Facts not Fiction - The Science behind Cycling Orthotics: PART 2.

Footbed vs Clinician

As we discussed in Part 1, it is possible to alter load through the feet and the lower limbs with the use of cycling footbeds and as such, they are great tools for altering in shoe pressure distribution. The cycling footbed has the potential to change force and load distribution to varying degrees dependant upon three elements.

1. The foot type
2. The properties of the chosen cycling shoe
3. The footbed's intrinsic design features

1. The foot

The foot is a constant in this scenario.  You only get one pair.  However, everyone's feet are different and as a consequence adapt to a cycling footbed differently.  The foot's range of motion, muscle function and osseous structure all alter the effect of a cycling footbed.  The anatomy of the lower limb proximal to the foot also influences the treatment of the cycling foot/leg pain. This is a separate discussion which is better covered in conjunction with a skilled bike fitter/physiotherapist/osteopath. In the interests of keeping this about footbeds, I won't touch on this too much further. We might cover this with a bike fitter in another discussion.

2. The shoe

A good shoe fitted with a poor footbed will always represent a better outcome than a poor shoe with the 'finest' of footbeds.

The second variable, the shoe, is very easy to change, however getting it right is never easy. Recommending footwear for individual cyclists probably represents one of our trickiest conversations. Cyclists have a huge and complex range of options available to them when selecting a shoe. Many of these shoes also provide varying degrees of customisation including heat moulding. There is no one shoe for every cyclist and I always encourage my clients to get their shoes fitted properly from a reputable bike shop first. A good shoe fitted with a poor footbed will always represent a better outcome then a poor shoe with the 'finest' of footbeds. This is simply because the cycling shoe has a huge potential to create either comfort or pain based upon its dimensions and design. My recommendation before fabricating any insole is to get the shoe fitted 'as is' and it is then the job of the technician to make the insole fit those dimensions. If you are recommended to buy a larger shoe to fit your footbed, then run for the hills. If the shoe is too big when fitted, it will always be too big and this can have dramatic ramifications for cleat placement, toe box shaping and fastening of the shoe to the foot.

Heat moulded shoes

Many of the top tier brands now have heat mouldable options. Whilst different brands heat mould their shoes through different methods, the desired end result is to get the best fit and contour possible. It also has the advantage of making the shoe adjustable around bony and soft tissue prominences. The main outcome of the heat moulding process is to customise the shape of the upper and the width of the shoe. It remains difficult to contour a carbon shoe to the desired shape on the plantar surface of the foot. This is because any dramatic shape change under the foot will result in cleat surface distortion. This would be especially relevant in situations when the desired shape is a higher arched profile. This does not mean that these shoes aren't custom. It is about degrees of customisation and heat moulded shoes represent the highest level available off the shelf.

3. The footbed

The third variable, the cycling footbed is really what we are here to discuss. What does the cycling footbed really do, and what is involved in creating one? Are they all the same? Does is matter who makes it? I have mentioned to many cyclists over the years that the brand of footbed is not always as important as the practitioner making it and the design features that go into it's creation. Some footbeds won't have the design features that you need to get the outcome you want and understanding this comes back to training and experience.

Cycling specific

It is important that the footbed should be cycling specific for a few reasons. One is the dimensions of the device. Standard off shelf insoles often just won't fit into the shoe and push the shoe away from the foot. The other is the profile. Cycling insoles have a different profile to a walking device and as a consequence, often they are not interchangeable.

Recently, a fair degree of emphasis has often placed on making the system of footbed prescription easy and formulaic despite the complexity of the underlying mechanics of the foot and the associated range of pathologies. The bike fit process from the ankle up is more scientific then ever before. However, when the foot is reached, the process often reverts to very simple assessment criteria. Specifically, static postural assessment, pressure mapping and resting foot position represent the major criteria for the selection of a footbed. These are useful inclusions for assessment but represent only a portion of a thorough assessment.

Flat feet?

It is useful at this point in time to insert some podiatry inspired myth busting as well. Weight bearing foot shape doesn't matter as much as many think. We are anchored to concepts that classify feet based upon weight bearing shape. "You have flat feet" is often delivered in a sombre and sympathetic tone normally reserved for funerals. I have lost count of the amount of clients who offer up this information and expect to be ridiculed for their pedal anomaly. The truth is, foot 'posture' is a poor predictor of pathology. Studies have not found any conclusive evidence that flat feet cause more problems then their high arched counterparts. Which brings us to the notion of 'normal/neutral'. What is normal/neutral and is it important?

Achieving neutral position

Getting a foot back to normal or 'neutral' is perhaps the biggest fallacy in all orthotic device prescription for a few reasons. I'll list them to demonstrate to obvious naivety of the concept.

1. First you need to establish 'neutral'. We have some funky methods of doing this, but studies have differing theories of where and whether this position exists.
2. Once you have found your 'neutral', the accuracy of this measurement alone represents a level of practitioner error commonly around plus/minus 5 degrees.
3. Now you have found your version of 'neutral', what do you intend to do with it? Hold the foot there? If so, for how long? (This is even more relevant when prescribing walking orthoses where dynamic foot movement through the gait cycle requires ongoing adaptation of the foot.
4. Will your footbed be able to hold the foot in your desired 'neutral' position. Does it need to? (No footbed can 'hold' a foot. You are not glued to your insole. Overestimation of 'support' is rife in the orthoses industry.)
5. How accurate will the footbed be after it is designed and fabricated? You would be incredibly lucky to only have another plus/minus 5 degrees of margin of error here with a prescription version let alone and off the shelf option.
6. Will holding the foot in 'neutral' actually give the client the outcome they want?
7. Will holding the foot in 'neutral' be comfortable? Does the foot have the desired range of motion required to maintain your prescription?

What makes the above even more ridiculous is how footbeds actually achieve their outcomes. As mentioned in the PART 1, they change the timing, direction and magnitude of force. You don't need to change the foot's position to achieve this! You can exert kinetic change with no kinematic (think posture) change at all.

Other theorised benefits of orthotic prescription

As a side note, there is also a theory that footbeds can effect neuro-motor feedback and hence alter our proprioception and cerebellum response. Put simply, this means unconscious change in function being driven by more 'noise' being generated by altered contact points on the foot. This area has not received a lot of study and the jury is still out on how much change is achieved through this concept. EMG studies show different firing patterns of some lower leg muscles with orthotic therapy but as to whether this is helpful or not is uncertain.

As you can see, footbeds can change some very crucial elements of foot and lower limb function. That is important and it bring us to the notion of how you decide on a cycling footbed. It all comes down to the clinician forming an idea of their end mechanical goal, then providing the necessary tools to get there. It demonstrates clearly that clinician skill and experience is crucial. That will take us into part 3.