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SATRA assists with development of Schawbel innovation

Reporting on how cooperation in research has led to a midsole design which cushions torsional forces.

SATRA’s expertise in research and product development in partnership with our members often plays a key role in the advancement of innovative technology while verifying its durability and efficacy. As may be expected, many of these developments are confidential.

One of these recent developments has been a patented design for a midsole with the primary purpose of cushioning torsional forces that may otherwise be transmitted through the ankle to the knees and hips. Comfort is a major selling point for footwear and innovations applicable to this vital characteristic are of a major interest to footwear manufacturers. The need for vertical shock absorption – especially in the heel area – has been recognised as an important property of footwear for many years, and yet until now there has been little development activity with regard to cushioning torque.

Footwear with increased traction can increase torsional forces which, over time, can lead to discomfort. During activities that involve a swivel (pivot) action of the foot, the torsional forces typically build quickly to a peak before the traction suddenly declines, thus making possible a swivelling action of the outsole against the surface.

An innovative approach

The new development allows the torsional forces to build far more slowly and smoothly than previously while, very importantly, permitting the tread pattern to maintain traction with the ground surface. This essentially means that the outsole can swivel in a controlled manner. The resultant ‘cushioning’ effect can reduce the transmitted torsional force by as much as 50 per cent. These torsional forces are not only present in activities such as sports – they can also be the result of simple, everyday tasks, such as pushing a trolley or getting in and out of a car. The design that has been created has potential applications in both active and comfort footwear and can provide an additional degree of freedom.


The swivel sole torque buffering mechanism

As the innovation is for a midsole, it can be incorporated in footwear with any tread pattern or design – even studded or cleated products. The footwear retains the slip resistance already afforded by the tread pattern and compound used, with the addition of preventing sudden traction loss, such as may occur when making a sharp turn. Several prototypes have been produced and evaluated at SATRA using the SATRA TM449:2020 – ‘Test methods to determine rotational slip (torque) of footwear and floorings’ test method. This is a dynamic assessment that simulates the surface interaction between the footwear and the ground during a turning motion. The product design can be altered to give different levels of cushioning, in order to reduce the torsional force that is exerted by as much as 50 per cent.


Prototype swivel sole shoes

Combined expertise

SATRA has brought together inventor Phil Muirhead and US-based Schawbel Technologies to work on this project. In previous years, SATRA has assisted Schawbel in the development of its in-shoe heating technology. The combined skill set of SATRA’s development expertise and Schawbel’s know-how in taking innovation to market has already proved a great success.

Licensing of the combined technologies is now available due to a business arrangement recently established between Mr Muirhead and Schawbel Technologies. This opportunity allows companies to license the swivel patents separately or in combination with the heated insoles patents for advanced comfort. Schawbel plans to globally market on behalf of Mr Muirhead and provide support for all contractual relationships stemming from these efforts.

Schawbel Technologies, under the leadership of William Schawbel, has an impressive 40-plus years’ history of consumer product innovation with the highest quality and safety ratings. The company is headquartered in Burlington, Massachusetts, and has a worldwide network of marketing, sales and engineering resources.

How can we help?

SATRA members can contact the partnership by email at

Publishing Data

This article was originally published on page 10 of the July/August 2022 issue of SATRA Bulletin.

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