NOTE: This post was originally entitled MATERIAL CHALLENGES: Scary Movie – How to lessen your ability to coordinate your actions without being aware of it. The Scary Movie part of the title has been deleted for reasons that will become obvious below.
Here is where we delve into bike fitting esoterica. There’s a lot of info on the site that is nuts and bolts stuff. Information that can be applied to improve how you interact with your bike. However, there is another level to bike fitting; the really fine detail that can make a perceptible difference for some clients, and this post is about one aspect of that.
There’s a couple of things that needs outlining before reading what follows below so as to place what you’ll read in context. If what you read seems hard to believe, there are step by step instructions following that will allow anyone with a little anatomical knowledge to duplicate what I talk about.
Firstly, read this post as background, as it will help make sense of what follows. Pay particular attention to the concept of Challenge and it’s implications.
Next a bit of history. About 7 years ago I started working on a way to quantify the degree to which the Central Nervous System (CNS) paid attention to the proprioceptive output of the feet and to restore that ‘connection’ as a priority task for the central nervous system. As you have read in Bike Fitting Philosophy – Basic Premise, I consider this a big deal. This didn’t happen instantly. It was the product of a lot of incremental realisations and discoveries over several years, each of which I could test empirically and build on. There were quite a few traps along the way; all of which I fell into. Those traps and the experience of understanding them and how to avoid them, furthered my knowledge of what is and isn’t possible when playing with procedures that ‘sharpen’ the CNS awareness of the feet.
Basically on a bike, allowing the reception of the proprioceptive output of the feet to be taken on by the CNS as a priority task all comes down to foot correction. No big deal there. The big deal is that you only have perfect long term autonomic awareness of the feet on the bike, loud and clear, if you have the individually perfect balance and placement of arch support, rear foot correction, and forefoot correction in whatever combination is dictated by the outcome of my testing procedure.. This doesn’t mean that you can’t ride a bike without perfect proprioceptive feedback from the feet; you can, but at some level, great or small, your ability to coordinate the pedaling action will not be as good and the compensations that you automatically and asymmetrically adopt that allow you to work around this lack, increases the chance of developing overuse injuries over time. Some people pedal for a lifetime without perfect proprioceptive response from the feet and don’t ever notice the lack. Others never progress beyond a certain level of proficiency or tendency to injury because of the lack. Such is the variety of humanity.
The testing procedure I evolved also showed me that a large number of cyclists require rear foot correction in addition to arch support. There is a need for forefoot correction in many cases and a need for a mix of rear foot and forefoot correction in others, but a majority need rear foot correction either alone or in combination with forefoot correction. It also taught me how sensitive to input the CNS is. A single degree of correction too little, too much, or in the wrong place, muffles the cerebellum’s awareness of the feet markedly (while pressure is being exerted on the pedals) and triggers asymmetric patterns of compensation. You need to understand here that proprioceptive feedback from the feet (and everywhere else in the body) always reaches the cerebellum. What matters is whether it is paid attention to.
The issue being that humans generate something like 1.5 million times more proprioceptive output than the CNS can ever process in any given second. The guts of my testing protocol and restoration procedure is that it allows the proprioceptive output of the feet to stand out from all of the background ‘noise’ and be taken on and acted upon as a priority task for the CNS without conscious thought. This benefits performance and reduces chance of injury via enhanced neuromuscular coordination and reduced tendency to (asymmetrically) compensate.
In the post I asked you to read above, a Challenge is any factor that decreases stability or increases any tendency to asymmetry of the rider. Challenges fall in to 3 categories, Positional, Functional and Neurological. A subsection of Neurological Challenges is what I call Material Challenges. Any Challenge to the rider will evoke a pattern of compensation. All compensatory responses to a Challenge increase the functional asymmetry of the rider and by so doing, increase the likelihood of overuse injury, because the rider is functioning with increased asymmetry while being in a more or less fixed relationship with a positionally symmetrical bike.
A simple example is the Challenge of too high a seat height. If the seat is too high, it is exceedingly rare for the rider to sit symmetrically on the seat and overextend both legs equally. Almost invariably, the rider will hang to one side (usually the right / occasionally the left) and overextend one leg more than the other.
