleretailer.com/downloads/news/Horizonzality%20of%20the%20saddle_Bottle%20position%20and%20dimensions_Industry_EN.pdf
Paul Richards
strategic foresight
Sean P - Thank you. You are correct, level saddles are seen as legal in competition, I stand corrected, I inverted my meaning. I had used Jan 2012 UCI rules and that was 2.5. If you say it is three that is fine, they do change rules, and my reference was to time trials. http://velonews.competitor.com/2011/12/news/saddlegate-revisited_200823#disqus_thread
Read moreStill does not alter the simple truth about sitting on the rear of a saddle and not tilting it rearward. To easy.
Is it any wonder Lance Armstrong…
Seamus Gardiner
Citizen
Most cyclists 'in the peleton' have their saddles level. Another couple of photos shows lance armstrong's saddle tilted to a less extreme angle at the front':
http://www.thehubsa.co.za/forum/topic/41200-lance-armstrongs-saddle/
http://autobus.cyclingnews.com/teamtech04.php?id=tech/2004/probikes/usps_trek
Lances saddle is not the best example as he used a selle San Marco concor which has a pronounced flare at the rear. This saddle appears tilted down because of this feature. Setting this…
Read morePaul Richards
strategic foresight
Sean P - don't have to bother with such issues as saddle setting anymore.
I stepped into an easy solution and own one of these;
http://youtu.be/65ssP0vJ5s4
Leslie Newsome
Senior Lecturer in Psychology (retired)
In my younger days I rode a racing bike in many long-distance races, and in training sessions every other morning. During the day I was a newspaper delivery boy, and then a messenger. Thus, I spent many hours in the saddle.
It didn't appear to affect my fertility as I have a daughter and two glorious grandchildren.
Lisa Ann Kelly
retired
Oh how I hate vivisectors and their unnecessary torturing/incarceration of animals. What the heck does this microscopic imaging of a guinea pig's clitoris have to do with this article? What does my clit have in common with a guinea pig's? Does this animal ride a mountain bike or a road bike?
Why not show a human clitoris? (Microscopically imaged, of course!)
BTW, my lover of 20+ years has been riding road and mountain bikes for nearly 25 years. He has no symptoms or problems . . .or have I been vigilant about the birth control all for nothing?
Josh Winderlich
logged in via Facebook
I don't think the micrograph was originally made to draw any comparisons between guinea pig and human anatomy/pathology. The article it was taken from states that the study was undertaken to improve our knowledge of the sensory innervation of guinea pig external genitalia, in which case it makes sense to section and image a guinea pig.
You needn't worry about animal cruelty in research conducted in Australia; ethics committees are excellent advocates for animal welfare who ensure both that the…
Read moreSue Ieraci
Public hospital clinician
Is there a marketing opportunity here for extra padding in cycle wear?
Perhaps the author is in the pocket of Big Lycra...
Seamus Gardiner
Citizen
Sue, I never picked you as a believer in conspiracy theory... (Big Lycra!)
Seamus Gardiner
Citizen
Sue, I never picked you as a believer in conspiracy theory... (Big Lycra!)
Sue Ieraci
Public hospital clinician
Sean - I picked up the technique from the anti-vaxxers.
Leon Smith
logged in via email @gmail.com
It's also worth mentioning that the harder you pedal (in the seated position), the less weight there is on your bum & tackle.
(Unless of course you are particularly good at pulling the pedals up with your hamstrings.)
Markie Linhart
Rouleur
Look, it's more than simply the relationship between the bars and seat. It's the whole fit - starting with the right size frame. The seat to pedal distance is probably the most critical dimension for safe injury-free riding. Most people have their seats too low, just so they can put their feet down without getting off the saddle…
The distance from the seat to bar is another - most head-stems are too short. Bar width is another - too narrow and the chest can't open enough to enable proper breathing.
If you're in any doubt as to bike fit go to a shop that has a fitting jig set-up…
Just out of interest, those hard as a rock Brookes saddles that have become a hipster-fixie must-have take 500 miles to break in and that's what the maker says!
Riddley Walker
.
Still better than gel, I reckon.