I think it depends a lot on the mileage and the athlete. The 16:00 5k runner who’s clocking 75-80 mpw will probably be a lock for sub 3:00:00, the 16:00 5k runner who’s running 25-30 mpw I’d be less confident in despite probably having more talent.
Of course Jakob and Hocker can bust a sub 3:00:00, they run regular 14-16 milers at sub 6:00 pace. I’d be less confident in athletes like Brazier and Hoey even though I’m sure they can both speed endurance their way to a mid 14:00 5k if not faster.
Most athletes hit the wall at 16 or so miles if they aren’t running adequate mileage/long runs. When I was running 16:00-16:30 in high school at 40ish mpw I don’t think I could’ve run a full marathon at sub 7:30 or even maybe sub 8:00 pace. In college when I was in about 15:00 shape I distinctly remember struggling a lot running 16 miles at about 6:40-6:50 pace because my regular long run was 10-12 miles and 13 or 14 miles had been my longest run at that point.
Good post, though given Arop ran a 71 HM last year I think it's safe to say top 800m guys can still break 3 pretty comfortably. Brazier especially has always had good natural endurance and competent in XC even though he hated it. Hoey as a sub 3:30 1500m guy shouldn't have problems with it either.
I think you are underestimating the drop off after half marathon in low mileage training. I don’t think the regular rules of running economy where it’s generally 20-30 seconds per mile every time you double your distance apply, because there’s an entire energy system missing there. You can have a well developed lactate threshold that’ll drag you to a fast half marathon, but I feel like there needs to be specific marathon training that doesn’t exist in the 800 and even 800/1500 types to tackle the sheer muscle fatigue/ glycogen depletion problems that tend to crop up around 20 miles in.
Nick Symmonds if I remember right signed up for a marathon almost immediately after retiring from track, trained fairly seriously for it, and didn’t crack 3:00:00. I think a lot of people vastly underestimate how much of a difference in marathon preparedness there is between “10 mile long run at 7:30 pace at peak training mileage” and being able to run a fast marathon. To be fair, Symmonds is a pretty unique athlete but if he, as a 1:42-3:34 guy failed to do it WITH marathon specific training I have a hard time seeing athletes with similar skillsets and generally less mileage than what Symmonds did being able to pull it off.
People never read these questions correctly. OP didn't ask for anecdotes. He didn't ask for an asmwere dependant on training. He only asked for the 5k time that guarantees 3 hours. We can all agree that all 13 minutes guys would do it. That means it is some number slower than 13 minutes. I don't think 14 minutes guarantees it because an elite guy like Fisher could run 14 minutes on little training which would limit his marathon time to a DNF. So I am going with 13:45 as the absolute guarantee.
Given 3hr marathon is 4:16/km the absolute minimum is 21:20
Back in late 90s, I was given a sheet which said you need to be able to run a 18:39 5K to run a sub3 marathon. Daniels VDOT says 18:48; Greg McMillan says 18:28.
Quite possibly someone is very slow-twitch and just chugs around doing nothing but endurance might be able to get away with a few seconds slower.
But if your 5K time is based on any significant amounts of speedwork then you're really looking at needing that 18:40ish time as a minimum
2. What 5k PR guarantees a sub 3 marathon if properly trained.
1. 15:30-16:00
2. 17:30
Anecdotally, I'm #1. I run 55-65 miles/week with no specific marathon training. The last 6 weeks I've gone on 3 runs over 16 miles with friends. The 18 miler that ended up at 644 pace tells me I could've run another hour at that pace without much trouble. Much faster would've been a struggle. That said, having better nutrition (I didn't carry any calories), wearing supershoes, a taper, and better attire makes me think that I could dip into the 240s without changing much training-wise.
I've never run a marathon based on my struggles with the half. Being unable to run faster than 71-73 minutes off 70 miles/week has made me realize that running 230-237 would require me to seriously increase mileage.
I “ran” my first marathon in 1992 with no specific training and managed 3:35 with a painful final six mile walk / jog / stagger after slamming into the wall. I was in about 20 minute 5k shape at the time. If I do the math, multiplying 20 minutes by 3:00 / 3:35 I get about 16:45. So I’d say you’d need to be in 16:45 or better shape to have a really good shot at breaking 3:00 without marathon training.
