They have a lower drop, or heel-to-toe differential than the shoes you're normally wearing. I remember a half in shoes that killed my calves and I still the shoes and think they're great for distances up to that. There are 2 ways around this
quote]eirus wrote:
Adizero boost[/quote]
This guy is right in the sense that the Adios, Boston, and Tempo (3 options from adidas - increasingly heavier and more shoe) have around 10mm drops, similar to many training shoes. 12 is about the most you'll find, so not that much lower than anything I can imagine you're wearing. Brooks does the same thing. The Racer 5 (a little heavier and more cushioned) and the Hyperion (a little less) both have solid 10mm drops and so are very close to the Launch as well as beefier shoes like the Glycerin or Transcend. Both of these brands solve the issue by offering high-differential racing shoes, or more importantly, a whole spectrum of shoes down to very light that are close to each other in drop.
Remember I mentioned I still have, and like very much, the shoes that destroyed my calves? I went another route: lower-drop training shoes. I try to run in shoes with 8mm or less for most of my miles. That way, a flat with 6mm isn't shocking for Achilles and calves. It's just not that big of a difference. I will put in several runs in the shoe in question when a race is approaching, so even a 4mm drop isn't brutal and I'm not starting at 12mm. The highest drop I have is 10mm until I wear out my Launch, but I'm not using them that often and doing most of my miles in 7-8mm drops. 5-6mm on race day no longer kills me. Tips: also have walking-around shoes that are close to flat and get into stretching Achilles and calves while standing around, on an escalator, near a curb, whenever.
Good Luck!