How important is your running shoe?

Choosing the “right” shoe is important to most runners, and they can make a big difference to your running, both in terms of performance and comfort. There have been big changes in the shoe industry over the last couple of decades and there are many things that have influenced shoe trends, from consumer demand to better materials and detailed scientific research.

In this article we will give brief overview of how shoes can impact your running style and can influence both injuries and performance. We’ll provide a summary of the running shoe industry today and how it fits with current thinking in the scientific and medical worlds.

Before we start discussing shoes in more detail, it’s important to cover the factors that influence a running injury. The main ones are illustrated in Figure 1.

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Training errors play a significant role in the development of most running related overuse injuries. These include running too much, too far, too fast, too often or sometimes even not enough!

Anatomical structure, joint range of motion, muscular strength and your running gait (the way you run) also influence your running injury risk, as does footwear. All of these factors need to be considered when analysing a running injury.

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What do we want to know about a shoe?

Questions to ask when choosing running shoes are:

1. Does the running shoe compliment your running mechanics?
2. Could the shoes have influenced an injury (or have the potential to)?

ANY change of shoe will influence mechanics. Sometimes these are small changes at the foot, other times they are bigger changes proximally (higher up the body) and we’ll be providing examples of this later in the article.

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What is a Running Shoe?

Running shoes are made-up of an:

• Upper - this can be made stiffer for more support.
• Midsole - where most of the technical components are located.
• Outsole - mostly for grip and durability, but can also influence the flexibility of the shoe.

At the midsole, there are a lot of variables to take into consideration including: softness, dual density posts, heel-to-toe offsets, carbon plates, and different geometries. Each brand will use different combinations of materials to try to achieve a running shoe that feels and performs at an optimum level. The huge number of variables is what makes shoe selection so difficult.

There are some general trends in the industry, which means you can often find similar shoe characteristics in most brands, with a few exceptions. Therefore, brand and shoe choice has more to do with fit and feel rather than one brand having much ‘better’ shoes than another.

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Shoe Classifications

Traditionally, running shoes are split into:

• Neutral (cushioned)
• Stability (to control movement or reduce ‘pronation’)
• Motion control (these are VERY stiff shoes to reduce movement at the foot and ankle)

There is not enough scientific evidence to claim that a supportive shoe can reduce running injuries. However, more restrictive shoes can be of benefit to control ankle motion if it is adversely impacting the motion at other joints.

The main physical difference between neutral and stability shoes is the materials with which they are made. A stability shoe is usually constructed from a stiffer (firmer density) material on the medial side (inside), which helps to restrict movement. With many brands, this is done by using a firmer ethylene-vinyl acetate (eva – a material used in many running shoes), or by wrapping plastic over the medial side of the midsole.  

Stability and motion control shoes are recommended FAR less than they used to be, especially as we move into more lightweight shoe trends.

According to Nigg et al. (2015), a runner uses what is known as a ‘comfort filter’ to select a shoe that they intuitively find comfortable to allow them to stay on a ‘preferred movement path’. It is theorised that by doing this, the runner automatically reduces risk of injury. According to Nigg, a world-renowned scientist in the field of running injuries and biomechanics, runners should prioritise comfort above all else when selecting their optimal running shoe (Nigg et al., 2015)

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The Run3D Shoe Study

Run3D tested 2 athletes in 5 different shoes each. All testing was carried-out on the same day. There were kinematic differences between all shoes, some more significant than others.

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The main findings were:

• ‍Larger changes were observed proximally (higher up the body) compared to at the foot.  
• There was a positive correlation between running kinematics and shoe comfort (the comfier the shoe, the better the kinematic results)  

This example (Figure 2.) shows the sagittal plane kinematics for one subject wearing two different pairs of running shoes. The results show that there was a large change in pelvic tilt and hip extension, but only relatively small changes at the foot. Remember it is a common misconception that the shoe will only change what is happening at the foot!

It was also noted that the more comfortable the shoe, the better the kinematic results.

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Offset – or Heel Drop

The Heel-drop or off-set of a shoe is the difference in height between the heel and the toe, for example 14mm in the shoe above.  It is generally considered that a lower heel drop can allow a person to land further forward on the foot (on the mid-foot), which can reduce the initial impact force.

Heel-drop is also an important consideration for those with calf or Achilles-related injuries, as more load is applied to these structures when foot-strike occurs on the mid- or fore-foot. For this reason, if you’re planning on changing to a significantly lower heel-drop shoe than you are used to running in, it’s recommended to do so gradually!

Barefoot running

Lieberman’s signature paper (Lieberman et al. (2010) and the popular book ‘Born to Run’ by Christopher McDougall (2009) set in motion an extensive barefoot running trend and the shoe industry had to respond with the ‘barefoot’ running shoe. It has been claimed that barefoot running is more “natural” and will reduce risk of injury, but there is very limited evidence to back it up and we wouldn’t recommend it.

Super Shoes

Or carbon plated shoes have the ability to improve running economy by 4% or more!  

The idea of super shoes was revealed to the world as part of Nike’s Breaking 2 project (2017). Their shoe claimed to reduce running economy by an average of 4%. This means that with the same energy expenditure you could run 4% faster over a marathon just by wearing their ground-breaking shoes shoes. For a four-hour marathon runner, that equates to almost 10 minutes faster with no extra effort!

Increased running economy is achieved by increasing the energy return from the shoe’s midsole and by using a carbon fibre plate to aid the action of the big toe. The geometry of the shoe also alters the runner’s biomechanics, creating what Nigg describes as a ‘teeter totter” effect. The point of application of the centre of force is moved distally, creating a greater lever arm and propelling the heel forwards.

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In Summary

• Running shoes do influence our running gait, proximally as well as at the foot and ankle.
• Don’t disregard the importance of comfort when selecting a running shoe.
• Running shoes are only part, not all, of the running injury puzzle. There are many other important factors that need to be taken into consideration.  

Note: Please note that Run3D is not currently associated with any running shoe brand and we do not advertise one specific product. Images are based purely on our photo supply and therefore brands shown are unintentional and are not to be confused with advertising.

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This blog has been written by Run3D. Any views or opinions represented in this blog are personal and belong soley to the blog owner and do not represent those of people, institutions, or organisations, that the owner may or may not be associated with in proffesional or personal capacity, unless explicity stated.

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Reference list:

• Nigg, B., Blatich, J., Hoerzer, S., & Enders, H. 2015, Running shoes and running injuries: mythbusting and a proposal for two new paradigms: ‘preferred movement path and comfort filter’, British Journal of Sports Medicine, Vol. 49, pp. 1290-1294.
• Jarvis, H.L., Nester, C.J., Bowden, P.D. et al. Challenging the foundations of the clinical model of foot function: further evidence that the root model assessments fail to appropriately classify foot function. J Foot Ankle Res10, 7 (2017).