Running store employees typically select shoes for customers based on the degree of a customer’s foot pronation. This is most typically assessed by having a customer run on a treadmill while the employee visually assesses them from behind. Often, the employee will also record a customer’s foot strike and play it back for them in slow-motion. Most customers will notice that their ankles roll inwards when striking the ground. This is termed, pronation. At this point, the customer is typically informed that due to the degree of pronation, they are likely best suited for a stability or motion control shoe, versus a neutral shoe.
The goal in recommending a stability or motion control shoe is to eliminate or greatly reduce the degree of pronation. To the uninformed consumer, this makes sense. How could the foot/ankle rolling inwards be a good thing? The takeaway is that the less the foot rolls inwards, the better.
WHY IS PRONATION BAD?
It’s not. Nor is it predictive of injury. Pronation is normal and necessary for the foot to absorb the impact of the foot strike. At the end range of pronation, the ankle ‘locks out’ to provide a stable platform for the foot push off against.
The term, overpronation is often used when the degree of pronation is substantial. The issue with this term and classification of overpronation is that there is no clear consensus regarding how many degrees of pronation equates to overpronation. Many clinicians believe that a subtalar joint (ankle joint) angle of 8-10 degrees is representative of overpronation. Even if this angle does represent overpronation, it is unlikely that a quick visual reference of the ankle joint by a running store employee would be accurate. It is important to note that overpronation can be caused in some part by muscle imbalances (weak hip abductor muscles) versus the foot and ankle structure.
PRONATION DOES NOT EQUAL INCREASED INJURY RATES
Multiple studies demonstrate minimal evidence to support the theory that shoe selection (i.e., motion control) due to pronation and, or foot arch type minimizes injury rates.
A 2009 study by Richards et al, found no randomized, controlled studies that correlated the prescription of shoe type to decreased injury rates. Due to this, Richards et at. concluded that prescription of shoe type based on the foot type (ex: pronation) is not an evidence-based practice.
A 2000 study by Kong et al, found that feet adapt to changes in shoe cushioning as well as varying running surfaces. Kong’s study consisted of 24 runners and assessed them over 200 miles of running. At the end of the study, there were no changes in impact forces of the runners, which supports the notion that the body adapts to changes in foot cushioning and support. Additionally, the study also found that regardless of the shoe brand/cushioning type, the primary source of cushioning was the midsole EVA foam.
Perhaps in this case, a new pair of shoes is in order!
Does this mean that you should run in your shoes until the soles fall off? No. As noted above, while the body is able to adapt to some changes in shoe cushioning, it’s likely that substantial changes in shoe cushioning (read: shoes that should be taken out back and shot!) will decrease a runner’s comfort and affect the fit and condition of the shoes. In other words, even if the body is able to adapt to changes in shoe wear, it is not the only performance factor.
DO SHOES NEED REST?
Likely not. While ‘resting’ shoes 24-48 hours between runs is common advice to let the shoes regain their full cushioning properties, a study by Cook et al., found that there was no difference in the retention of cushioning between ‘rested’ shoes and those that were not within a 24-48 hour period.
While swapping out shoes can be a good idea (see below), it’s not for the purpose of allowing shoes to decompress.
Swapping out different shoes while training can reduce the potential for injury. A study found that the likely reason for this was due to the variation of load applied to the musculoskeletal system.
If you get injured or are prone to injury, the starting place to look is not your shoes. Seek out a specialist such as a physical therapist who can assess your posture and running form to identify and ideally rectify any ‘muscle imbalances’ and discomfort/pain. Remember, the body is one big interconnected system so the pain you’re having in your ankle likely has its origin somewhere else on the body. To this point, several studies theorize that most running injuries are the result of training errors and hip dysfunction.
This is not to say that shoes may not influence or contribute to pain or injury, however, it’s likely not the only factor.
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Wen DY, Puffer JC, Schmalzried TP, et al: “Injuries in runners: a prospective study of alignment.” Clinical Journal of Sport Medicine 8: 187, 1998
Kong P.W., Candelaria N.G., Smith D.R., “Running in new and worn shoes: A comparision of three types of cushioning footwear”. Br J Sports Med 2009; 43(10): 745-749.
Reinking MF, Austin TM, Hayes AM: “Risk factors for self-reported exercise-related leg pain in high school cross-country athletes.” Journal of Athletic Training 45: 51, 2010
Franettovich M, Chapman AR, Blanch P, et al: “Altered neuromuscular control in individuals with exercise-related leg pain.” Medicine and Science in Sport and Exercise 42: 546, 2010
James SL, Bates BT, Osternig LR: “Injuries to runners.” American Journal of Sports Medicine 6: 40, 1978
Richards C.E., Magin P.J., Callister R. “Is your prescription of distance running shoes evidence-based?”. Br J Sports Med. 2009; 43(3): 159-162. doi: 10.1136/bjsm.2008.046680. Epub 2008 Apr 18.
Cook SD, Kester MA, Brunet ME.“Shock absorption characteristics of running shoes.” Am J Sports Med. 1985 Jul-Aug;13(4):248-53.