Running is a great activity for maintaining and improving ones health, and contrary to popular belief, running does not lead to early onset of knee osteoarthritis (unless you run on an injured knee or are an elite athlete involved in high amounts of running). Yet running injuries, particularly of soft tissues such as muscles and tendons, do occur from time to time in those who run. There are many reasons for this, including drastic increases in training volume, muscle weakness/imbalance, poor biomechanics, and others. One eternal question with running is what type of shoe is best? This is a hard question to answer, as the research is continually developing and the question is also very personal. Every person varies in his or her needs, so there is no one right answer.
With respect to running shoes, however, I did come across interesting research lately. The authors of a recent study questioned whether wearing two different pairs of running shoes over the same time period, but alternating between them, would reduce injury rates. The idea is that running is a very repetitive activity, and that wearing two different shoes (with varying support, amount of drop, etc.) may help reduce injury rates. With every repetitive step, if you are always wearing the same shoes, the leg is going to be loaded in the same way with each step. Add this activity up over a period of time and you have a possible repetitive stress injury. Throw in a different shoe for a percentage of the workouts however, and now the leg is loaded in a slightly different way.
It turns out that not wearing the same pair of shoes for every run did reduce injury rates, by 39%. In the study referenced below, participants did not wear their predominant pair of shoes for more than 58% of their runs. So if you are someone who suffers from running injuries once in a while, or you want to be proactive and prevent an injury from occurring, perhaps consider using two different running shoes as part of your plan to keep running injury free.
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, 25(1), 110-115.