People saying 16 are delusional. I'm sure plenty of people could easily go sub 3 off of their sub 16 5k training, but plenty couldn't. Sub 14 sounds better for a 98% success rate with no additional training.
My 5k pr is 15:50 from a time trial right after my last college track season. I was a decent 800m runner and ran that off of around 35 miles a week, with a 1 hr / 8ish miler feeling like a long run. I imagine a more talented 800m runner could go 90+ seconds faster off of similar or lower volume.
I signed up for a marathon for the next fall, with a plan of getting in some decent mileage and a solid time. I lowered my expectations after I couldn't get comfortable with 60+ mile weeks, and ended up settling in to 50 mpw with plenty of tempo runs. During the race I went out in 2:55 pace, figuring that it would feel easy and I could pick it up at the end for a strong finish. And it did feel easy up until the last 10k, were I completely crashed and slogged it in to a 3:01.
People saying 16 are delusional. I'm sure plenty of people could easily go sub 3 off of their sub 16 5k training, but plenty couldn't. Sub 14 sounds better for a 98% success rate with no additional training.
My 5k pr is 15:50 from a time trial right after my last college track season. I was a decent 800m runner and ran that off of around 35 miles a week, with a 1 hr / 8ish miler feeling like a long run. I imagine a more talented 800m runner could go 90+ seconds faster off of similar or lower volume.
I signed up for a marathon for the next fall, with a plan of getting in some decent mileage and a solid time. I lowered my expectations after I couldn't get comfortable with 60+ mile weeks, and ended up settling in to 50 mpw with plenty of tempo runs. During the race I went out in 2:55 pace, figuring that it would feel easy and I could pick it up at the end for a strong finish. And it did feel easy up until the last 10k, were I completely crashed and slogged it in to a 3:01.
This is an interesting question as there is more than one way to race a fast 5K in absence of marathon specific training.
800m fast-twitch runners (your typical HS track kids) can grind out a 15:xx time off of low mileage and natural speed. Meanwhile your local subelite hobbyjogger who prioritises the 5k/10k/HM will also get there off of greater mileage but still without ever going over 13 miles in a single run.
Both will crash and burn in the last 10k of a marathon if they were forced to run one all-out tomorrow, but the latter would have a much much greater chance of hitting sub-3 than the former.
16:00 probably guarantees it for the 2nd type of person whereas the former might need to dip under 15 to make it a guarantee, and even then they might have the aerobic ability to do it but might end up getting injured in the execution due to never having ran remotely close to the distance in one go before.
Brazier ran 15 minutes in high school. He would have been lucky to walk a marathon in 6 hours. 15 minutes is not close to a guarantee for 3 hours. You guys have no idea how hard it is to run 3 hours without training.
Brazier ran 15 minutes in high school. He would have been lucky to walk a marathon in 6 hours. 15 minutes is not close to a guarantee for 3 hours. You guys have no idea how hard it is to run 3 hours without training.
You guys are talking about pros and elite 800 runners when you should be thinking about teenagers who can run sub 16 with next to no training and probably couldn't finish a marathon
Well the obvious answer is no 5k guarantees you sub 3, but in general most guys I know who run ~16 min can decide to run a marathon and finish under 3 with no specific training. ~17 min guys seem to often end up closer to 3:10 even with one or two long runs to prep.
So if you want a really high probability, it’s probably somewhere under 16. Under 15 is closer to ‘guaranteed.’
This seems like a good answer. You could have a good 800/1500 runner that can scrape out a 16:00 5k but is still out of their comfort zone at that distance. Their drop off up the distances might be quite high and a 3-hour marathon might be too much. But once you get down to 15 minutes, you're quite well inside and it would be a surprise to see someone not be able to go sub-3.
Bear in mind also that a 3-hour marathon is said to be "equivalent" to 19 mins for 5k, so a properly trained 19-minute runner who isn't specifically worse over longer distances should be aiming for around 3 hours. Being fully 4 minutes inside that and not training for a marathon is likely to be enough.
