There was some other thread about a New Zealander who ran 13:2x for 5k, Hayden Wilde I think is his name. It shouldn’t come as too big of a surprise really. Austin Hindman from Lafayette high school in Missouri ran 8:43 at Arcadia in 2017, outkicked clinger, grijalva, pretty much everyone and placed second. That time is ridiculously quick and he was doing a lot of biking and swimming to compliment the probably lesser running he did. I think he ran 4:02-4:04 for a full mile as well. Triathletes can really build their aerobic capacity higher than a lot of runners because the chances of getting injured while swimming and biking are pretty minimal. Also with biking you recover a lot faster so you can do more/longer workouts. A lot people say cycling doesn’t help running, but it really does