I got the impression that a compromised peroneus longus and tibialis posterior went hand in hand in the case of ankle instability and heel pain - which seems to be the case for me. ie 'peroneal muscles should also be examined as they often contain active TrPs when tibialis posterior is involved'. In my case, I often have mild to severe achilles tendonitis in the morning, which improves as it warms up. When running I no power through the affected calf, compared to the good leg. I've tried to find further info but drawn a blank. Can you comment on whether this makes any sense, and any further references you may suggest?