Advancing Technology in Running Shoes

The recent advent of advanced running shoe technologies, such as Nike Vaporfly, has taken the world of competitive distance running by storm. These shoes offer a unique combination of highly compliant and resilient foams with embedded rigid architecture, which improves a runner’s submaximal running economy (RE) and performance.

However, the biomechanical mechanisms of these improvements are unknown.

Personalized Fit

Personalized shoes can boost running performance and decrease risk of injury for beginner runners. The structured cushioning of advanced shoe technologies stabilizes the foot, absorbs impact force, and reduces fatigue from repetitive impacts. These features can help beginners feel confident tackling longer distances, which will encourage them to commit to and build their training routines.

A recent study explored how the use of advanced footwear influences training practices and reported outcomes in non-elite runners. The researchers surveyed 61 non-elite runners who competed in distances from 5 km to marathons. The survey included questions about demographics, training parameters, and footwear usage. Respondents were also asked to report on perceived changes in their running mechanics and injury status. The results showed moderate correlations between the number of years of AFT use and several training variables, including weekly training volume. AFT use was also associated with decreased injury rates and higher average training speeds.

While AFT is not a magic bullet that can instantly improve a runner’s performance, it can significantly decrease the energetic cost of running at a given speed by reducing the amount of energy needed to generate forward motion. For example, Nike Vaporfly shoes (with a carbon-fiber plate and compliant foams) have been shown to increase RE by 4.2% compared with a conventional “modern” EVA racing shoe with embedded architecture and less resilient foams.

The research shows that high-tech shoes can be a useful tool to improve efficiency, increase endurance, and reduce the risk of injury. However, the benefits are most pronounced when they are used in conjunction with proper training. Runners should develop strong biomechanics, train on varied surfaces, and reserve high-tech shoes for racing or key workouts to prolong their lifespan.

While AFT is becoming increasingly popular among non-elite runners, its effect on performance and injury risks remains under investigation. The reliance on self-reported survey data introduces the possibility of recall bias, which could affect the accuracy of the reported correlations. Future studies should include a control group to determine whether AFT has an independent effect on a runner’s training and injury rate. Additionally, the researchers should investigate the impact of a runner’s training environment and specific running surface on their response to AFT.

Biomechanics

Athletes have long used footwear to enhance their running performance. The most successful athletes, including elite professionals and recreational runners, have embraced innovative technologies in recent years to improve running efficiency and prevent injuries. These technologies include carbon plates and responsive foam that reduce the amount of energy needed to run at a given speed.

This increase in running economy reduces fatigue and enables faster times. Athletes can also cover a greater distance before becoming exhausted, making the sport more accessible to recreational runners and those who are interested in completing a marathon. The underlying technology for these innovations is complex. A recent study examined the effect of commercially available “postmodern” running shoes incorporating carbon plates and innovative midsole foams on the running biomechanics and injury risk factors of non-elite runners.

Researchers assessed the effects of this new footwear on the foot strike pattern, load response, and muscle force in a group of recreational runners. They recruited a diverse group of participants from a local area to participate in the study, which included runners training for or competing at distances ranging from 5 km to a marathon. Participants were asked to wear running shoes in their normal training and competition that incorporated AFT, which is defined as commercially available running shoes incorporating carbon fiber plates and innovative midsole technologies intended to enhance energy return and improve running economy.

The main distinguishing features of AFT are rigid, curved carbon-fiber plates and lightweight, reactive foams. The plates increase the stiffness of the metatarsophalangeal (MTP) joint, reducing the loss of energy due to MTP flexion. The highly resilient foams provide cushioning and structure to reduce fatigue from impact loading. The combination of these features allows the runner to maintain a lower body center of gravity, which improves stability and control of the foot during landing.

The primary effect of AFT is a 1% enhancement in submaximal running efficiency, which reduces the energetic cost of running at a given speed. The degree of plate curvature and the material and polymer properties of the elastomeric foams mediate this response.

