Final ReportSummary - HEELLESS (Development of a heelless shoe to reduce injury during running)
Project context and objectives:
The HEELLESS overall aim was to develop and optimise a light-weight new type of running shoe, with the main characteristic.
The more specific objectives of the HEELLESS project have been dedicated to:
(i) refining the materials needed for the novel components of the heelless running shoe, as well as
(ii) to validation of the heelless concept.
Ad (i)
This includes the materials and shapes needed for the outer sole, which is very different from the average running shoe as it will lack a heel. For this reason, an additional component - the sole plate, which must support the entire foot - must be thoroughly researched, in terms of material, composition, physical and mechanical properties and the shape to ensure that these materials can carry out the function of the sole plate and remain comfortable for the user.
In brief, the objectives of HEELLESS were to design and develop a heelless running shoe that will:
- decrease the force experienced at foot-floor impact by at least 50 %;
- enable running without injury for a twice longer period than with conventional running shoes;
- have an improved optimised rigidity and strength of the top sole layer and the midsole with at least 150 %, by applying natural fibre (flax, hemp or jute) reinforced plastics.
Ad (ii)
Validation included both laboratory tests and field tests:
- had a material cost reduction of at least 40 %, a few % fall-out and high production quality and a closed loop and clean process of the sole;
- evaluated to what degree wearing the shoe alters postural control, gait pattern and running style;
- tested the shoes for comfort, performance and durability, while worn by end-users.
Project results:
In relation to the project scientific and technological (S&T) objectives, of improving rigidity and strength of the top sole layer, first all partners assembled their knowledge (including confidential background) to establish the starting point for the materials properties of the shoe. Specific, measurable qualities (mechanical, physical properties of the components, the appearance, comfort, durability of the shoe etc) were defined to ensure that a compromised, yet optimised set of parameters was established. Additionally, the SME partners defined an innovation strategy for the R&D activities. These requirements included definitions of material, ecodesign aspects, construction and process definition of prototypes of heelless shoe products. On the basis of a SWOT analysis, specifications of the shoe have based on the market requirements, and a clear market analysis of the shoe, including user requirements, have been carried out with input from all SMEs and RTD performers. Final decisions regarding the marketing parameters of the final shoe were established, including product price, product appearance, product durability, product performance, and product environmental impact. These parameters were converted into technical requirements and properties of the shoe and its constituting components.
Material and processing research
Material and production research focussed primarily on the material used for the heelless sole of the shoe. This material is a composite made from natural fibres in a thermoplastic matrix. Based on the overall project objectives and specifications, material research was carried out to identify the most optimal combination of fibre, yarn, type of fabric, thermoplastic matrix and compression method has been carried out, in order to achieve the objective of cost reduction of materials, a high production quality, and closed loop and clean process method necessary for the sole of the heelless shoe. Different process methods and different compression machines were utilised to develop a test production line where product tests were made to establish the development state of a NFRP production line. A mission-critical aspect is the condition and the cleansing of the natural fibre textile. Pre-treatment processes such as retting, hackling, combing, cleaning, spinning of the yarns as well as filament opening methods were tested and further optimised. Testing and optimisation of the fibre isolation process, with respect to the optimisation of fibre strength used for the semi-finished products were carried out. A textile that could be well impregnated and is strong enough for the sole of a sports shoe has been developed.
Sole plate development
Once a few promising material combinations for the composite material were established, a couple of sole plate prototypes with different reinforcements were produced for initial evaluation of mechanical, price / performance, processing and ecological properties. The work involved design of the sole plate, development of production technology, manufacturing of sole plate prototypes, mechanical testing of the prototypes, analysis of mechanical tests, and validation of materials / prototype model.
The most important result has been that a groove in the sole plate is required for increased stiffness, but stiffness must be adjustable during development so to be able to empirically determine the optimal stiffness. Therefore, moulds should have an adjustable groove. For this reason, in the 'male' mould different grooves can be attached (by screwing), whereas in the counter mould ('female'), made from rubber, inserts can easily be changed by casting them in.
Shoe prototyping
Next, the manufacturing process was developed, including:
a) determination of the optimal manufacturing processing parameters;
b) material composition and handling method;
c) deformation / consolidation technology and the required tooling / hardware; and
d) continuous production and automation technology.
Preliminary field tests were performed by Adri Hartveld and Koos Rademaker (the CEO's of SMEs HTL and RSBV respectively), both performance marathon runners, of several of these preliminary prototypes (90 miles running) with Innov8-HEELLESS prototype.
Samples have been investigated by HSMD (requirements, weight, structure, chemistry of material, and alike), and is a contuing effort; changes will be made as appropriate.
