Athletic Footwear Prescription

Introduction

Athletic footwear prescription has long been a complex and confusing area for practitioners and patients alike. Various methods of deriving prescriptions have been used in both clinics and running shoe retail shops to varied success. Over the past thirty years we have witnessed shifts in the industry from motion controlling shoes, to minimalist and more recently maximalist footwear. (Read more about our commentary on the growing trends of both minimalist and maximalist athletic footwear here). Advocates of these have staunchly defended their preferred shoe styles, but unfortunately there remains little conclusive scientific evidence to back up their bold claims. So the complex question once again arises, “What type of athletic shoe is best for my patient?”. In this article we aim to give an honest and unbiased analysis of the current predicament of athletic footwear prescription. We will briefly look at the various methods used to determine a prescription and the success of each thus far.  

Background of Athletic Shoe Prescription

The following is an overview of the historical categorisation of patients based on their foot type and the research, or lack thereof, to support this method of prescription. 

Arch Type

The original proposal from the athletic footwear industry was that shoes should be prescribed based on a patient’s natural arch height, measured from a wet foot test and later pressure plates. Cushioning shoes were developed for runners with high-arched, rigid feet that tended to excessively supinate or exhibit reduced pronation. These shoes were relatively flexible, with midsoles of lower density. Stability shoes were designed with some cushioning and some control and were intended for runners with a neutral foot and normal mechanics. Motion-control shoes were intended for runners with flat feet and were designed to control rearfoot and midfoot pronation. They were constructed with higher-density midsoles and additional stiffening of the heel counter. However, it has since been proven that arch type alone is insufficient grounds for basing your prescription on. One such study was conducted by Knapik et al 2010 (1), who found that assigning shoes based on the shape of the plantar foot surface had little influence on injuries even after considering other injury risk factors.

Pronation / Supination

Following on from arch typing, manufacturers began promoting footwear based on the level of pronation, or “over pronation”, a patient exhibits. I use air quotes here due to the fact that there is no consensus on what “over pronation” is and how to reliably measure it. If we cannot even measure it then how can we promote footwear based on it. As we know, pronation is an important component of an efficient gait cycle. However, problems can occur when this pronation occurs either too early or too late in the cycle. Shoes alone will have little influence on this mistiming and are unlikely to alter biomechanics significantly (2). There is certainly a rationale for reducing excessive pronatory moments in conditions such as Tibialis Posterior Dysfunction, and medially posted footwear may assist in achieving this. However, your patient needs to be made aware that the footwear alone will not correct their biomechanical abnormality and is merely a part of the overall solution.

Minimalist vs Maximalist

As stated above, we covered this topic in detail previously and recommend reviewing the article here. In recent years, athletic footwear prescription has increasingly fallen into either of these two categories. In short, minimalist footwear refers to shoes which mimic barefoot conditions by having as little material covering the foot as possible. Maximalist footwear has been designed with the intention of providing as much cushioning and shock attenuation as possible, while also remaining lightweight and stable. Since writing the article over two years ago, the popularity of maximalist footwear has grown even more and is now almost viewed as conventional athletic footwear. Indeed, with the growth of brands such as Hoka One One, the range of shoes available has grown exponentially and athletes are no longer constrained to the original ugly, bulky styles.

While both styles of footwear have their benefits, they should be prescribed in conjunction with a sensible training protocol. One of the primary concerns of barefoot/minimalist running is that although foot musculature may be strengthened, injury may result from the added stress placed on the bones in the foot, especially throughout the adaptation period when runners transition from traditional running shoes (3). This view was supported by a study conducted by Ryan et al, 2013 (4).

Runners interested in transitioning to minimalist running shoes, such as Vibram Five Fingers should transition very slowly and gradually in order to avoid potential stress injury in the foot.

While footwear is an important factor, foot strike patterns have been identified as a potential injury mechanism (5). Kinematic and kinetic characteristics of barefoot running are more likely due to a more plantarflexed footstrike than to the footwear condition (6). Therefore, without adaption of foot strike patterns when wearing minimalist footwear, injuries will be more prevalent. It is vital to properly educate your patients on the risk of wearing this type of footwear and instruct them on its correct use. Contrastingly, maximalist footwear takes very little breaking in period. However, in some styles with very thick midsoles, caution is advised in the early stages as the patient accustoms to the increased height off the ground.

