Lateral or medial rolling/material fatigue

The human body is built for walking barefoot on natural terrain. This trains and strengthens the feet with every step from day to day. In contrast, civilised man walks on flat surfaces in shoes with stiff soles or heels, impairing the movement of the foot and thus weakening it. If such a weakened foot is inserted into a kybun shoe, it will probably be overtaxed at first. Lateral/medial rolling is an initial sign of this weakness.

In the kybun shoe or on the kybun mat, you can build up your foot musculature again so that your feet regain power and stability and lateral/medial rolling occurs less or not at all.


With every step, your heels roll to the inside or the outside.
The kybun shoe becomes soft on one side, and the rolling increases.

Possible foot malpositions and instability that could exacerbate the danger of ankle buckling in the kybun shoe:

  • Flat valgus foot, flatfoot
    The condition in which the longitudinal foot arch (the arch on the inside of the foot behind the balls of the feet) is flattened is called flatfoot. In extreme cases of flatfoot, full load is placed on the skin of the sole under the longitudinal arch, or the contour of the inside of the foot is concave.

    The condition in which the back of the foot is displaced to the outside, causing the inner ankle bone to protrude prominently is called pes valgus deformity. The two conditions can appear simultaneously or in such a way that a distinction cannot be made between them.

  • Unstable ankles:
    Ankle instability can arise if the ligaments have been strained or torn and have remained too loose after growing back together (mechanical instability).
    Some people have naturally loose ligaments.


Because modern daily routines (with cement floors, mobility-limiting shoes and the like) scarcely train the feet, most people’s foot musculature is severely weakened. This makes the feet less stable and more prone to rolling sideways, particularly on uneven surfaces. The kybun shoe has an elastic springy sole that allows the foot a three-dimensional range of movement. This makes improper loading (such as lateral/medial rolling) immediately apparent. The foot is much more stable in ‘normal, hard shoes’. But improper loading occurs with those as well. You can observe this on heel wear in hard soles, where it often occurs on one side only. The elastic springy kybun shoe has a great advantage: it yields immediately when weight is unevenly distributed, making one-sided loading obvious to the wearer and allowing them to counteract it. The more weight the wearer puts on the kybun sole, the more obvious the uneven loading on the foot becomes.

In most cases, only one foot rolls to the inside or outside. Why is that?

  • Most people have a strong hand and a weak hand. The same is true of the legs and feet.
  • If a person were to walk barefoot in sand every day, both feet would be trained to exactly the same extent and would therefore be almost equally strong.
  • A person trained in this way would not roll to the side at all if they wore a kybun shoe.
  • Because hard surfaces have made it easy on modern man’s foot musculature, the feet always remain weak. We unconsciously relieve the feet by engaging only one leg when standing for a long time, for example.
  • Because the unequally strong feet are challenged to exactly the same extent in the kybun shoe, the differences become immediately apparent, with one foot buckling in varying degrees in relation to the other foot.

Long-term consequences

  • Overloading/improper loading of ankle and knee
  • Leads to muscular imbalances, asymmetries and painful irritation
  • Increases the risk of falling
The kybun shoe is the perfect training shoe for those with very mobile ligaments or unstable ankles. You should definitely train your feet so that they become more stable and less susceptible to further injuries.

Conventional therapy

  • Orthopaedic insoles are often prescribed to passively stabilise unstable, weak feet.
    Stabilising, confining shoes do exactly the opposite: The foot is scarcely able to roll over and becomes increasingly weak. This leads to malpositions such as pes valgus deformity or hallux valgus and joint overload.
  • In physiotherapy, foot and lower leg muscles are actively and equally strengthened with exercises.

The kybun principle of operation – being proactive

kybun has two different soles in its product range.

If you have unstable ankles with loose ligaments or experience lateral/medial rolling in a kybun sole with a higher Rebound-Effect, we recommend that you try a kybun shoe with with a thinner sole and a lower Rebound-Effect. You will feel more secure on this sole.

