I've "never" knowingly run without landing heal first. Had my gait analysed and was told that actually my heal strike isn't too heavy, so to stick with it.
On Monday I (stupidly?) decided to consciously try and land on the balls of my feet. Surprised myself by managing (and did over 30 mins despite being on the mountain). Warmed down, stretched and showered, but then yesterday afternoon (Tues) my calves were in agony. They feel so tight. I can hardly walk normally (it's now Wed morning) and stairs are a particular challenge! It is a little better now than first thing this morning.
It does seem a bit strange that it was such a delayed reaction - or maybe it's something else causing the pain? (I had a fever last night - collapsed into bed at 8!).
Am thinking that perhaps I should do just a few minutes of running on the balls of my feet within each run rather than 30 mins in one go and then build up to the whole run ... or perhaps I shouldn't bother at all?