Last updated on December 26, 2020
A properly constructed and tuned footbed will do two things:
The increased contact area between the sole of the foot and the interior of the boot will enhance proprioceptive feedback.
Stabilizing the foot will reduce the amount of muscular activity required for balance in the lower extremities. As the footbed takes on more of the balancing task, those muscles can be used for pro-active, rather than re-active movements.
Construction is the craft. Tuning is the art.
The Wobble Problem
The wobbly foot will collapse either inward or outward until that motion is detected and corrected. The further it falls inward, for instance, the greater the mechanical disadvantage for the muscles used to restore the foot to it’s upright position. This being the case, it now takes more effort and more time to pull it back to center.
There are three problems with this in the alpine context:
First, time spent on correction is time spent moving across the snow in a particular direction, possibly not where you intend to go.
Second, effort spent on correction is effort not available for desired directional control of the platform.
Third, as the foot falls to one side, it provides unintentional pressure and edging inputs to the platform. This in turn requires further correction, which takes more effort, more time, more distance, etc. The athlete can certainly become more proficient at correction, but why correct something with muscle, when you can resolve it mechanically?
The phrase ‘arch support’ is a bit of a misnomer, in that a proper arch derives strength from it’s form, not the underpinnings. In classic stone arch construction, the individual blocks are supported by a temporary structure (also called ‘falsework/centering’) until the final key stone is installed, at which point the bracing is removed. If it’s left in place, the load carried by the arch structure itself cannot be properly directed toward each end of the arch. Instead, the arch pushes down on the bracing, the bracing pushes up on the arch, and the structure begins to crack and fail.
The takeaway here is that a product that relies primarily on strong arch fill as a means of supporting a wobbly foot might do more harm than good, particularly under fluctuating load.
That said, generic arch support can help to stabilize, so long as it meets two criteria:
First, it has to be firm enough that when the foot rocks to one side, it’s presence can be identified by the somatosensory system.
Second, it has to be soft enough so as not to adversely affect or inflame the connective tissue under the foot.
When both conditions are met, the following takes place: As the foot begins to collapse inward under load, the arch fill is quickly detected, at which time muscles can be fired to stabilize the foot. If the range of the wobble is constrained in this manner, the foot can remain closer to ‘upright’ with less stress on the system.
To summarize: non-obtrusive arch supports can assist in stabilizing a wobbly foot, but they don’t stabilize in the mechanical sense, and therefore don’t optimally reduce muscle activity in the lower extremities. Nor will they account for what happens when the loads of skiing or snowboarding exceed the ‘pull’ capacity of the stabilizing muscles.
Mechanical stability starts with an understanding of how a foot works in context.
The foot is a structural variant of the hand, one that should serve as a solid base of support for a variety of movements. While there are twenty-six bones in the foot, it’s most useful to think of the structure as a tripod. Three points of contact are inherently more stable than two, or four, so long as the structure behind those points is solid.
The three primary points of contact in the foot are the heel, the first metatarsal head, and the fifth metatarsal head. The latter being the distal ends of the bones to which the first and fifth toe attach. In my experience, the truly solid foot is a rarity. It’s most common to see some upward deflection at the first metatarsal head. This upward mobility allows the foot to roll downward toward the arch under load. This collapse is often referred to as pronation.
If the fifth metatarsal deflects, the foot can roll outward, and this is called supination.
It should be apparent by this point that neither pronation or supination are ideal for skiing or snowboarding.
The fix is to identify the nature and extent of structural anomaly, then account for it’s effect so the tripod remains stable.
This is what I do.
BeckmannAG footbeds go beyond simply imprinting your feet, to a tuned support for your unique movement signature. This requires a particular mix of time, materials, and skill.
I began skiing in the early 70’s. I’ve been modifying my boots since the late 80’s, and fabricating footbeds since 1997. I’ve learned a few things along the way; things that can help you reach your athletic goals.