Author(s): Clara Solves Camallonga, Sergio Puigcerver Palau, José Laparra Hernández, Sara Gil Mora and Juan Carlos González García.

Although safety footwear has an important role to play in ensuring the safety, comfort and health of workers in work environments that require the use of personal protective equipment (PPE), until now there has been no such thing as safety footwear designed specifically for women.

In collaboration with the Instituto de Biomecánica (IBV), the company DIADORA has developed Athena, a new safety shoe for women. The design of Athena has involved a study of the needs of working women, provided by working women themselves, a morphological study of their feet, and an analysis of their functional requirements.

The result is a shoe that provides an exceptional fit thanks to components designed to adapt perfectly to the user's tread, providing optimum functionality at every step.

 

INTRODUCTION

Women make up approximately 22% of the workforce in the industrial and construction sectors ( Q4 2022, source: INE - the Spanish National Statistics Institute). To ensure their safety, comfort and health in work environments that require the use of PPE, they need to use PPE specifically adapted to their needs. Safety footwear is one of the most widely used forms of PPE.

Lack of availability of sizes and styles specifically designed for women is a common problem faced by women who need to wear safety footwear at work. Typically, a number of models designed for men are scaled down to smaller sizes without taking into account the specific requirements of women. This approach leads to serious problems such as inadequate contouring to the shape of the foot, excessive weight due to the oversizing of some components, and poor adaptation to the movements of the female foot. This poor fit has a negative impact on comfort and, even more worryingly, on the safety of the wearer.

The Italian company Diadora, a leader in the safety footwear and clothing sector, has taken on the challenge of developing safety footwear and clothing designed specifically for women and has developed Athena, a new concept in safety footwear, in collaboration with the Instituto de Biomecánica (IBV). Athena incorporates:

- Anthropometric information on women's feet, to adapt the fit to the shapes and proportions of their feet.

- Specific materials to ensure optimal functionality at every stage of the gait.

- Different components, designed to improve the adaptation of the footwear to the tread.

DEVELOPMENT AND IMPLEMENTATION

The development of the new footwear involved three successive phases.

Requirements for the new footwear

Anyone developing a new footwear product needs a thorough understanding of two things to ensure the product does what it is supposed to do: the mechanisms of foot-shoe interaction, and the requirements of the potential users. Accordingly, the first phase of Athena's development was an analysis of the functional, anthropometric and biomechanical requirements of women’s safety footwear and how these requirements differed from those of men’s footwear. It also looked at the problems associated with current footwear and the needs of potential users.

- A scientific and technical review of the most relevant literature. This provided information on the biomechanical and functional requirements of the new footwear. The results showed that comfort and fit were key issues for female users of safety footwear. Other important aspects were the lightness of the footwear and the mobility of the foot.

- A study of the differences in the anthropometry of men’s and women’s feet. The IBV used its databases of feet to study these differences (Figure 1). For example, if we compare the feet of men and women with a foot length equivalent to a European size 40, which is proportionally the most common size for both sexes, we find that women's feet are significantly narrower than men's feet.

- Surveys of female users of safety footwear. Information was gathered on women’s needs, requirements and problems associated with current footwear. Cushioning, flexibility, lightness and fit were the most important aspects for the women who took part in the study, as well as the issues that caused the most problems.

Figure 1. Example of gender differences between two feet of the same size: pink male foot and blue female foot.

Design advice

The IBV provided Diadora with advice on the development of the different components of the footwear according to the requirements derived from the previous phase. This advice focused on designing a specific last for women and on optimizing the materials and geometries of the sole, the insole and the cut.

- The last. The geometry of the last was evaluated by comparing its dimensions with reference values based on the anthropometry of the female population (Figure 2 left). In addition, the ideal heel drop or height was determined in order to distribute the load between the forefoot area, which is where the metatarsal heads are located, and the heel.

- The insole. The IBV's new insole is anatomically adapted to the female foot (Figure 2, right), with the aim of supporting the foot, improving load distribution to reduce overpressure on the sole of the foot, and helping to reduce the impact transmitted to the body.

- The sole. The IBV worked with Diadora to select the materials and define the geometry of the sole to enhance shock absorption and ensure optimal friction on both dry and wet surfaces.

- The cut. The IBV made design recommendations to ensure a good fit, facilitate flexibility and provide support to the foot without causing discomfort, seeking to ensure that the footwear follows the movements of the foot.

Figure 2. Left: design of the new last; right: design of the new insole.

Functional validation of the new footwear

Diadora produced a series of functional prototypes of the new footwear, using the final materials and designs: an open-cell, bi-density polyurethane foam insole and a D-Light polyurethane foam midsole. Wear tests were carried out with women who regularly wear safety footwear (Figure 3). Issues such as fit and adjustment, various functional aspects of the footwear (flexibility, shock absorption, friction, etc.) and the overall comfort perceived by the users were assessed. Users rated the footwear as very comfortable after use, and even increased their initial rating after the footwear test. Mechanical testing of the footwear was also carried out to simulate actual use conditions (Figure 4). The results showed a significant improvement over the previous footwear in terms of lightness, flexibility, ability to distribute pressure across the sole of the foot, friction and energy return when walking.

Figure 3. Footwear fit and comfort validation tests.

Figure 4. Component tests simulating real-life conditions.

CONCLUSIONS

The availability of safety footwear specifically designed for women is a major step towards gender equality in the workplace. Athena footwear offers an optimal fit tailored to the morphology of the female foot and a design adapted to the characteristic weight and physiology of women. Its highly casual design is the result of asking and understanding what female users of this type of footwear really need, and of integrating the latest findings in anthropometry and biomechanics. The use of this footwear will be an improvement on current footwear, which is predominantly based on men's models scaled down to women's sizes. The use of this footwear will reduce the problems of fit and fatigue associated with ill-fitting footwear, thereby improving the protection and safety conditions of female users in the workplace.

ACKNOWLEDGEMENTS

We would like to thank Diadora for the trust they have placed in the IBV for the development of their new footwear.

AUTHOR'S AFFILIATION

Instituto de Biomecánica de Valencia
Universitat Politècnica de València
Edificio 9C. Camino de Vera s/n
(46022) Valencia. Spain