Slowest 5k for a sub 3 hour marathon

I ran a (negative split) 2:56:05 off a 17:58 5k and 80mpw.

I had a ~17:40 5K, ~38:30 10K going into training for my first marathon last January. I ended up averaging about 31 mpw for the 20 weeks leading into the marathon, with a peak week of 48 miles. (I'm also a soccer referee, so I do a decent bit of running while doing that.) I had to take about one week off in October and five days off in December with some Achilles issues. I ran a 1:26 half (my PR) 7 weeks out from the marathon. But I blew up pretty horribly and finished in 3:21 after a 1:28 first half.

So I think a low-18s 5K guy who averaged 40+ mpw for at least 13 weeks, and peaked around 55, would have a pretty good shot at breaking 3.

This is completely believable, I mean that it took you a few trys. Even posting it took you two trys.

Yeah, at the pro level it’s 40-45 sec slower than 5K pace. For typical amateurs it’s about twice that, 1.5 min slower.

For your solid hobby jogger type, who peaks at 50-60 mpw, about a minute.

Your 20min 5K runner is typically a 320-25 marathoner.

how much did that hurt? or would you say that you're just much more suited to the marathon? i just can't fathom holding 25 seconds slower than one's 5k pace for a marathon

If you found someone with absolutely no speed speed at all, but freakishly good endurance, I think its even possible for them to run a 3:00 marathon off of a 19:30 5k. It would have to be Paula Radcliffe level relative endurance to speed (she ran a 2:15 marathon, yet never broke 4:05 in the 1500m despite several serious attempts at the distance, although she had a super fast 8:22 3k).

Paula Radcliffe's 5k PB was 14:29 when she ran her 2:15:25. So she ran roughly 4:40 per mile in a 5k and 5:10 per mile in a marathon, which is roughly 10.8% slower pace (insane, but we know its possible because she did it). An 18:30 is 5:57 per mile. So it seems concievable that an insane indurance over speed type (such as a radcliffe, but slower) could manage 6:32 pace or so for a marathon (a 2:52) off of 18:30 shape. Extrapolating, this means someone running as slow as 6:10 - 6:15 pace for 5k could manage the 6:52 per mile required for a 3:00 thon, but it would be pretty rediculous.

To get to a 3:00 marathon off of 18:30 or slower 5k shape, it takes a ton of mileage. I'd say you'd need to be running 50 - 60 miles per week, consistently, for a full year to build up the propper base to run so close to your 5k pace for a marathon. But its definitely possible. For a 19+ min 5k runner, it would require elite marathon training (100+ miles per week) to get to a 3:00 marathon.

I'm just much more suited to the marathon. I never had much speed, but could hold close to my maximum speed for a very long time. At my best, I struggled mightily to do a quarter in 82-83 sec (5:30 mile pace), but could hold 6:15 pace for a marathon. And running absolutely as fast as I could for 5K was way more painful than running what felt like a fast but comfortable pace for a marathon.

When I did sub 3 my PRs were 18:12 and 36:57. I couldn't run sub 18 to save my life (still struggle to this day).

I try to race at 185 or a pound lighter, but my typical weight is around 188-193 I would say. I would LOVE to see 179 on that scale, but just can't friggin do it

Well, that is only partly true for me. Yes definitely life outside running, physical therapist, three kids, etc. But I actually feel pretty committed to the marathon, not a "professional" commitment of course, but I'd say putting in proper training. Done 7 marathons so far, one a year, also race other distances and give them their own dedicated blocks. Over the years gradually built up mileage, this past marathon cycle hit high 70's for like 5 weeks, six long runs of 20-22 miles. Over the years have gradually whittled down my marathon time to 3:08, dream is to BQ (sub 3:05 for me). But the marathon is always my weakest relative to other distances (18:305k and 1:26 half). I've always wanted to start a thread about why that is actually

I hope this is me this year, would love 18:12. Ran 18:30 PR a year ago, currently in a 5k training block, but hitting workouts a bit faster this year than in the build up last year, and mileage is also a bit more. No way I'm running sub 3 though. Just want to go 3:05 for a BQ

It’s a size thing. As a group, the women are much smaller than the men and don’t wear down as much.

My PRs:

18:35

1:20:35 (half)

2:53:45.

I have a bent spine and exceptionally bad form at certain speeds.

I think my form is worst- 1 mile to 5k.

Best from 10k- half marathon.

Then bad again beyond 20 miles.

"So it seems concievable that an insane indurance over speed type (such as a radcliffe, but slower) could manage 6:32 pace or so for a marathon (a 2:52) off of 18:30 shape."

I can confirm that since that is exactly what I did. After four years of marathon racing, PR'd at 2:52, then ran some 5K at coach's suggestion. It went like 19:05, 18:50, 18:35 and that was the best I ever did. Perhaps age was a factor? This happened at age 54-55.

N=1 but I have run 2:59 off of 40mpw, with a peak week of 45 miles. I have been running consistently for years though.

85% easy running, 15% marathon pace, occasionally strides.

I think my 5k PR is soft because I never do speed work - I'm 51 and this is what works for me.

Wow! That's in the same league as my 18:10/1:18:59/2:42:50.

I have weird form too, but it seems about equally bad at all paces.

A female friend of mine ran 2:57 and 18:20 (both her PRs) at around the same time.

Another female friend ran just under 2:59 with an 18:30 5K PR. It took her a few attempts to finally break 3. Most of her 5Ks were around high 18s, maybe 19 flat.

I find this mind boggling! I'm a woman - ran the 400 m in 70 s in high school, not fast enough by the way to run it in meets unless our team was truly desperate. But I couldn't even run 6:15 pace for a 5K, never mind a mile! Heck, 6:15 pace was touch for the 3200 meters.

Of course, this was back in the low mileage / lots of speedwork 90s.

The times I quoted were also run in the early 90s, but I learned very early that I had no speed and I worked at optimizing what I could be best at. I typically ran 75-90 mpw during this time but did very little speed work, maybe quarter-mile intervals a couple times per month. I'm sure I could have been faster at the shorter distances had I trained differently, but I was never going to be nearly as good at 5K as I was at the marathon.