Other research has poured cold water on the idea that injury risk can be reduced by putting runners who overpronate into stability shoes and other runners in neutral shoes. In a 2013 study, Danish researchers recruited 927 healthy volunteers, and subjected them to sophisticated testing. The runners were then divided into five groups, ranging from severe overpronators to severe underpronators. Once this was done, the subjects were given the same model of neutral running shoes to run in for the next year.
In theory, the injury rate during that year should have been higher among the overpronators and severe overpronators—for whom the neutral running shoe was the "wrong" shoe—than it was among the other groups. But that's not what happened. In fact, injury rates were about the same in all five groups.
Studies about the effects of choosing running shoes based on comfort have been very different. In a 2009 study, Benno Nigg of the University of Calgary and colleagues brought 13 male subjects into their lab. Each was given five pairs of running shoes in his size to try on and rate for comfort.
The subjects ran on a treadmill in all five pairs (one pair at a time) at a fixed pace while their oxygen consumption was measured. This allowed the researchers to determine how the shoes affected the participants' running economy. A lower rate of oxygen consumption at the same pace would indicate better economy. Nigg found that, on average, the subjects were significantly more economical in the most comfortable shoes than in the least comfortable shoes.
No study has ever directly addressed the effect of shoe comfort on injury risk. However, a study conducted by Benno Nigg found that military recruits who were allowed to choose a shoe insert based on comfort were less likely to get injured during basic training. So there is reason to believe that greater comfort in running shoes equals lower injury risk.
Comfort As Information
Every runner knows that comfort is important. But most runners assume that comfort is something separate from the features (stability, cushioning, etc.) that make a certain shoe the "right" shoe for a given runner. But it's not. The feeling of comfort that you get when running in some shoes is far from arbitrary. Your brain generates this feeling based on afferent feedback that it receives from your body.