There's been a fair bit of rain in the Peak District, although nothing like as much as in the Lake District. The paths are muddy so for this afternoon's run I thought the ASICS shoes would be best. I planned to run very steadily up to Oxstones for the sunset but after about 40 minutes (6km) of ascent it was clear that my left ankle was being irritated as I found last time I wore the shoes.
I had been unsure whether this problem was due to the reduced heel drop of these shoes or simple friction from the neoprene cuff. Well now I'm fairly confident it's to do with heel drop because as soon as I set off downhill the problem largely went away. The heel drop is not publicised by ASICS as far as I can tell but a few reviews put it at just under 6mm.
There's quite a good article here relating peroneus injuries to forefoot striking and minimal shoes. A low heel drop shoe is simply a mild version of that - basically encouraging the muscle and tendons to work at a longer length than they are used to.
So now I know that the shoes should currently only be used for 5km or so and that I need to transition into them for longer runs. It is perhaps noteworthy that the shoes are marketed for obstacle race use, not ultras although the manufacturer's blurb says "You can take on half-marathon distances...". Ultimately I think that I do want to be comfortable in lower shoes as many trail and fell shoes are going that way so I need to persevere.