Running shoe buyers: beware of deception!

Running is one of the most popular sports and fitness activities across the globe, which can be done anytime, anywhere and with minimal equipment investment. The downside however is that unlike sports such as swimming and cycling, running carries a significant risk of injury⁽¹⁾. Understandably, there has been much of research investigating training-related injury risk factors as distance, frequency, training intensity, which has provided some solid evidence for minimizing this risk.

Which shoe is best?

Another factor that runners need to consider when mitigating injury risk is correct shoe design and choice, but unlike training, our knowledge about footwear design and related risk factors is still quite limited. This is largely due to the vast number of different shoe designs on the market, and the fact that even within a manufacturer’s model range, shoe design often changes year on year. Indeed, many runners report they feel overwhelmed by the possible choices. However, despite the changing technology and proclamations by shoe manufacturers of better stability and motion control, lower impact forces, more efficient running gait (stride pattern), the plain truth is that running injury incidence has NOT changed noticeably over the last few decades⁽²⁾.

In a previous SPB article, we investigated the evidence for and against different shoe designs for reducing injury. In summary, the findings were as follows:

• Data accumulated over a 25-year period on impact forces and foot pronation and the development of running-related injuries, which found many contradictions in the experimental results and the established theories – most notably that impact forces are NOT an important factor in the development of chronic and/or acute running-related injuries’^(3,4). This may be because increasing cushioning and reducing foot strike impact seems to interfere with the body’s ability to alter and adapt its neuromuscular response and maintain its preferred joint movement path for a given movement task, which effectively results in a less than optimal running gait – for example by landing with a stiffer leg.
• If extra cushioning and support is correctly located in the midsole of a running shoe, that design attribute can reduce the risk of plantar faciitis (learn more about this condition in runners here)⁽⁵⁾.
• Regular runners can benefit from a heel-to-toe drop (the height difference between the forward-most and rear-most parts of the inside of the shoe, where the foot actually rests) of around 10mm while occasional runners (eg athletes whose main sport does not involve running) will benefit from a flatter profiled sole⁽⁶⁾.
• Wearing shoes with moderate lateral torsional stiffness (how resistant the shoe is to torsional twisting around the toe-to-heel axis – see figure 1) makes it less likely to incur any type of lower extremity injury than wearing shoes with minimal or extreme lateral torsional stiffness, both of which make an injury more likely⁽⁷⁾. This suggests that shoes need to have enough torsional stiffness to accommodate foot movement while preventing excessive movement (from too little stiffness).
• Runners with a history of metatarsophalangeal (MTP) joint or plantar injury should avoid shoes with high levels of midsole bending stiffness⁽⁸⁾. This might include ‘energy return’ shoes, that often harness a stiffer, springy midsole structure to help return energy to the following stride after foot impact.

Figure 1: Depiction of lateral (torsional) stiffness in running shoes