I am a sophomore college athlete, and although my coach isn't a big fan of it, I've worn Luna Origen Sandals for nearly all of my mileage for over a year now. I tend to average about 80-90 miles a week in them and the vast majority of my workouts I have done while wearing them. I train for XC and 10K on track, and the sandals haven't hindered my training whatsoever. Although it can be challenging to run in them in very wet or muddy conditions, I have no complaints 99% of the time that I'm running. I get anywhere from 1,000-1,500 miles per pair, and they're perfectly usable for fast workouts on the track. Rough sandal P.R.s in workout off of memory would be 16:10 5K, 4:45 mile, 2:17 800m, 64 second 400m, and 28 second 200m. Not crazy fast by any means, but fast enough to prove that workouts can be done in them relatively hassle free. My average run in them would be about 12-14 miles at 6:40-7:40 pace across 1,500ft of climbing and all manner of terrain, and just the same as the kid that inspired this post, I've not taken any time off due to injury since I started wearing them. While I obviously wouldn't recommend them for everyone, I don't see athletes running in them as being especially worrisome either. If it brings the runners joy and no negative effects are being seen, I say just let them be. We're all just trying to get better, and as long as we continue to do so, I don't see any harm being done.