A bit of this most difficult activity is much more stressful for my vulnerable back than what passes for a speed workout these days, which generally seems favorable.
It is quite ironic, isn't it? It's purely anecdotal, but collectively my worst and most prolonged injuries seem to have started during what at the time seemed just a trivial, easy run, no different from any of hundreds and hundreds of other easy runs.
I've read that hip imbalances (core/groin included here) sometimes manifest as calf issues, since they end up compensating for whatever is out of alignment. Might be worth looking into?
I realized after the post-Pig 8-hour drive home that groin stretches ease my psoas discomfort. Starting to wonder if shoulder stretches might benefit my feet!