Shoe Analysis - Basic Anatomy of a Running Shoe

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Original Editor - Dawn Nunes Top Contributors - Wanda van Niekerk, Kim Jackson, Lucinda hampton and Jess Bell

Introduction

A large variety of running shoes are available on the market. They vary in brands, styles, colours, and specific shoes for a specific type of running e.g. road, trail, or track. It is vital to have a good understanding of the makeup of a running shoe and to be specific about the need of the runner and what would best suit them for their training and racing. Runners may even need more than one shoe if they train on both trail and road or even require different types of trail shoes for different terrain.

Not only is there a large selection to choose from, but there has been an enormous change in shoe design over the past 100 years. Today, running shoes are technical and engineered specifically for their intended purpose and include descriptions such as support, cushioning, light weight, minimalist and barefoot. A basic understanding of these structures is necessary to effectively assess, treat and recommend shoes to runners.

Running shoes play a vital role in the biomechanics and running economy of runners. Vercruyssen et al. compared the effects of footwear and fatigue on running economy and biomechanics in trail runners. The difference between a minimalist group and traditional shod group in trail running was investigated. It was found that calf pain increased significantly in the minimalist wearing group after the trail run compared with the traditional shod group.

Motion control (supported or anti-pronation) shoes are also a consideration when choosing/selecting a shoe for a runner. Cheung et al. investigated a small group of runners and showed that the plantar force over the medial foot structures increased with mileage of running with neutral shoes but not with motion control shoes. This study was for recreational runners who have more than 6 degrees of foot pronation.

Wakeling et al. conducted a small study of six runners and showed that by altering the material hardness of the midsole of a running shoe the response and muscle activation to the loading rate of the impact forces at heel-strike can be changed.

The weight of a shoe also has an implication on biomechanical changes. Wang et al. did a biomechanical analysis of running foot strike of 20 runners in shoes of different mass – 175g, 255g, 335g and 415g. The main findings showed that the peak vertical ground reaction force increased significantly with the increase in shoe mass. This might increase the risk of injury. Interestingly, the tibialis anterior muscle was the most activated with the 175g and 415g shoe in the pre-activation phase. During the push-off phase, the semitendinosus, lateral gastrocnemius and soleus muscles displayed significantly higher activation with heavier shoes. Furthermore, the centre of pressure moved forward, and this resulted in mid foot striking. Every individual has an unique running strategy, but the mass of the running shoe may alter the strike pattern and coordination of the running strategy.  These aspects need to be considered for runners to stay in their preferred movement path.  

These studies show how the different types of shoes, and the different material of the running shoe has an impact on the runner and their muscle activation. Nigg et al. proposed two interesting paradigms; the first one being that the skeleton of an individual athlete attempts to stay in the same movement path for a given task (eg heel-toe running) which is termed the “preferred movement path”. Secondly, the comfort level of the shoe which the runner selects is due to the runner’s own comfort filter. This automatically reduces the injury risk and may explain why a trend for running injury frequencies over time does not show a specific trend.

Hoitz et al. compared three different styles of shoes (minimalist; cushioned and large heel-toe drop) to see what influence the shoe had on lower limb muscle activation. The authors concluded that a movement path can be maintained with small changes in muscle activation when running conditions are similar with similar shoes. Large adaptations in muscle activation, however, are needed when running conditions are drastically different – for example, changing from a minimalist to a cushioned or extreme heel-toe drop. When a movement path is not maintained the adaptations in muscle activation are drastic.

Research shows the importance of knowing your running shoe to fit your runner, the impact it has on muscle activation and that the comfort level of a shoe may also have a significant influence of reducing the risk of injury.

Importance of Shoe Anatomy

• Variety and significance
  • Be specific for each runner
  • Understand the goals of the runner
  • What are their aims and what to they want to achieve

These factors will play an integral role to determine what type of shoe should be recommended

More information available here: Introduction to understanding your runner; Subjective assessment of a runner

• Finding the right fit
  • Consider the following:
    • The runner’s anatomy
    • The shape of the foot
    • Pre-existing or previous conditions – certain shoes may assist in supporting certain structures and not irritate other conditions
• Fit correctly
  • to prevent blisters
  • to maintain good circulation
  • to prevent tightness especially as feet swell
  • to prevent pins and needles (paraesthesia)
  • to ensure shoes are comfortable to wear

It is important to know on what type of surface the runner is predominantly running: road, trail, or track? Does the runner need one versatile shoe for both road and trail? Is your runner wanting to have different pairs of shoes for road running and trail running? Also consider the affordability of this.

Fit the Shoe Correctly

These are guidelines but need to be adapted for each individual runner.

• Ideally fit a shoe at the end of the day
• Put the shoe on; then test while standing to see that there is a finger space in the front to allow room for the toes.
• Walk in the shoe and determine comfort
• Ensure that the heel doesn’t slide up
• Check the lacing - lace the shoe as normal to get an accurate feel of the shoe.
• Proper fitting of the shoe may prevent blisters.
• The running shoe must not be too tight – allow for feet to swell and especially for ultra runners spending a long period in their shoes.
• Some trail runners, in particular, prefer a more snug fit especially for technical terrain. This comes down to what has worked for the specific runner and personal preference.
• If the shoe is too tight it could possibly cause circulation problems or even pins and needles (paraesthesia).
• The way the shoe is laced may also have an impact on the above, even if a correct size shoe is worn.

These guidelines will help you fit the shoe well, understand the shoe and be able to have the knowledge to guide runners into which shoe may be the best for them.