Uppers materials should also be environmentally friendly and have recycling potential and adequate waste management properties. The best way for joining upper materials and the sole depends on the materials used (EVA, BioPreg/ polyesters, polyamide) and could not be established; the best method has to be adapted to the facilities / technologies of the shoe manufacturer and may involve 'conventional' assembling of upper and sole (midsole / shockplate / outer sole) by using stitching / lasting, adhesive bonding or hotmelt bonding.
Testing and validation
A study has been performed to evaluate the HEELLESS shoe on biomechanical, kinematical and energetic parameters compared to barefoot running and running in conventional running shoes. Due to time constraints only a cross-sectional design could be used. No conclusions regarding injury prevention can be made based on this study design. Speculations and conclusions on the link between specific footwear and injuries require a longitudinal study design of long duration with large subject populations.
A biomechanical evaluation of running have been performed, based on a review of the literature. This literature study was aimed at finding representative numerical values for typical biomechanical parameters of running, and was conducted by RRD and StUni. Also, a predictive biomechanical model based on parameters from the literature findings has been defined by StUni.
The literature also revealed controversies in landing on the foot: both heel strike and forefoot strike are observed, the latter in particular when running barefoot. The heelless concept is supposed to have a positive effect to the foot strike pattern and the ground reaction force, which in turn suggests an indirect positive effect on injury prevention, as force, motion control and muscle activation patterns are presumably superior when compared to conventional running shoes. Lower peaks in ground reaction forces relate to a smoother running, and less horizontal oscillation of the centre of mass due to heelless landing (i.e. landing on the midfoot or forefoot).
The ground reaction model parameters were extracted by fitting the surface to the data. A critical deformation was calculated for the stiffness and damping that allows comparison of the stiffness and viscosity between the HEELLESS and the control shoe.
It can be concluded that generally making a shoe heelless modifies the ground reaction model parameters, and this will affect the two important characteristics of the sole unit, including the soft / elastic characteristics as well as energy return efficiency.
Twenty participants were selected through specialised running shops in the Netherlands against predefined criteria (age, physical condition, etc.).
Potential impact:
The HEELLESS shoe is a directly exploitable product. Furthermore, the material for the mid sole, BioPreg, is an outcome that can be exploited in many other applications, where light-weight, stiffness and durability is of importance.
HEELLESS running shoe
The athletic footwear industry typically divides sport shoes into two macro categories:
(i) purely sport shoes, i.e. athletic footwear designed to play sport;
(ii) and leisure / lifestyle shoes, that is sport-inspired shoes essentially used for convenience and leisure (i.e. non-sport or fitness) purposes.
Within the family of sport shoes, a second segmentation of the market is generally based on sports categories, i.e. football, running, basketball, tennis, fitness, etc. but market studies reveal that specific shoes for particular sports are actually used across sports making distinction rather blurry.
Total sales of athletic footwear in 2005 were about EUR 30 billion, with running shoes the largest segment of some 31 % (EUR 9.3 billion). Interviews among sport shoe buyers reveal, however, that 30 - 40 % of the consumers buy running shoes for convenience or leisure purposes. The heelless shoe is not aimed at the non-sport applications. With these figures, the market size can be estimated at EUR 6 billion / year.
The closest competitor of the HEELLESS, in terms of benefits and specialised market would be the MBT shoe, as mentioned above. This shoe is considerably expensive; however, according to their statistics, they are now available in over twenty countries worldwide, and have sold approximately one million pairs every year, since 1996.
The market for athletic footwear is large and is growing significantly. There is certainly market potential for high-quality sports products like the HEELLESS shoe; consumers are increasingly aware of safety factors and the prevention of injuries, and they are willing to pay for high-quality products. The HEELLESS project therefore offers the SMEs participating in the project the knowledge and experience that can help them to become more competitive. By focusing on niche markets with a high-quality product through intensive cooperation with partners from around Europe, the SMEs will become more competitive and benefit significantly from the HEELLESS project.
Although the sales are difficult to quantify, an economical model has been made with the help of a spreadsheet with a number of assumptions taking into account initial market size, the predicted market growth rate, market price development, predicted market diffusion and an assumed addressable profit.
The SMEs anticipate to work further together to commercialise this shoe concept for a period of 6 - 12 months after the project and the activities include:
- shoe design, focussing on customer appeal;
- further testing;
- organising demonstration workshops and trial runs;
- packaging development and user information sheet;
- preparing market roll-out, including promotion materials nad instruction video.