The key thing to remember about Challenges is that many result in a lateral pelvic shift, and it is this shift which increases the functional asymmetry of the rider. The legs hang down from the pelvis, the torso extends from the pelvis, so any change to pelvic alignment can have an effect on remote parts of the body. Material Challenges can arise from unlikely sources.
Several years ago I began to experience an inability apply my procedure of quantifying and maximising proprioceptive feedback from the feet to some fitting clients. In each case these clients were using Specialized in shoe wedges. At the time I was using Bike Fit in shoe wedges as a diagnostic tool and wasn’t having any problems with them. So I removed any Specialized in shoe wedges that fitting clients had and ‘Hey Presto’ my procedures worked again, which of course, tweaked my interest.
Then Specialized released leg length compensation shims to suit a variety of pedal systems and the same damned problem arose with any clients who came if with Specialized leg length shims already fitted.
Bear in mind, that the Specialized in shoe wedges and Bike Fit in shoe wedges have the same taper and approximate appearance. Specialized shims and shims that we’ve been producing for the last 7 years perform the same task; they raise the foot above the pedal. The difference in response had to be the material of the products themselves, not the shape. After a bit of research and some educated guesswork, I felt that I had an idea what the likely problem was. So I had a comparative analysis done of the material make up of the problematic items versus the non problematic items on a mass spectrometer. The information that I gained from that means that I am reasonably sure what the problem is with the material makeup of Specialized in shoe wedges and shims.
I contribute to the Fitness Forum on CyclingNews which is a Q&A forum where cyclists can seek answers for a variety of problems. At around the same time that I got the chemical analysis report back, a query came my way via the Fitness Forum. Based on what the querier told me of his issues and equipment, I told him to remove his Specialized wedges and he should resolve the issue, which apparently it did. These and similar Q & A posts were later deleted by CN because they felt they were leaving themselves open to legal issues arising from what I was saying. Particularly as I wasn’t prepared to explain the method I had used to determine the problem.
My reluctance to explain how I came to my view about the Specialized in shoe wedges and shims was because I was part way through the process of patent grant for my testing protocol re quantifying and maximising proprioceptive feedback from the feet. Publicly revealing how I had worked out what the problem was with the Specialized stuff would have invalidated my patent applications on ‘knowledge already in the public domain’ grounds.
Well things have moved on in several ways. Firstly, the patent applications are further along but still ongoing. (Stop Press: Patent approved in U.S.A, U.K., Australia and New Zealand)
Secondly, I found a number of other items commonly used by cyclists triggered the same clouding of proprioceptive feedback from the feet. It isn’t just Specialized shims and wedges. Other items with a negative effect are some brands and models of generic arch supports for shoes, most plastic charity style plastic wrist bands, Power Balance bracelets, one brand of bicycle inner tube and rim tape, many sunglasses; certainly a majority of black plastic framed sunglasses, including many big name brands / models, and the anti glare coatings on some prescription lenses and the coatings on some sunglass lenses.
Lastly, I’ve found that there is another consequence of the inhibitory effect of these products. All result in a lateral pelvic shift in standing posture.This means that I can tell you what happens without invalidating my patent pending testing procedure. One of the purposes of this site is to provide real world empirically tested bike fitting info that works as an antidote and counterbalance to the formulaic, marketing driven stuff, of which there is an overload out there. I’ve wanted to talk about this subject for some time, so here it is.
The original idea for this post was to have a Physician that I have shown this stuff to, demonstrate the pelvic shift on camera by drawing attention to the relative heights of the subjects iliac crests on film on a before and after basis. He was willing, we had subjects, a camera man and film, but we struck a hitch. The camera had to be far enough behind the subjects to show them from head to foot. This is necessary because I wanted to show that any of the items listed below can be a problem if placed within a metre and a half of a person. With subjects stripped to the waist, the movement of the pelvis when subject to Material Challenge was obvious to all in the flesh. On film, the low contrast of a large area of white skin filmed under bright lights from several metres back and reduced to the size of a computer screen, didn’t show what I wanted nearly as clearly as in the flesh as it did with the naked eye. I mentioned this post as “coming soon” a couple of weeks ago and don’t want to drag things out and so have decided to go ahead anyway, in the sense of listing a protocol that can be duplicated by readers. My Physician friend is trying to get hold of a portable ultrasound machine. If / when that happens, then there will be an addendum to this post with the ultrasound scans of pelvic shifts added.
