Active Voice: In Pursuit of Injury-free Running — Does Footwear Matter?
By Hannah M. Rice, Ph.D., and Irene S. Davis, Ph.D., P.T., FACSM, FAPTA, FASB
Hannah M. Rice, Ph.D., is a lecturer in biomechanics at the University of Exeter, with a research focus on lower limb overuse injury. After her Ph.D. research investigating mechanisms for stress fractures among military recruits, she completed postdoctoral training at the Spaulding National Running Center at Harvard Medical School in Massachusetts.
Irene S. Davis, Ph.D., P.T., FACSM, FAPTA, FASB, is a professor in the Department of Physical Medicine and Rehabilitation at Harvard Medical School, and director of the Spaulding National Running Center. Her research focuses on mechanical factors that influence running-related injuries and the effectiveness of interventions to minimize risk of these injuries and to improve post-injury rehabilitation.
This commentary presents Dr. Rice's and Dr. Davis' views on the topic of the research article which they and their colleagues had published in the December 2016 issue of Medicine & Science in Sports & Exercise® (MSSE).
Research aimed at reducing the high incidence of running-related injuries has been ongoing for decades, yet there is no evidence to indicate any reduction over time. There has been much discussion in recent years around the influence of footwear and foot strike on injury risk. This was fueled by the observation that runners in modern-day cushioned footwear tend to land on their heels (rearfoot strike – RFS), whereas habitually barefoot runners tend to land on the ball of their foot (forefoot strike – FFS). As barefoot is our natural state, this led to discussions as to whether modern-day footwear, which influences foot strike pattern, has contributed to the high rate of running injuries in the modern day.
Running with an RFS results in an abrupt, upward or vertical force experienced by the body that is associated with high vertical loading rates as the heel strikes the ground. Loading rates are important because higher values have been associated with running injuries. Running with an FFS typically eliminates this abrupt vertical force, and vertical loading rates are markedly reduced. However, it is important to note that, along with vertical forces, our body also experiences forces in the anteroposterior and mediolateral directions. Summing all of these forces together provides the resultant or total force the body experiences with each footfall. This total force is beginning to receive more attention in the literature.
A recent MSSE paper reported that, while vertical loading rates were lower when running with an FFS than an RFS in traditional running shoes, the anteroposterior and mediolateral loading rates were higher with FFS. This resulted in total loading rates that were not different between FFS and RFS runners, suggesting that foot strike pattern doesn't matter. However, we suspected that the same may not be true of runners who regularly run in minimal shoes, which don’t have the cushioning provided by traditional running shoes.
Therefore, our study, published in the December 2016 MSSE, compared loading rates in runners who habitually exhibited RFS or FFS in traditional running shoes with those who habitually ran with an FFS pattern in minimal shoes. As with the previous study, we also found that total loading rates were similar between FFS and RFS when running in traditional running shoes. However, we found that total loading rates (and loading rates in each direction) were considerably lower when running in minimal shoes with an FFS than in traditional shoes with either foot strike. This tells us that becoming accustomed to running with an FFS in shoes that lack cushioning promotes a landing with the lowest loading rates.
If questioning whether footwear really matters, we would say “YES.” Foot strike is important too, but loading rates can be just as high with either foot strike if wearing traditional, cushioned running shoes. Becoming habituated to running with an FFS in minimal shoes may reduce the risk of injury. Any transition to new footwear or to a different foot strike pattern should be undertaken gradually and with guidance.