Lead time reduction with new product developments in determining optimised formulation and product design, as the final result can be achieved with less compound trials. Improved environmental performance by utilising natural fibres:
- Less trials will ensure that less energy is used in the building of these samples.
- New business opportunities with the specifically designed HEELLESS sole plate manufacturing.
- Higher customer satisfaction and higher customer loyalty.
General health of the European population is promoted as the heelless shoe will invite more people to take on physical fitness. This can be reasonably expected because the overall effect on the skeleton and muscles is less disturbing than for the classical shoe. Physical fitness in turn is beneficial for people in the short term for their fitness condition and feeling of well-being, as well as for the longer term, as a good physical condition helps prevent obesity, heart and circulation illnesses and stroke occurrences.
Given its importance for the competitiveness of the European economy, innovation is one of the cornerstones of the Lisbon strategy to facilitate transition from a traditionally resource-intensive to a knowledge-based industry, such as running shoe manufacturing.
The 2012 Olympics will be held in London. Leading up to that event, commercialisation and use of the shoe will be intense. It is our goal that professional athletes become acquainted with our shoe, before this event and that as a result of athletes wearing these shoes, it will become popular not only with other less serious athletes, but also the general public. To reach this goal, participation in trade shows and sporting events will be necessary. Additionally, advertising and publicity is planned through successful participation in marathons and advertising mechanisms at these events.
The partners have anticipated cooperation into commercial applications in the future. At the end of the project the partners with commercial experience will commercialise the resulting shoe, while the other participants will receive software concessions and royalties pro rata the input they provided to the project.
Biopreg material
HEELLESS has implemented a natural fibre reinforced composite for the mid-sole. This material is suitable for other applications where eco-friendly, light-weight and mechanical performace are required, such as portable goods, products for the transport sector, and products for the construction sector. It is known that e.g. glass reinforced composites are very difficult to recycle. This is not good for our environment. This was a primary reason for searching for alternative, more environmentally friendly materials. It has been found that, to the advantage of the HEELLESS shoe, that natural fibre reinforced composites are not only more environmentally friendly, they are also stronger and lighter.
Project website:
A project website (see http://www.heelless.org online) has been set-up as one of the dissemination activities to ensure that the improved comfort, performance and durability of the HEELLESS shoe, as well as reduced impact force and injury rate experienced due to wearing the HEELLESS shoe in comparison to regular running shoes, are made known to the targeted clients / market segments.
Main contact: Adri Hartveld, Healus Ltd
The HEELLESS overall aim was to develop and optimise a light-weight new type of running shoe, with the main characteristic.
The more specific objectives of the HEELLESS project have been dedicated to:
(i) refining the materials needed for the novel components of the heelless running shoe, as well as
(ii) to validation of the heelless concept.
Ad (i)
This includes the materials and shapes needed for the outer sole, which is very different from the average running shoe as it will lack a heel. For this reason, an additional component - the sole plate, which must support the entire foot - must be thoroughly researched, in terms of material, composition, physical and mechanical properties and the shape to ensure that these materials can carry out the function of the sole plate and remain comfortable for the user.
In brief, the objectives of HEELLESS were to design and develop a heelless running shoe that will:
- decrease the force experienced at foot-floor impact by at least 50 %;
- enable running without injury for a twice longer period than with conventional running shoes;
- have an improved optimised rigidity and strength of the top sole layer and the midsole with at least 150 %, by applying natural fibre (flax, hemp or jute) reinforced plastics.
Ad (ii)
Validation included both laboratory tests and field tests:
- had a material cost reduction of at least 40 %, a few % fall-out and high production quality and a closed loop and clean process of the sole;
- evaluated to what degree wearing the shoe alters postural control, gait pattern and running style;
- tested the shoes for comfort, performance and durability, while worn by end-users.
Project results:
In relation to the project scientific and technological (S&T) objectives, of improving rigidity and strength of the top sole layer, first all partners assembled their knowledge (including confidential background) to establish the starting point for the materials properties of the shoe. Specific, measurable qualities (mechanical, physical properties of the components, the appearance, comfort, durability of the shoe etc) were defined to ensure that a compromised, yet optimised set of parameters was established. Additionally, the SME partners defined an innovation strategy for the R&D activities. These requirements included definitions of material, ecodesign aspects, construction and process definition of prototypes of heelless shoe products. On the basis of a SWOT analysis, specifications of the shoe have based on the market requirements, and a clear market analysis of the shoe, including user requirements, have been carried out with input from all SMEs and RTD performers. Final decisions regarding the marketing parameters of the final shoe were established, including product price, product appearance, product durability, product performance, and product environmental impact. These parameters were converted into technical requirements and properties of the shoe and its constituting components.