Follow the instructions below and you will be able to duplicate what I’ve talked about above with any problematic object providing you have enough anatomic knowledge to accurately and repeatedly find the iliac crests. This is not hard to do, but you need to know what you are looking for, so it helps if you’ve had practice. I know a number of structural health professionals regularly read the site, so if any of them care to duplicate the protocol below, I’d be interested to hear what they have to say.
1. Find a subject that does not display a lateral pelvic tilt in standing posture. This isn’t as easy as it sounds but there are plenty of people like this out there. If this isn’t possible, use whomever you have. If they have a pelvic tilt, place a partly opened magazine under the foot of the low side until the iliac crests on both sides are level. Strictly speaking, this isn’t necessary, as the pelvis will shift anyway; but if you are not practised at this, it is easier to see the shift if the starting point for the pelvis is that it is levelled between iliac crests.
2. Have the subject strip to the waist and remove their shoes and socks. Now have them sit on a low, firm stool facing away from you and extend their arms as hard as they can towards the ceiling. Check from the rear that both iliac crests are level in seated posture while they do this. This is merely to check that your subject is not one of the fraction of 1% of riders who has a pelvis that is smaller on one side than the other.
3. Have the subject stand barefooted facing away from you. Before moving on to step 4 etc, make sure that any item you are testing is at least 2 metres away from the subject. Sensitivity to these objects varies from half a metre to up to 2 metres in some people I have tested.
4. Locate their posterior iliac crests and confirm that left and right sides are level. If they are not level, note down the approximate difference in heights between left and right sides .
5. Remove your hands from the subject and have them hold a problematic object in one hand. Removing your hands is necessary so that the subject does not have pressure from your hands to help them locate themselves in space. While I prefer this method, the majority will shift if exposed to a Material Challenge whether your hands are on their iliac crests or not, and the tester will be able to feel the shift in many cases.
6. Now recheck the position of both iliac crests. You will note that the subject’s iliac crest is now higher on one side than the other. Typically 5- 20mm higher, with 10 -12 mm being the most common response. It is more common for the left iliac crest to rise but a significant minority raise the right side. If your subject didn’t have level iliac crests, there will still be a shift if the item is a problem, with the shift being in either direction. That is, if not level as a starting point, the pelvis may become more level or less level if there is a problem with the item.
7. Remove the object from the subject’s hand and make sure that it is at least 2 metres away from them. Now recheck iliac crest height and you will find that the crests are level again. Or back to their original relationship, if not level to start with.
8. Place a problematic object on the floor near to, but not touching the subject. Say 100mm (4″) – 150mm (6″) in front of them. This can be done with or without a blindfold worn by the subject.
9. Recheck iliac crest heights and you will again find that there has been a shift with one side noticeably higher than the other. Keep repeating this test while moving the object further from the subject and you will find that the effect is present with the problematic object up to half a metre away with just about anybody, and up to 2 metres away in the occasional subject.
What are the problematic objects?
MOST PLASTIC CHARITY BRACELETS
I tripped over this when fitting a rider some years ago. I used my testing protocol off the bike to determine what amount and placement of foot correction he needed and but could not get a response from his feet on the bike. After much hair pulling and frustration, I found a Livestrong bracelet wrapped around his spare tube in his tool bag. Once that was removed, end of problem. Subsequently, I started testing the effect of the plastic charity bracelets that clients came in with. This was around the time that charity bracelets first appeared. To date, the effect is the same with all of them.
SPECIALIZED IN SHOE WEDGES AND SPECIALIZED CLEAT SHIMS
I’ve mentioned the history of these at the outset above. A pelvic shift in all cases.
Many sunglass frames have a negative effect. I hasten to say not all, but of the ones that I’ve seen, a majority of black or dark coloured plastic framed sunglasses are problematic. The only brand that I have never found a problem with anyone is Salice. There is less of a problem with coloured sunglass frames. However, some coloured frames are a problem.
