Running shoes are known to wreak havoc on running efficiency. A 2008 study by French researchers found that running shoes decreased running economy both by adding weight to the feet and by altering biomechanics in ways that reduced the ability of the legs to capture €œfree energy from ground impact forces and reuse it to propel forward motion.9 On the biomechanical side, the core problem is that running shoes encourage runners to overstride, striking the ground heel first with the leg extended ahead of the body, instead of flat-footed with the foot underneath the hips. Overstriding exerts a strong braking effecta pronounced heel strike even looks like pressing the brake of an automobile. No runner overstrides without shoes, because heel striking without the presence of cushioning material between the foot and the ground would be painful and injurious. Fully 80 percent of runners instantly become heel strikers when they put on a pair of shoes. It is not clear why four in five runners overstride in shoes but not in bare feet. There is some evidence that naturally gifted runners are more resistant to the stride-ruining effects of shoes, as the minority of runners that do not overstride in shoes also tend to be more efficient without shoes. In any case, it is safe to say that overstriding is unnatural, because no runner does it in the natural, unshod state. For this reason, I believe that overstriding is one of the easier stride technique €œerrors to correct. Again, though, correcting this error is best done primarily through means other than conscious control. Practicing running barefoot on grass, on sand, and/or on an at-home treadmill will get your neuromuscular system accustomed to making ground contact with a flat foot underneath the body’s center of gravity. Wearing the lightest, least-cushioned running shoes in which you are comfortable in your everyday training will help you transfer your barefoot running form over to your shod running. But you will probably need to exercise a conscious effort for a while to keep from reverting back to over-striding while wearing your shoes. I am living proof that this is one gross motor stride change that can be made fairly easily. I switched from traditional to minimalist running shoes and from a moderate heel strike to a midfoot landing to overcome a prolonged case of runner’s knee, and it worked.