Understandable, also do you put socks on with them? That’s what fixed my heel problem. My feet sweat like crazy in those though.Had these guys literally only for a week so can't tell you about PRs but they've been great (plus my running dipped a bit for the past 6 months but I'm going to up the milage again having seen you people on Strava).. My other shoes are Merrel Vapors so I was definitely breaking 20 on 5ks for that - I rarely run for time though - keep chuggin away on longer, slower distances mostly.