Ann, this sounds nice, but I really don't like learning.

To promote a business case as well as more sustainable consumption and production patterns, there is an increase in the resale and consumption of secondhand (shoes). While the business case is growing with an expected networth of 1.27 billion USD by 2027, the resale value in terms of “health promotion” might decrease. That is because of the potential effects of shoe resale on consumer health. For example, the materials of most shoes such as for the inner and outer soles have the tendency not to be adjustable to a new consumer footprint. Because we all have a unique footprint, wearing someone else’s shoes means that our footprint does not fit and that can be problematic. Because I am not an expert in the field, I set up an interview with Prof. Dr. med. Stefan Sesselmann who specializes in orthopaedics. Through the interview I learned that buying secondhand shoes can indeed be disadvantagous because of our different footprints and to my suprise it might be better to buy new shoes instead of secondhand shoes. At the same time, it made me think that buying secondhand shoes could be health promoting too, if they had an integrated design in which the outer and inner sole of a shoe could be exchanged before, during and after resale.

Of course there is much more to it and I am happy to share the full interview with you;

Ann: When I contacted you, I mentioned that I experiment with second hand boots and I got worried about the health of my feet and the feet of my customers. I am not an expert and understand, how little I know about feet and feet health in general. How would you describe a healthy foot?

Prof Dr. Stefan Sesselmann: If you start to define health in general, you find that it cannot be defined that simple. For example, according to the World Health Organization, health is a state of perfect physical, mental and social well-being. And if you think about a foot, you could have a first physical look and find that it doesn’t show any signs of ill-health. To elaborate, you then might consider the skeleton of the foot, how it is positioned, its arche structure, and also the foots’ joints. Then there are also ligaments, tendons and so that all has to work well together, including the foot muscles. They, I would even argue are extremely important. At the same time, purely visually a healthy looking foot can also cause pain that cannot be objectified. And as in the case of spinal complaints, the psychological component can also play a role by perceiving that pain is a result of ill-physiology, when it is caused by a psychological phenomenon instead. For example, back pain has been linked to stress too as oppose to an inconvenient sitting posture only. There are no studies on the foot, but one could transfer this principle in similar ways to the foot.

Ann: I was not aware about the potential role of the psyche in relation to perceived (ill)-health of our feet. It makes me think about how little I am connected to my feet and their physiological components. There seem many factors that influence a healthy foot, if it can even be described like that. Would you say there is a shoe that is most suitable for our feet?

Prof Dr. Stefan Sesselmann:  Very general, I would say that shoes can be poison for our feet. The best thing one could be doing is to walk barefoot on a soft floor. To give you an example, when an arm is broken, a cast is placed around it, with the intend to heal it. While it is supportive, it also relieves the muscles. Taking off the cast, one can notice that muscles have become correspondingly thinner, simply because these muscles were not used for a while. A similar principle can be applied to our feet in relation to shoes. Most shoes, unlike the barefoot shoe, relieve most muscles not extremely like a cast, but worn over a longer time it does. Accordingly, shoes can turn our muscles lazy and they degrade. Here many foot problems can be found; Because of a weakened muscle structure, that is no longer competent to support the foot itself.

Ann: Oh, you know, last week I purposely bought a pair of sport sneakers, because I thought it would be the best for my feet. They seem(ed) to be very supportive, kind of tight and light to wear. Is such sneaker bad to wear then?

Prof Dr. Stefan Sesselmann: You cannot conclude something like that. For example, insoles are good for the short term, to relive acute pain, but not in the long-term. There are, for example, sensorimotor insoles, which are deliberately designed to provide stimuli and these stimuli are intended to activate muscles. They actively stabilize the foot. If I take a shoe like that for a run and don’t wear it all day, that’s okay. But again, at home, walking barefoot is definitely better. Across the wide range of shoes, you cannot say they are bad. For example, barefoot shoes activate most foot muscles. But you have to get used to it. And if I notice that my foot does not have the optimal pose, I should train it actively to begin with. Such training can also help to balance out mal positions in the skeleton through an improved muscle structure.

Ann: What exactly are mal positions and why do they occur? To ask a bit biased, do they originate from wearing the wrong shoes?

Prof Dr. Stefan Sesselmann: It means that I may not have the most optimal foot skeleton posture due to certain malalignments. These can be inherent. In addition to that, I may have been wearing shoes for many years that on top of such malalignments relieve my muscles too much. Then I may need specific shoes again to provide that supporting function.  

Ann: I understood that malalignment can be inherent. But again, can it be caused from wearing the wrong shoes too? For example, I had a shoemaker repair the shoe soles of two boots that were worn off. So, I thought if I resell them without a small refurb, the next customer might get problems with their posture and possible backpain.