Material and processing research
Material and production research focussed primarily on the material used for the heelless sole of the shoe. This material is a composite made from natural fibres in a thermoplastic matrix. Based on the overall project objectives and specifications, material research was carried out to identify the most optimal combination of fibre, yarn, type of fabric, thermoplastic matrix and compression method has been carried out, in order to achieve the objective of cost reduction of materials, a high production quality, and closed loop and clean process method necessary for the sole of the heelless shoe. Different process methods and different compression machines were utilised to develop a test production line where product tests were made to establish the development state of a NFRP production line. A mission-critical aspect is the condition and the cleansing of the natural fibre textile. Pre-treatment processes such as retting, hackling, combing, cleaning, spinning of the yarns as well as filament opening methods were tested and further optimised. Testing and optimisation of the fibre isolation process, with respect to the optimisation of fibre strength used for the semi-finished products were carried out. A textile that could be well impregnated and is strong enough for the sole of a sports shoe has been developed.
Sole plate development
Once a few promising material combinations for the composite material were established, a couple of sole plate prototypes with different reinforcements were produced for initial evaluation of mechanical, price / performance, processing and ecological properties. The work involved design of the sole plate, development of production technology, manufacturing of sole plate prototypes, mechanical testing of the prototypes, analysis of mechanical tests, and validation of materials / prototype model.
The most important result has been that a groove in the sole plate is required for increased stiffness, but stiffness must be adjustable during development so to be able to empirically determine the optimal stiffness. Therefore, moulds should have an adjustable groove. For this reason, in the 'male' mould different grooves can be attached (by screwing), whereas in the counter mould ('female'), made from rubber, inserts can easily be changed by casting them in.
Shoe prototyping
Next, the manufacturing process was developed, including:
a) determination of the optimal manufacturing processing parameters;
b) material composition and handling method;
c) deformation / consolidation technology and the required tooling / hardware; and
d) continuous production and automation technology.
Preliminary field tests were performed by Adri Hartveld and Koos Rademaker (the CEO's of SMEs HTL and RSBV respectively), both performance marathon runners, of several of these preliminary prototypes (90 miles running) with Innov8-HEELLESS prototype.
Samples have been investigated by HSMD (requirements, weight, structure, chemistry of material, and alike), and is a contuing effort; changes will be made as appropriate.
Uppers materials should also be environmentally friendly and have recycling potential and adequate waste management properties. The best way for joining upper materials and the sole depends on the materials used (EVA, BioPreg/ polyesters, polyamide) and could not be established; the best method has to be adapted to the facilities / technologies of the shoe manufacturer and may involve 'conventional' assembling of upper and sole (midsole / shockplate / outer sole) by using stitching / lasting, adhesive bonding or hotmelt bonding.
Testing and validation
A study has been performed to evaluate the HEELLESS shoe on biomechanical, kinematical and energetic parameters compared to barefoot running and running in conventional running shoes. Due to time constraints only a cross-sectional design could be used. No conclusions regarding injury prevention can be made based on this study design. Speculations and conclusions on the link between specific footwear and injuries require a longitudinal study design of long duration with large subject populations.
A biomechanical evaluation of running have been performed, based on a review of the literature. This literature study was aimed at finding representative numerical values for typical biomechanical parameters of running, and was conducted by RRD and StUni. Also, a predictive biomechanical model based on parameters from the literature findings has been defined by StUni.
The literature also revealed controversies in landing on the foot: both heel strike and forefoot strike are observed, the latter in particular when running barefoot. The heelless concept is supposed to have a positive effect to the foot strike pattern and the ground reaction force, which in turn suggests an indirect positive effect on injury prevention, as force, motion control and muscle activation patterns are presumably superior when compared to conventional running shoes. Lower peaks in ground reaction forces relate to a smoother running, and less horizontal oscillation of the centre of mass due to heelless landing (i.e. landing on the midfoot or forefoot).
The ground reaction model parameters were extracted by fitting the surface to the data. A critical deformation was calculated for the stiffness and damping that allows comparison of the stiffness and viscosity between the HEELLESS and the control shoe.
It can be concluded that generally making a shoe heelless modifies the ground reaction model parameters, and this will affect the two important characteristics of the sole unit, including the soft / elastic characteristics as well as energy return efficiency.
Twenty participants were selected through specialised running shops in the Netherlands against predefined criteria (age, physical condition, etc.).
Potential impact:
The HEELLESS shoe is a directly exploitable product. Furthermore, the material for the mid sole, BioPreg, is an outcome that can be exploited in many other applications, where light-weight, stiffness and durability is of importance.
