An overuse injury is due to the cumulative load in the tissue being beyond what the tissue can take. To prevent an injury, you have to reduce that cumulative load and/or increase the ability of the tissues to take that load. There are many strategies for doing both. One strategy is to vary the running technique: ie different running techniques load different tissues different, so mixing it up makes sense and has the potential to reduce the cumulative load on any one particular tissue at the expense of another and if this is regularly varied, then you can see the how it might reduce injury risk. Personally I mix up my Hoka’s, with the NB Minimus’s and the Kinvara, but that is me and that is an anecdote. We know from previous research that to make blanket recommendations based on anecdotes is destined to fail (the plural of anecdotes is not data). Now we have some data:
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
The aim of this study was to determine if runners who use concomitantly different pairs of running shoes are at a lower risk of running-related injury (RRI). Recreational runners (n = 264) participated in this 22-week prospective follow-up and reported all information about their running session characteristics, other sport participation and injuries on a dedicated Internet platform. A RRI was defined as a physical pain or complaint located at the lower limbs or lower back region, sustained during or as a result of running practice and impeding planned running activity for at least 1 day. One-third of the participants (n = 87) experienced at least one RRI during the observation period. The adjusted Cox regression analysis revealed that the parallel use of more than one pair of running shoes was a protective factor [hazard ratio (HR) = 0.614; 95% confidence interval (CI) = 0.389–0.969], while previous injury was a risk factor (HR = 1.722; 95%CI = 1.114–2.661). Additionally, increased mean session distance (km; HR = 0.795; 95%CI = 0.725–0.872) and increased weekly volume of other sports (h/week; HR = 0.848; 95%CI = 0.732–0.982) were associated with lower RRI risk. Multiple shoe use and participation in other sports are strategies potentially leading to a variation of the load applied to the musculoskeletal system. They could be advised to recreational runners to prevent RRI.
Pretty much what they showed was that multiple shoe use did reduce the risk for injury. Participation in other sports activity also reduced the risk which strengthens the cross-training argument. The study also confirmed that a previous injury was a risk factor (which every study I can recall that looked at that found the same thing). Another figure that jumped out, was that only a third got an injury which is around what almost all of the recent studies are now showing (which is way down on the 70% from just one study the fan boys still keep quoting).
As always, I go where the evidence takes me until convinced otherwise and this study shows that mixing up the running shoes is a good thing and protective from injury.
Malisoux L, Ramesh J, Mann R, Seil R, Urhausen A, & Theisen D (2013). Can parallel use of different running shoes decrease running-related injury risk? Scandinavian journal of medicine & science in sports PMID: 24286345