In the kybun shoe, the foot relearns how to roll naturally from the heel, which makes it stronger and more mobile. The initial unstable feeling in the kybun shoe or on the kybun mat will diminish after a few days or weeks as your ankles become more active and the musculature stronger. That will allow you to keep your balance better in the kybun shoe or on the kybun mat – even on uneven terrain.

Wearing the kybun shoe every day will decrease the stability and power difference between the two feet, even if it never goes away entirely – in the same way that a left-hander can never train their right hand to be quite as good as the left. In the feet, which are the body’s foundation, it is very important that differences between left and right be corrected; otherwise, protective postures can develop, possibly triggering back, hip, knee and foot problems.

 Overview of kybun soles

Initial reactions

Specific initial reactions with unstable ankles:

Lateral/medial rolling in the kyBoot over a long period of time can lead to pain and irritation in the foot or on the side of the knee or hip. It is therefore important to prevent lateral/medial rolling and actively correct the foot position.


Click here for the general initial reactions experienced by kyBounder and kyBoot beginners: Initial reactions

kybun exercises

For information about the special kybun shoe exercises or the basic kybun mat exercises , please click here: kybun exercises

Application tips

In the beginning, it is important to ensure a correct foot position in the kybun shoe. This means that the foot should remain straight on the kybun sole without lateral/medial rolling. Any lateral/medial rolling in the kybun shoe is not the fault of the kybun shoe, but is caused by foot weakness, which must be gradually reduced through training. You will notice immediately when you place one-sided strain on your feet because the sole yields greatly in the corresponding area.

Try to focus on the foot position and correct lateral/medial rolling; this strengthens your foot musculature, which will in time prevent lateral/medial rolling of the ankle joint. Make sure that your body does not cramp up.

Be sure not to take steps that are too long, since this makes it easier to stabilise the foot over the kybun sole and reduces the tendency towards lateral/medial rolling of the ankle joint.

If walking upright in the kybun shoe is no longer possible or you notice that you are ‘standing beside the shoe’ and are unable to correct this any longer, take this as a sign of body fatigue that means that you should take a short break from wearing the kybun shoes.

Gradually increase the amount of time you wear the shoes until the strength and coordination of your feet is sufficient for walking in the kybun shoes for several hours at a time. For some people, this is possible after just a few days, while others may take longer. It is highly individual.
The kybun shoe is a training device and can, but does not have to, become an everyday shoe later.

If your foot musculature is very weak, it may make sense to make your first kybun shoe a model with a lower rebound-effect sole. This sole is more stable in the midfoot section. (Please consult your kybun partner or online support team for more information.)

Try various kybun models; some models with a higher cut provide more stability.

Opinions/customer testimonials

One benefit that I’ve come across is that when I step awkwardly on uneven ground the kybun sole absorbs the impact. You don’t go over on your ankle like you definitely would with a conventional, hard sole. Instead, unevenness under foot such as a stone or tree root is simply absorbed or taken in by the sole and I can walk over it as if there were nothing on the ground.

How did you find out about the consultation day? We visited the headquarters here in Roggwil. We had a look around for ourselves. We heard about it from lots of different people. We tried on some shoes here. All it took was 10 or 20 minutes. We felt really good in them and decided to buy them. Then we tried them out in day-to-day life. After wearing these shoes for six months, I can now say for sure that it’s much better than it was. How would you describe how it feels to wear kybun shoes? Well, how can I describe it? It feels as though you’re walking on a cloud. The only disadvantage is that you walk a bit unevenly to start with. But you get used to it. Other than that, they are very warm. I was still having problems with my left leg. I used to walk with my foot tilted outwards. That has straightened up since I’ve been wearing these shoes. The pain has also disappeared. I used to have a painful knee, probably for that reason. The doctor said he’d give me an injection for it. Then I enquired about it and he said that one cortisone injection lasts three months. It’s four months with another method, and then you have to get it again. So I decided to leave it for a while. I was exercising anyway and moving my leg about. And now I’ve got these shoes and it’s been fine ever since. Would you recommend kybun shoes to others? Yes, definitely! We just recommended them to someone earlier today. He was staying with us but was heading on to Germany and said he’d look for some in Cologne.