Enhanced Sensors

As the sport of running has become more popular, athletes have continued to push their limits on the track. Recently, 3 runners broke the 4:30 mile barrier and 17 ran a sub-4:36 mark that some consider more equivalent to the men’s barrier. The common trait among these athletes was the use of a new type of footwear known as advanced footgear. These shoes have rigid plates embedded within the midsole, a structure that has been shown to enhance a runner’s submaximal running economy by increasing the longitudinal bending stiffness of the foot (LBS).

This new generation of footwear was first introduced as a high-end racing shoe called the Nike Vaporfly. Its unique design combines a rigid carbon-fiber plate and a reactive foam to improve the foot’s ability to absorb shock and redirect energy into forward motion. Since the introduction of this technology, a variety of different brands have released versions with their own distinct features. However, only a few of these shoes can be classified as AFT because they have a combination of a rigid architecture and a highly resilient, compliant, and lightweight foam. These shoes include the Nike Vaporfly, AFTNVF; Asics Metaspeed Sky, AMS; Hoka Carbon Rocket X, AHTHCX; Brooks Hyperion Elite, BHE; and New Balance Fuel Cell Elite, NFC.

In our lab, we used a displacement-controlled 3-point bend test to characterize the LBS of AFT shoes and conventional shoes using an adapted version of the standard test method described by Joubert and Jones. We also compared the hysteresis and resilience of these shoes to those of mass-matched EVA racing models. The results showed that a shoe’s hysteresis and resilience decrease with increasing time of use, but their values are still significantly higher than those of a fresh EVA shoe.

In addition, we found that the stiffness of AFT shoes increased with weekly training volume and years of shoe ownership. This finding is consistent with the assumption that amateur runners adopt AFT shoes across a range of competitive contexts to meet their specific performance demands. The lower flexibility of AFT shoes also reduces the force exerted on the metatarsophalangeal joint during walking and hiking, which may explain why this technology is preferred by mountain runners.

Sustainability

Besides their specialized design, many advanced running shoe technologies also incorporate eco-conscious materials to reduce their environmental impact. For example, the running footwear brand On uses bio-based innovations and recycled materials in their shoes to lower their carbon footprint. In addition, they use recycled packaging and employ circular economy principles to minimize their environmental impact.

One of the most promising advanced running shoe technologies is the 4% model that was introduced by Nike in late 2016-early 2017. This type of shoe is designed to improve runners’ running economy by increasing the midsole bending stiffness, stack height, and energy return foams. These features are expected to increase the efficiency of the runner, especially in marathon races. In fact, a study found that 4% models are associated with a 1.0% reduction in the world marathon records for both men and women.

To test the effectiveness of this technology, the study analyzed runners’ official marathon results from 2012-2019. The study included elite runners from various age groups and both genders. The participants also completed a questionnaire that collected details about specific shoe models and contexts of use. This allowed the researchers to evaluate the impact of AFT shoes on marathon performance.

The findings showed that AFT shoes are associated with faster marathon times and improved energy return, as well as a reduced mechanical load on the calves. The researchers speculate that this improvement is related to the increased rigidity of the curved carbon fiber plate and a more reactive foam material. Furthermore, the 4% model is designed to support the foot’s natural movement and reduce the stress on the knees and ankles.

However, the researchers note that despite the potential benefits of AFT shoes, recreational runners may not be able to fully capitalize on these advantages due to the varying abilities of different individuals. They also warn that excessive or inappropriate usage of AFT shoes can increase the risk of overuse injuries.

To help bolster the sustainability of their products, the company On uses renewable and recycled materials, and they monitor their water and chemical use. They also promote the reuse of their shoes through their Cyclon program, which offers a subscription-based recycling initiative that allows customers to exchange worn-out sneakers for new ones. The recycled sneakers are then completely repurposed into new On products. Furthermore, the company is committed to working with manufacturers that are compliant with a strict code of conduct and fair wages for employees.