Spivey ran 13:15, also Padilla 13:15 on similar low mileage in the '80s
http://www.letsrun.com/forum/flat_read.php?thread=907089
"Jim Spivey: 1984 mileage: Each month- week's totals/notable race
January: 54.5,40.5, 27.0, 45.0
February: 45.5, 42.5, 48.0, 33.5 / 3:56.17 Bloomington-I
March: 40.5, 29.0, 31.0, 43.5, 45.0 / 3:44.90 Florida
April: 60.0, 50.5, 56.0, 42.0 / 13:46.61 5k Drake 1st
May: 47.5, 42.5, 39, 22 / 3:53.88 Pepsi, 13:37 Knoxville
June: 34, 40.5, 27, 41.5, 33 / 3:36.42 Olympic trials, 1st
July: 36.5, 38, 40, 42.5 / 2:16.54 1k Prefontaine
August: 38.5, 30, 22, 35 / 3:36.60 Olympic Games, 5th
3:34.19 Zurich PR"