I am also training for Boston. Ran my first two marathons this summer along with a 1:32 HM and a few other races including 5Ks in the spring and fall with a friend. I still can't believe I ran the HM in 1:32 given that pace has been about as fast as I have managed to run 5 mile competitive training runs with a running group. 2nd 5K was a PR (post high school) of 19:15. I only run the 5Ks because they are with a close friend who is my speed and I can't convince him to move up in distance. He runs my speed with just a few runs under 5 miles a week I think while I run 35 mpw minimum and have upped my mile to 50 to 70 a few times this winter. I now don't like 5K's due to the speed. A 400m will really feel fast to me now and hurt. I have not done any hard training runs under 5 miles in the last two years. I am running out of routes to keep my long runs interesting too. I did happen to come across and run with a former D1, female, runner today at a local busy park today which made for a mile or two of interesting conversation since my daughter is now running for the same team and coach.
Age: 51
Height: 6'0"
Weight: 165 lbs down from 230 a few years ago. Currently trying to get down to 150 before Boston after feeling fat shamed while reading some other Letsrun threads recently--learned that over 150 for a distance runner is considered fat. I weighed 145 at the same height when running on high school team.
400m time: low 70's when doing 400s 2 years ago in training with some track runners. I may try an all out 400 in a few days to see if I can do one, all out, 400 in under 70 seconds. I ran 17+ miles for my 2+ hour marathon training run today so it will be about 4 days until my legs feel fresh again and allow me to try an all-out 400.