Same here as far as the treadmill. My calves in the past got so tight that at easy pace it felt like something might snap. Figured that wasn't sustainable and changed my form to land more midfoot to even heel first. Also discovered slow and strenuous calf release techniques that do wonders for me. Now after years of this approach, I'm going back to a forefoot to heel strike because my hips hurt. With the calf release sessions every 3-5 days, I think I should be OK but if not I'll figure something out. Funny how in the end, I'm clueless but my curiosity and persistence has as of yet always got me running through whatever challenge.