Can parallel use of different running shoes decrease running-related injury risk?L. Malisoux, J. Ramesh, R. Mann, R. Seil, A. Urhausen, D. Theisen Scandinavian Journal of Medicine & Science in Sports; Early View

This article has been getting a ton of press lately. Many are suggesting that by varying your running shoes, you can potentially reduce the likelihood of developing a running injury. How? The article really doesn’t provide any evidence to suggest why injury would be reduced other then sharing the data collected via the internet on a group of 264 recreational runners. In fact, other variables were also linked to reduction in injury such as increased distance and increased weekly volume of other sports. The reality of this is there were 39% less reported injuries in those who reported wearing different pairs of shoes during the study period of 22 weeks.

I had the opportunity to read the entire article today and not just the abstract so I could provide more of an opinion on the the findings being reported.

After reading some other posts on this article, I was under the impression that the study was able to establish how often the runner was rotating their shoes during this running period. This was not the case. Surprisingly, all the participant had to do was report they were using more then one pair of shoes and this qualifies the runner as a multiple shoe user (The runners who wore multiple shoes were in their predominant shoes 58% of the time). There was no reporting as to how often the shoes were rotated during the running period.
“Multiple shoe users were identified as those who reported a minimum of two different pairs of running shoes (different brand, model or version) in the system and who alternated a minimum of two times between them over the observation period.”

We also see those who had less injuries reported were also those who were more experienced runners and had run more miles.
Multiple shoe users were more regular in their running training over the 12 months prior to the study (P=0.001), more experienced in half- marathon (P < 0.001) and competitions (P < 0.001). Furthermore, they had a higher volume of other sports practice (P = 0.045), and a greater running training load regarding frequency (P < 0.001), distance (P < 0.001) and duration (P < 0.001) during the observation period.

Even if we were to examine the physics behind the running shoes absorptive properties there is still no evidence in regards to preventing injury. What exactly is occurring from a physics standpoint to the shoes that would be preventing injury by simply waiting a few days to wear then again is beyond me. There may be some return of absorptive quality in the EVA but is it really significant? With diabetic patients, it is the standard of care to replace the plastizote heat moldable inserts every four months in their diabetic shoes as it helps to offload pressure areas. There are no studies that I am aware of that shows we improve pressure releif or shock absorptive properties by letting any material set for 48 hours (the time it would take to rotate two pairs of shoes.). There has actually been a study published that demonstrated the longer a running shoe was worn, the more cushioning was lost from the shoe, and the more stable the foot became. In other words there was less “wobbling” of the foot on the shoe and therefore less muscle activation to stabilize the foot and ankle. We all would agree the more muscles are used, the more at risk we are for overuse injuries and overuse injuries account for the majority of running injuries.

In conclusion, does alternating your running shoes prevent injury? I don’t think we can draw that conclusion from this article. Especially since we understand the physiology behind how our bodies respond to change. The more variables introduced to the body during sustained activity the higher the likelihood of injury. Any change in surface increases a runners chance of sustaining an overuse injury. We have to gradually adapt to a shoe or surface or we are at risk for a overuse injury. That’s not to say that if one does adapt to several pairs of shoes they could wear them during their training and not get injured. I test and review a large variety of running shoes and log a lot of my miles in many different shoes without injury but I can’t directly make the correlation to changing shoes causing a decrease in running related injuries nor do I think this article can make that claim.

I’m curious to hear what others have to say! Please comment below.