I must respectfully disagree with Toby. Forefoot striking is reputed to be most efficient, but the evidence appears to be less science and more opinion. Heel striking does not necessarily mean over-striding, braking or beating you up. I would also debate the "get your foot to land under your knee" since you can do that and still be over-striding. Rather, you want your foot to land under your body, rather than in front. (This also usually means your foot lands below or slightly behind you knee.) One video study of elite runners (283 of them) at a half-marathon showed that about 75% of them were heel-strikers. Only 4 of them were forefoot strikers. If you want to be more confused, but also have the matter somewhat illuminated, read the articles at http://www.sportsscientists.com/2008/01/running-technique.html . Of particular interest is #6 under Running Technique, notably the section "The feet - most important of all" (quote below). The study of elite half-marathoners is article #5 under Running Shoes. There are also articles dealing with Pose Running, one technique for forefoot striking.

From "Some suggested changes YOU can make . . ."

"Finally, perhaps the most important thing of all - don't worry about how your foot is landing! The moment you start becoming pre-occupied with whether you are landing on the heel, the midfoot or forefoot, you're in trouble. . . . .So what should you do? First of all, remember that the landing of the foot depends on the position of the foot under the body. If you 'reach' for the landing, then you will land more on the heel (unless you plantar flex, which is a BAD idea!), whereas if you allow your foot to land under the body, then you land midfoot. That's all you need to know, the rest is details. So don't worry about it."

From "The footstrike: How should your foot be landing . . . "

"Why would you want to change your foot landing to begin with? Science has little to offer you in support of this. And so my advice, having read this far (well done!), is to forget about the possibility that you're landing "wrongly", and just let your feet land where, and how they land, and worry about all the other things you can when you run!

If there is one thing you change in your running, don't focus on your footstrike, but rather on WHERE your feet land relative to your body. Because if you are over-reaching and throwing your foot out in front of you, that's a problem, but what happens when the rubber meets the road is less relevant!"

Len

That is a point made in the articles I mentioned above. In general, the faster you run, the further forward you tend to land on your foot. So when you sprint (100 yard dash), you are likely to be a forefoot striker. The articles explain it better, but it ties into how you stride and where you plant your foot relative to your body as you speed up. (You can land midfoot, even with a short stride, if you plant your foot directly under your body.) You can teach yourself to change your footplant but you need to approach it cautiously, because it changes what parts of your leg take the stresses. Again the articles explain it better but it seems as you move your footplant "forward" (midfoot / forefoot), the calves and ankles take more of the stress and there is a definite adjustment period. I have been moving toward a midfoot strike because of problems with my heel that are alleviated by landing midfoot. But I can really feel it in my calves!

Len