Speaking from experience, I'd say that he can run his 5k pace (with 20 mpw) for a marathon on 80-100 mpw.
Speaking from experience, I'd say that he can run his 5k pace (with 20 mpw) for a marathon on 80-100 mpw.
I think the times posted here are too optimistic.
The average US male over 20 is 5' 9" and weights 198 lbs. I'd speculate a nine minute mile and 32 min for a 5K, assuming they indeed just average as far as athletic talent goes.
A healthy weight might be 165 lbs. Again, if they are just average--i.e.,the average 25 year old you'd see at the local mall, then I'd guess maybe a 7:00-7:30 mile and 24:00-25:00 5K. Faster times if they have any "runner" genes.