POWER BALANCE BRACELETS
These are a con. They are sold as some sort of performance enhancement device. I can’t see how performance can be enhanced if anyone wearing one is walking or running around with a lateral pelvic tilt.
‘NEAT FEET’ GENERIC ARCH SUPPORT (AS WELL AS SOME OTHER BRANDS /MODELS)
This particular generic arch support as well as some others is problematic. Most of the ones to avoid have a two tone colour scheme. If in doubt, test a number of people with an item that you are concerned about.
FOSS INNER TUBES AND RIM TAPES
A bicycle wheel is within the exposure distance to the rider on the bike that will affect many people.
ANTI GLARE COATINGS ON SOME PRESCRIPTION GLASSES
These and others like them are an exception. There will be no change in pelvic angle if the item is placed near the subject or held by the subject. There will be a pelvic shift when the subject wears the glasses and looks through them with eyes open. A number of people I’ve tested had 2 pairs of glasses with the same prescription, one for indoors without anti glare coating and one for outdoors with anti glare coating. In those cases the problematic ones were the ones with the anti glare coating. I have discussed this with a number of Behavioural Optometrists. Most were unaware of the issue but 2 that I have spoken with had already come to the same conclusion before ever they heard from me.
SOME SUNGLASS LENS COATINGS
I’ve seen this a number of times with the brand above as well as several others. No problem holding or being near the glasses, but a pelvic shift when they are looked through.If the lenses are removed and held, no problem. But if the lenses are removed and looked through, the pelvis shifts. So again, like anti glare coated prescription lenses, it is not the material itself, but some form of coating on the lens that is the problem. With this type of item, there are differing individual responses. I had two athletes in from a national squad. Their kit is blue and white so they had white framed sunglasses with blue mirror lenses to match that were not team issue. They had provided their own and each had a different brand. Athlete 1 had glasses that were problematic for him but fine for his team mate. Athlete 2 had glasses that were fine for both of them . After seeing what happened to their pelvises while facing a large mirror, they swapped glasses.
It is important when testing sunglasses, that when there is no apparent pelvic shift when the subject holds the glasses, that the subject is retested with the glasses on and looking through them.
So how did this situation arise?
The simple answer is that the people responsible for product development of the items above weren’t aware of the negative implications for the human nervous system of the choices they made regarding the material make up of these products. I don’t think anyone was. I fell over this because I am a keen observer and seem to notice a lot of small things that others don’t. By all means wear or use any of these items if you wish because you aren’t going to die. What will happen is that at some level, great or small, you will function more asymmetrically which in turn lowers the threshold past which you will develop overuse injuries because of a Material Challenge induced decrease in pelvic symmetry.
Several brief case studies.
The one I mentioned above . I had a gent who had a history of minor but constant knee niggles on one side. I was able to trace that to the LiveStrong bracelet he was using to keep his spare tube in place inside his under seat tool bag. Once that was removed, his pelvis functioned more symmetrically and the knee pain disappeared.
Another was a women with right side low back pain on a bike. She was more functional than average. I felt she needed a small shim under one cleat. She already had a Specialized one. I removed it and replaced it with the same height of the type we manufacture. End of problem.
I don’t want to overstate this. Injuries that occur from riding a bike, crashes aside, are always overuse injuries. In simple terms there is a problem with the interaction of an asymmetric rider and a positionally symmetrical bicycle creating strain and misalignment somewhere that sooner or later causes an injury. No one functions perfectly symmetrically and so there is an individual degree of lack of symmetry and training load after which injury occurs. If you are going to use a product that will increase your functional asymmetry, you are one step closer to developing an overuse injury by reducing that threshold. So why would you take the risk?
As a post script, the unanswered question is why?
The spectroscopic analysis I referred to above showed that the Specialized wedges and shims are composed of plastics made with a heavy metals component. Testing of some of the other items above confirms the same thing. Some plastics have a heavy metal component and human nervous systems are very sensitive to heavy metals. My assumption, and I’m happy to be corrected if anyone reading this can add anything , is that any of these items placed with in a human magnetic field triggers a compensatory response. And as I’ve said ad infinitum on this site, all compensatory responses work by increasing asymmetry.
If anyone reading this can shed any further light on this, please feel free in the Comments section below.
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