OP here bumping this thread two years later. After being stuck with this problem for over five years, I made a few key changes which finally helped me get over this injury.
Here is a list of changes I made, from what I considered to be the most important to least
important. This is my personal experience, but I sincerely hope it can help
anybody else dealing with this very frustrating problem.
1) I modified my pace so that my aerobic, easy runs were actually easy. There is a difference between "easy" and "not hard". Frankly, I was not being honest with myself about effort level. Faster running stresses the Achilles much more than truly easy running.
I gave HR training a shot. It is extremely humbling plodding along at 9+ minute miles. But, without unnecessary speed, running no longer kills my Achilles. I feel that this base training approach has strengthened my tendons and made me much more durable.
2) I identified and addressed personal muscle imbalances I had. Instead of doing stereotypical "Gym Bro" activities in the gym (heavy squats, deadlifts, bench) I spend my time in the gym doing much more focused running work. Lots of single leg activities (single leg calf raises, single leg deadlifts, single leg split squats).
The single leg split squats actually made me aware of a Glute Medius weakness on my right side. This is the same side as the injured Achilles. My hip would tilt in, and my body would look super lopsided in the mirror when I performed this exercise on my right side (even with just body weight).
Despite my PT telling me my hips are strong overall, I still had a severe muscle imbalance with this muscle. I spent lots of time working on this hip. I did lots of of lying leg lateral raises, banded walks, clamshells, fire hydrants, etc.
I also spend some time addressing other weaknesses in my body caused by dumb injuries in my youth. (3 X Sprained Ankle / 1 X Dislocated Shoulder, if anybody is curious). I also do much more core work. This has made me more balanced and durable.
3) I do heavy calf raises. In the past, I would do light weight, but high reps at the advice of my PT. They definitely helped me initially! But once I progressed to truly heavy weight, I felt that my healing rate increased significantly. Something like 3-5 sets of 3-5 reps, where I am going slow and in control. When I do these, I get a crazy pump to my calves, hamstrings, and even my core. I never, ever had this sensation with the higher reps of calf raises.
4) This contrasts 1, but I started throwing in a small amount of faster running. I used to only do easy runs because I was injured all the time and scared to overload the tendon.
Just doing some strides + a light tempo or fartlek every week has subtly changed my
form and made me stronger. I notice when I run a cooldown after a workout, my
core is more engaged, and my hip position is different. I believe that running
faster (once I built up enough easy running) has strengthened my body.
5) Idk if this actually helps, but I wear more minimal shoes when I am not running. I wear zero drop shoes at work or when I go out. These don't have a lot of cushion. I would
/ could never run or walk a lot in these. However, I suspect that walking in them day to day has made my feet stronger. I wear the Altra Escalante for work, and the Xero Glenn for more formal occasions (occasionally for work, but the Xero shoe requires A LOT of foot strength to wear). I still run in traditional shoes for 100% of my mileage.
That's pretty much it! I am sorry to write so much, but this is a complex injury. It took a lot of attention and concentrated effort to get under control.
I am slow compared to most here, but I am now running a consistent 40 MPW including a workout, and more importantly, very minimal Achilles pain. This is in contrast to me getting
up to 20 MPW, hurting myself, restarting from 0, and inevitably repeating the cycle.
I suspect my right Achilles will never be the same it was before the injury. Sometimes, it still
is a little sore / stiff in the morning. But it rarely hurts while running, and it is improving despite me increasing running volume. It's good enough for me. Maybe one day I will need surgery, but for the first time in a while, I am comfortably increasing my volume and running consistently.
I hope this helps somebody out there. It was frustrating not being able to train properly in my mid to late 20's. But this experience has fundamentally changed how I view
training and overall athleticism. I think I will be a stronger runner for it.
Peace and happy running.