SLR - October 2020 - Emily Khuc

Shoe Cushioning Influences the Running Injury Risk According to Body Mass: A Randomized Controlled Trial Involving 848 Recreational Runners

Reference: Malisoux L, Delattre N, Urhausen A, Theisen D. Shoe Cushioning Influences the Running Injury Risk According to Body Mass: A Randomized Controlled Trial Involving 848 Recreational Runners. Am J Sports Med. 2020;48(2):473-480. doi:10.1177/0363546519892578

Scientific Literature Review

Reviewed By: Emily Khuc, DPM 
Residency Program: St. Mary’s Medical Center – San Francisco, CA 

Podiatric Relevance: Foot and ankle specialists are often asked for personalized running shoe recommendations. The better we understand how shoe choice affects injury rates, the more injuries we can prevent. The authors of this study hypothesized that (1) stiffer shoes are associated with higher injury risk (2) higher body mass is associated with higher injury risk and (3) runners with higher body mass have lower injury risk when wearing stiffer shoes.

Methods: This randomized control trial compared rate of injury in recreational runners using almost identical hard or soft running shoes (35.4 percent difference in midsole material hardness). Adults in Luxemburg aged 18-65 years, in good health, and able to run 15 minutes were recruited. Individuals were excluded if running was medically contraindicated, they had recent lower extremity or back surgery, or if they used orthotics. 848 people were given a pair of either hard or soft study shoes to use for all running activities, running at least once per week, and reporting about injuries or pain at least once per week through an online system for six months.

Results: The participants reported 54 running-related injuries in the soft shoe group (12.6 percent) and 74 running-related injuries in the hard shoe group (17.6 percent), a statistically significant difference (P = 0.018). Most running-related injuries in this study were related to the lower leg, ankle, or foot (60.9 percent). Having a previous injury was a risk factor for running-related injury (P <0.001). Age, sex, height, body mass, fat mass and training habits were not associated with risk of injury. Median values used for cut off between light and heavy participants were 78.2 kilograms for males and 62.8 kilograms for females. Stratified analysis showed there was higher running injury risk among those who used the hard shoe in the group of lighter runners, while no shoe effect was observed in the group of heavier runners. 

Conclusions: With increased interest in recreational running comes increased incidence of running-related injuries. Prevention of future injury is especially important, as many studies, including this one, show that history of previous injury places runners at risk for future injury. We have limited data available on the topic of running shoes and injury rates, with ever-changing trends in shoe design and materials. In this study, the hypothesis that harder shoes are associated with higher running-injury risk was found to be true. However, the authors’ hypotheses about body mass were false. Heavier participants did not get more injuries and experienced no shoe effect. Shoe effect was only seen within the group of lighter runners, who had higher risk of injury when wearing hard shoes. This was an adequately powered study, but had weaknesses, including the use of self-reported outcomes and missed opportunity to do further stratified analysis. Still, the conclusions from this study can be used to think more deeply about shoe recommendations for recreational runners, and it may be worth emphasizing cushioning when educating patients with lower body mass about what features to look for in a good shoe.

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