Thin and alone wrote:
Background
30 years ago:
1500M runner at a D3 school
3:57 PR
Height 6'
Weight 145
Today
Age 52
Weight 175
I run once a week at a 9 minute pace for 20 mins
I lift weights at the local YMCA 2-3 times a week.
The YMCA was very crowded so I decided to skip lifting and go to the Middle School track. I did an easy warm up and timed myself for a 400M. I was wearing longer basketball type shorts and Nike Pegasus training shoes.
Guess my time!
And go............................
One think I wished I knew before predicting: Have you been keeping up this running/lifting schedule for 20-30 years, or is it a new thing after possibly 2 decades+ of complete inactivity? That would change my answer considerably.
If the lifting /20 min weekly run is a relatively new thing after doing nothing for decades, the age and weight differences alone make me think you probably would be lucky to break 80 seconds, even with your background. Thirty years is a long time ago.
However if you've been following your current "training" more or less for 20+ years up to now and stayed some semblance of 'fit' all this time (gym, weekly short jogs) , I predict a 73 second quarter.