Definition of Fit
It’s What’s Inside That Counts

This week’s post is an exchange between a Realskiers subscriber (whom we call Kate) writing in response to a recent entry, Helpful Fictions, and myself.

She found it so useful she suggested we pass it on to our readers. I concur and have here done so, with my remarks in italics.

 


Kate:

It is much easier to try different skis than to ‘try’ different boots. I have been the recipient of many, “so how does that feel” questions by the guru’s ‘helping’ me. Problem is that I am not an expert to know how it should feel.

I have definitely found out how poor a loose boot is and I have definitely found out how restrictive a stiff ‘130’ boot is.

I am not a racer, but do behave like one, if given the chance and love trees and moguls as well.

Realskiers:

Correctly cradling the rear- to mid-foot and confining the lower leg to allow an optimal ankle ROM are the first objectives of any boot-fit meant for performance skiing.

Kate:

Could you expand on what optimal ankle ROM should be?

Realskiers: 

In a ski boot, 12 degrees of ankle dorsiflexion is the minimum ROM; over 22 degrees represents hyper-mobility.  

Kate:

I mean, should I be able to lift the heel of my foot off from the sole of the boot and if so how far?

Realskiers:

Ah, not so fast, Grasshopper. Heel lift can occur due to a taut calf, a limited ankle ROM or other biomechanical causes that have little to do with “fit” in the normal sense.

Barring physiological causes, heel lift can usually be achieved by leveraging hard at the ball of the foot; i.e., the ability to force the heel upwards by any and all means is not the measure.  (If the foot couldn’t do this, we’d have to hop instead of stride.) Rather, the rule is, does the heel stay planted when the boot is repeatedly flexed forward?

Kate:

Should there be any lateral movement in this ROM?

Realskiers:

Not so you’d notice. The ankle tends to move in an asymmetric channel fore and aft, but as the cuff should move with it, even movement on this axis should be limited.  The subtalar joint should be held in neutral by the boot (and insole); ergo, lateral play is not desirable and should not be detectable.  

Kate:

Seems to me (my experience) that the stiffness should be in the sides of the boot more than the front of the boot?  I am on my edge of my ski when pushing hard.

Realskiers:

In fact, you need both (in the right measure).  Anyone can “steer” by tilting the boot sideways, but no one can truly ski if this is the only steering the boot allows for.  (This particular nightmare is being revisited upon the American skiing public by a certain trendy brand, but I digress).   To ski dynamically, you need a boot that is sensitive to forward pressure.  This is precisely the problem of the person with limited ankle ROM. She can’t dorsiflex enough to influence the boot sufficiently to transfer energy to the ski, and when she does press forward, her heel lifts.  BTW, this is not an insoluble problem.  

Kate:

But the main question is, “What should proper ROM of the heel feel like to the person fitting into the boot.”

Realskiers:

The HEEL should have NO ROM during normal motions.  It needs to be planted.  The ANKLE needs 12 degrees and if it has less, the skier needs to be repositioned in the boot to optimize what limited range he/she has. The best bootfitters know how to do this. The average boot fitter won’t even recognize the condition, much less know how to address it.