Conclusion

Firstly, forget the hyped-up reports you will no doubt have heard from footwear manufacturers and suppliers alike, promising a reduction of injuries and increase in performance through prescription of shoes based on foot type. Of course this may be the case in many instances, however we now know from the literature that there is no evidence to promote footwear prescription based on foot typing or pronation/supination (7). Once again, there is no doubt that a large percentage of people who have been prescribed pronation controlling footwear have benefited. However, there are numerous features of footwear which could be attributing to this including shock attenuation, heel-to-toe height differential, heel counter, midsole stiffness and so on. While footwear can certainly play a part in rehabilitation and performance enhancement, it is just one component of a complex mechanism. Different types of footwear, place varying stress levels on both soft tissue and bony structures of the lower limb. By altering these stress levels, you are merely moving the load from one site to another. So in effect, we can reduce the risk of injury in one area by redistributing the load elsewhere. For example, a patient with achilles tendinopathy would likely benefit from a higher heel-to-toe height differential to assist with offloading this area. Each patient is different and should not be classified based solely on their foot type.

Law of Conservation of Energy = Energy cannot naturally be created or destroyed

Dr. Benno Nigg, one of the world's leading researchers on lower limb biomechanics over the past 30 years, has proposed some thought provoking theories in recent years. His research has concluded that comfort is the primary parameter of footwear prescription (8). After treadmill tests with five different pairs of shoes, they found that runners increased their running economy in shoes they deemed “most comfortable” versus those they felt were “least comfortable".

Take Home Messages on Prescription

• Find out what is causing biomechanical abnormalities associated with your patient's injury and ensure your prescription will not exacerbate the symptoms.
• Try on at least three appropriate models. From there, choose the one that is most comfortable.
• Ensure the shoe is well fitted for both length, width and depth. (Our Dr. Comfort range feature wide, extra wide, deep and extra deep fits).
• Ensure fit for purpose - trail shoes for off road, light weight for sprints, cushioned shoes for endurance runs.
• Run in them! Go to a specialist store with a treadmill or a running track where you can trial run the shoes.

References

1. Knapik JJ, Brosch LC, Venuto M, et al. Effect on injuries of assigning shoes based on foot shape in Air Force Basic Training. Am J Prev Med. 2010;38:S197-S211
2. Ryan MB, Valiant GA, McDonald K, Taunton JE. The effect of three different levels of footwear stability on pain outcomes in women runners: a randomised controlled trial. Br J Sports Med, 2011, 45, 715–721.
3. Giuliani J, Masini B, Alitz C, Owens BD. Barefoot-simulating footwear associated with metatarsal stress injury in 2 runners. Orthopedics 2011;34(7):e320-3.
4. Ryan M, Elashi M, Newsham-West R, Taunton J. Examining injury risk and pain perception in runners using minimalist footwear. Br J Sports Med. 2014; 48: 1257–1262. doi: 10.1136/bjsports-2012-092061. pmid:24357642
5. Lieberman DE, Venkadesan M, Werbel Wa, Daoud AI, D'Andrea S, Davis IS, et al. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature. 2010; 463: 531–535. doi:10.1038/nature08723 [PubMed]
6. Shih Y, Lin KL, Shiang TY. Is the foot striking pattern more important than barefoot or shod conditions in running? Gait & posture. 2013; 38: 490–494.
7. Richards, Craig E., Parker J. Magin, and Robin Callister. 2009. “Is Your Prescription of Distance Running Shoes Evidence Based?” British Journal of Sports Medicine 43(3): 159-162.
8. Nigg BM, Baltich J, Hoerzer S, Enders H. Running shoes and running injuries: mythbusting and a proposal for two new paradigms: ‘preferred movement path’ and ‘comfort filter.’ Br J Sports Med. Doi: 10.1136/bjsports-2015-095054.