HOW MIDSOLE CUSHIONING CAN HELP YOU RUN FASTER
RUN FASTER WITH NEW CUSHIONING TECHNOLOGY
By Steve Manning – Podiatrist, Marathoner & Coach
There has always been a tenuous link between cushioning and injury risk. While the shoe companies have pushed their midsole compounds as having the “best” cushioning until recently it has been hard to justify the claim.
The scientific term for cushioning is shock attenuation. When looking at a normal force/time curve of impact forces the goal of cushioning in a shoe is to dampen the maximum or peak impact force. The total amount of force does not change but it is spread out over a longer time or more evenly during ground contact.
Does Cushioning Prevent Injuries?
Unfortunately, the research currently does not support cushioning reducing injury risk in running but it can change the types of injuries that are most prevalent. Biomechanics research guru Benno Nigg did a review of research that assessed the association between vertical impact force peaks and vertical loading rates and running injuries. He concluded that “there is no conclusive evidence that vertical impact forces are associated with running injury“(1).
Is softness the same as Cushioning?
The link between softness and shock attenuation may be the inverse of what you might expect. Research examining impact forces through the knee showed that running on softer surfaces increased rather than decreased the forces impacting on the knees. A 2018 study on the “Influence of HOKA running shoes concluded that: “Runners exhibited increased impact forces and loading rate when running in a maximal versus neutral shoe”(2). The loss of a feel for the ground or reduced proprioception may lead to impaired coordination of the contraction of muscles needed to dampen impact forces.
In the past the difference in midsole cushioning properties was less important than the individual runners biomechanics. Your weight and how hard you struck the ground determined the ideal firmness in the midsole required to get maximum dampening of impact force peaks.
Why do Super Shoes make you run faster?
However, of more interest lately with the introduction of super shoes is the influence on the performance of softer and thicker midsoles. These new super shoes are characterised by having: maximal midsole thickness up to 40mm; a rigid plate embedded in the midsole linked to extreme toe spring or rocker sole; and new super soft midsole compounds like Pebax.
Why is stiffness Important?
The Mass Spring model of running efficiency shows that as systems get stiffer they become more efficient(3). This may be the main reason that these new shoes work as the thickness in the midsole and the carbon plates combine to increase stiffness when running. The mechanical advantage of a thick midsole with an extreme toe spring may also be a major factor in improving running performance. Flexion of the carbon plate that stores energy to spring back and aid propulsion does not appear to be a major factor although this is the thing that most runners think is the advantage of these shoes.
How the new cushioning technology can help you!
The soft light midsoles may be the significant factor that makes these shoes feel so much better during long races. The anecdotal reports are that your legs are not hammered at the end of a marathon like they are in traditional minimalist racing shoes. The soft initial feel at contact is matched by a significant increase in the rebound properties of these new generation midsoles. While there may be a benefit in performance from the energy return this is likely less significant than being able to maintain ideal biomechanics with legs that are less fatigued and still able to dampen impact forces.
Running shoes in the 1970s first started using EVA foams in the midsole. This revolutionised running shoes comfort and performance. It then led to compression-moulded EVA which could be shaped and have variable densities. Other compounds like polyurethane have been used and mixed with EVA to increase durability, reduce weight and improve performance.
Advances in material technology have leapt ahead in the last few years. The result has been scientifically proven performances gains combined with shoes that make you feel like you are being propelled off the ground. A critical factor in this has been the new midsole materials that have helped to revolutionise running shoe design.
3 New Midsole compounds that will make you run faster.
1.Enerzy – Mizuno
Which Shoes? Mizuno Rider Neo and Sky Neo.
What’s so special about it? This is a totally new compound placed in the core of the midsole. It was created to deliver a higher than ever energy return and softness. They say it offers 293% more softness and 56% more energy return than the previously used midsoles.
The Mizuno Sky and Rider were already very comfortable shoes but the addition of Enerzy takes the smooth feel and ride in these shoes to a new level.
Definitely, a worthwhile shoe to try on and compare when it is time to get a new shoe.
2. Pebax – Saucony
Which Shoes? Pebax is used by a variety of different brands. In Saucony, it is used in the Endorphin range of shoes (Endorphin Pro, Endorphin Speed, Endorphin Shift).
What’s so special about it? It is very light so works well in maximal thickness midsoles without making the shoe too heavy to use in a race. Its superior performance comes from block copolymer technology” which utilises two different chemistries (polyether and polyamide) on the same polymer backbone while retaining the performance properties of both. This offers flexibility and elasticity, and polyamide “blocks” that enable tremendous lightness, strength, and energy return.
3.DNA Flash – Brooks
Which Shoes? Hyperion Elite 2 and Hyperion Tempo.
What’s so special about it? This Nitrogen-infused midsole compound has a very soft initial feel while offering superior firmness compared to other midsoles used in super shoes. This gives it increased durability and stability while maintaining all of the advantages of lightweight and efficiency.