Quick stats. Started running five and a half years ago, which as an adult means I never did track and my first "goal" race was a marathon. Ran 3:09 (2011), 2:57 (2012), 2:40 (2013), 2:33 (2014), and now my PR is 2:28 (2016).
My 5K PR is 15:59 (2014), half is 1:12 (2016).
I haven't run faster than about 16:15 for two and a half years, and I'd really like to get my PR down in the 15:3x range and around 15:5x when I'm training through the race. I also expect I'll improve other PRs in the process, but one wrinkle is that I'd like to not get slower in the marathon.
My training works out to a minimum of 90 miles per week, usually over 100 and peaking at 110-115. I don't really feel like I'm tired or dipping into the well when I'm in that 90-100 sweet spot so that's my plan for now. Here's a few sample weeks from my last training period to give you an idea of the workouts I enjoy:
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Monday AM: 8x1k avg 3:05. 10 miles total
Monday PM: 9 easy (7:00)
Tuesday: 13 medium long (7:00)
Wednesday: 10 easy, strides (6:40)
Thursday: 22 mile run with 30k progression (37:10, 35:17, 33:40 10k splits)
Friday: 8 easy (7:00)
Saturday: 11 mile fartlek 1'/1'
Sunday: 10 easy + short hill sprints
Monday: 10x1 mile off 1m jog, starting around 5:40, ending under 5:20. 15 miles total
Tuesday: 13 medium long (6:50/mi)
Wednesday: 10 + 6 easy double, strides (7:00+)
Thursday AM: 4x2 mile tempo off 2m jog (11:00 avg). 13 miles total
Thursday PM: 7 easy
Friday: 8 easy
Saturday: 20 hard (~6:00/mi)
Sunday: 10 easy + short hill sprints
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You get the idea. It's a marathon training plan with a long run every ~10 days and 2 workouts in between. Early in the season I would do 2 minute hills at 5k pace and some 20x400, 8x800, etc workouts, but they were done with by about 8 weeks from my last marathon.
I can't say I've ever felt comfortable on a Vo2 workout. I usually need a 3 mile warm up and 2 slow reps just to touch my goal pace, and sometimes I still blow up. In 5k races if I go out at goal 5:10 pace I blow up at the end of mile 2 and have to limp it in. I've never successfully negative split a 5K - even if I go out at 5:15. My PR split was 5:00, 5:10, 5:18. I feel like I should be running 5:00-5:05 pace pretty comfortably, but it ain't happening.
So, Letsrun, give me some ideas on how I can get better at the 5k without sacrificing my ability to run long. Should I be doing shorter, more high intensity stuff in my 2 workouts between long runs? More strides? Do I have to sacrifice the hard long runs? Should I just run 1x5k and quit being such a whiner?
Note: I'm not looking for a 2 week solution and I understand periodization. If I learn anything from this it will go into a 10 week plan peaking at a goal race in April, after my other more important races are done. But I also don't feel particularly tied to many of the supplement workouts I do during marathon training and I feel like I can replace them at will.