SLR - August 2020 - John A. Martucci
Reference: Silva ÉQ, Miana AN, Ferreira JSSP, Kiyomoto HD, Dinato MCME, Sacco ICN. The Association Between Rearfoot Motion While Barefoot and Shod in Different Types of Running Shoes in Recreational Runners. J Sports Sci Med. 2020 May 1;19(2):383-389. PMID: 32390732; PMCID: PMC7196748.Scientific Literature Review
Reviewed By: John A. Martucci, DPM
Residency Program: Beth Israel Deaconess Medical Center – Boston, MA
Podiatric Relevance: A significant amount of sports injuries occur in the lower extremity. One way to help reduce the risk of injury is motion-controlled or mechanics-specific footwear. But do they help? This study sought to explore three questions: do the shoes of recreational runners match their barefoot rearfoot positions, does rearfoot eversion change regardless of shoe, and do shoes designed to correct or neutralize eversion do so? They hypothesized that runners chose shoes based on their subjective perceptions (as either neutral, overpronator or supinator), that these shoes alter the rearfoot eversion angle during running, and that these shoes neutralize or correct excessive eversion.
Methods: The study examined 111 runners (81 men, 30 women) who ran an average of 3.4 times/week and 31.8 kilometers/week. Those with no injuries in the last six months, no history of orthopedic surgery, and no degenerative conditions were included. Runners ran on a treadmill at a self-selected speed for five minutes and were captured with infrared cameras. Four markers were placed along the posterior aspect of the calf and heel. Patients wore their own shoes but the pair had to be less than six months old with less than 500 kilometers run in them. Brands from Adidas, Asics, Brooks, Nike, etc. and motion-control types were included.
Maximum eversion angle during stance phase was calculated using Visual 3D software. This angle was classified as supination (0-7 degrees), normal (8-15 degrees), and excessive pronation (>15 degrees). Chi-square test was used to compare between shoe performance and category and between barefoot and shod conditions. Barefoot versus shod for each type of rearfoot motion was compared using the Wilcoxon signed-rank test.
Results: When comparing barefoot motion to shoe type, only 31.5 percent of neutral runners wore neutral shoes. Further, 50.0 percent of overpronators and 40.7 percent of supinators wore motion-appropriate shoes. Chi-square analysis revealed no association between type of shoe and rearfoot motion but there was a significant association between barefoot versus shod with regards to the rearfoot angle. Neutral runners went from 10.10 to 11.81 degrees, supinators 5.12 to 5.66, and overpronators 16.67 to 18.36 when shod. There was an average increase of 4 degrees when shod. While shoes designed for neutral or supinators did not produce significant effects, overpronators were kept supinated or neutral (n=5).
Conclusions: The researchers found that runners’ selections of shoes did not correspond to their rearfoot motion, eversion increased regardless of shoe, and shoes specific for rearfoot motion did not correct or neutralize eversion. While the population of overpronators was small, motion-controlled shoes may play a role for these patients.
Increased eversion while shod is a consistent finding in studies. Further, the literature cited supports the idea that footwear specific to one’s rearfoot motion may not reduce the risk of injury or pain. This study highlights the limitations of external devices on the biomechanics of the lower extremity. While evaluating a patient’s foot type and providing recommendations, providers should caution patients about the effect shoes alone may or may not have on their biomechanics.