Just recently I was experiencing achilles pain in both left and right achilles. The pain would be the most severe in the morning and right after running. It wasn't severe enough to actually quit running, but it was unnerving and had me worried it would lead to something more severe or chronic. I decided to take matters in my own hands, probably not the best idea, but I am stubborn and I have a bunch of races coming up and preparing for mileage build up for two planned fall marathons.
First, let me give you a little history to help explain how I got here and what I did. I have been running in minimalist/low heel to toe drop shoes exclusively for almost two years, including several mileage build ups leading up to fulls, halfs, 30K's, etc. I transitioned slowly and had no issues except sore calves. I am a neutral midfoot striker and consider myself to be a biomechanically efficient runner. I average approximately 40 miles per week and really haven't changed much in my training, although I am running much faster now than when I first started running in minimalist/transitional shoes.
Okay enough about that, here's what I did: I self diagnosed myself (I know, again not a good idea) with the onset of achilles tendinitis and I figured I would try to mix in a pair of higher heel to toe drop shoes a couple times a week to give my achilles' a break. A few weeks ago I purchased a shiny new pair of Mizuno Wave Rider 16's (I know, I know...) from my LRS. I figured if was going to go higher heel to toe, I would go all the way...LOL. I also figured that I would get something firm and responsive. I'm digging firmer shoes nowadays (absolutely LOVE my Fastwitch!).
To make a long story longer, guess what? No more achilles pain!! Still running in low and zero drop shoes (just PR'd a half in the Fastwitch), and just mixing the Wave Riders in a couple times a week. I actually like them a lot. Firm, responsive, narrow heel, and wide forefoot. And I actually, to my surprise, have no problem maintaining a forefoot/midfoot strike.
I am NOT a doctor, just saying...