Road Running Shoes vs Trail Running Shoes

Trial running shoes with lugs on the outer sole

Road running shoes and trail running shoes look different. The main difference is the outer soles, underneath, with trail running shoes having lugs and road running shoes being smooth. There are many different types of both road and trail shoes. Trail shoes can have varied lugs:

• Large and spaced out
• Smaller lugs with more of them on the outer sole
• Large, deep ones that are fairly dense

The different lugs have different functions. Shoes with deeper lugs are suitable for muddy terrain with the aim of the mud not getting stuck in between and able to grip better with the bigger surface area. Shoes with a smaller and greater number of lugs are used for more technical trails and more likely to be more comfortable over longer distances.

Road running shoes

The road running shoe is flat underneath with no lugs as grip is not really needed but the shoes vary in cushioning depending on function or preference needed for the shoe.

Should a runner prefer one shoe for trail and road it is best to recommend a trail shoe with smaller lugs. Be aware that the lugs will most likely wear out quicker with road running than with trail running and this should be taken into consideration.

The upper part of the shoe is also specifically designed for road or trail. The uppers of trail shoes vary but tend to be firmer to sustain the harsh terrain without ripping, but still needs to be breathable. Trail shoes will often have a firmer part at the front of the shoe.

Important Aspects in Selecting Running Shoes

Stack height/ Cushioning

Stack height of running shoe

The cushioning of a shoe decreases the impact on your feet between the shoe and the surface area (road/ trail). For the longer runs it is recommended to have more cushioning so that the feet are more comfortable and cushioned. The midsole thickness can change how and how long the runner contacts the ground. Furthermore, the distribution of sole thickness from under the heel and toe affects running motion.

Heel to Toe Drop/ Heel Drop

Heel to toe drop

This is the difference in the height between the heel and the toe of the shoe. There is usually a drop between 0 and 11mm. With 0mm being a minimalist heel drop, 5mm a middle heel drop and the 11mm being the maximal heel drop.

Important to remember with these two aspects of the cushioning and heel drop is that one can have a shoe with a large cushioning but with a minimalistic (0mm) heel drop. In other words, the shoe is flat like being barefoot, but it is cushioned so it will have cushioning especially for the longer runs. You can also get a cushioned shoe with a heel toe drop of 5 or 10mm.

You can also get a shoe with minimal cushioning and low heel toe drop – which would be your minimalistic shoe (barefoot running as such), or minimal cushioning with a high heel drop of 5 to 10mm.

Flexibility

Two ways to easily test the flexibility of running shoes are:

1. Flex the toe part of the shoe upwards to test the flexibility of the sole – mimicking toe off.
2. Torsional test - How easy is it to twist the shoe and are there any resistance offered? How much does the shoe twist?

The reason for testing the flexibility is to see the kind of support the shoe may offer. If there is a large play, or movement, in either or both movements, the shoe is probably not going to be very supportive, while if there is a bit of resistance and less movement, more support will be available.

Supported Shoes

Antipronation shoe is another name for a supported shoe although this name is falling away. A firmer base is made on the inner part (medial side) of the shoe to provide the additional support to prevent the over – pronation movement. Pronation is defined as the inward rotation of the rear foot about the subtalar joint axis, while supination is the outward rotation of the rear foot about the subtalar joint axis. If the runner has a supported shoe and it works for them, keep it. If, when they changed to a supported shoe they started to develop an injury, this may be a possible cause to keep in mind.

If the runner has not got a supported shoe and maybe some additional support is needed, opt for a neutral shoe and consult/refer to an orthotist/podiatrist to create orthotics according to the necessary specifics i.e. the amount to build up as well as the exact area of support.

Different Parts of the Shoe

Always compare the runner’s shoes, the left with the right and especially the old shoes.

• Heel collar
  • Assess if there is any asymmetry which may indicate pronation with the collar bending inwards
  • Video analysis of the runner is better to identify specifically if it is forefoot or rearfoot pronation or a combination.

• Identify the tongue of the shoe

• Upper
  • What is it made of? For example, mesh and how dense?
  • Specifically on trail shoes there is a toe bumper which is a solid part to protect the toes from being hit by rocks.
  • What is the wear on the upper? This might indicate where a runner scuffs one leg on the other.

• Toe box
  • Important aspect of the shoe
  • Different sizes available in the same make shoe – so check that they have what they need.
  • Toes bulging out the sides or is it loose with too much space?
  • How wide or narrow is the toe box and does it fit well?

• Lacing
  • Note how the runner laces their shoe. This may have an influence on possible niggles or injuries developing.
  • The shoe can be laced differently to accommodate areas which need either more or less support.
  • Lock laces are also an option but depends on personal preference. The lock lace is great in that once it is in place, you won’t have to stop and tie a shoelace!

Read more about lacing techniques in this blogpost by RunRepeat: The top 12 shoe lacing techniques.

Race versus Training Running Shoes

There are a variety of brands and within each brand they have their different types of shoes. Trail, road, track, and a combination of these. It is important to note if the runner, in particular road runners, likes to use a racing shoe and a training shoe. In general the racing shoe is lighter – so the overall weight of the shoe is less – and the material that the shoe is made of, in particular the cushioning, is extremely good material, but may not last long with the impact and so has a shorter run life. Training shoes may be more cushioned and possibly more stable – longer time in the shoe for comfort and longevity.

Different brands

Different brands may be known for specific aspects of a shoe like a narrower fit or a brand which offers different toe box sizes. Ultimately, if the runner comes with a specific brand and it works for them, don’t change it unless necessary. Look at the introduction to understanding your runner and subjective assessment of a runner for more information on how to be specific for analysing the runner and their needs.

Vary Shoes

If possible, it is recommended to have two pairs of shoes that the runner can vary while training. It can even be the same make but you wear at different times and it allows your feet to have a different feel and adapt rather than the same shoe all the time.

Most important aspect of a shoe

Ensure that you recommend the shoe that suits the runners’ needs, abilities and terrain, and NOT the looks!

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