You have to know that there were no consensus on the definition of a minimalist running shoe until 2015.
To reach a consensus of what is a minimalist runninf shoe, 42 experts from 11 countries has participated in a study led by researchers from Laval University. After going through a process of four rounds of question, the results were conclusive. 95% of the participants agreed on this definition :
“Footwear providing minimal interference with the natural movement of the foot due to its high flexibility, low heel to toe drop, weight and stack height, and the absence of motion control and stability devices.”
Alright, but how can you calculated the minimalist index?
Shoes are evaluated on a scale of 0 to 100.
0 to up to 5 points are distributed for each one of these five categories :
The more flexible is the shoe, the more your foot is going to be able to move easily and naturally.
First, the shoe is evaluated by testing for longitudinal flexibility. Grab the front part of the shoe and try to reach the heel part of the shoe.
Second is torsional flexibility, try to rotate the toe part in opposite direction of the heel part and see how it bends.
In short, the more flexibility, the higher score on the minimalist index!
Low Heel To Toe Drop
The drop is the difference between the height of the sole thickness on the heel part and the height of the toe part.
You get max points if the difference is less that 1 mm and no points if it is greater than 13 mm.
The more minimalist is the shoe, the more the shoe is light.
5 points if the weight of the shoes is below 125 grams and no points if the shoe is more than 325 grams.
Stack height is the term to design the thickness of the sole just under the heel. Minimalist shoe will have more thin sole than regular shoe.
Max points if the thickness is less than 8 mm and 0 points if it is more than 32 mm
Motion Control And Stability (Technologies) Devices
Minimalist shoes offered not much in technologies for stability and motion control.
Motion control shoes type are intend to be firm and to hold the foot in place while you are running. Typically, they don’t show much flexibility and they have a pretty straight design.
Stability shoes offer some motion control but more flexibility and cushioning. Commonly these type of shoes are a little bit larger on the front and the back part of the shoe.
The shoe start with 5 points and lose 1 points per technology device.
Add all these points and multiply that score by four and you will get the minimalist index. Keep in mind that the score of the shoe doesn’t guaranty quality. It only tells the degree of minimalism!
Mainly, the minimal index is a guide for the runners who wants to transition to another pair of shoe. The transition to a shoe with different minimal index should be done gradually. Experts suggest 1 month of adaptation per 10% change of the minimal index. Suppose that your shoe has a minimalist index of 30% and you want to transition to a shoe with a minimal index of 60%, 3 months would be required to fully use your new shoe within all your trainings!
Transition to minimalist shoes
Basically anyone can run with minimalist shoes. But if you have a foot condition (ex.: Plantar fasciitis, hammertoes, flat foot, tendinitis, etc.), you should check with doctor before you start.
Also, just like traditional shoes, make sure you get advice from a footwear specialist before you choose your new pair and wait for the evening before you go to the store because your foot swell during the day.
Now like I said earlier, the key to a smooth transition is to start gradually. Don’t throw away (yet) your “traditional” shoes. Too quick of a transition could lead you to injury. I suggest you begin by incorporate minimalist running a few minutes in your training for the first week. You can then increase the duration of running in minimalist shoes the following weeks. This technique will help to strengthen your arches and improve your running gait.
If you feel any pain during the transition period, STOP! It could be a sign that the progression may be too fast and that you need to slow down.
At the end of the day, minimalist shoes or not, don’t forget that the best shoe to choose is the one you are comfortable with.