HEELLESS running shoe
The athletic footwear industry typically divides sport shoes into two macro categories:
(i) purely sport shoes, i.e. athletic footwear designed to play sport;
(ii) and leisure / lifestyle shoes, that is sport-inspired shoes essentially used for convenience and leisure (i.e. non-sport or fitness) purposes.
Within the family of sport shoes, a second segmentation of the market is generally based on sports categories, i.e. football, running, basketball, tennis, fitness, etc. but market studies reveal that specific shoes for particular sports are actually used across sports making distinction rather blurry.
Total sales of athletic footwear in 2005 were about EUR 30 billion, with running shoes the largest segment of some 31 % (EUR 9.3 billion). Interviews among sport shoe buyers reveal, however, that 30 - 40 % of the consumers buy running shoes for convenience or leisure purposes. The heelless shoe is not aimed at the non-sport applications. With these figures, the market size can be estimated at EUR 6 billion / year.
The closest competitor of the HEELLESS, in terms of benefits and specialised market would be the MBT shoe, as mentioned above. This shoe is considerably expensive; however, according to their statistics, they are now available in over twenty countries worldwide, and have sold approximately one million pairs every year, since 1996.
The market for athletic footwear is large and is growing significantly. There is certainly market potential for high-quality sports products like the HEELLESS shoe; consumers are increasingly aware of safety factors and the prevention of injuries, and they are willing to pay for high-quality products. The HEELLESS project therefore offers the SMEs participating in the project the knowledge and experience that can help them to become more competitive. By focusing on niche markets with a high-quality product through intensive cooperation with partners from around Europe, the SMEs will become more competitive and benefit significantly from the HEELLESS project.
Although the sales are difficult to quantify, an economical model has been made with the help of a spreadsheet with a number of assumptions taking into account initial market size, the predicted market growth rate, market price development, predicted market diffusion and an assumed addressable profit.
The SMEs anticipate to work further together to commercialise this shoe concept for a period of 6 - 12 months after the project and the activities include:
- shoe design, focussing on customer appeal;
- further testing;
- organising demonstration workshops and trial runs;
- packaging development and user information sheet;
- preparing market roll-out, including promotion materials nad instruction video.
Lead time reduction with new product developments in determining optimised formulation and product design, as the final result can be achieved with less compound trials. Improved environmental performance by utilising natural fibres:
- Less trials will ensure that less energy is used in the building of these samples.
- New business opportunities with the specifically designed HEELLESS sole plate manufacturing.
- Higher customer satisfaction and higher customer loyalty.
General health of the European population is promoted as the heelless shoe will invite more people to take on physical fitness. This can be reasonably expected because the overall effect on the skeleton and muscles is less disturbing than for the classical shoe. Physical fitness in turn is beneficial for people in the short term for their fitness condition and feeling of well-being, as well as for the longer term, as a good physical condition helps prevent obesity, heart and circulation illnesses and stroke occurrences.
Given its importance for the competitiveness of the European economy, innovation is one of the cornerstones of the Lisbon strategy to facilitate transition from a traditionally resource-intensive to a knowledge-based industry, such as running shoe manufacturing.
The 2012 Olympics will be held in London. Leading up to that event, commercialisation and use of the shoe will be intense. It is our goal that professional athletes become acquainted with our shoe, before this event and that as a result of athletes wearing these shoes, it will become popular not only with other less serious athletes, but also the general public. To reach this goal, participation in trade shows and sporting events will be necessary. Additionally, advertising and publicity is planned through successful participation in marathons and advertising mechanisms at these events.
The partners have anticipated cooperation into commercial applications in the future. At the end of the project the partners with commercial experience will commercialise the resulting shoe, while the other participants will receive software concessions and royalties pro rata the input they provided to the project.
Biopreg material
HEELLESS has implemented a natural fibre reinforced composite for the mid-sole. This material is suitable for other applications where eco-friendly, light-weight and mechanical performace are required, such as portable goods, products for the transport sector, and products for the construction sector. It is known that e.g. glass reinforced composites are very difficult to recycle. This is not good for our environment. This was a primary reason for searching for alternative, more environmentally friendly materials. It has been found that, to the advantage of the HEELLESS shoe, that natural fibre reinforced composites are not only more environmentally friendly, they are also stronger and lighter.
Project website:
A project website (see http://www.heelless.org online) has been set-up as one of the dissemination activities to ensure that the improved comfort, performance and durability of the HEELLESS shoe, as well as reduced impact force and injury rate experienced due to wearing the HEELLESS shoe in comparison to regular running shoes, are made known to the targeted clients / market segments.
Main contact: Adri Hartveld, Healus Ltd