Prof Dr. Stefan Sesselmann: If my foot is bent, the arch flattens out and my leg axis shifts slightly so that my knees tend to bend inwards. As a result, it feels like my knees have to carry a unilateral overload in the lateral portion of the knee. In many cases it can create asymmetry. While such asymmetry is often natural, it creates a functional difference in my leg length but also a slight pelvic obliquity. This may affect the spine and can cause back pain. An asymmetrical shoe could reinforce that. That’s why you should change shoes more often. Buying a new shoe, I can assume it to be completely symmetrical and in a sense health promoting. This might differ with a secondhand shoe, which may do the opposite depending on how long it has been worn by a different pre-owner.

Ann: Can you elaborate that?

Prof Dr. Stefan Sesselmann: For shoes it is typical that they are rather worn off from the inside or outside. It depends on the foot properties of the person who did wear these shoes before. For example, if my foot properties differ and I wear shoes of a different pre-owner, this can cause problems. However, while a worn off outer sole of a shoe is easily visible, more attention should be paid on the shoes’ inside, because there most footprints are (pre)-fixated. Because we all have a unique footprint, wearing someone else’s shoes, means that our footprint does not fit. For shoes this is problematic too, because most are made of materials that are difficult or not possible to adjust to a new foot. This differs to new shoes, that we tend to break in first.

Ann: That makes me think of that most shoes I resell have been worn for around a season and that means I resell a seasonal footprint with multiple wears a day. Could I conclude that this is even harmful, because of how pre-owned shoes counteract our unique physiology?

Prof Dr. Stefan Sesselmann: Perhaps not directly harmful, but not favorable. It is not beneficial to health. If you want to pay more attention to health than ecological sustainability, it could be recommendable to buy a new shoe or a secondhand shoe with a small previous shoe life. Because unlike textiles, the effects of a secondhand sweater on my body are rather small. But the foot, you could say is the foundation of our body. It influences the statics; when we walk, stand, run. Its a different relationship, one could say.

I think that overall, buying secondhand shoes is not bad, especially if the pre-owned shoe was worn only around 2-3 times. But if the shoe has been worn rather often, it could be rather disadvantageous. So if I would buy such shoe, I would look at it too with a critical lense. How is this shoe made? Does it suit my footprint. And when I think about environmental sustainability specifically, I could also think of whether a recycled shoe, but a new shoe is even more sustainable in terms of my health and the environment as well.

Ann: That makes me think about design for circularity and business models too. For example, there are approaches in which products should be designed to last a life-time. This should incentivize consumers to pay a higher price and products could be produced better. But you are kind of encouraged to wear only a limited pair of shoes, because they last a “life-time”. This goes a bit into the direction of resale, but also to wear the same over and over. What are your views on that? Should we wear less, but better?

Prof Dr. Stefan Sesselmann: There are studies specifically for runners that show that runners are encouraged to change shoes more often. And there are strong effects between two pairs and even a third pair has shown a positive effect. One could consider whether this is also valid for everyday shoes. I suppose that such a change could be beneficial for feet, because of such new stimuli. Different shoes have different structures and because of that stimulate different muscles. Of course the shoe owner has to get used to it. Still, it likely is not as good as to run barefoot on repeatedly uneven ground, but likely better than to always wear the same shoe.

Ann:  So even if I would find the perfect and most “sustainable” shoe that I am eager to invest lets say a couple of hundred Euros in to last a life-time. It wouldn’t be good over time, because it activates only a particular set of muscles. While the environment benefits, I might not. This makes me  question whether a most sustainable shoe can even exist or designed. What do you think?

Prof Dr. Stefan Sesselmann: We humans are very individual and our feet are just as individual. There is no one size or style that fits all. In addition to that, different shoes might be worn in different seasons and for different activities. Some people may even have 30-40 pairs of shoes. The perfect shoe, when specifically looked at from a health perspective is less about design, but it relieves our foot muscles; intrinsic foot muscles (in the foot itself) and extrinsic foot muscles (on the leg itself).  The ideal shoe affects these muscles at least, or even irritates, so that they remain in training. One could even wear a high-heeled or plateau shoe, but the dose makes the poison, as with drugs. If I can wear it once to go out for a few hours it is perfectly okay, it even positively stimulates feet, because different muscles are activated.

Ann: I may even call this ambivalent. From an environmental perspective we should overall consume less and I also hear that more consumption in terms of shoe is advantages when it comes to our physical health. Makes me think of new approaches for shoe designs and value sold too; whether health could become a more integrated part in product design for circularity. I liked your mentioning on sensory inlays. Or I might also like a barefoot shoe, if it looked a bit more casual.

Prof Dr. Stefan Sesselmann: Yes, the barefoot shoe is great, but yes, the design is very particular.

Ann: In a small research I did on consumer purchasing interests in relation to their shoes, the aspect of design was mentioned more often, indeed. But yes, I would say that’s a topic for a different interview. Thank you for your time!

Prof Dr. Stefan Sesselmann: You are welcome.

[I hope you enjoyed the interview. Feel free to reach out to me, comment and contact Prof. Dr. Stefan Sesselmann on his LinkedIn for further discussions on the topic]

References

Moorhouse, D., & Moorhouse, D. (2017). Sustainable design: circular economy in fashion and textiles. The Design Journal, 20(sup1), S1948-S1959.