But 16-min runners not making it might also be fairly uncommon.
Good post, though given Arop ran a 71 HM last year I think it's safe to say top 800m guys can still break 3 pretty comfortably. Brazier especially has always had good natural endurance and competent in XC even though he hated it. Hoey as a sub 3:30 1500m guy shouldn't have problems with it either.
I think you are underestimating the drop off after half marathon in low mileage training. I don’t think the regular rules of running economy where it’s generally 20-30 seconds per mile every time you double your distance apply, because there’s an entire energy system missing there. You can have a well developed lactate threshold that’ll drag you to a fast half marathon, but I feel like there needs to be specific marathon training that doesn’t exist in the 800 and even 800/1500 types to tackle the sheer muscle fatigue/ glycogen depletion problems that tend to crop up around 20 miles in.
Nick Symmonds if I remember right signed up for a marathon almost immediately after retiring from track, trained fairly seriously for it, and didn’t crack 3:00:00. I think a lot of people vastly underestimate how much of a difference in marathon preparedness there is between “10 mile long run at 7:30 pace at peak training mileage” and being able to run a fast marathon. To be fair, Symmonds is a pretty unique athlete but if he, as a 1:42-3:34 guy failed to do it WITH marathon specific training I have a hard time seeing athletes with similar skillsets and generally less mileage than what Symmonds did being able to pull it off.
Fair, and as an 800m guy yourself I guess you would know better. I didn't realize Symmonds attempted it while he was still in good shape and not way after his days of serious training.
I remember there being questions of whether or not prime Rudisha could do it back then too.
Out of the current guys the most likely to do it would be Wanyonyi - pretty high volume for an 800m guy, signs of being a strong miler (2k XC as well) and regular 25k long runs.
As others have said, there are no guarantees. For info, I had a 5k PB of about 19 mins when I ran my first marathon in just outside 3 hrs off 8 weeks training - 30 - 40 miles a week with longest run of 10 miles.
Have you read any posts? Are you a moron? Thousands of high school kids run sub 17 minutes. Nearly none would break 3 hours. The question is what line guarantees 3 hours. The correct answer is 13:45.
It’s 15:59. If you can break 16 you are a lock for sub 3 even if you didn’t run the proper mileage or long runs. The caveat to this is that you can’t ever get greedy and would have to swallow your pride during the race which is hard for a lot of people. You would be racing with people much slower than you (think 17:30-18:30 5k guys) but they put in the time on their feet so they would be getting the most out of their bodies that day to run the time while the sub 16 guy would have to play it safe. The reason why a sub 16 guy wouldn’t break 3 would be that they went out too hard since it feels ridiculously easy in the beginning and they would probably think they are leaving seconds out there but aren’t. 2:59:59 is 6:52 pace, a sub 16 guy would casually run that on a training run. As long as they robotically stuck to that pace and didn’t go faster they would easily do it.
This question also hits close to home for me since I’ve been there. I’m a middle distance runner but have qualified for Boston and gone sub 3 at Boston without any marathon specific work. The biggest thing is swallowing your pride and respecting the distance which a lot of faster runners don’t do. They think because they’ve run a fast 5k on and the VDOT table shows that they can run 2:30 or something like that they can run close to that time. But it doesn’t work like that unless you run the proper mileage.
It’s gotta be “fast” (right around 15 for 5k) and several years of building the aerobic engine easy base, where 50 mpw of unspecific running occasionally capped by periods with extended long runs where you might have a few weeks of 65-75 miles total (all easy - unspecific running). All this, while still being able to run a 15’ 5k. Then, envision giving that 15’ person 4’ more to complete each 5k task. That’s tantamount to having a thousand meters to play with each 5k. Eat and drink properly during the marathon (don’t waste the gift), and barring excessive weather conditions, label it guaranteed. give me 4” every 5k I could shock the world!
I feel that once the aerobic base is truly solid then you’ll be able to let the 5k time slack to 17’ or even 18’ and then even a little specific marathon training will get you well below 3 hours.