By Jordana Bieze Foster
Switching between different pairs of shoes may help prevent running-related injuries, but switching from a rearfoot strike pattern to a nonrearfoot strike pattern may not, according to two separate studies from Luxembourg and Iowa State University.
In a study of 264 recreational runners, researchers from the Public Research Centre for Health in Luxembourg found that those who used multiple pairs of running shoes over a 22-week observation period had a significantly lower risk of running-related injury than those who played favorites.
During the study, the runners recorded information about their running and other sporting activities, running shoe use, and running-related injuries on an Internet-based electronic database. Multiple shoe users were defined as those who reported at least two different pairs of running shoes (different brand, model, or version) in the system and who alternated between them at least two times during the observation period. Multiple shoe users wore their predominant pair of shoes for an average of only 58% of their running sessions.
Runners in the multiple-shoe group had a 39% lower rate of running-related injury than runners who predominantly used only one pair of shoes, and had a hazard ratio of .614. Increased mean session distance (hazard ratio .795) and increased weekly participation in sports other than running (hazard ratio .848) were also found to be protective against running-related injury, while history of previous injury was a risk factor (hazard ratio 1.722). The findings were epublished in late November by the Scandinavian Journal of Medicine & Science in Sports.
The authors theorized that alternating running shoes may reduce injury risk by providing variation in the type of physical load applied to the body. However, because the available information about specific shoe characteristics was limited, shoe design may also be a factor, said Laurent Malisoux, PhD, a researcher at the center’s Sports Medicine Research Laboratory and first author of the study.
“We have to underline that whether the reduced injury risk can be ascribed to alternation of different shoe characteristics—such as midsole densities, structures, or geometries—cannot be determined from these results and warrants future research,” Malisoux said.
Foot strike pattern during running can also affect the loads experienced by the body, but researchers from Iowa State University in Ames have found that switching from a rearfoot strike pattern to a midfoot or forefoot strike pattern may not necessarily reduce impact-
related injury risk.
The investigators analyzed 30 competitive runners (15 habitual rearfoot strikers and 15 habitual nonrearfoot strikers) as they ran down a 30-m runway, first using their habitual foot strike pattern and then, after a practice session, using the opposite pattern. All runners wore the same brand and model of running shoe.
The results were somewhat surprising. The habitual nonrearfoot strikers had resultant loading rates that were similar to those of habitual rearfoot strikers, and only slightly smaller vertical loading rates. On average, the habitual nonrearfoot strikers had higher ground reaction forces (GRFs) and loading rates in all directions than the habitual rearfoot strikers who switched to a midfoot or forefoot strike. And nonrearfoot strike patterns, despite not exhibiting much of a vertical impact peak, were associated with impact peaks in the posterior and medial directions that were not seen during rearfoot striking. The findings were epublished in December by Medicine & Science in Sports & Exercise.
Although the results call into question the impact-related benefits of switching to a nonrearfoot strike pattern in competitive runners, unpublished research from the same group suggests that loading rates in nonrearfoot strikers may not be as high in recreational runners as in their competitive counterparts, according to Elizabeth Boyer, MS, a graduate student in the department of kinesiology at the university and first author of the study.
Malisoux L, Ramesh J, Mann R, et al. Can parallel use of different running shoes decrease running-related injury risk? Scan J Med Sci Sports 2013 Nov 28. [Epub ahead of print.]
Boyer ER, Rooney BD, Derrick TR. Rearfoot and midfoot/forefoot impacts in habitually shod runners. Med Sci Sports Exerc 2013 Dec 2. [Epub ahead of print.]