Michael Chan

my insole 

The project explores the use of a DuPont™ material: Hytrel®, on the trainer insole to provide consistent comfort and ergonomic support for people with low arches.

The insole of a trainer is often overlooked, but it is an important factor in providing a comfortable and supportive wearing experience. Most trainers on the market come with sock-liners, not insoles, and many of them have flat footbeds that do not provide much or any arch support. A sock-liner covers the construction linings in a shoe, while an insole provides functionality to the performance of a shoe.

According to the podiatrist, approximately 80% of the population pronate when walking or running, and 40% have different degrees of overpronation. Pronation is a natural inward roll mechanism of the foot to evenly absorb impact force. Overpronation is not an injury, but a state where the foot is less capable of shock absorption. This disperses impact forces to the other parts of the body which becomes more vulnerable to injuries. People with flat feet or lower arches are known to be more prone to overpronation and wearing supportive insoles can assist the feet to function more effectively.

Over-the-counter insoles available now on the market are mostly made out of PU or EVA foam with TPU plate attached and have suggested product life-cycle of 6 to 12 months. Foam is a good shock absorption material but permanently compresses at higher temperatures and moisture levels. This compromises the supportive level of the insole over time, especially at the arch area.

Hytrel® is a material that has the flexibility of rubber and the resistance of plastic. The use of Hytrel® as the only material for the arch support eliminates the foam compression and break-in time issues with other insoles. At the optimal weight to density ratio, the Hytrel® material should provide a comfortable and flexible arch support that can maintain its consistency over time.  

The Hytrel base structure of the insole is topped with a Velcro®-attached PORON® urethane to cushion the high-pressure points of the foot at the heel and the ball. PORON® is an open cell structured cushioning material that should maintain its form over usage. The Velcro® system also allows replacement of the PORON® layer when necessary. The pull tab design should ease the switching experience of insoles between trainers.