Running Specific Shoes
Running shoes, on the other hand are constantly evolving; with trends, fashion and fads, as well as research, all having an impact. (graphic/ video)
Let’s have a closer look at the construction and features of sports shoes, avoiding the fads and trends as much as possible!
First we’ll look at the Toeguard which, as the name describes, is the piece of fabric that covers the toes of a shoe.
This is the Vamp, a single piece of material that gives the shape to the upper and forms the toebox. The vamp holds the eyelets and lacing section.
Under the lacing is the Tongue which protects the top of the foot from the laces.
At the back of the shoe is the Clutch Collar which may be padded to protect the heel and the achilles tendon.
The back of the shoe upper is called the ‘Foxing’. Beneath this is often a plastic Heel Counter. At times the plastic heel counter is placed external to the foxing. Sometimes the heel counter may be made of less rigid or less durable material, such as fibreboard. Sometimes the heel counter may be absent altogether.
Overlays, and stitching of the upper add to the reinforcement and stability for the top of the foot and to prevent distortion of the upper on the sole unit.
Moving now to the sole unit, which typically has four main components:
- The Outsole which provides traction and durability, and adds to the cushioning mechanisms of the shoe.
- The Mid Sole which provides the primary cushioning and support features.
- The Shank, also known as a Trustic within the Asics brand, provides both flexion and torsional rigidity through the mid portion of the shoe.
- And finally, the Insole or Sock Liner which provides additional comfort and cushioning for the foot inside the shoe. Generally the sock liner is removable in a sports shoe and can be replaced with a custom foot orthosis as required.
Sports footwear design features and their functional implications.
The ‘Drop’, ‘Heel Pitch’ or ‘Stack Height’ are all terms used to describe the slope form heel to forefoot in a running shoe. This may vary from 4mm in a racing flat to 12mm in some road running shoes, with something on offer every 2mm in between.
Ankle Dorsiflexion is a necessary component of normal gait. The drop of the shoe, heel to forefoot slope, can assist, or inhibit forward progression. The higher or greater the pitch, the less dorsiflexion range is required by the ankle joint.
We know that limited ankle dorsiflexion has a significant negative impact on gait function and effective sagittal plane motion of the foot. As a clinician, this is an area worth becoming familiar with and considering as part of your individualised management plan for each of your patients.
Dual Density Midsoles – this is where a harder density of midsole material is used especially along the medial aspect of the sole unit. The rationale here is that the harder foam material will prevent excessive pronation of the foot within the shoe. Recent research has not supported this theory and has indeed found that a foot will continue to excessively pronate within the shoe, it is just that the shoe appears to remain more upright and less prone to medial collapse.
Another consideration – the harder the density of foam used, the heavier the shoe will be; AND we do know that shoe weight reduces performance and increases injury risk in runners.
This study on :
The effect of footwear on running performance and running economy in distance runners
A significant positive association between shoe mass and metabolic cost of running. Certain models of footwear and footwear characteristics can improve running economy.
Continuing with the midsole theme:
The ‘Midsole Flare’ is the angle from the side wall of the shoe to the outersole. This can affect stability, especially in the frontal plane, and ground contact surface area. The flare may be medial and lateral, or even posterior. This feature will affect the way the foot interacts with the shoe and is likely to influence function.
Moving to the posterior aspect of the shoe, heel counters can be considered as a means to potentially alter rearfoot kinematics. Rigid heel counters have not been shown in the literature, however, to reduce rearfoot pronation within the shoe. The main function of the heel counter is probably more that they hold the heel of the shoe stable and play a part in the feel and comfort of the shoe.
Let’s look at midsole flexibility – this is the point at which the midsole flexes and is usually across the forefoot to match the point at which the foot itself flexes during the propulsive phase of gait.
This is an extremely important factor as it largely determines the feel and comfort of the shoe, and has an impact on proprioception. It is extremely important to consider the flex points of the shoe, matching them as necessary to the needs of your patient.
It is ideal, for normal sagittal plane function and forward motion for the forefoot flex grooves to be just over 1 cm behind the bisection of the first to fifth metatarsal phalangeal joints. Flexion at this location promotes effective windlass mechanics and forward propulsion. Flexion at any other location does not!
In the same way that we customise orthotic management to our patient, their dysfunction, pain and pathology; footwear plays and essential part in the rehabilitative puzzle. A shoe can positively enhance, or negatively affect our patients’ management plan.