You don't think OP is trolling?
I'm too experienced as a runner, and was too fast for 400/800/1500m, to accept the vagueness of OP as anything but written by a person who routinely sets up these threads to get some reactions.
50-60 miles a week to run 48-49 in relay splits? The 400m runners on my HS ran as fast and faster, and at the college where I ran the 400m runners were among the best in the NCAA Div I.
The 400m runners in HS and college would fall over after just 1 week of 50 miles, and refuse to do another week.
Sure but we aren't talking about a 400m guy. We are talking about an 800m guy. For them running 40-50 mpw is in the realm of normal. The 400m/800m guy at my HS were doing about 45mpw during XC and running 49 high relays/1:55/16:20 XC. The unrealistic part is any of these guys deciding that they want to go run 70+ MPW:)
It is surprising at how few sub 50 guys some schools have. Pretty sure the ND national champion DMR had 400m guy had a PR that was like 48.9. When you get to 4th on your depth chart you are looking at hurdlers and 800m guys at a lot of schools.