I could be wrong, but I'd guess that you're landing way up on your forefoot with your foot plantar-flexed very far, your heel way up off of the ground, and your calf shortened a lot. If you're doing that, you're essentially braking with every footstrike. If you are doing this, an observer would probably think that you were prancing.If you land with your forefoot directly underneath your center of mass (approximately directly underneath your hips, or only slightly forward from your hips) you can land on your forefoot without plantar flexing much, if at all. An observer would think that you were landing flat-footed, but your forefoot would actually contact the ground before your heel would, if your heel were to touch the ground at all. For people who don't naturally do this, it takes practice and conscious effort, but is much easier on the calves than prancing on your toes.
toro wrote:
I have been trying for years to convert myself from a toe runner to a heel striker because of the pain caused to my calves and achilles. I wish I could train on my heels and race on my toes but it feels awkward to land on my heel.