Fabricating a Shoe Last: The LAST word
A few words about lasts (but not the last)
Dr. Ivo Waerlop & Dr Shawn Allen
A last is the mold or template for creating the shoe. It defines the shape of a shoe. The last can create a high, medium or low volume shoe. They can also be relatively straight or curved (this refers to the shape of the “sole” of the shoe). If you turn the shoe over and stare at the sole, mentally bisect the heel with a line going to the front of the shoe. If the line bisects it, it is a straight lasted shoe (this corresponds to the axis of the 2nd metatarsal, or slightly lateral to it). If more of the shoe falls medial to this (more of the sole on the big toe side) it has a curved last. Curved last shoes can vary in the degree of curvature. Curved last shoes are designed to help control pronation, as they provide medial support and slow its rate by causing a relative supination of the foot after heel strike (it weights the lateral border of the shoe for a longer period of time, theoretically allowing less pronation). Curved last shoes can put more motion into a foot, especially one with limited rearfoot motion (it still must pronate, but due to the lack of rearfoot motion, the forefoot must compensate and now must do so in a shorter period of time).
Last also refers to the material (or way that the material) overlays the midsole of the shoe. The last (look inside the shoe on top of the shank) is the surface that the insole of the shoe lays on, where the sole and upper are attached). Shoes are board lasted, slip lasted or combination lasted. A board lasted shoe is very stiff and has a piece of cardboard or fiber overlying the shank and sole (sometimes the shank is incorporated into the midsole or last). It is very effective for motion control (pronation) but can be uncomfortable for somebody who does not have this problem. A slip lasted shoe is made like a slipper and is sewn up the middle. It allows great amounts of flexibility, which is better for people with more rigid feet. A combination lasted shoe has a board lasted heel and slip lasted front portion, giving you the best of both worlds (theoretically).
A general rule of thumb is: You really can’t go wrong with a straight last. It will work for all feet, especially if you are using an orthotic. This is especially important with people with forefoot abductus, moderate to severe pronators and rigid feet (rear or forefoot). A forefoot abductus and severe pronator’s feet will move laterally in the shoe, often causing crushing, rubbing, cramping and blistering of the little toe against the side of the shoe. A rigid foot, because the foot needs to be able to pronate at the mid and forefoot, will have a similar problem. You can use a curved last with people with mobile or hypermobile feet, provided their pronation is not too severe (clinical judgment, trial and error).
I hope this clarifies some of the issues surrounding lasts, their shape, and usage. This will probably not be the last word on lasts, but hopefully will suffice some of the burning curiosities surrounding the subject.
* important addendum to the youtube video: please note that the last that was created has a raised heel (if you look closely). This will put the shoe and foot in relative plantarflexion. This is likely for a traditional trainer running shoe or daily dress shoe where there is a 20+mm heal lift in comparison to the forefoot platform. Beware, this is not how the foot was designed, ie. rearfoot and forefoot are supposed to be on the same plane for anatomically designed biomechanics. This plays into the mechanical features of the minimalistic shoe trend of Newtons, Vibrams, NB minimus, Atra Adam and EVE, TEraPlana etc.
We hope this was helpful,…….Ivo and Shawn……..we are, The Gait Guys